Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1 | /* |
| 2 | * Generic ring buffer |
| 3 | * |
| 4 | * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com> |
| 5 | */ |
| 6 | #include <linux/ring_buffer.h> |
Ingo Molnar | 14131f2 | 2009-02-26 18:47:11 +0100 | [diff] [blame] | 7 | #include <linux/trace_clock.h> |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 8 | #include <linux/spinlock.h> |
| 9 | #include <linux/debugfs.h> |
| 10 | #include <linux/uaccess.h> |
Steven Rostedt | a81bd80 | 2009-02-06 01:45:16 -0500 | [diff] [blame] | 11 | #include <linux/hardirq.h> |
Vegard Nossum | 1744a21 | 2009-02-28 08:29:44 +0100 | [diff] [blame] | 12 | #include <linux/kmemcheck.h> |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 13 | #include <linux/module.h> |
| 14 | #include <linux/percpu.h> |
| 15 | #include <linux/mutex.h> |
Tejun Heo | 5a0e3ad | 2010-03-24 17:04:11 +0900 | [diff] [blame] | 16 | #include <linux/slab.h> |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 17 | #include <linux/init.h> |
| 18 | #include <linux/hash.h> |
| 19 | #include <linux/list.h> |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 20 | #include <linux/cpu.h> |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 21 | #include <linux/fs.h> |
| 22 | |
Christoph Lameter | 7961576 | 2010-01-05 15:34:50 +0900 | [diff] [blame] | 23 | #include <asm/local.h> |
Steven Rostedt | 182e9f5 | 2008-11-03 23:15:56 -0500 | [diff] [blame] | 24 | #include "trace.h" |
| 25 | |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 26 | static void update_pages_handler(struct work_struct *work); |
| 27 | |
Steven Rostedt | 033601a | 2008-11-21 12:41:55 -0500 | [diff] [blame] | 28 | /* |
Steven Rostedt | d1b182a | 2009-04-15 16:53:47 -0400 | [diff] [blame] | 29 | * The ring buffer header is special. We must manually up keep it. |
| 30 | */ |
| 31 | int ring_buffer_print_entry_header(struct trace_seq *s) |
| 32 | { |
| 33 | int ret; |
| 34 | |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 35 | ret = trace_seq_printf(s, "# compressed entry header\n"); |
| 36 | ret = trace_seq_printf(s, "\ttype_len : 5 bits\n"); |
Steven Rostedt | d1b182a | 2009-04-15 16:53:47 -0400 | [diff] [blame] | 37 | ret = trace_seq_printf(s, "\ttime_delta : 27 bits\n"); |
| 38 | ret = trace_seq_printf(s, "\tarray : 32 bits\n"); |
| 39 | ret = trace_seq_printf(s, "\n"); |
| 40 | ret = trace_seq_printf(s, "\tpadding : type == %d\n", |
| 41 | RINGBUF_TYPE_PADDING); |
| 42 | ret = trace_seq_printf(s, "\ttime_extend : type == %d\n", |
| 43 | RINGBUF_TYPE_TIME_EXTEND); |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 44 | ret = trace_seq_printf(s, "\tdata max type_len == %d\n", |
| 45 | RINGBUF_TYPE_DATA_TYPE_LEN_MAX); |
Steven Rostedt | d1b182a | 2009-04-15 16:53:47 -0400 | [diff] [blame] | 46 | |
| 47 | return ret; |
| 48 | } |
| 49 | |
| 50 | /* |
Steven Rostedt | 5cc9854 | 2009-03-12 22:24:17 -0400 | [diff] [blame] | 51 | * The ring buffer is made up of a list of pages. A separate list of pages is |
| 52 | * allocated for each CPU. A writer may only write to a buffer that is |
| 53 | * associated with the CPU it is currently executing on. A reader may read |
| 54 | * from any per cpu buffer. |
| 55 | * |
| 56 | * The reader is special. For each per cpu buffer, the reader has its own |
| 57 | * reader page. When a reader has read the entire reader page, this reader |
| 58 | * page is swapped with another page in the ring buffer. |
| 59 | * |
| 60 | * Now, as long as the writer is off the reader page, the reader can do what |
| 61 | * ever it wants with that page. The writer will never write to that page |
| 62 | * again (as long as it is out of the ring buffer). |
| 63 | * |
| 64 | * Here's some silly ASCII art. |
| 65 | * |
| 66 | * +------+ |
| 67 | * |reader| RING BUFFER |
| 68 | * |page | |
| 69 | * +------+ +---+ +---+ +---+ |
| 70 | * | |-->| |-->| | |
| 71 | * +---+ +---+ +---+ |
| 72 | * ^ | |
| 73 | * | | |
| 74 | * +---------------+ |
| 75 | * |
| 76 | * |
| 77 | * +------+ |
| 78 | * |reader| RING BUFFER |
| 79 | * |page |------------------v |
| 80 | * +------+ +---+ +---+ +---+ |
| 81 | * | |-->| |-->| | |
| 82 | * +---+ +---+ +---+ |
| 83 | * ^ | |
| 84 | * | | |
| 85 | * +---------------+ |
| 86 | * |
| 87 | * |
| 88 | * +------+ |
| 89 | * |reader| RING BUFFER |
| 90 | * |page |------------------v |
| 91 | * +------+ +---+ +---+ +---+ |
| 92 | * ^ | |-->| |-->| | |
| 93 | * | +---+ +---+ +---+ |
| 94 | * | | |
| 95 | * | | |
| 96 | * +------------------------------+ |
| 97 | * |
| 98 | * |
| 99 | * +------+ |
| 100 | * |buffer| RING BUFFER |
| 101 | * |page |------------------v |
| 102 | * +------+ +---+ +---+ +---+ |
| 103 | * ^ | | | |-->| | |
| 104 | * | New +---+ +---+ +---+ |
| 105 | * | Reader------^ | |
| 106 | * | page | |
| 107 | * +------------------------------+ |
| 108 | * |
| 109 | * |
| 110 | * After we make this swap, the reader can hand this page off to the splice |
| 111 | * code and be done with it. It can even allocate a new page if it needs to |
| 112 | * and swap that into the ring buffer. |
| 113 | * |
| 114 | * We will be using cmpxchg soon to make all this lockless. |
| 115 | * |
| 116 | */ |
| 117 | |
| 118 | /* |
Steven Rostedt | 033601a | 2008-11-21 12:41:55 -0500 | [diff] [blame] | 119 | * A fast way to enable or disable all ring buffers is to |
| 120 | * call tracing_on or tracing_off. Turning off the ring buffers |
| 121 | * prevents all ring buffers from being recorded to. |
| 122 | * Turning this switch on, makes it OK to write to the |
| 123 | * ring buffer, if the ring buffer is enabled itself. |
| 124 | * |
| 125 | * There's three layers that must be on in order to write |
| 126 | * to the ring buffer. |
| 127 | * |
| 128 | * 1) This global flag must be set. |
| 129 | * 2) The ring buffer must be enabled for recording. |
| 130 | * 3) The per cpu buffer must be enabled for recording. |
| 131 | * |
| 132 | * In case of an anomaly, this global flag has a bit set that |
| 133 | * will permantly disable all ring buffers. |
| 134 | */ |
| 135 | |
| 136 | /* |
| 137 | * Global flag to disable all recording to ring buffers |
| 138 | * This has two bits: ON, DISABLED |
| 139 | * |
| 140 | * ON DISABLED |
| 141 | * ---- ---------- |
| 142 | * 0 0 : ring buffers are off |
| 143 | * 1 0 : ring buffers are on |
| 144 | * X 1 : ring buffers are permanently disabled |
| 145 | */ |
| 146 | |
| 147 | enum { |
| 148 | RB_BUFFERS_ON_BIT = 0, |
| 149 | RB_BUFFERS_DISABLED_BIT = 1, |
| 150 | }; |
| 151 | |
| 152 | enum { |
| 153 | RB_BUFFERS_ON = 1 << RB_BUFFERS_ON_BIT, |
| 154 | RB_BUFFERS_DISABLED = 1 << RB_BUFFERS_DISABLED_BIT, |
| 155 | }; |
| 156 | |
Hannes Eder | 5e39841 | 2009-02-10 19:44:34 +0100 | [diff] [blame] | 157 | static unsigned long ring_buffer_flags __read_mostly = RB_BUFFERS_ON; |
Steven Rostedt | a358324 | 2008-11-11 15:01:42 -0500 | [diff] [blame] | 158 | |
Steven Rostedt | 499e547 | 2012-02-22 15:50:28 -0500 | [diff] [blame] | 159 | /* Used for individual buffers (after the counter) */ |
| 160 | #define RB_BUFFER_OFF (1 << 20) |
| 161 | |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 162 | #define BUF_PAGE_HDR_SIZE offsetof(struct buffer_data_page, data) |
| 163 | |
Steven Rostedt | a358324 | 2008-11-11 15:01:42 -0500 | [diff] [blame] | 164 | /** |
Steven Rostedt | 033601a | 2008-11-21 12:41:55 -0500 | [diff] [blame] | 165 | * tracing_off_permanent - permanently disable ring buffers |
| 166 | * |
| 167 | * This function, once called, will disable all ring buffers |
Wenji Huang | c3706f0 | 2009-02-10 01:03:18 -0500 | [diff] [blame] | 168 | * permanently. |
Steven Rostedt | 033601a | 2008-11-21 12:41:55 -0500 | [diff] [blame] | 169 | */ |
| 170 | void tracing_off_permanent(void) |
| 171 | { |
| 172 | set_bit(RB_BUFFERS_DISABLED_BIT, &ring_buffer_flags); |
Steven Rostedt | a358324 | 2008-11-11 15:01:42 -0500 | [diff] [blame] | 173 | } |
| 174 | |
Steven Rostedt | e3d6bf0 | 2009-03-03 13:53:07 -0500 | [diff] [blame] | 175 | #define RB_EVNT_HDR_SIZE (offsetof(struct ring_buffer_event, array)) |
Andrew Morton | 67d3472 | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 176 | #define RB_ALIGNMENT 4U |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 177 | #define RB_MAX_SMALL_DATA (RB_ALIGNMENT * RINGBUF_TYPE_DATA_TYPE_LEN_MAX) |
Steven Rostedt | c7b0930 | 2009-06-11 11:12:00 -0400 | [diff] [blame] | 178 | #define RB_EVNT_MIN_SIZE 8U /* two 32bit words */ |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 179 | |
Steven Rostedt | 2271048 | 2010-03-18 17:54:19 -0400 | [diff] [blame] | 180 | #if !defined(CONFIG_64BIT) || defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) |
| 181 | # define RB_FORCE_8BYTE_ALIGNMENT 0 |
| 182 | # define RB_ARCH_ALIGNMENT RB_ALIGNMENT |
| 183 | #else |
| 184 | # define RB_FORCE_8BYTE_ALIGNMENT 1 |
| 185 | # define RB_ARCH_ALIGNMENT 8U |
| 186 | #endif |
| 187 | |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 188 | /* define RINGBUF_TYPE_DATA for 'case RINGBUF_TYPE_DATA:' */ |
| 189 | #define RINGBUF_TYPE_DATA 0 ... RINGBUF_TYPE_DATA_TYPE_LEN_MAX |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 190 | |
| 191 | enum { |
| 192 | RB_LEN_TIME_EXTEND = 8, |
| 193 | RB_LEN_TIME_STAMP = 16, |
| 194 | }; |
| 195 | |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 196 | #define skip_time_extend(event) \ |
| 197 | ((struct ring_buffer_event *)((char *)event + RB_LEN_TIME_EXTEND)) |
| 198 | |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 199 | static inline int rb_null_event(struct ring_buffer_event *event) |
| 200 | { |
Steven Rostedt | a1863c2 | 2009-09-03 10:23:58 -0400 | [diff] [blame] | 201 | return event->type_len == RINGBUF_TYPE_PADDING && !event->time_delta; |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 202 | } |
| 203 | |
| 204 | static void rb_event_set_padding(struct ring_buffer_event *event) |
| 205 | { |
Steven Rostedt | a1863c2 | 2009-09-03 10:23:58 -0400 | [diff] [blame] | 206 | /* padding has a NULL time_delta */ |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 207 | event->type_len = RINGBUF_TYPE_PADDING; |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 208 | event->time_delta = 0; |
| 209 | } |
| 210 | |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 211 | static unsigned |
| 212 | rb_event_data_length(struct ring_buffer_event *event) |
| 213 | { |
| 214 | unsigned length; |
| 215 | |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 216 | if (event->type_len) |
| 217 | length = event->type_len * RB_ALIGNMENT; |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 218 | else |
| 219 | length = event->array[0]; |
| 220 | return length + RB_EVNT_HDR_SIZE; |
| 221 | } |
| 222 | |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 223 | /* |
| 224 | * Return the length of the given event. Will return |
| 225 | * the length of the time extend if the event is a |
| 226 | * time extend. |
| 227 | */ |
| 228 | static inline unsigned |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 229 | rb_event_length(struct ring_buffer_event *event) |
| 230 | { |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 231 | switch (event->type_len) { |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 232 | case RINGBUF_TYPE_PADDING: |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 233 | if (rb_null_event(event)) |
| 234 | /* undefined */ |
| 235 | return -1; |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 236 | return event->array[0] + RB_EVNT_HDR_SIZE; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 237 | |
| 238 | case RINGBUF_TYPE_TIME_EXTEND: |
| 239 | return RB_LEN_TIME_EXTEND; |
| 240 | |
| 241 | case RINGBUF_TYPE_TIME_STAMP: |
| 242 | return RB_LEN_TIME_STAMP; |
| 243 | |
| 244 | case RINGBUF_TYPE_DATA: |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 245 | return rb_event_data_length(event); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 246 | default: |
| 247 | BUG(); |
| 248 | } |
| 249 | /* not hit */ |
| 250 | return 0; |
| 251 | } |
| 252 | |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 253 | /* |
| 254 | * Return total length of time extend and data, |
| 255 | * or just the event length for all other events. |
| 256 | */ |
| 257 | static inline unsigned |
| 258 | rb_event_ts_length(struct ring_buffer_event *event) |
| 259 | { |
| 260 | unsigned len = 0; |
| 261 | |
| 262 | if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) { |
| 263 | /* time extends include the data event after it */ |
| 264 | len = RB_LEN_TIME_EXTEND; |
| 265 | event = skip_time_extend(event); |
| 266 | } |
| 267 | return len + rb_event_length(event); |
| 268 | } |
| 269 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 270 | /** |
| 271 | * ring_buffer_event_length - return the length of the event |
| 272 | * @event: the event to get the length of |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 273 | * |
| 274 | * Returns the size of the data load of a data event. |
| 275 | * If the event is something other than a data event, it |
| 276 | * returns the size of the event itself. With the exception |
| 277 | * of a TIME EXTEND, where it still returns the size of the |
| 278 | * data load of the data event after it. |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 279 | */ |
| 280 | unsigned ring_buffer_event_length(struct ring_buffer_event *event) |
| 281 | { |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 282 | unsigned length; |
| 283 | |
| 284 | if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) |
| 285 | event = skip_time_extend(event); |
| 286 | |
| 287 | length = rb_event_length(event); |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 288 | if (event->type_len > RINGBUF_TYPE_DATA_TYPE_LEN_MAX) |
Robert Richter | 465634a | 2009-01-07 15:32:11 +0100 | [diff] [blame] | 289 | return length; |
| 290 | length -= RB_EVNT_HDR_SIZE; |
| 291 | if (length > RB_MAX_SMALL_DATA + sizeof(event->array[0])) |
| 292 | length -= sizeof(event->array[0]); |
| 293 | return length; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 294 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 295 | EXPORT_SYMBOL_GPL(ring_buffer_event_length); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 296 | |
| 297 | /* inline for ring buffer fast paths */ |
Andrew Morton | 34a148b | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 298 | static void * |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 299 | rb_event_data(struct ring_buffer_event *event) |
| 300 | { |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 301 | if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) |
| 302 | event = skip_time_extend(event); |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 303 | BUG_ON(event->type_len > RINGBUF_TYPE_DATA_TYPE_LEN_MAX); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 304 | /* If length is in len field, then array[0] has the data */ |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 305 | if (event->type_len) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 306 | return (void *)&event->array[0]; |
| 307 | /* Otherwise length is in array[0] and array[1] has the data */ |
| 308 | return (void *)&event->array[1]; |
| 309 | } |
| 310 | |
| 311 | /** |
| 312 | * ring_buffer_event_data - return the data of the event |
| 313 | * @event: the event to get the data from |
| 314 | */ |
| 315 | void *ring_buffer_event_data(struct ring_buffer_event *event) |
| 316 | { |
| 317 | return rb_event_data(event); |
| 318 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 319 | EXPORT_SYMBOL_GPL(ring_buffer_event_data); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 320 | |
| 321 | #define for_each_buffer_cpu(buffer, cpu) \ |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 322 | for_each_cpu(cpu, buffer->cpumask) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 323 | |
| 324 | #define TS_SHIFT 27 |
| 325 | #define TS_MASK ((1ULL << TS_SHIFT) - 1) |
| 326 | #define TS_DELTA_TEST (~TS_MASK) |
| 327 | |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 328 | /* Flag when events were overwritten */ |
| 329 | #define RB_MISSED_EVENTS (1 << 31) |
Steven Rostedt | ff0ff84 | 2010-03-31 22:11:42 -0400 | [diff] [blame] | 330 | /* Missed count stored at end */ |
| 331 | #define RB_MISSED_STORED (1 << 30) |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 332 | |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 333 | struct buffer_data_page { |
Steven Rostedt | e4c2ce8 | 2008-10-01 11:14:54 -0400 | [diff] [blame] | 334 | u64 time_stamp; /* page time stamp */ |
Wenji Huang | c3706f0 | 2009-02-10 01:03:18 -0500 | [diff] [blame] | 335 | local_t commit; /* write committed index */ |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 336 | unsigned char data[]; /* data of buffer page */ |
| 337 | }; |
| 338 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 339 | /* |
| 340 | * Note, the buffer_page list must be first. The buffer pages |
| 341 | * are allocated in cache lines, which means that each buffer |
| 342 | * page will be at the beginning of a cache line, and thus |
| 343 | * the least significant bits will be zero. We use this to |
| 344 | * add flags in the list struct pointers, to make the ring buffer |
| 345 | * lockless. |
| 346 | */ |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 347 | struct buffer_page { |
Steven Rostedt | 778c55d | 2009-05-01 18:44:45 -0400 | [diff] [blame] | 348 | struct list_head list; /* list of buffer pages */ |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 349 | local_t write; /* index for next write */ |
Steven Rostedt | 6f807ac | 2008-10-04 02:00:58 -0400 | [diff] [blame] | 350 | unsigned read; /* index for next read */ |
Steven Rostedt | 778c55d | 2009-05-01 18:44:45 -0400 | [diff] [blame] | 351 | local_t entries; /* entries on this page */ |
Steven Rostedt | ff0ff84 | 2010-03-31 22:11:42 -0400 | [diff] [blame] | 352 | unsigned long real_end; /* real end of data */ |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 353 | struct buffer_data_page *page; /* Actual data page */ |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 354 | }; |
| 355 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 356 | /* |
| 357 | * The buffer page counters, write and entries, must be reset |
| 358 | * atomically when crossing page boundaries. To synchronize this |
| 359 | * update, two counters are inserted into the number. One is |
| 360 | * the actual counter for the write position or count on the page. |
| 361 | * |
| 362 | * The other is a counter of updaters. Before an update happens |
| 363 | * the update partition of the counter is incremented. This will |
| 364 | * allow the updater to update the counter atomically. |
| 365 | * |
| 366 | * The counter is 20 bits, and the state data is 12. |
| 367 | */ |
| 368 | #define RB_WRITE_MASK 0xfffff |
| 369 | #define RB_WRITE_INTCNT (1 << 20) |
| 370 | |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 371 | static void rb_init_page(struct buffer_data_page *bpage) |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 372 | { |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 373 | local_set(&bpage->commit, 0); |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 374 | } |
| 375 | |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 376 | /** |
| 377 | * ring_buffer_page_len - the size of data on the page. |
| 378 | * @page: The page to read |
| 379 | * |
| 380 | * Returns the amount of data on the page, including buffer page header. |
| 381 | */ |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 382 | size_t ring_buffer_page_len(void *page) |
| 383 | { |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 384 | return local_read(&((struct buffer_data_page *)page)->commit) |
| 385 | + BUF_PAGE_HDR_SIZE; |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 386 | } |
| 387 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 388 | /* |
Steven Rostedt | ed56829 | 2008-09-29 23:02:40 -0400 | [diff] [blame] | 389 | * Also stolen from mm/slob.c. Thanks to Mathieu Desnoyers for pointing |
| 390 | * this issue out. |
| 391 | */ |
Andrew Morton | 34a148b | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 392 | static void free_buffer_page(struct buffer_page *bpage) |
Steven Rostedt | ed56829 | 2008-09-29 23:02:40 -0400 | [diff] [blame] | 393 | { |
Andrew Morton | 34a148b | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 394 | free_page((unsigned long)bpage->page); |
Steven Rostedt | e4c2ce8 | 2008-10-01 11:14:54 -0400 | [diff] [blame] | 395 | kfree(bpage); |
Steven Rostedt | ed56829 | 2008-09-29 23:02:40 -0400 | [diff] [blame] | 396 | } |
| 397 | |
| 398 | /* |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 399 | * We need to fit the time_stamp delta into 27 bits. |
| 400 | */ |
| 401 | static inline int test_time_stamp(u64 delta) |
| 402 | { |
| 403 | if (delta & TS_DELTA_TEST) |
| 404 | return 1; |
| 405 | return 0; |
| 406 | } |
| 407 | |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 408 | #define BUF_PAGE_SIZE (PAGE_SIZE - BUF_PAGE_HDR_SIZE) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 409 | |
Steven Rostedt | be957c4 | 2009-05-11 14:42:53 -0400 | [diff] [blame] | 410 | /* Max payload is BUF_PAGE_SIZE - header (8bytes) */ |
| 411 | #define BUF_MAX_DATA_SIZE (BUF_PAGE_SIZE - (sizeof(u32) * 2)) |
| 412 | |
Steven Rostedt | d1b182a | 2009-04-15 16:53:47 -0400 | [diff] [blame] | 413 | int ring_buffer_print_page_header(struct trace_seq *s) |
| 414 | { |
| 415 | struct buffer_data_page field; |
| 416 | int ret; |
| 417 | |
| 418 | ret = trace_seq_printf(s, "\tfield: u64 timestamp;\t" |
Tom Zanussi | 26a5074 | 2009-10-06 01:09:50 -0500 | [diff] [blame] | 419 | "offset:0;\tsize:%u;\tsigned:%u;\n", |
| 420 | (unsigned int)sizeof(field.time_stamp), |
| 421 | (unsigned int)is_signed_type(u64)); |
Steven Rostedt | d1b182a | 2009-04-15 16:53:47 -0400 | [diff] [blame] | 422 | |
| 423 | ret = trace_seq_printf(s, "\tfield: local_t commit;\t" |
Tom Zanussi | 26a5074 | 2009-10-06 01:09:50 -0500 | [diff] [blame] | 424 | "offset:%u;\tsize:%u;\tsigned:%u;\n", |
Steven Rostedt | d1b182a | 2009-04-15 16:53:47 -0400 | [diff] [blame] | 425 | (unsigned int)offsetof(typeof(field), commit), |
Tom Zanussi | 26a5074 | 2009-10-06 01:09:50 -0500 | [diff] [blame] | 426 | (unsigned int)sizeof(field.commit), |
| 427 | (unsigned int)is_signed_type(long)); |
Steven Rostedt | d1b182a | 2009-04-15 16:53:47 -0400 | [diff] [blame] | 428 | |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 429 | ret = trace_seq_printf(s, "\tfield: int overwrite;\t" |
| 430 | "offset:%u;\tsize:%u;\tsigned:%u;\n", |
| 431 | (unsigned int)offsetof(typeof(field), commit), |
| 432 | 1, |
| 433 | (unsigned int)is_signed_type(long)); |
| 434 | |
Steven Rostedt | d1b182a | 2009-04-15 16:53:47 -0400 | [diff] [blame] | 435 | ret = trace_seq_printf(s, "\tfield: char data;\t" |
Tom Zanussi | 26a5074 | 2009-10-06 01:09:50 -0500 | [diff] [blame] | 436 | "offset:%u;\tsize:%u;\tsigned:%u;\n", |
Steven Rostedt | d1b182a | 2009-04-15 16:53:47 -0400 | [diff] [blame] | 437 | (unsigned int)offsetof(typeof(field), data), |
Tom Zanussi | 26a5074 | 2009-10-06 01:09:50 -0500 | [diff] [blame] | 438 | (unsigned int)BUF_PAGE_SIZE, |
| 439 | (unsigned int)is_signed_type(char)); |
Steven Rostedt | d1b182a | 2009-04-15 16:53:47 -0400 | [diff] [blame] | 440 | |
| 441 | return ret; |
| 442 | } |
| 443 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 444 | /* |
| 445 | * head_page == tail_page && head == tail then buffer is empty. |
| 446 | */ |
| 447 | struct ring_buffer_per_cpu { |
| 448 | int cpu; |
Richard Kennedy | 985023d | 2010-03-25 11:27:36 +0000 | [diff] [blame] | 449 | atomic_t record_disabled; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 450 | struct ring_buffer *buffer; |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 451 | raw_spinlock_t reader_lock; /* serialize readers */ |
Thomas Gleixner | 445c895 | 2009-12-02 19:49:50 +0100 | [diff] [blame] | 452 | arch_spinlock_t lock; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 453 | struct lock_class_key lock_key; |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 454 | unsigned int nr_pages; |
Steven Rostedt | 3adc54f | 2009-03-30 15:32:01 -0400 | [diff] [blame] | 455 | struct list_head *pages; |
Steven Rostedt | 6f807ac | 2008-10-04 02:00:58 -0400 | [diff] [blame] | 456 | struct buffer_page *head_page; /* read from head */ |
| 457 | struct buffer_page *tail_page; /* write to tail */ |
Wenji Huang | c3706f0 | 2009-02-10 01:03:18 -0500 | [diff] [blame] | 458 | struct buffer_page *commit_page; /* committed pages */ |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 459 | struct buffer_page *reader_page; |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 460 | unsigned long lost_events; |
| 461 | unsigned long last_overrun; |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 462 | local_t entries_bytes; |
Steven Rostedt | e4906ef | 2009-04-30 20:49:44 -0400 | [diff] [blame] | 463 | local_t entries; |
Slava Pestov | 884bfe8 | 2011-07-15 14:23:58 -0700 | [diff] [blame] | 464 | local_t overrun; |
| 465 | local_t commit_overrun; |
| 466 | local_t dropped_events; |
Steven Rostedt | fa74395 | 2009-06-16 12:37:57 -0400 | [diff] [blame] | 467 | local_t committing; |
| 468 | local_t commits; |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 469 | unsigned long read; |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 470 | unsigned long read_bytes; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 471 | u64 write_stamp; |
| 472 | u64 read_stamp; |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 473 | /* ring buffer pages to update, > 0 to add, < 0 to remove */ |
| 474 | int nr_pages_to_update; |
| 475 | struct list_head new_pages; /* new pages to add */ |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 476 | struct work_struct update_pages_work; |
Vaibhav Nagarnaik | 05fdd70 | 2012-05-18 13:29:51 -0700 | [diff] [blame] | 477 | struct completion update_done; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 478 | }; |
| 479 | |
| 480 | struct ring_buffer { |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 481 | unsigned flags; |
| 482 | int cpus; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 483 | atomic_t record_disabled; |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 484 | atomic_t resize_disabled; |
Arnaldo Carvalho de Melo | 00f62f6 | 2009-02-09 17:04:06 -0200 | [diff] [blame] | 485 | cpumask_var_t cpumask; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 486 | |
Peter Zijlstra | 1f8a6a1 | 2009-06-08 18:18:39 +0200 | [diff] [blame] | 487 | struct lock_class_key *reader_lock_key; |
| 488 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 489 | struct mutex mutex; |
| 490 | |
| 491 | struct ring_buffer_per_cpu **buffers; |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 492 | |
Steven Rostedt | 59222ef | 2009-03-12 11:46:03 -0400 | [diff] [blame] | 493 | #ifdef CONFIG_HOTPLUG_CPU |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 494 | struct notifier_block cpu_notify; |
| 495 | #endif |
Steven Rostedt | 37886f6 | 2009-03-17 17:22:06 -0400 | [diff] [blame] | 496 | u64 (*clock)(void); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 497 | }; |
| 498 | |
| 499 | struct ring_buffer_iter { |
| 500 | struct ring_buffer_per_cpu *cpu_buffer; |
| 501 | unsigned long head; |
| 502 | struct buffer_page *head_page; |
Steven Rostedt | 492a74f | 2010-01-25 15:17:47 -0500 | [diff] [blame] | 503 | struct buffer_page *cache_reader_page; |
| 504 | unsigned long cache_read; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 505 | u64 read_stamp; |
| 506 | }; |
| 507 | |
Steven Rostedt | f536aaf | 2008-11-10 23:07:30 -0500 | [diff] [blame] | 508 | /* buffer may be either ring_buffer or ring_buffer_per_cpu */ |
Steven Rostedt | 077c540 | 2009-09-03 19:53:46 -0400 | [diff] [blame] | 509 | #define RB_WARN_ON(b, cond) \ |
| 510 | ({ \ |
| 511 | int _____ret = unlikely(cond); \ |
| 512 | if (_____ret) { \ |
| 513 | if (__same_type(*(b), struct ring_buffer_per_cpu)) { \ |
| 514 | struct ring_buffer_per_cpu *__b = \ |
| 515 | (void *)b; \ |
| 516 | atomic_inc(&__b->buffer->record_disabled); \ |
| 517 | } else \ |
| 518 | atomic_inc(&b->record_disabled); \ |
| 519 | WARN_ON(1); \ |
| 520 | } \ |
| 521 | _____ret; \ |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 522 | }) |
Steven Rostedt | f536aaf | 2008-11-10 23:07:30 -0500 | [diff] [blame] | 523 | |
Steven Rostedt | 37886f6 | 2009-03-17 17:22:06 -0400 | [diff] [blame] | 524 | /* Up this if you want to test the TIME_EXTENTS and normalization */ |
| 525 | #define DEBUG_SHIFT 0 |
| 526 | |
Jiri Olsa | 6d3f1e1 | 2009-10-23 19:36:19 -0400 | [diff] [blame] | 527 | static inline u64 rb_time_stamp(struct ring_buffer *buffer) |
Steven Rostedt | 88eb012 | 2009-05-11 16:28:23 -0400 | [diff] [blame] | 528 | { |
| 529 | /* shift to debug/test normalization and TIME_EXTENTS */ |
| 530 | return buffer->clock() << DEBUG_SHIFT; |
| 531 | } |
| 532 | |
Steven Rostedt | 37886f6 | 2009-03-17 17:22:06 -0400 | [diff] [blame] | 533 | u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu) |
| 534 | { |
| 535 | u64 time; |
| 536 | |
| 537 | preempt_disable_notrace(); |
Jiri Olsa | 6d3f1e1 | 2009-10-23 19:36:19 -0400 | [diff] [blame] | 538 | time = rb_time_stamp(buffer); |
Steven Rostedt | 37886f6 | 2009-03-17 17:22:06 -0400 | [diff] [blame] | 539 | preempt_enable_no_resched_notrace(); |
| 540 | |
| 541 | return time; |
| 542 | } |
| 543 | EXPORT_SYMBOL_GPL(ring_buffer_time_stamp); |
| 544 | |
| 545 | void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer, |
| 546 | int cpu, u64 *ts) |
| 547 | { |
| 548 | /* Just stupid testing the normalize function and deltas */ |
| 549 | *ts >>= DEBUG_SHIFT; |
| 550 | } |
| 551 | EXPORT_SYMBOL_GPL(ring_buffer_normalize_time_stamp); |
| 552 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 553 | /* |
| 554 | * Making the ring buffer lockless makes things tricky. |
| 555 | * Although writes only happen on the CPU that they are on, |
| 556 | * and they only need to worry about interrupts. Reads can |
| 557 | * happen on any CPU. |
| 558 | * |
| 559 | * The reader page is always off the ring buffer, but when the |
| 560 | * reader finishes with a page, it needs to swap its page with |
| 561 | * a new one from the buffer. The reader needs to take from |
| 562 | * the head (writes go to the tail). But if a writer is in overwrite |
| 563 | * mode and wraps, it must push the head page forward. |
| 564 | * |
| 565 | * Here lies the problem. |
| 566 | * |
| 567 | * The reader must be careful to replace only the head page, and |
| 568 | * not another one. As described at the top of the file in the |
| 569 | * ASCII art, the reader sets its old page to point to the next |
| 570 | * page after head. It then sets the page after head to point to |
| 571 | * the old reader page. But if the writer moves the head page |
| 572 | * during this operation, the reader could end up with the tail. |
| 573 | * |
| 574 | * We use cmpxchg to help prevent this race. We also do something |
| 575 | * special with the page before head. We set the LSB to 1. |
| 576 | * |
| 577 | * When the writer must push the page forward, it will clear the |
| 578 | * bit that points to the head page, move the head, and then set |
| 579 | * the bit that points to the new head page. |
| 580 | * |
| 581 | * We also don't want an interrupt coming in and moving the head |
| 582 | * page on another writer. Thus we use the second LSB to catch |
| 583 | * that too. Thus: |
| 584 | * |
| 585 | * head->list->prev->next bit 1 bit 0 |
| 586 | * ------- ------- |
| 587 | * Normal page 0 0 |
| 588 | * Points to head page 0 1 |
| 589 | * New head page 1 0 |
| 590 | * |
| 591 | * Note we can not trust the prev pointer of the head page, because: |
| 592 | * |
| 593 | * +----+ +-----+ +-----+ |
| 594 | * | |------>| T |---X--->| N | |
| 595 | * | |<------| | | | |
| 596 | * +----+ +-----+ +-----+ |
| 597 | * ^ ^ | |
| 598 | * | +-----+ | | |
| 599 | * +----------| R |----------+ | |
| 600 | * | |<-----------+ |
| 601 | * +-----+ |
| 602 | * |
| 603 | * Key: ---X--> HEAD flag set in pointer |
| 604 | * T Tail page |
| 605 | * R Reader page |
| 606 | * N Next page |
| 607 | * |
| 608 | * (see __rb_reserve_next() to see where this happens) |
| 609 | * |
| 610 | * What the above shows is that the reader just swapped out |
| 611 | * the reader page with a page in the buffer, but before it |
| 612 | * could make the new header point back to the new page added |
| 613 | * it was preempted by a writer. The writer moved forward onto |
| 614 | * the new page added by the reader and is about to move forward |
| 615 | * again. |
| 616 | * |
| 617 | * You can see, it is legitimate for the previous pointer of |
| 618 | * the head (or any page) not to point back to itself. But only |
| 619 | * temporarially. |
| 620 | */ |
| 621 | |
| 622 | #define RB_PAGE_NORMAL 0UL |
| 623 | #define RB_PAGE_HEAD 1UL |
| 624 | #define RB_PAGE_UPDATE 2UL |
| 625 | |
| 626 | |
| 627 | #define RB_FLAG_MASK 3UL |
| 628 | |
| 629 | /* PAGE_MOVED is not part of the mask */ |
| 630 | #define RB_PAGE_MOVED 4UL |
| 631 | |
| 632 | /* |
| 633 | * rb_list_head - remove any bit |
| 634 | */ |
| 635 | static struct list_head *rb_list_head(struct list_head *list) |
| 636 | { |
| 637 | unsigned long val = (unsigned long)list; |
| 638 | |
| 639 | return (struct list_head *)(val & ~RB_FLAG_MASK); |
| 640 | } |
| 641 | |
| 642 | /* |
Jiri Olsa | 6d3f1e1 | 2009-10-23 19:36:19 -0400 | [diff] [blame] | 643 | * rb_is_head_page - test if the given page is the head page |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 644 | * |
| 645 | * Because the reader may move the head_page pointer, we can |
| 646 | * not trust what the head page is (it may be pointing to |
| 647 | * the reader page). But if the next page is a header page, |
| 648 | * its flags will be non zero. |
| 649 | */ |
Jesper Juhl | 42b16b3 | 2011-01-17 00:09:38 +0100 | [diff] [blame] | 650 | static inline int |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 651 | rb_is_head_page(struct ring_buffer_per_cpu *cpu_buffer, |
| 652 | struct buffer_page *page, struct list_head *list) |
| 653 | { |
| 654 | unsigned long val; |
| 655 | |
| 656 | val = (unsigned long)list->next; |
| 657 | |
| 658 | if ((val & ~RB_FLAG_MASK) != (unsigned long)&page->list) |
| 659 | return RB_PAGE_MOVED; |
| 660 | |
| 661 | return val & RB_FLAG_MASK; |
| 662 | } |
| 663 | |
| 664 | /* |
| 665 | * rb_is_reader_page |
| 666 | * |
| 667 | * The unique thing about the reader page, is that, if the |
| 668 | * writer is ever on it, the previous pointer never points |
| 669 | * back to the reader page. |
| 670 | */ |
| 671 | static int rb_is_reader_page(struct buffer_page *page) |
| 672 | { |
| 673 | struct list_head *list = page->list.prev; |
| 674 | |
| 675 | return rb_list_head(list->next) != &page->list; |
| 676 | } |
| 677 | |
| 678 | /* |
| 679 | * rb_set_list_to_head - set a list_head to be pointing to head. |
| 680 | */ |
| 681 | static void rb_set_list_to_head(struct ring_buffer_per_cpu *cpu_buffer, |
| 682 | struct list_head *list) |
| 683 | { |
| 684 | unsigned long *ptr; |
| 685 | |
| 686 | ptr = (unsigned long *)&list->next; |
| 687 | *ptr |= RB_PAGE_HEAD; |
| 688 | *ptr &= ~RB_PAGE_UPDATE; |
| 689 | } |
| 690 | |
| 691 | /* |
| 692 | * rb_head_page_activate - sets up head page |
| 693 | */ |
| 694 | static void rb_head_page_activate(struct ring_buffer_per_cpu *cpu_buffer) |
| 695 | { |
| 696 | struct buffer_page *head; |
| 697 | |
| 698 | head = cpu_buffer->head_page; |
| 699 | if (!head) |
| 700 | return; |
| 701 | |
| 702 | /* |
| 703 | * Set the previous list pointer to have the HEAD flag. |
| 704 | */ |
| 705 | rb_set_list_to_head(cpu_buffer, head->list.prev); |
| 706 | } |
| 707 | |
| 708 | static void rb_list_head_clear(struct list_head *list) |
| 709 | { |
| 710 | unsigned long *ptr = (unsigned long *)&list->next; |
| 711 | |
| 712 | *ptr &= ~RB_FLAG_MASK; |
| 713 | } |
| 714 | |
| 715 | /* |
| 716 | * rb_head_page_dactivate - clears head page ptr (for free list) |
| 717 | */ |
| 718 | static void |
| 719 | rb_head_page_deactivate(struct ring_buffer_per_cpu *cpu_buffer) |
| 720 | { |
| 721 | struct list_head *hd; |
| 722 | |
| 723 | /* Go through the whole list and clear any pointers found. */ |
| 724 | rb_list_head_clear(cpu_buffer->pages); |
| 725 | |
| 726 | list_for_each(hd, cpu_buffer->pages) |
| 727 | rb_list_head_clear(hd); |
| 728 | } |
| 729 | |
| 730 | static int rb_head_page_set(struct ring_buffer_per_cpu *cpu_buffer, |
| 731 | struct buffer_page *head, |
| 732 | struct buffer_page *prev, |
| 733 | int old_flag, int new_flag) |
| 734 | { |
| 735 | struct list_head *list; |
| 736 | unsigned long val = (unsigned long)&head->list; |
| 737 | unsigned long ret; |
| 738 | |
| 739 | list = &prev->list; |
| 740 | |
| 741 | val &= ~RB_FLAG_MASK; |
| 742 | |
Steven Rostedt | 08a4081 | 2009-09-14 09:31:35 -0400 | [diff] [blame] | 743 | ret = cmpxchg((unsigned long *)&list->next, |
| 744 | val | old_flag, val | new_flag); |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 745 | |
| 746 | /* check if the reader took the page */ |
| 747 | if ((ret & ~RB_FLAG_MASK) != val) |
| 748 | return RB_PAGE_MOVED; |
| 749 | |
| 750 | return ret & RB_FLAG_MASK; |
| 751 | } |
| 752 | |
| 753 | static int rb_head_page_set_update(struct ring_buffer_per_cpu *cpu_buffer, |
| 754 | struct buffer_page *head, |
| 755 | struct buffer_page *prev, |
| 756 | int old_flag) |
| 757 | { |
| 758 | return rb_head_page_set(cpu_buffer, head, prev, |
| 759 | old_flag, RB_PAGE_UPDATE); |
| 760 | } |
| 761 | |
| 762 | static int rb_head_page_set_head(struct ring_buffer_per_cpu *cpu_buffer, |
| 763 | struct buffer_page *head, |
| 764 | struct buffer_page *prev, |
| 765 | int old_flag) |
| 766 | { |
| 767 | return rb_head_page_set(cpu_buffer, head, prev, |
| 768 | old_flag, RB_PAGE_HEAD); |
| 769 | } |
| 770 | |
| 771 | static int rb_head_page_set_normal(struct ring_buffer_per_cpu *cpu_buffer, |
| 772 | struct buffer_page *head, |
| 773 | struct buffer_page *prev, |
| 774 | int old_flag) |
| 775 | { |
| 776 | return rb_head_page_set(cpu_buffer, head, prev, |
| 777 | old_flag, RB_PAGE_NORMAL); |
| 778 | } |
| 779 | |
| 780 | static inline void rb_inc_page(struct ring_buffer_per_cpu *cpu_buffer, |
| 781 | struct buffer_page **bpage) |
| 782 | { |
| 783 | struct list_head *p = rb_list_head((*bpage)->list.next); |
| 784 | |
| 785 | *bpage = list_entry(p, struct buffer_page, list); |
| 786 | } |
| 787 | |
| 788 | static struct buffer_page * |
| 789 | rb_set_head_page(struct ring_buffer_per_cpu *cpu_buffer) |
| 790 | { |
| 791 | struct buffer_page *head; |
| 792 | struct buffer_page *page; |
| 793 | struct list_head *list; |
| 794 | int i; |
| 795 | |
| 796 | if (RB_WARN_ON(cpu_buffer, !cpu_buffer->head_page)) |
| 797 | return NULL; |
| 798 | |
| 799 | /* sanity check */ |
| 800 | list = cpu_buffer->pages; |
| 801 | if (RB_WARN_ON(cpu_buffer, rb_list_head(list->prev->next) != list)) |
| 802 | return NULL; |
| 803 | |
| 804 | page = head = cpu_buffer->head_page; |
| 805 | /* |
| 806 | * It is possible that the writer moves the header behind |
| 807 | * where we started, and we miss in one loop. |
| 808 | * A second loop should grab the header, but we'll do |
| 809 | * three loops just because I'm paranoid. |
| 810 | */ |
| 811 | for (i = 0; i < 3; i++) { |
| 812 | do { |
| 813 | if (rb_is_head_page(cpu_buffer, page, page->list.prev)) { |
| 814 | cpu_buffer->head_page = page; |
| 815 | return page; |
| 816 | } |
| 817 | rb_inc_page(cpu_buffer, &page); |
| 818 | } while (page != head); |
| 819 | } |
| 820 | |
| 821 | RB_WARN_ON(cpu_buffer, 1); |
| 822 | |
| 823 | return NULL; |
| 824 | } |
| 825 | |
| 826 | static int rb_head_page_replace(struct buffer_page *old, |
| 827 | struct buffer_page *new) |
| 828 | { |
| 829 | unsigned long *ptr = (unsigned long *)&old->list.prev->next; |
| 830 | unsigned long val; |
| 831 | unsigned long ret; |
| 832 | |
| 833 | val = *ptr & ~RB_FLAG_MASK; |
| 834 | val |= RB_PAGE_HEAD; |
| 835 | |
Steven Rostedt | 08a4081 | 2009-09-14 09:31:35 -0400 | [diff] [blame] | 836 | ret = cmpxchg(ptr, val, (unsigned long)&new->list); |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 837 | |
| 838 | return ret == val; |
| 839 | } |
| 840 | |
| 841 | /* |
| 842 | * rb_tail_page_update - move the tail page forward |
| 843 | * |
| 844 | * Returns 1 if moved tail page, 0 if someone else did. |
| 845 | */ |
| 846 | static int rb_tail_page_update(struct ring_buffer_per_cpu *cpu_buffer, |
| 847 | struct buffer_page *tail_page, |
| 848 | struct buffer_page *next_page) |
| 849 | { |
| 850 | struct buffer_page *old_tail; |
| 851 | unsigned long old_entries; |
| 852 | unsigned long old_write; |
| 853 | int ret = 0; |
| 854 | |
| 855 | /* |
| 856 | * The tail page now needs to be moved forward. |
| 857 | * |
| 858 | * We need to reset the tail page, but without messing |
| 859 | * with possible erasing of data brought in by interrupts |
| 860 | * that have moved the tail page and are currently on it. |
| 861 | * |
| 862 | * We add a counter to the write field to denote this. |
| 863 | */ |
| 864 | old_write = local_add_return(RB_WRITE_INTCNT, &next_page->write); |
| 865 | old_entries = local_add_return(RB_WRITE_INTCNT, &next_page->entries); |
| 866 | |
| 867 | /* |
| 868 | * Just make sure we have seen our old_write and synchronize |
| 869 | * with any interrupts that come in. |
| 870 | */ |
| 871 | barrier(); |
| 872 | |
| 873 | /* |
| 874 | * If the tail page is still the same as what we think |
| 875 | * it is, then it is up to us to update the tail |
| 876 | * pointer. |
| 877 | */ |
| 878 | if (tail_page == cpu_buffer->tail_page) { |
| 879 | /* Zero the write counter */ |
| 880 | unsigned long val = old_write & ~RB_WRITE_MASK; |
| 881 | unsigned long eval = old_entries & ~RB_WRITE_MASK; |
| 882 | |
| 883 | /* |
| 884 | * This will only succeed if an interrupt did |
| 885 | * not come in and change it. In which case, we |
| 886 | * do not want to modify it. |
Lai Jiangshan | da706d8 | 2009-07-15 16:27:30 +0800 | [diff] [blame] | 887 | * |
| 888 | * We add (void) to let the compiler know that we do not care |
| 889 | * about the return value of these functions. We use the |
| 890 | * cmpxchg to only update if an interrupt did not already |
| 891 | * do it for us. If the cmpxchg fails, we don't care. |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 892 | */ |
Lai Jiangshan | da706d8 | 2009-07-15 16:27:30 +0800 | [diff] [blame] | 893 | (void)local_cmpxchg(&next_page->write, old_write, val); |
| 894 | (void)local_cmpxchg(&next_page->entries, old_entries, eval); |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 895 | |
| 896 | /* |
| 897 | * No need to worry about races with clearing out the commit. |
| 898 | * it only can increment when a commit takes place. But that |
| 899 | * only happens in the outer most nested commit. |
| 900 | */ |
| 901 | local_set(&next_page->page->commit, 0); |
| 902 | |
| 903 | old_tail = cmpxchg(&cpu_buffer->tail_page, |
| 904 | tail_page, next_page); |
| 905 | |
| 906 | if (old_tail == tail_page) |
| 907 | ret = 1; |
| 908 | } |
| 909 | |
| 910 | return ret; |
| 911 | } |
| 912 | |
| 913 | static int rb_check_bpage(struct ring_buffer_per_cpu *cpu_buffer, |
| 914 | struct buffer_page *bpage) |
| 915 | { |
| 916 | unsigned long val = (unsigned long)bpage; |
| 917 | |
| 918 | if (RB_WARN_ON(cpu_buffer, val & RB_FLAG_MASK)) |
| 919 | return 1; |
| 920 | |
| 921 | return 0; |
| 922 | } |
| 923 | |
| 924 | /** |
| 925 | * rb_check_list - make sure a pointer to a list has the last bits zero |
| 926 | */ |
| 927 | static int rb_check_list(struct ring_buffer_per_cpu *cpu_buffer, |
| 928 | struct list_head *list) |
| 929 | { |
| 930 | if (RB_WARN_ON(cpu_buffer, rb_list_head(list->prev) != list->prev)) |
| 931 | return 1; |
| 932 | if (RB_WARN_ON(cpu_buffer, rb_list_head(list->next) != list->next)) |
| 933 | return 1; |
| 934 | return 0; |
| 935 | } |
| 936 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 937 | /** |
| 938 | * check_pages - integrity check of buffer pages |
| 939 | * @cpu_buffer: CPU buffer with pages to test |
| 940 | * |
Wenji Huang | c3706f0 | 2009-02-10 01:03:18 -0500 | [diff] [blame] | 941 | * As a safety measure we check to make sure the data pages have not |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 942 | * been corrupted. |
| 943 | */ |
| 944 | static int rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer) |
| 945 | { |
Steven Rostedt | 3adc54f | 2009-03-30 15:32:01 -0400 | [diff] [blame] | 946 | struct list_head *head = cpu_buffer->pages; |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 947 | struct buffer_page *bpage, *tmp; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 948 | |
Steven Rostedt | 308f7ee | 2012-05-16 19:46:32 -0400 | [diff] [blame] | 949 | /* Reset the head page if it exists */ |
| 950 | if (cpu_buffer->head_page) |
| 951 | rb_set_head_page(cpu_buffer); |
| 952 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 953 | rb_head_page_deactivate(cpu_buffer); |
| 954 | |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 955 | if (RB_WARN_ON(cpu_buffer, head->next->prev != head)) |
| 956 | return -1; |
| 957 | if (RB_WARN_ON(cpu_buffer, head->prev->next != head)) |
| 958 | return -1; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 959 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 960 | if (rb_check_list(cpu_buffer, head)) |
| 961 | return -1; |
| 962 | |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 963 | list_for_each_entry_safe(bpage, tmp, head, list) { |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 964 | if (RB_WARN_ON(cpu_buffer, |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 965 | bpage->list.next->prev != &bpage->list)) |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 966 | return -1; |
| 967 | if (RB_WARN_ON(cpu_buffer, |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 968 | bpage->list.prev->next != &bpage->list)) |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 969 | return -1; |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 970 | if (rb_check_list(cpu_buffer, &bpage->list)) |
| 971 | return -1; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 972 | } |
| 973 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 974 | rb_head_page_activate(cpu_buffer); |
| 975 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 976 | return 0; |
| 977 | } |
| 978 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 979 | static int __rb_allocate_pages(int nr_pages, struct list_head *pages, int cpu) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 980 | { |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 981 | int i; |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 982 | struct buffer_page *bpage, *tmp; |
Steven Rostedt | 3adc54f | 2009-03-30 15:32:01 -0400 | [diff] [blame] | 983 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 984 | for (i = 0; i < nr_pages; i++) { |
Vaibhav Nagarnaik | 7ea5906 | 2011-05-03 17:56:42 -0700 | [diff] [blame] | 985 | struct page *page; |
Vaibhav Nagarnaik | d7ec4bf | 2011-06-07 17:01:42 -0700 | [diff] [blame] | 986 | /* |
| 987 | * __GFP_NORETRY flag makes sure that the allocation fails |
| 988 | * gracefully without invoking oom-killer and the system is |
| 989 | * not destabilized. |
| 990 | */ |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 991 | bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()), |
Vaibhav Nagarnaik | d7ec4bf | 2011-06-07 17:01:42 -0700 | [diff] [blame] | 992 | GFP_KERNEL | __GFP_NORETRY, |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 993 | cpu_to_node(cpu)); |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 994 | if (!bpage) |
Steven Rostedt | e4c2ce8 | 2008-10-01 11:14:54 -0400 | [diff] [blame] | 995 | goto free_pages; |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 996 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 997 | list_add(&bpage->list, pages); |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 998 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 999 | page = alloc_pages_node(cpu_to_node(cpu), |
Vaibhav Nagarnaik | d7ec4bf | 2011-06-07 17:01:42 -0700 | [diff] [blame] | 1000 | GFP_KERNEL | __GFP_NORETRY, 0); |
Vaibhav Nagarnaik | 7ea5906 | 2011-05-03 17:56:42 -0700 | [diff] [blame] | 1001 | if (!page) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1002 | goto free_pages; |
Vaibhav Nagarnaik | 7ea5906 | 2011-05-03 17:56:42 -0700 | [diff] [blame] | 1003 | bpage->page = page_address(page); |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1004 | rb_init_page(bpage->page); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1005 | } |
| 1006 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1007 | return 0; |
| 1008 | |
| 1009 | free_pages: |
| 1010 | list_for_each_entry_safe(bpage, tmp, pages, list) { |
| 1011 | list_del_init(&bpage->list); |
| 1012 | free_buffer_page(bpage); |
| 1013 | } |
| 1014 | |
| 1015 | return -ENOMEM; |
| 1016 | } |
| 1017 | |
| 1018 | static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, |
| 1019 | unsigned nr_pages) |
| 1020 | { |
| 1021 | LIST_HEAD(pages); |
| 1022 | |
| 1023 | WARN_ON(!nr_pages); |
| 1024 | |
| 1025 | if (__rb_allocate_pages(nr_pages, &pages, cpu_buffer->cpu)) |
| 1026 | return -ENOMEM; |
| 1027 | |
Steven Rostedt | 3adc54f | 2009-03-30 15:32:01 -0400 | [diff] [blame] | 1028 | /* |
| 1029 | * The ring buffer page list is a circular list that does not |
| 1030 | * start and end with a list head. All page list items point to |
| 1031 | * other pages. |
| 1032 | */ |
| 1033 | cpu_buffer->pages = pages.next; |
| 1034 | list_del(&pages); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1035 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1036 | cpu_buffer->nr_pages = nr_pages; |
| 1037 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1038 | rb_check_pages(cpu_buffer); |
| 1039 | |
| 1040 | return 0; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1041 | } |
| 1042 | |
| 1043 | static struct ring_buffer_per_cpu * |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1044 | rb_allocate_cpu_buffer(struct ring_buffer *buffer, int nr_pages, int cpu) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1045 | { |
| 1046 | struct ring_buffer_per_cpu *cpu_buffer; |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1047 | struct buffer_page *bpage; |
Vaibhav Nagarnaik | 7ea5906 | 2011-05-03 17:56:42 -0700 | [diff] [blame] | 1048 | struct page *page; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1049 | int ret; |
| 1050 | |
| 1051 | cpu_buffer = kzalloc_node(ALIGN(sizeof(*cpu_buffer), cache_line_size()), |
| 1052 | GFP_KERNEL, cpu_to_node(cpu)); |
| 1053 | if (!cpu_buffer) |
| 1054 | return NULL; |
| 1055 | |
| 1056 | cpu_buffer->cpu = cpu; |
| 1057 | cpu_buffer->buffer = buffer; |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 1058 | raw_spin_lock_init(&cpu_buffer->reader_lock); |
Peter Zijlstra | 1f8a6a1 | 2009-06-08 18:18:39 +0200 | [diff] [blame] | 1059 | lockdep_set_class(&cpu_buffer->reader_lock, buffer->reader_lock_key); |
Thomas Gleixner | edc35bd | 2009-12-03 12:38:57 +0100 | [diff] [blame] | 1060 | cpu_buffer->lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1061 | INIT_WORK(&cpu_buffer->update_pages_work, update_pages_handler); |
Vaibhav Nagarnaik | 05fdd70 | 2012-05-18 13:29:51 -0700 | [diff] [blame] | 1062 | init_completion(&cpu_buffer->update_done); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1063 | |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1064 | bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()), |
Steven Rostedt | e4c2ce8 | 2008-10-01 11:14:54 -0400 | [diff] [blame] | 1065 | GFP_KERNEL, cpu_to_node(cpu)); |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1066 | if (!bpage) |
Steven Rostedt | e4c2ce8 | 2008-10-01 11:14:54 -0400 | [diff] [blame] | 1067 | goto fail_free_buffer; |
| 1068 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1069 | rb_check_bpage(cpu_buffer, bpage); |
| 1070 | |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1071 | cpu_buffer->reader_page = bpage; |
Vaibhav Nagarnaik | 7ea5906 | 2011-05-03 17:56:42 -0700 | [diff] [blame] | 1072 | page = alloc_pages_node(cpu_to_node(cpu), GFP_KERNEL, 0); |
| 1073 | if (!page) |
Steven Rostedt | e4c2ce8 | 2008-10-01 11:14:54 -0400 | [diff] [blame] | 1074 | goto fail_free_reader; |
Vaibhav Nagarnaik | 7ea5906 | 2011-05-03 17:56:42 -0700 | [diff] [blame] | 1075 | bpage->page = page_address(page); |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1076 | rb_init_page(bpage->page); |
Steven Rostedt | e4c2ce8 | 2008-10-01 11:14:54 -0400 | [diff] [blame] | 1077 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1078 | INIT_LIST_HEAD(&cpu_buffer->reader_page->list); |
Vaibhav Nagarnaik | 44b9946 | 2012-06-22 11:50:05 -0700 | [diff] [blame] | 1079 | INIT_LIST_HEAD(&cpu_buffer->new_pages); |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1080 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1081 | ret = rb_allocate_pages(cpu_buffer, nr_pages); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1082 | if (ret < 0) |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1083 | goto fail_free_reader; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1084 | |
| 1085 | cpu_buffer->head_page |
Steven Rostedt | 3adc54f | 2009-03-30 15:32:01 -0400 | [diff] [blame] | 1086 | = list_entry(cpu_buffer->pages, struct buffer_page, list); |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1087 | cpu_buffer->tail_page = cpu_buffer->commit_page = cpu_buffer->head_page; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1088 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1089 | rb_head_page_activate(cpu_buffer); |
| 1090 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1091 | return cpu_buffer; |
| 1092 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1093 | fail_free_reader: |
| 1094 | free_buffer_page(cpu_buffer->reader_page); |
| 1095 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1096 | fail_free_buffer: |
| 1097 | kfree(cpu_buffer); |
| 1098 | return NULL; |
| 1099 | } |
| 1100 | |
| 1101 | static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer) |
| 1102 | { |
Steven Rostedt | 3adc54f | 2009-03-30 15:32:01 -0400 | [diff] [blame] | 1103 | struct list_head *head = cpu_buffer->pages; |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1104 | struct buffer_page *bpage, *tmp; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1105 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1106 | free_buffer_page(cpu_buffer->reader_page); |
| 1107 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1108 | rb_head_page_deactivate(cpu_buffer); |
| 1109 | |
Steven Rostedt | 3adc54f | 2009-03-30 15:32:01 -0400 | [diff] [blame] | 1110 | if (head) { |
| 1111 | list_for_each_entry_safe(bpage, tmp, head, list) { |
| 1112 | list_del_init(&bpage->list); |
| 1113 | free_buffer_page(bpage); |
| 1114 | } |
| 1115 | bpage = list_entry(head, struct buffer_page, list); |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1116 | free_buffer_page(bpage); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1117 | } |
Steven Rostedt | 3adc54f | 2009-03-30 15:32:01 -0400 | [diff] [blame] | 1118 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1119 | kfree(cpu_buffer); |
| 1120 | } |
| 1121 | |
Steven Rostedt | 59222ef | 2009-03-12 11:46:03 -0400 | [diff] [blame] | 1122 | #ifdef CONFIG_HOTPLUG_CPU |
Frederic Weisbecker | 09c9e84 | 2009-03-21 04:33:36 +0100 | [diff] [blame] | 1123 | static int rb_cpu_notify(struct notifier_block *self, |
| 1124 | unsigned long action, void *hcpu); |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 1125 | #endif |
| 1126 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1127 | /** |
| 1128 | * ring_buffer_alloc - allocate a new ring_buffer |
Robert Richter | 68814b5 | 2008-11-24 12:24:12 +0100 | [diff] [blame] | 1129 | * @size: the size in bytes per cpu that is needed. |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1130 | * @flags: attributes to set for the ring buffer. |
| 1131 | * |
| 1132 | * Currently the only flag that is available is the RB_FL_OVERWRITE |
| 1133 | * flag. This flag means that the buffer will overwrite old data |
| 1134 | * when the buffer wraps. If this flag is not set, the buffer will |
| 1135 | * drop data when the tail hits the head. |
| 1136 | */ |
Peter Zijlstra | 1f8a6a1 | 2009-06-08 18:18:39 +0200 | [diff] [blame] | 1137 | struct ring_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags, |
| 1138 | struct lock_class_key *key) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1139 | { |
| 1140 | struct ring_buffer *buffer; |
| 1141 | int bsize; |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1142 | int cpu, nr_pages; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1143 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1144 | /* keep it in its own cache line */ |
| 1145 | buffer = kzalloc(ALIGN(sizeof(*buffer), cache_line_size()), |
| 1146 | GFP_KERNEL); |
| 1147 | if (!buffer) |
| 1148 | return NULL; |
| 1149 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 1150 | if (!alloc_cpumask_var(&buffer->cpumask, GFP_KERNEL)) |
| 1151 | goto fail_free_buffer; |
| 1152 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1153 | nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1154 | buffer->flags = flags; |
Steven Rostedt | 37886f6 | 2009-03-17 17:22:06 -0400 | [diff] [blame] | 1155 | buffer->clock = trace_clock_local; |
Peter Zijlstra | 1f8a6a1 | 2009-06-08 18:18:39 +0200 | [diff] [blame] | 1156 | buffer->reader_lock_key = key; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1157 | |
| 1158 | /* need at least two pages */ |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1159 | if (nr_pages < 2) |
| 1160 | nr_pages = 2; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1161 | |
Frederic Weisbecker | 3bf832c | 2009-03-19 14:47:33 +0100 | [diff] [blame] | 1162 | /* |
| 1163 | * In case of non-hotplug cpu, if the ring-buffer is allocated |
| 1164 | * in early initcall, it will not be notified of secondary cpus. |
| 1165 | * In that off case, we need to allocate for all possible cpus. |
| 1166 | */ |
| 1167 | #ifdef CONFIG_HOTPLUG_CPU |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 1168 | get_online_cpus(); |
| 1169 | cpumask_copy(buffer->cpumask, cpu_online_mask); |
Frederic Weisbecker | 3bf832c | 2009-03-19 14:47:33 +0100 | [diff] [blame] | 1170 | #else |
| 1171 | cpumask_copy(buffer->cpumask, cpu_possible_mask); |
| 1172 | #endif |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1173 | buffer->cpus = nr_cpu_ids; |
| 1174 | |
| 1175 | bsize = sizeof(void *) * nr_cpu_ids; |
| 1176 | buffer->buffers = kzalloc(ALIGN(bsize, cache_line_size()), |
| 1177 | GFP_KERNEL); |
| 1178 | if (!buffer->buffers) |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 1179 | goto fail_free_cpumask; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1180 | |
| 1181 | for_each_buffer_cpu(buffer, cpu) { |
| 1182 | buffer->buffers[cpu] = |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1183 | rb_allocate_cpu_buffer(buffer, nr_pages, cpu); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1184 | if (!buffer->buffers[cpu]) |
| 1185 | goto fail_free_buffers; |
| 1186 | } |
| 1187 | |
Steven Rostedt | 59222ef | 2009-03-12 11:46:03 -0400 | [diff] [blame] | 1188 | #ifdef CONFIG_HOTPLUG_CPU |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 1189 | buffer->cpu_notify.notifier_call = rb_cpu_notify; |
| 1190 | buffer->cpu_notify.priority = 0; |
| 1191 | register_cpu_notifier(&buffer->cpu_notify); |
| 1192 | #endif |
| 1193 | |
| 1194 | put_online_cpus(); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1195 | mutex_init(&buffer->mutex); |
| 1196 | |
| 1197 | return buffer; |
| 1198 | |
| 1199 | fail_free_buffers: |
| 1200 | for_each_buffer_cpu(buffer, cpu) { |
| 1201 | if (buffer->buffers[cpu]) |
| 1202 | rb_free_cpu_buffer(buffer->buffers[cpu]); |
| 1203 | } |
| 1204 | kfree(buffer->buffers); |
| 1205 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 1206 | fail_free_cpumask: |
| 1207 | free_cpumask_var(buffer->cpumask); |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 1208 | put_online_cpus(); |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 1209 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1210 | fail_free_buffer: |
| 1211 | kfree(buffer); |
| 1212 | return NULL; |
| 1213 | } |
Peter Zijlstra | 1f8a6a1 | 2009-06-08 18:18:39 +0200 | [diff] [blame] | 1214 | EXPORT_SYMBOL_GPL(__ring_buffer_alloc); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1215 | |
| 1216 | /** |
| 1217 | * ring_buffer_free - free a ring buffer. |
| 1218 | * @buffer: the buffer to free. |
| 1219 | */ |
| 1220 | void |
| 1221 | ring_buffer_free(struct ring_buffer *buffer) |
| 1222 | { |
| 1223 | int cpu; |
| 1224 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 1225 | get_online_cpus(); |
| 1226 | |
Steven Rostedt | 59222ef | 2009-03-12 11:46:03 -0400 | [diff] [blame] | 1227 | #ifdef CONFIG_HOTPLUG_CPU |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 1228 | unregister_cpu_notifier(&buffer->cpu_notify); |
| 1229 | #endif |
| 1230 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1231 | for_each_buffer_cpu(buffer, cpu) |
| 1232 | rb_free_cpu_buffer(buffer->buffers[cpu]); |
| 1233 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 1234 | put_online_cpus(); |
| 1235 | |
Eric Dumazet | bd3f022 | 2009-08-07 12:49:29 +0200 | [diff] [blame] | 1236 | kfree(buffer->buffers); |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 1237 | free_cpumask_var(buffer->cpumask); |
| 1238 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1239 | kfree(buffer); |
| 1240 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 1241 | EXPORT_SYMBOL_GPL(ring_buffer_free); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1242 | |
Steven Rostedt | 37886f6 | 2009-03-17 17:22:06 -0400 | [diff] [blame] | 1243 | void ring_buffer_set_clock(struct ring_buffer *buffer, |
| 1244 | u64 (*clock)(void)) |
| 1245 | { |
| 1246 | buffer->clock = clock; |
| 1247 | } |
| 1248 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1249 | static void rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer); |
| 1250 | |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1251 | static inline unsigned long rb_page_entries(struct buffer_page *bpage) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1252 | { |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1253 | return local_read(&bpage->entries) & RB_WRITE_MASK; |
| 1254 | } |
| 1255 | |
| 1256 | static inline unsigned long rb_page_write(struct buffer_page *bpage) |
| 1257 | { |
| 1258 | return local_read(&bpage->write) & RB_WRITE_MASK; |
| 1259 | } |
| 1260 | |
Vaibhav Nagarnaik | 5040b4b | 2012-05-03 18:59:51 -0700 | [diff] [blame] | 1261 | static int |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1262 | rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned int nr_pages) |
| 1263 | { |
| 1264 | struct list_head *tail_page, *to_remove, *next_page; |
| 1265 | struct buffer_page *to_remove_page, *tmp_iter_page; |
| 1266 | struct buffer_page *last_page, *first_page; |
| 1267 | unsigned int nr_removed; |
| 1268 | unsigned long head_bit; |
| 1269 | int page_entries; |
| 1270 | |
| 1271 | head_bit = 0; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1272 | |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 1273 | raw_spin_lock_irq(&cpu_buffer->reader_lock); |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1274 | atomic_inc(&cpu_buffer->record_disabled); |
| 1275 | /* |
| 1276 | * We don't race with the readers since we have acquired the reader |
| 1277 | * lock. We also don't race with writers after disabling recording. |
| 1278 | * This makes it easy to figure out the first and the last page to be |
| 1279 | * removed from the list. We unlink all the pages in between including |
| 1280 | * the first and last pages. This is done in a busy loop so that we |
| 1281 | * lose the least number of traces. |
| 1282 | * The pages are freed after we restart recording and unlock readers. |
| 1283 | */ |
| 1284 | tail_page = &cpu_buffer->tail_page->list; |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1285 | |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1286 | /* |
| 1287 | * tail page might be on reader page, we remove the next page |
| 1288 | * from the ring buffer |
| 1289 | */ |
| 1290 | if (cpu_buffer->tail_page == cpu_buffer->reader_page) |
| 1291 | tail_page = rb_list_head(tail_page->next); |
| 1292 | to_remove = tail_page; |
| 1293 | |
| 1294 | /* start of pages to remove */ |
| 1295 | first_page = list_entry(rb_list_head(to_remove->next), |
| 1296 | struct buffer_page, list); |
| 1297 | |
| 1298 | for (nr_removed = 0; nr_removed < nr_pages; nr_removed++) { |
| 1299 | to_remove = rb_list_head(to_remove)->next; |
| 1300 | head_bit |= (unsigned long)to_remove & RB_PAGE_HEAD; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1301 | } |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1302 | |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1303 | next_page = rb_list_head(to_remove)->next; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1304 | |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1305 | /* |
| 1306 | * Now we remove all pages between tail_page and next_page. |
| 1307 | * Make sure that we have head_bit value preserved for the |
| 1308 | * next page |
| 1309 | */ |
| 1310 | tail_page->next = (struct list_head *)((unsigned long)next_page | |
| 1311 | head_bit); |
| 1312 | next_page = rb_list_head(next_page); |
| 1313 | next_page->prev = tail_page; |
| 1314 | |
| 1315 | /* make sure pages points to a valid page in the ring buffer */ |
| 1316 | cpu_buffer->pages = next_page; |
| 1317 | |
| 1318 | /* update head page */ |
| 1319 | if (head_bit) |
| 1320 | cpu_buffer->head_page = list_entry(next_page, |
| 1321 | struct buffer_page, list); |
| 1322 | |
| 1323 | /* |
| 1324 | * change read pointer to make sure any read iterators reset |
| 1325 | * themselves |
| 1326 | */ |
| 1327 | cpu_buffer->read = 0; |
| 1328 | |
| 1329 | /* pages are removed, resume tracing and then free the pages */ |
| 1330 | atomic_dec(&cpu_buffer->record_disabled); |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 1331 | raw_spin_unlock_irq(&cpu_buffer->reader_lock); |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1332 | |
| 1333 | RB_WARN_ON(cpu_buffer, list_empty(cpu_buffer->pages)); |
| 1334 | |
| 1335 | /* last buffer page to remove */ |
| 1336 | last_page = list_entry(rb_list_head(to_remove), struct buffer_page, |
| 1337 | list); |
| 1338 | tmp_iter_page = first_page; |
| 1339 | |
| 1340 | do { |
| 1341 | to_remove_page = tmp_iter_page; |
| 1342 | rb_inc_page(cpu_buffer, &tmp_iter_page); |
| 1343 | |
| 1344 | /* update the counters */ |
| 1345 | page_entries = rb_page_entries(to_remove_page); |
| 1346 | if (page_entries) { |
| 1347 | /* |
| 1348 | * If something was added to this page, it was full |
| 1349 | * since it is not the tail page. So we deduct the |
| 1350 | * bytes consumed in ring buffer from here. |
Vaibhav Nagarnaik | 48fdc72 | 2012-06-29 12:31:41 -0700 | [diff] [blame] | 1351 | * Increment overrun to account for the lost events. |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1352 | */ |
Vaibhav Nagarnaik | 48fdc72 | 2012-06-29 12:31:41 -0700 | [diff] [blame] | 1353 | local_add(page_entries, &cpu_buffer->overrun); |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1354 | local_sub(BUF_PAGE_SIZE, &cpu_buffer->entries_bytes); |
| 1355 | } |
| 1356 | |
| 1357 | /* |
| 1358 | * We have already removed references to this list item, just |
| 1359 | * free up the buffer_page and its page |
| 1360 | */ |
| 1361 | free_buffer_page(to_remove_page); |
| 1362 | nr_removed--; |
| 1363 | |
| 1364 | } while (to_remove_page != last_page); |
| 1365 | |
| 1366 | RB_WARN_ON(cpu_buffer, nr_removed); |
Vaibhav Nagarnaik | 5040b4b | 2012-05-03 18:59:51 -0700 | [diff] [blame] | 1367 | |
| 1368 | return nr_removed == 0; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1369 | } |
| 1370 | |
Vaibhav Nagarnaik | 5040b4b | 2012-05-03 18:59:51 -0700 | [diff] [blame] | 1371 | static int |
| 1372 | rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1373 | { |
Vaibhav Nagarnaik | 5040b4b | 2012-05-03 18:59:51 -0700 | [diff] [blame] | 1374 | struct list_head *pages = &cpu_buffer->new_pages; |
| 1375 | int retries, success; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1376 | |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 1377 | raw_spin_lock_irq(&cpu_buffer->reader_lock); |
Vaibhav Nagarnaik | 5040b4b | 2012-05-03 18:59:51 -0700 | [diff] [blame] | 1378 | /* |
| 1379 | * We are holding the reader lock, so the reader page won't be swapped |
| 1380 | * in the ring buffer. Now we are racing with the writer trying to |
| 1381 | * move head page and the tail page. |
| 1382 | * We are going to adapt the reader page update process where: |
| 1383 | * 1. We first splice the start and end of list of new pages between |
| 1384 | * the head page and its previous page. |
| 1385 | * 2. We cmpxchg the prev_page->next to point from head page to the |
| 1386 | * start of new pages list. |
| 1387 | * 3. Finally, we update the head->prev to the end of new list. |
| 1388 | * |
| 1389 | * We will try this process 10 times, to make sure that we don't keep |
| 1390 | * spinning. |
| 1391 | */ |
| 1392 | retries = 10; |
| 1393 | success = 0; |
| 1394 | while (retries--) { |
| 1395 | struct list_head *head_page, *prev_page, *r; |
| 1396 | struct list_head *last_page, *first_page; |
| 1397 | struct list_head *head_page_with_bit; |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1398 | |
Vaibhav Nagarnaik | 5040b4b | 2012-05-03 18:59:51 -0700 | [diff] [blame] | 1399 | head_page = &rb_set_head_page(cpu_buffer)->list; |
| 1400 | prev_page = head_page->prev; |
| 1401 | |
| 1402 | first_page = pages->next; |
| 1403 | last_page = pages->prev; |
| 1404 | |
| 1405 | head_page_with_bit = (struct list_head *) |
| 1406 | ((unsigned long)head_page | RB_PAGE_HEAD); |
| 1407 | |
| 1408 | last_page->next = head_page_with_bit; |
| 1409 | first_page->prev = prev_page; |
| 1410 | |
| 1411 | r = cmpxchg(&prev_page->next, head_page_with_bit, first_page); |
| 1412 | |
| 1413 | if (r == head_page_with_bit) { |
| 1414 | /* |
| 1415 | * yay, we replaced the page pointer to our new list, |
| 1416 | * now, we just have to update to head page's prev |
| 1417 | * pointer to point to end of list |
| 1418 | */ |
| 1419 | head_page->prev = last_page; |
| 1420 | success = 1; |
| 1421 | break; |
| 1422 | } |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1423 | } |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1424 | |
Vaibhav Nagarnaik | 5040b4b | 2012-05-03 18:59:51 -0700 | [diff] [blame] | 1425 | if (success) |
| 1426 | INIT_LIST_HEAD(pages); |
| 1427 | /* |
| 1428 | * If we weren't successful in adding in new pages, warn and stop |
| 1429 | * tracing |
| 1430 | */ |
| 1431 | RB_WARN_ON(cpu_buffer, !success); |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 1432 | raw_spin_unlock_irq(&cpu_buffer->reader_lock); |
Vaibhav Nagarnaik | 5040b4b | 2012-05-03 18:59:51 -0700 | [diff] [blame] | 1433 | |
| 1434 | /* free pages if they weren't inserted */ |
| 1435 | if (!success) { |
| 1436 | struct buffer_page *bpage, *tmp; |
| 1437 | list_for_each_entry_safe(bpage, tmp, &cpu_buffer->new_pages, |
| 1438 | list) { |
| 1439 | list_del_init(&bpage->list); |
| 1440 | free_buffer_page(bpage); |
| 1441 | } |
| 1442 | } |
| 1443 | return success; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1444 | } |
| 1445 | |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1446 | static void rb_update_pages(struct ring_buffer_per_cpu *cpu_buffer) |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1447 | { |
Vaibhav Nagarnaik | 5040b4b | 2012-05-03 18:59:51 -0700 | [diff] [blame] | 1448 | int success; |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1449 | |
Vaibhav Nagarnaik | 5040b4b | 2012-05-03 18:59:51 -0700 | [diff] [blame] | 1450 | if (cpu_buffer->nr_pages_to_update > 0) |
| 1451 | success = rb_insert_pages(cpu_buffer); |
| 1452 | else |
| 1453 | success = rb_remove_pages(cpu_buffer, |
| 1454 | -cpu_buffer->nr_pages_to_update); |
| 1455 | |
| 1456 | if (success) |
| 1457 | cpu_buffer->nr_pages += cpu_buffer->nr_pages_to_update; |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1458 | } |
| 1459 | |
| 1460 | static void update_pages_handler(struct work_struct *work) |
| 1461 | { |
| 1462 | struct ring_buffer_per_cpu *cpu_buffer = container_of(work, |
| 1463 | struct ring_buffer_per_cpu, update_pages_work); |
| 1464 | rb_update_pages(cpu_buffer); |
Vaibhav Nagarnaik | 05fdd70 | 2012-05-18 13:29:51 -0700 | [diff] [blame] | 1465 | complete(&cpu_buffer->update_done); |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1466 | } |
| 1467 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1468 | /** |
| 1469 | * ring_buffer_resize - resize the ring buffer |
| 1470 | * @buffer: the buffer to resize. |
| 1471 | * @size: the new size. |
| 1472 | * |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1473 | * Minimum size is 2 * BUF_PAGE_SIZE. |
| 1474 | * |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1475 | * Returns 0 on success and < 0 on failure. |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1476 | */ |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1477 | int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size, |
| 1478 | int cpu_id) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1479 | { |
| 1480 | struct ring_buffer_per_cpu *cpu_buffer; |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1481 | unsigned nr_pages; |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1482 | int cpu, err = 0; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1483 | |
Ingo Molnar | ee51a1d | 2008-11-13 14:58:31 +0100 | [diff] [blame] | 1484 | /* |
| 1485 | * Always succeed at resizing a non-existent buffer: |
| 1486 | */ |
| 1487 | if (!buffer) |
| 1488 | return size; |
| 1489 | |
Steven Rostedt | 6a31e1f | 2012-05-23 15:35:17 -0400 | [diff] [blame] | 1490 | /* Make sure the requested buffer exists */ |
| 1491 | if (cpu_id != RING_BUFFER_ALL_CPUS && |
| 1492 | !cpumask_test_cpu(cpu_id, buffer->cpumask)) |
| 1493 | return size; |
| 1494 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1495 | size = DIV_ROUND_UP(size, BUF_PAGE_SIZE); |
| 1496 | size *= BUF_PAGE_SIZE; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1497 | |
| 1498 | /* we need a minimum of two pages */ |
| 1499 | if (size < BUF_PAGE_SIZE * 2) |
| 1500 | size = BUF_PAGE_SIZE * 2; |
| 1501 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1502 | nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); |
| 1503 | |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1504 | /* |
| 1505 | * Don't succeed if resizing is disabled, as a reader might be |
| 1506 | * manipulating the ring buffer and is expecting a sane state while |
| 1507 | * this is true. |
| 1508 | */ |
| 1509 | if (atomic_read(&buffer->resize_disabled)) |
| 1510 | return -EBUSY; |
| 1511 | |
| 1512 | /* prevent another thread from changing buffer sizes */ |
| 1513 | mutex_lock(&buffer->mutex); |
| 1514 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1515 | if (cpu_id == RING_BUFFER_ALL_CPUS) { |
| 1516 | /* calculate the pages to update */ |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1517 | for_each_buffer_cpu(buffer, cpu) { |
| 1518 | cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1519 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1520 | cpu_buffer->nr_pages_to_update = nr_pages - |
| 1521 | cpu_buffer->nr_pages; |
Vaibhav Nagarnaik | d7ec4bf | 2011-06-07 17:01:42 -0700 | [diff] [blame] | 1522 | /* |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1523 | * nothing more to do for removing pages or no update |
Vaibhav Nagarnaik | d7ec4bf | 2011-06-07 17:01:42 -0700 | [diff] [blame] | 1524 | */ |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1525 | if (cpu_buffer->nr_pages_to_update <= 0) |
| 1526 | continue; |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1527 | /* |
| 1528 | * to add pages, make sure all new pages can be |
| 1529 | * allocated without receiving ENOMEM |
| 1530 | */ |
| 1531 | INIT_LIST_HEAD(&cpu_buffer->new_pages); |
| 1532 | if (__rb_allocate_pages(cpu_buffer->nr_pages_to_update, |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1533 | &cpu_buffer->new_pages, cpu)) { |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1534 | /* not enough memory for new pages */ |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1535 | err = -ENOMEM; |
| 1536 | goto out_err; |
| 1537 | } |
| 1538 | } |
| 1539 | |
| 1540 | get_online_cpus(); |
| 1541 | /* |
| 1542 | * Fire off all the required work handlers |
Vaibhav Nagarnaik | 05fdd70 | 2012-05-18 13:29:51 -0700 | [diff] [blame] | 1543 | * We can't schedule on offline CPUs, but it's not necessary |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1544 | * since we can change their buffer sizes without any race. |
| 1545 | */ |
| 1546 | for_each_buffer_cpu(buffer, cpu) { |
| 1547 | cpu_buffer = buffer->buffers[cpu]; |
Vaibhav Nagarnaik | 05fdd70 | 2012-05-18 13:29:51 -0700 | [diff] [blame] | 1548 | if (!cpu_buffer->nr_pages_to_update) |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1549 | continue; |
| 1550 | |
Vaibhav Nagarnaik | 05fdd70 | 2012-05-18 13:29:51 -0700 | [diff] [blame] | 1551 | if (cpu_online(cpu)) |
| 1552 | schedule_work_on(cpu, |
| 1553 | &cpu_buffer->update_pages_work); |
| 1554 | else |
| 1555 | rb_update_pages(cpu_buffer); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1556 | } |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1557 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1558 | /* wait for all the updates to complete */ |
| 1559 | for_each_buffer_cpu(buffer, cpu) { |
| 1560 | cpu_buffer = buffer->buffers[cpu]; |
Vaibhav Nagarnaik | 05fdd70 | 2012-05-18 13:29:51 -0700 | [diff] [blame] | 1561 | if (!cpu_buffer->nr_pages_to_update) |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1562 | continue; |
| 1563 | |
Vaibhav Nagarnaik | 05fdd70 | 2012-05-18 13:29:51 -0700 | [diff] [blame] | 1564 | if (cpu_online(cpu)) |
| 1565 | wait_for_completion(&cpu_buffer->update_done); |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1566 | cpu_buffer->nr_pages_to_update = 0; |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1567 | } |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1568 | |
| 1569 | put_online_cpus(); |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1570 | } else { |
Vaibhav Nagarnaik | 8e49f41 | 2012-10-10 16:40:27 -0700 | [diff] [blame] | 1571 | /* Make sure this CPU has been intitialized */ |
| 1572 | if (!cpumask_test_cpu(cpu_id, buffer->cpumask)) |
| 1573 | goto out; |
| 1574 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1575 | cpu_buffer = buffer->buffers[cpu_id]; |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1576 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1577 | if (nr_pages == cpu_buffer->nr_pages) |
| 1578 | goto out; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1579 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1580 | cpu_buffer->nr_pages_to_update = nr_pages - |
| 1581 | cpu_buffer->nr_pages; |
| 1582 | |
| 1583 | INIT_LIST_HEAD(&cpu_buffer->new_pages); |
| 1584 | if (cpu_buffer->nr_pages_to_update > 0 && |
| 1585 | __rb_allocate_pages(cpu_buffer->nr_pages_to_update, |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1586 | &cpu_buffer->new_pages, cpu_id)) { |
| 1587 | err = -ENOMEM; |
| 1588 | goto out_err; |
| 1589 | } |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1590 | |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1591 | get_online_cpus(); |
| 1592 | |
| 1593 | if (cpu_online(cpu_id)) { |
| 1594 | schedule_work_on(cpu_id, |
| 1595 | &cpu_buffer->update_pages_work); |
Vaibhav Nagarnaik | 05fdd70 | 2012-05-18 13:29:51 -0700 | [diff] [blame] | 1596 | wait_for_completion(&cpu_buffer->update_done); |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1597 | } else |
| 1598 | rb_update_pages(cpu_buffer); |
| 1599 | |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1600 | cpu_buffer->nr_pages_to_update = 0; |
Vaibhav Nagarnaik | 05fdd70 | 2012-05-18 13:29:51 -0700 | [diff] [blame] | 1601 | put_online_cpus(); |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1602 | } |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1603 | |
| 1604 | out: |
Steven Rostedt | 659f451 | 2012-05-14 17:02:33 -0400 | [diff] [blame] | 1605 | /* |
| 1606 | * The ring buffer resize can happen with the ring buffer |
| 1607 | * enabled, so that the update disturbs the tracing as little |
| 1608 | * as possible. But if the buffer is disabled, we do not need |
| 1609 | * to worry about that, and we can take the time to verify |
| 1610 | * that the buffer is not corrupt. |
| 1611 | */ |
| 1612 | if (atomic_read(&buffer->record_disabled)) { |
| 1613 | atomic_inc(&buffer->record_disabled); |
| 1614 | /* |
| 1615 | * Even though the buffer was disabled, we must make sure |
| 1616 | * that it is truly disabled before calling rb_check_pages. |
| 1617 | * There could have been a race between checking |
| 1618 | * record_disable and incrementing it. |
| 1619 | */ |
| 1620 | synchronize_sched(); |
| 1621 | for_each_buffer_cpu(buffer, cpu) { |
| 1622 | cpu_buffer = buffer->buffers[cpu]; |
| 1623 | rb_check_pages(cpu_buffer); |
| 1624 | } |
| 1625 | atomic_dec(&buffer->record_disabled); |
| 1626 | } |
| 1627 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1628 | mutex_unlock(&buffer->mutex); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1629 | return size; |
| 1630 | |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1631 | out_err: |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1632 | for_each_buffer_cpu(buffer, cpu) { |
| 1633 | struct buffer_page *bpage, *tmp; |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1634 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1635 | cpu_buffer = buffer->buffers[cpu]; |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1636 | cpu_buffer->nr_pages_to_update = 0; |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1637 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1638 | if (list_empty(&cpu_buffer->new_pages)) |
| 1639 | continue; |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1640 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1641 | list_for_each_entry_safe(bpage, tmp, &cpu_buffer->new_pages, |
| 1642 | list) { |
| 1643 | list_del_init(&bpage->list); |
| 1644 | free_buffer_page(bpage); |
| 1645 | } |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1646 | } |
Vegard Nossum | 641d2f6 | 2008-11-18 19:22:13 +0100 | [diff] [blame] | 1647 | mutex_unlock(&buffer->mutex); |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 1648 | return err; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1649 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 1650 | EXPORT_SYMBOL_GPL(ring_buffer_resize); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1651 | |
David Sharp | 750912f | 2010-12-08 13:46:47 -0800 | [diff] [blame] | 1652 | void ring_buffer_change_overwrite(struct ring_buffer *buffer, int val) |
| 1653 | { |
| 1654 | mutex_lock(&buffer->mutex); |
| 1655 | if (val) |
| 1656 | buffer->flags |= RB_FL_OVERWRITE; |
| 1657 | else |
| 1658 | buffer->flags &= ~RB_FL_OVERWRITE; |
| 1659 | mutex_unlock(&buffer->mutex); |
| 1660 | } |
| 1661 | EXPORT_SYMBOL_GPL(ring_buffer_change_overwrite); |
| 1662 | |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 1663 | static inline void * |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1664 | __rb_data_page_index(struct buffer_data_page *bpage, unsigned index) |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 1665 | { |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1666 | return bpage->data + index; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 1667 | } |
| 1668 | |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1669 | static inline void *__rb_page_index(struct buffer_page *bpage, unsigned index) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1670 | { |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 1671 | return bpage->page->data + index; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1672 | } |
| 1673 | |
| 1674 | static inline struct ring_buffer_event * |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1675 | rb_reader_event(struct ring_buffer_per_cpu *cpu_buffer) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1676 | { |
Steven Rostedt | 6f807ac | 2008-10-04 02:00:58 -0400 | [diff] [blame] | 1677 | return __rb_page_index(cpu_buffer->reader_page, |
| 1678 | cpu_buffer->reader_page->read); |
| 1679 | } |
| 1680 | |
| 1681 | static inline struct ring_buffer_event * |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1682 | rb_iter_head_event(struct ring_buffer_iter *iter) |
| 1683 | { |
Steven Rostedt | 6f807ac | 2008-10-04 02:00:58 -0400 | [diff] [blame] | 1684 | return __rb_page_index(iter->head_page, iter->head); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1685 | } |
| 1686 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1687 | static inline unsigned rb_page_commit(struct buffer_page *bpage) |
| 1688 | { |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 1689 | return local_read(&bpage->page->commit); |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1690 | } |
| 1691 | |
Lucas De Marchi | 25985ed | 2011-03-30 22:57:33 -0300 | [diff] [blame] | 1692 | /* Size is determined by what has been committed */ |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1693 | static inline unsigned rb_page_size(struct buffer_page *bpage) |
| 1694 | { |
| 1695 | return rb_page_commit(bpage); |
| 1696 | } |
| 1697 | |
| 1698 | static inline unsigned |
| 1699 | rb_commit_index(struct ring_buffer_per_cpu *cpu_buffer) |
| 1700 | { |
| 1701 | return rb_page_commit(cpu_buffer->commit_page); |
| 1702 | } |
| 1703 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1704 | static inline unsigned |
| 1705 | rb_event_index(struct ring_buffer_event *event) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1706 | { |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1707 | unsigned long addr = (unsigned long)event; |
| 1708 | |
Steven Rostedt | 22f470f | 2009-06-11 09:29:58 -0400 | [diff] [blame] | 1709 | return (addr & ~PAGE_MASK) - BUF_PAGE_HDR_SIZE; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1710 | } |
| 1711 | |
Steven Rostedt | 0f0c85f | 2009-05-11 16:08:00 -0400 | [diff] [blame] | 1712 | static inline int |
Steven Rostedt | fa74395 | 2009-06-16 12:37:57 -0400 | [diff] [blame] | 1713 | rb_event_is_commit(struct ring_buffer_per_cpu *cpu_buffer, |
| 1714 | struct ring_buffer_event *event) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1715 | { |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1716 | unsigned long addr = (unsigned long)event; |
| 1717 | unsigned long index; |
| 1718 | |
| 1719 | index = rb_event_index(event); |
| 1720 | addr &= PAGE_MASK; |
| 1721 | |
| 1722 | return cpu_buffer->commit_page->page == (void *)addr && |
| 1723 | rb_commit_index(cpu_buffer) == index; |
| 1724 | } |
| 1725 | |
Andrew Morton | 34a148b | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 1726 | static void |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1727 | rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer) |
| 1728 | { |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1729 | unsigned long max_count; |
| 1730 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1731 | /* |
| 1732 | * We only race with interrupts and NMIs on this CPU. |
| 1733 | * If we own the commit event, then we can commit |
| 1734 | * all others that interrupted us, since the interruptions |
| 1735 | * are in stack format (they finish before they come |
| 1736 | * back to us). This allows us to do a simple loop to |
| 1737 | * assign the commit to the tail. |
| 1738 | */ |
Steven Rostedt | a8ccf1d | 2008-12-23 11:32:24 -0500 | [diff] [blame] | 1739 | again: |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 1740 | max_count = cpu_buffer->nr_pages * 100; |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1741 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1742 | while (cpu_buffer->commit_page != cpu_buffer->tail_page) { |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1743 | if (RB_WARN_ON(cpu_buffer, !(--max_count))) |
| 1744 | return; |
| 1745 | if (RB_WARN_ON(cpu_buffer, |
| 1746 | rb_is_reader_page(cpu_buffer->tail_page))) |
| 1747 | return; |
| 1748 | local_set(&cpu_buffer->commit_page->page->commit, |
| 1749 | rb_page_write(cpu_buffer->commit_page)); |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1750 | rb_inc_page(cpu_buffer, &cpu_buffer->commit_page); |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 1751 | cpu_buffer->write_stamp = |
| 1752 | cpu_buffer->commit_page->page->time_stamp; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1753 | /* add barrier to keep gcc from optimizing too much */ |
| 1754 | barrier(); |
| 1755 | } |
| 1756 | while (rb_commit_index(cpu_buffer) != |
| 1757 | rb_page_write(cpu_buffer->commit_page)) { |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1758 | |
| 1759 | local_set(&cpu_buffer->commit_page->page->commit, |
| 1760 | rb_page_write(cpu_buffer->commit_page)); |
| 1761 | RB_WARN_ON(cpu_buffer, |
| 1762 | local_read(&cpu_buffer->commit_page->page->commit) & |
| 1763 | ~RB_WRITE_MASK); |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 1764 | barrier(); |
| 1765 | } |
Steven Rostedt | a8ccf1d | 2008-12-23 11:32:24 -0500 | [diff] [blame] | 1766 | |
| 1767 | /* again, keep gcc from optimizing */ |
| 1768 | barrier(); |
| 1769 | |
| 1770 | /* |
| 1771 | * If an interrupt came in just after the first while loop |
| 1772 | * and pushed the tail page forward, we will be left with |
| 1773 | * a dangling commit that will never go forward. |
| 1774 | */ |
| 1775 | if (unlikely(cpu_buffer->commit_page != cpu_buffer->tail_page)) |
| 1776 | goto again; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1777 | } |
| 1778 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1779 | static void rb_reset_reader_page(struct ring_buffer_per_cpu *cpu_buffer) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1780 | { |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 1781 | cpu_buffer->read_stamp = cpu_buffer->reader_page->page->time_stamp; |
Steven Rostedt | 6f807ac | 2008-10-04 02:00:58 -0400 | [diff] [blame] | 1782 | cpu_buffer->reader_page->read = 0; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1783 | } |
| 1784 | |
Andrew Morton | 34a148b | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 1785 | static void rb_inc_iter(struct ring_buffer_iter *iter) |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1786 | { |
| 1787 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; |
| 1788 | |
| 1789 | /* |
| 1790 | * The iterator could be on the reader page (it starts there). |
| 1791 | * But the head could have moved, since the reader was |
| 1792 | * found. Check for this case and assign the iterator |
| 1793 | * to the head page instead of next. |
| 1794 | */ |
| 1795 | if (iter->head_page == cpu_buffer->reader_page) |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1796 | iter->head_page = rb_set_head_page(cpu_buffer); |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 1797 | else |
| 1798 | rb_inc_page(cpu_buffer, &iter->head_page); |
| 1799 | |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 1800 | iter->read_stamp = iter->head_page->page->time_stamp; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1801 | iter->head = 0; |
| 1802 | } |
| 1803 | |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 1804 | /* Slow path, do not inline */ |
| 1805 | static noinline struct ring_buffer_event * |
| 1806 | rb_add_time_stamp(struct ring_buffer_event *event, u64 delta) |
| 1807 | { |
| 1808 | event->type_len = RINGBUF_TYPE_TIME_EXTEND; |
| 1809 | |
| 1810 | /* Not the first event on the page? */ |
| 1811 | if (rb_event_index(event)) { |
| 1812 | event->time_delta = delta & TS_MASK; |
| 1813 | event->array[0] = delta >> TS_SHIFT; |
| 1814 | } else { |
| 1815 | /* nope, just zero it */ |
| 1816 | event->time_delta = 0; |
| 1817 | event->array[0] = 0; |
| 1818 | } |
| 1819 | |
| 1820 | return skip_time_extend(event); |
| 1821 | } |
| 1822 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1823 | /** |
David Sharp | 01e3e71 | 2012-06-07 16:46:24 -0700 | [diff] [blame] | 1824 | * rb_update_event - update event type and data |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1825 | * @event: the even to update |
| 1826 | * @type: the type of event |
| 1827 | * @length: the size of the event field in the ring buffer |
| 1828 | * |
| 1829 | * Update the type and data fields of the event. The length |
| 1830 | * is the actual size that is written to the ring buffer, |
| 1831 | * and with this, we can determine what to place into the |
| 1832 | * data field. |
| 1833 | */ |
Andrew Morton | 34a148b | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 1834 | static void |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 1835 | rb_update_event(struct ring_buffer_per_cpu *cpu_buffer, |
| 1836 | struct ring_buffer_event *event, unsigned length, |
| 1837 | int add_timestamp, u64 delta) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1838 | { |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 1839 | /* Only a commit updates the timestamp */ |
| 1840 | if (unlikely(!rb_event_is_commit(cpu_buffer, event))) |
| 1841 | delta = 0; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1842 | |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 1843 | /* |
| 1844 | * If we need to add a timestamp, then we |
| 1845 | * add it to the start of the resevered space. |
| 1846 | */ |
| 1847 | if (unlikely(add_timestamp)) { |
| 1848 | event = rb_add_time_stamp(event, delta); |
| 1849 | length -= RB_LEN_TIME_EXTEND; |
| 1850 | delta = 0; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1851 | } |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 1852 | |
| 1853 | event->time_delta = delta; |
| 1854 | length -= RB_EVNT_HDR_SIZE; |
| 1855 | if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT) { |
| 1856 | event->type_len = 0; |
| 1857 | event->array[0] = length; |
| 1858 | } else |
| 1859 | event->type_len = DIV_ROUND_UP(length, RB_ALIGNMENT); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 1860 | } |
| 1861 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1862 | /* |
| 1863 | * rb_handle_head_page - writer hit the head page |
| 1864 | * |
| 1865 | * Returns: +1 to retry page |
| 1866 | * 0 to continue |
| 1867 | * -1 on error |
| 1868 | */ |
| 1869 | static int |
| 1870 | rb_handle_head_page(struct ring_buffer_per_cpu *cpu_buffer, |
| 1871 | struct buffer_page *tail_page, |
| 1872 | struct buffer_page *next_page) |
| 1873 | { |
| 1874 | struct buffer_page *new_head; |
| 1875 | int entries; |
| 1876 | int type; |
| 1877 | int ret; |
| 1878 | |
| 1879 | entries = rb_page_entries(next_page); |
| 1880 | |
| 1881 | /* |
| 1882 | * The hard part is here. We need to move the head |
| 1883 | * forward, and protect against both readers on |
| 1884 | * other CPUs and writers coming in via interrupts. |
| 1885 | */ |
| 1886 | type = rb_head_page_set_update(cpu_buffer, next_page, tail_page, |
| 1887 | RB_PAGE_HEAD); |
| 1888 | |
| 1889 | /* |
| 1890 | * type can be one of four: |
| 1891 | * NORMAL - an interrupt already moved it for us |
| 1892 | * HEAD - we are the first to get here. |
| 1893 | * UPDATE - we are the interrupt interrupting |
| 1894 | * a current move. |
| 1895 | * MOVED - a reader on another CPU moved the next |
| 1896 | * pointer to its reader page. Give up |
| 1897 | * and try again. |
| 1898 | */ |
| 1899 | |
| 1900 | switch (type) { |
| 1901 | case RB_PAGE_HEAD: |
| 1902 | /* |
| 1903 | * We changed the head to UPDATE, thus |
| 1904 | * it is our responsibility to update |
| 1905 | * the counters. |
| 1906 | */ |
| 1907 | local_add(entries, &cpu_buffer->overrun); |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 1908 | local_sub(BUF_PAGE_SIZE, &cpu_buffer->entries_bytes); |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 1909 | |
| 1910 | /* |
| 1911 | * The entries will be zeroed out when we move the |
| 1912 | * tail page. |
| 1913 | */ |
| 1914 | |
| 1915 | /* still more to do */ |
| 1916 | break; |
| 1917 | |
| 1918 | case RB_PAGE_UPDATE: |
| 1919 | /* |
| 1920 | * This is an interrupt that interrupt the |
| 1921 | * previous update. Still more to do. |
| 1922 | */ |
| 1923 | break; |
| 1924 | case RB_PAGE_NORMAL: |
| 1925 | /* |
| 1926 | * An interrupt came in before the update |
| 1927 | * and processed this for us. |
| 1928 | * Nothing left to do. |
| 1929 | */ |
| 1930 | return 1; |
| 1931 | case RB_PAGE_MOVED: |
| 1932 | /* |
| 1933 | * The reader is on another CPU and just did |
| 1934 | * a swap with our next_page. |
| 1935 | * Try again. |
| 1936 | */ |
| 1937 | return 1; |
| 1938 | default: |
| 1939 | RB_WARN_ON(cpu_buffer, 1); /* WTF??? */ |
| 1940 | return -1; |
| 1941 | } |
| 1942 | |
| 1943 | /* |
| 1944 | * Now that we are here, the old head pointer is |
| 1945 | * set to UPDATE. This will keep the reader from |
| 1946 | * swapping the head page with the reader page. |
| 1947 | * The reader (on another CPU) will spin till |
| 1948 | * we are finished. |
| 1949 | * |
| 1950 | * We just need to protect against interrupts |
| 1951 | * doing the job. We will set the next pointer |
| 1952 | * to HEAD. After that, we set the old pointer |
| 1953 | * to NORMAL, but only if it was HEAD before. |
| 1954 | * otherwise we are an interrupt, and only |
| 1955 | * want the outer most commit to reset it. |
| 1956 | */ |
| 1957 | new_head = next_page; |
| 1958 | rb_inc_page(cpu_buffer, &new_head); |
| 1959 | |
| 1960 | ret = rb_head_page_set_head(cpu_buffer, new_head, next_page, |
| 1961 | RB_PAGE_NORMAL); |
| 1962 | |
| 1963 | /* |
| 1964 | * Valid returns are: |
| 1965 | * HEAD - an interrupt came in and already set it. |
| 1966 | * NORMAL - One of two things: |
| 1967 | * 1) We really set it. |
| 1968 | * 2) A bunch of interrupts came in and moved |
| 1969 | * the page forward again. |
| 1970 | */ |
| 1971 | switch (ret) { |
| 1972 | case RB_PAGE_HEAD: |
| 1973 | case RB_PAGE_NORMAL: |
| 1974 | /* OK */ |
| 1975 | break; |
| 1976 | default: |
| 1977 | RB_WARN_ON(cpu_buffer, 1); |
| 1978 | return -1; |
| 1979 | } |
| 1980 | |
| 1981 | /* |
| 1982 | * It is possible that an interrupt came in, |
| 1983 | * set the head up, then more interrupts came in |
| 1984 | * and moved it again. When we get back here, |
| 1985 | * the page would have been set to NORMAL but we |
| 1986 | * just set it back to HEAD. |
| 1987 | * |
| 1988 | * How do you detect this? Well, if that happened |
| 1989 | * the tail page would have moved. |
| 1990 | */ |
| 1991 | if (ret == RB_PAGE_NORMAL) { |
| 1992 | /* |
| 1993 | * If the tail had moved passed next, then we need |
| 1994 | * to reset the pointer. |
| 1995 | */ |
| 1996 | if (cpu_buffer->tail_page != tail_page && |
| 1997 | cpu_buffer->tail_page != next_page) |
| 1998 | rb_head_page_set_normal(cpu_buffer, new_head, |
| 1999 | next_page, |
| 2000 | RB_PAGE_HEAD); |
| 2001 | } |
| 2002 | |
| 2003 | /* |
| 2004 | * If this was the outer most commit (the one that |
| 2005 | * changed the original pointer from HEAD to UPDATE), |
| 2006 | * then it is up to us to reset it to NORMAL. |
| 2007 | */ |
| 2008 | if (type == RB_PAGE_HEAD) { |
| 2009 | ret = rb_head_page_set_normal(cpu_buffer, next_page, |
| 2010 | tail_page, |
| 2011 | RB_PAGE_UPDATE); |
| 2012 | if (RB_WARN_ON(cpu_buffer, |
| 2013 | ret != RB_PAGE_UPDATE)) |
| 2014 | return -1; |
| 2015 | } |
| 2016 | |
| 2017 | return 0; |
| 2018 | } |
| 2019 | |
Andrew Morton | 34a148b | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 2020 | static unsigned rb_calculate_event_length(unsigned length) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2021 | { |
| 2022 | struct ring_buffer_event event; /* Used only for sizeof array */ |
| 2023 | |
| 2024 | /* zero length can cause confusions */ |
| 2025 | if (!length) |
| 2026 | length = 1; |
| 2027 | |
Steven Rostedt | 2271048 | 2010-03-18 17:54:19 -0400 | [diff] [blame] | 2028 | if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2029 | length += sizeof(event.array[0]); |
| 2030 | |
| 2031 | length += RB_EVNT_HDR_SIZE; |
Steven Rostedt | 2271048 | 2010-03-18 17:54:19 -0400 | [diff] [blame] | 2032 | length = ALIGN(length, RB_ARCH_ALIGNMENT); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2033 | |
| 2034 | return length; |
| 2035 | } |
| 2036 | |
Steven Rostedt | c7b0930 | 2009-06-11 11:12:00 -0400 | [diff] [blame] | 2037 | static inline void |
| 2038 | rb_reset_tail(struct ring_buffer_per_cpu *cpu_buffer, |
| 2039 | struct buffer_page *tail_page, |
| 2040 | unsigned long tail, unsigned long length) |
| 2041 | { |
| 2042 | struct ring_buffer_event *event; |
| 2043 | |
| 2044 | /* |
| 2045 | * Only the event that crossed the page boundary |
| 2046 | * must fill the old tail_page with padding. |
| 2047 | */ |
| 2048 | if (tail >= BUF_PAGE_SIZE) { |
Steven Rostedt | b3230c8 | 2010-05-21 11:55:21 -0400 | [diff] [blame] | 2049 | /* |
| 2050 | * If the page was filled, then we still need |
| 2051 | * to update the real_end. Reset it to zero |
| 2052 | * and the reader will ignore it. |
| 2053 | */ |
| 2054 | if (tail == BUF_PAGE_SIZE) |
| 2055 | tail_page->real_end = 0; |
| 2056 | |
Steven Rostedt | c7b0930 | 2009-06-11 11:12:00 -0400 | [diff] [blame] | 2057 | local_sub(length, &tail_page->write); |
| 2058 | return; |
| 2059 | } |
| 2060 | |
| 2061 | event = __rb_page_index(tail_page, tail); |
Linus Torvalds | b0b7065 | 2009-06-20 10:56:46 -0700 | [diff] [blame] | 2062 | kmemcheck_annotate_bitfield(event, bitfield); |
Steven Rostedt | c7b0930 | 2009-06-11 11:12:00 -0400 | [diff] [blame] | 2063 | |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 2064 | /* account for padding bytes */ |
| 2065 | local_add(BUF_PAGE_SIZE - tail, &cpu_buffer->entries_bytes); |
| 2066 | |
Steven Rostedt | c7b0930 | 2009-06-11 11:12:00 -0400 | [diff] [blame] | 2067 | /* |
Steven Rostedt | ff0ff84 | 2010-03-31 22:11:42 -0400 | [diff] [blame] | 2068 | * Save the original length to the meta data. |
| 2069 | * This will be used by the reader to add lost event |
| 2070 | * counter. |
| 2071 | */ |
| 2072 | tail_page->real_end = tail; |
| 2073 | |
| 2074 | /* |
Steven Rostedt | c7b0930 | 2009-06-11 11:12:00 -0400 | [diff] [blame] | 2075 | * If this event is bigger than the minimum size, then |
| 2076 | * we need to be careful that we don't subtract the |
| 2077 | * write counter enough to allow another writer to slip |
| 2078 | * in on this page. |
| 2079 | * We put in a discarded commit instead, to make sure |
| 2080 | * that this space is not used again. |
| 2081 | * |
| 2082 | * If we are less than the minimum size, we don't need to |
| 2083 | * worry about it. |
| 2084 | */ |
| 2085 | if (tail > (BUF_PAGE_SIZE - RB_EVNT_MIN_SIZE)) { |
| 2086 | /* No room for any events */ |
| 2087 | |
| 2088 | /* Mark the rest of the page with padding */ |
| 2089 | rb_event_set_padding(event); |
| 2090 | |
| 2091 | /* Set the write back to the previous setting */ |
| 2092 | local_sub(length, &tail_page->write); |
| 2093 | return; |
| 2094 | } |
| 2095 | |
| 2096 | /* Put in a discarded event */ |
| 2097 | event->array[0] = (BUF_PAGE_SIZE - tail) - RB_EVNT_HDR_SIZE; |
| 2098 | event->type_len = RINGBUF_TYPE_PADDING; |
| 2099 | /* time delta must be non zero */ |
| 2100 | event->time_delta = 1; |
Steven Rostedt | c7b0930 | 2009-06-11 11:12:00 -0400 | [diff] [blame] | 2101 | |
| 2102 | /* Set write to end of buffer */ |
| 2103 | length = (tail + length) - BUF_PAGE_SIZE; |
| 2104 | local_sub(length, &tail_page->write); |
| 2105 | } |
Steven Rostedt | 6634ff2 | 2009-05-06 15:30:07 -0400 | [diff] [blame] | 2106 | |
Steven Rostedt | 747e94a | 2010-10-08 13:51:48 -0400 | [diff] [blame] | 2107 | /* |
| 2108 | * This is the slow path, force gcc not to inline it. |
| 2109 | */ |
| 2110 | static noinline struct ring_buffer_event * |
Steven Rostedt | 6634ff2 | 2009-05-06 15:30:07 -0400 | [diff] [blame] | 2111 | rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer, |
| 2112 | unsigned long length, unsigned long tail, |
Steven Rostedt | e8bc43e | 2010-10-20 10:58:02 -0400 | [diff] [blame] | 2113 | struct buffer_page *tail_page, u64 ts) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2114 | { |
Steven Rostedt | 5a50e33 | 2009-11-17 08:43:01 -0500 | [diff] [blame] | 2115 | struct buffer_page *commit_page = cpu_buffer->commit_page; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2116 | struct ring_buffer *buffer = cpu_buffer->buffer; |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 2117 | struct buffer_page *next_page; |
| 2118 | int ret; |
Steven Rostedt | aa20ae8 | 2009-05-05 21:16:11 -0400 | [diff] [blame] | 2119 | |
| 2120 | next_page = tail_page; |
| 2121 | |
Steven Rostedt | aa20ae8 | 2009-05-05 21:16:11 -0400 | [diff] [blame] | 2122 | rb_inc_page(cpu_buffer, &next_page); |
| 2123 | |
Steven Rostedt | aa20ae8 | 2009-05-05 21:16:11 -0400 | [diff] [blame] | 2124 | /* |
| 2125 | * If for some reason, we had an interrupt storm that made |
| 2126 | * it all the way around the buffer, bail, and warn |
| 2127 | * about it. |
| 2128 | */ |
| 2129 | if (unlikely(next_page == commit_page)) { |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 2130 | local_inc(&cpu_buffer->commit_overrun); |
Steven Rostedt | aa20ae8 | 2009-05-05 21:16:11 -0400 | [diff] [blame] | 2131 | goto out_reset; |
| 2132 | } |
| 2133 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 2134 | /* |
| 2135 | * This is where the fun begins! |
| 2136 | * |
| 2137 | * We are fighting against races between a reader that |
| 2138 | * could be on another CPU trying to swap its reader |
| 2139 | * page with the buffer head. |
| 2140 | * |
| 2141 | * We are also fighting against interrupts coming in and |
| 2142 | * moving the head or tail on us as well. |
| 2143 | * |
| 2144 | * If the next page is the head page then we have filled |
| 2145 | * the buffer, unless the commit page is still on the |
| 2146 | * reader page. |
| 2147 | */ |
| 2148 | if (rb_is_head_page(cpu_buffer, next_page, &tail_page->list)) { |
Steven Rostedt | aa20ae8 | 2009-05-05 21:16:11 -0400 | [diff] [blame] | 2149 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 2150 | /* |
| 2151 | * If the commit is not on the reader page, then |
| 2152 | * move the header page. |
| 2153 | */ |
| 2154 | if (!rb_is_reader_page(cpu_buffer->commit_page)) { |
| 2155 | /* |
| 2156 | * If we are not in overwrite mode, |
| 2157 | * this is easy, just stop here. |
| 2158 | */ |
Slava Pestov | 884bfe8 | 2011-07-15 14:23:58 -0700 | [diff] [blame] | 2159 | if (!(buffer->flags & RB_FL_OVERWRITE)) { |
| 2160 | local_inc(&cpu_buffer->dropped_events); |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 2161 | goto out_reset; |
Slava Pestov | 884bfe8 | 2011-07-15 14:23:58 -0700 | [diff] [blame] | 2162 | } |
Steven Rostedt | aa20ae8 | 2009-05-05 21:16:11 -0400 | [diff] [blame] | 2163 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 2164 | ret = rb_handle_head_page(cpu_buffer, |
| 2165 | tail_page, |
| 2166 | next_page); |
| 2167 | if (ret < 0) |
| 2168 | goto out_reset; |
| 2169 | if (ret) |
| 2170 | goto out_again; |
| 2171 | } else { |
| 2172 | /* |
| 2173 | * We need to be careful here too. The |
| 2174 | * commit page could still be on the reader |
| 2175 | * page. We could have a small buffer, and |
| 2176 | * have filled up the buffer with events |
| 2177 | * from interrupts and such, and wrapped. |
| 2178 | * |
| 2179 | * Note, if the tail page is also the on the |
| 2180 | * reader_page, we let it move out. |
| 2181 | */ |
| 2182 | if (unlikely((cpu_buffer->commit_page != |
| 2183 | cpu_buffer->tail_page) && |
| 2184 | (cpu_buffer->commit_page == |
| 2185 | cpu_buffer->reader_page))) { |
| 2186 | local_inc(&cpu_buffer->commit_overrun); |
| 2187 | goto out_reset; |
| 2188 | } |
Steven Rostedt | aa20ae8 | 2009-05-05 21:16:11 -0400 | [diff] [blame] | 2189 | } |
| 2190 | } |
| 2191 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 2192 | ret = rb_tail_page_update(cpu_buffer, tail_page, next_page); |
| 2193 | if (ret) { |
| 2194 | /* |
| 2195 | * Nested commits always have zero deltas, so |
| 2196 | * just reread the time stamp |
| 2197 | */ |
Steven Rostedt | e8bc43e | 2010-10-20 10:58:02 -0400 | [diff] [blame] | 2198 | ts = rb_time_stamp(buffer); |
| 2199 | next_page->page->time_stamp = ts; |
Steven Rostedt | aa20ae8 | 2009-05-05 21:16:11 -0400 | [diff] [blame] | 2200 | } |
| 2201 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 2202 | out_again: |
Steven Rostedt | aa20ae8 | 2009-05-05 21:16:11 -0400 | [diff] [blame] | 2203 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 2204 | rb_reset_tail(cpu_buffer, tail_page, tail, length); |
Steven Rostedt | aa20ae8 | 2009-05-05 21:16:11 -0400 | [diff] [blame] | 2205 | |
| 2206 | /* fail and let the caller try again */ |
| 2207 | return ERR_PTR(-EAGAIN); |
| 2208 | |
Steven Rostedt | 45141d4 | 2009-02-12 13:19:48 -0500 | [diff] [blame] | 2209 | out_reset: |
Lai Jiangshan | 6f3b344 | 2009-01-12 11:06:18 +0800 | [diff] [blame] | 2210 | /* reset write */ |
Steven Rostedt | c7b0930 | 2009-06-11 11:12:00 -0400 | [diff] [blame] | 2211 | rb_reset_tail(cpu_buffer, tail_page, tail, length); |
Lai Jiangshan | 6f3b344 | 2009-01-12 11:06:18 +0800 | [diff] [blame] | 2212 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 2213 | return NULL; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2214 | } |
| 2215 | |
Steven Rostedt | 6634ff2 | 2009-05-06 15:30:07 -0400 | [diff] [blame] | 2216 | static struct ring_buffer_event * |
| 2217 | __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 2218 | unsigned long length, u64 ts, |
| 2219 | u64 delta, int add_timestamp) |
Steven Rostedt | 6634ff2 | 2009-05-06 15:30:07 -0400 | [diff] [blame] | 2220 | { |
Steven Rostedt | 5a50e33 | 2009-11-17 08:43:01 -0500 | [diff] [blame] | 2221 | struct buffer_page *tail_page; |
Steven Rostedt | 6634ff2 | 2009-05-06 15:30:07 -0400 | [diff] [blame] | 2222 | struct ring_buffer_event *event; |
| 2223 | unsigned long tail, write; |
| 2224 | |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 2225 | /* |
| 2226 | * If the time delta since the last event is too big to |
| 2227 | * hold in the time field of the event, then we append a |
| 2228 | * TIME EXTEND event ahead of the data event. |
| 2229 | */ |
| 2230 | if (unlikely(add_timestamp)) |
| 2231 | length += RB_LEN_TIME_EXTEND; |
| 2232 | |
Steven Rostedt | 6634ff2 | 2009-05-06 15:30:07 -0400 | [diff] [blame] | 2233 | tail_page = cpu_buffer->tail_page; |
| 2234 | write = local_add_return(length, &tail_page->write); |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 2235 | |
| 2236 | /* set write to only the index of the write */ |
| 2237 | write &= RB_WRITE_MASK; |
Steven Rostedt | 6634ff2 | 2009-05-06 15:30:07 -0400 | [diff] [blame] | 2238 | tail = write - length; |
| 2239 | |
| 2240 | /* See if we shot pass the end of this buffer page */ |
Steven Rostedt | 747e94a | 2010-10-08 13:51:48 -0400 | [diff] [blame] | 2241 | if (unlikely(write > BUF_PAGE_SIZE)) |
Steven Rostedt | 6634ff2 | 2009-05-06 15:30:07 -0400 | [diff] [blame] | 2242 | return rb_move_tail(cpu_buffer, length, tail, |
Steven Rostedt | 5a50e33 | 2009-11-17 08:43:01 -0500 | [diff] [blame] | 2243 | tail_page, ts); |
Steven Rostedt | 6634ff2 | 2009-05-06 15:30:07 -0400 | [diff] [blame] | 2244 | |
| 2245 | /* We reserved something on the buffer */ |
| 2246 | |
Steven Rostedt | 6634ff2 | 2009-05-06 15:30:07 -0400 | [diff] [blame] | 2247 | event = __rb_page_index(tail_page, tail); |
Vegard Nossum | 1744a21 | 2009-02-28 08:29:44 +0100 | [diff] [blame] | 2248 | kmemcheck_annotate_bitfield(event, bitfield); |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 2249 | rb_update_event(cpu_buffer, event, length, add_timestamp, delta); |
Steven Rostedt | 6634ff2 | 2009-05-06 15:30:07 -0400 | [diff] [blame] | 2250 | |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 2251 | local_inc(&tail_page->entries); |
Steven Rostedt | 6634ff2 | 2009-05-06 15:30:07 -0400 | [diff] [blame] | 2252 | |
| 2253 | /* |
Steven Rostedt | fa74395 | 2009-06-16 12:37:57 -0400 | [diff] [blame] | 2254 | * If this is the first commit on the page, then update |
| 2255 | * its timestamp. |
Steven Rostedt | 6634ff2 | 2009-05-06 15:30:07 -0400 | [diff] [blame] | 2256 | */ |
Steven Rostedt | fa74395 | 2009-06-16 12:37:57 -0400 | [diff] [blame] | 2257 | if (!tail) |
Steven Rostedt | e8bc43e | 2010-10-20 10:58:02 -0400 | [diff] [blame] | 2258 | tail_page->page->time_stamp = ts; |
Steven Rostedt | 6634ff2 | 2009-05-06 15:30:07 -0400 | [diff] [blame] | 2259 | |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 2260 | /* account for these added bytes */ |
| 2261 | local_add(length, &cpu_buffer->entries_bytes); |
| 2262 | |
Steven Rostedt | 6634ff2 | 2009-05-06 15:30:07 -0400 | [diff] [blame] | 2263 | return event; |
| 2264 | } |
| 2265 | |
Steven Rostedt | edd813bf | 2009-06-02 23:00:53 -0400 | [diff] [blame] | 2266 | static inline int |
| 2267 | rb_try_to_discard(struct ring_buffer_per_cpu *cpu_buffer, |
| 2268 | struct ring_buffer_event *event) |
| 2269 | { |
| 2270 | unsigned long new_index, old_index; |
| 2271 | struct buffer_page *bpage; |
| 2272 | unsigned long index; |
| 2273 | unsigned long addr; |
| 2274 | |
| 2275 | new_index = rb_event_index(event); |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 2276 | old_index = new_index + rb_event_ts_length(event); |
Steven Rostedt | edd813bf | 2009-06-02 23:00:53 -0400 | [diff] [blame] | 2277 | addr = (unsigned long)event; |
| 2278 | addr &= PAGE_MASK; |
| 2279 | |
| 2280 | bpage = cpu_buffer->tail_page; |
| 2281 | |
| 2282 | if (bpage->page == (void *)addr && rb_page_write(bpage) == old_index) { |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 2283 | unsigned long write_mask = |
| 2284 | local_read(&bpage->write) & ~RB_WRITE_MASK; |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 2285 | unsigned long event_length = rb_event_length(event); |
Steven Rostedt | edd813bf | 2009-06-02 23:00:53 -0400 | [diff] [blame] | 2286 | /* |
| 2287 | * This is on the tail page. It is possible that |
| 2288 | * a write could come in and move the tail page |
| 2289 | * and write to the next page. That is fine |
| 2290 | * because we just shorten what is on this page. |
| 2291 | */ |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 2292 | old_index += write_mask; |
| 2293 | new_index += write_mask; |
Steven Rostedt | edd813bf | 2009-06-02 23:00:53 -0400 | [diff] [blame] | 2294 | index = local_cmpxchg(&bpage->write, old_index, new_index); |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 2295 | if (index == old_index) { |
| 2296 | /* update counters */ |
| 2297 | local_sub(event_length, &cpu_buffer->entries_bytes); |
Steven Rostedt | edd813bf | 2009-06-02 23:00:53 -0400 | [diff] [blame] | 2298 | return 1; |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 2299 | } |
Steven Rostedt | edd813bf | 2009-06-02 23:00:53 -0400 | [diff] [blame] | 2300 | } |
| 2301 | |
| 2302 | /* could not discard */ |
| 2303 | return 0; |
| 2304 | } |
| 2305 | |
Steven Rostedt | fa74395 | 2009-06-16 12:37:57 -0400 | [diff] [blame] | 2306 | static void rb_start_commit(struct ring_buffer_per_cpu *cpu_buffer) |
| 2307 | { |
| 2308 | local_inc(&cpu_buffer->committing); |
| 2309 | local_inc(&cpu_buffer->commits); |
| 2310 | } |
| 2311 | |
Steven Rostedt | d9abde2 | 2010-10-19 13:17:08 -0400 | [diff] [blame] | 2312 | static inline void rb_end_commit(struct ring_buffer_per_cpu *cpu_buffer) |
Steven Rostedt | fa74395 | 2009-06-16 12:37:57 -0400 | [diff] [blame] | 2313 | { |
| 2314 | unsigned long commits; |
| 2315 | |
| 2316 | if (RB_WARN_ON(cpu_buffer, |
| 2317 | !local_read(&cpu_buffer->committing))) |
| 2318 | return; |
| 2319 | |
| 2320 | again: |
| 2321 | commits = local_read(&cpu_buffer->commits); |
| 2322 | /* synchronize with interrupts */ |
| 2323 | barrier(); |
| 2324 | if (local_read(&cpu_buffer->committing) == 1) |
| 2325 | rb_set_commit_to_write(cpu_buffer); |
| 2326 | |
| 2327 | local_dec(&cpu_buffer->committing); |
| 2328 | |
| 2329 | /* synchronize with interrupts */ |
| 2330 | barrier(); |
| 2331 | |
| 2332 | /* |
| 2333 | * Need to account for interrupts coming in between the |
| 2334 | * updating of the commit page and the clearing of the |
| 2335 | * committing counter. |
| 2336 | */ |
| 2337 | if (unlikely(local_read(&cpu_buffer->commits) != commits) && |
| 2338 | !local_read(&cpu_buffer->committing)) { |
| 2339 | local_inc(&cpu_buffer->committing); |
| 2340 | goto again; |
| 2341 | } |
| 2342 | } |
| 2343 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2344 | static struct ring_buffer_event * |
Steven Rostedt | 62f0b3e | 2009-09-04 14:11:34 -0400 | [diff] [blame] | 2345 | rb_reserve_next_event(struct ring_buffer *buffer, |
| 2346 | struct ring_buffer_per_cpu *cpu_buffer, |
Steven Rostedt | 1cd8d73 | 2009-05-11 14:08:09 -0400 | [diff] [blame] | 2347 | unsigned long length) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2348 | { |
| 2349 | struct ring_buffer_event *event; |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 2350 | u64 ts, delta; |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 2351 | int nr_loops = 0; |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 2352 | int add_timestamp; |
Steven Rostedt | 140ff89 | 2010-10-08 10:50:30 -0400 | [diff] [blame] | 2353 | u64 diff; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2354 | |
Steven Rostedt | fa74395 | 2009-06-16 12:37:57 -0400 | [diff] [blame] | 2355 | rb_start_commit(cpu_buffer); |
| 2356 | |
Steven Rostedt | 85bac32 | 2009-09-04 14:24:40 -0400 | [diff] [blame] | 2357 | #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP |
Steven Rostedt | 62f0b3e | 2009-09-04 14:11:34 -0400 | [diff] [blame] | 2358 | /* |
| 2359 | * Due to the ability to swap a cpu buffer from a buffer |
| 2360 | * it is possible it was swapped before we committed. |
| 2361 | * (committing stops a swap). We check for it here and |
| 2362 | * if it happened, we have to fail the write. |
| 2363 | */ |
| 2364 | barrier(); |
| 2365 | if (unlikely(ACCESS_ONCE(cpu_buffer->buffer) != buffer)) { |
| 2366 | local_dec(&cpu_buffer->committing); |
| 2367 | local_dec(&cpu_buffer->commits); |
| 2368 | return NULL; |
| 2369 | } |
Steven Rostedt | 85bac32 | 2009-09-04 14:24:40 -0400 | [diff] [blame] | 2370 | #endif |
Steven Rostedt | 62f0b3e | 2009-09-04 14:11:34 -0400 | [diff] [blame] | 2371 | |
Steven Rostedt | be957c4 | 2009-05-11 14:42:53 -0400 | [diff] [blame] | 2372 | length = rb_calculate_event_length(length); |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 2373 | again: |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 2374 | add_timestamp = 0; |
| 2375 | delta = 0; |
| 2376 | |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 2377 | /* |
| 2378 | * We allow for interrupts to reenter here and do a trace. |
| 2379 | * If one does, it will cause this original code to loop |
| 2380 | * back here. Even with heavy interrupts happening, this |
| 2381 | * should only happen a few times in a row. If this happens |
| 2382 | * 1000 times in a row, there must be either an interrupt |
| 2383 | * storm or we have something buggy. |
| 2384 | * Bail! |
| 2385 | */ |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 2386 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 1000)) |
Steven Rostedt | fa74395 | 2009-06-16 12:37:57 -0400 | [diff] [blame] | 2387 | goto out_fail; |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 2388 | |
Jiri Olsa | 6d3f1e1 | 2009-10-23 19:36:19 -0400 | [diff] [blame] | 2389 | ts = rb_time_stamp(cpu_buffer->buffer); |
Steven Rostedt | 140ff89 | 2010-10-08 10:50:30 -0400 | [diff] [blame] | 2390 | diff = ts - cpu_buffer->write_stamp; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2391 | |
Steven Rostedt | 140ff89 | 2010-10-08 10:50:30 -0400 | [diff] [blame] | 2392 | /* make sure this diff is calculated here */ |
| 2393 | barrier(); |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 2394 | |
Steven Rostedt | 140ff89 | 2010-10-08 10:50:30 -0400 | [diff] [blame] | 2395 | /* Did the write stamp get updated already? */ |
| 2396 | if (likely(ts >= cpu_buffer->write_stamp)) { |
Steven Rostedt | 168b6b1 | 2009-05-11 22:11:05 -0400 | [diff] [blame] | 2397 | delta = diff; |
| 2398 | if (unlikely(test_time_stamp(delta))) { |
Jiri Olsa | 31274d7 | 2011-02-18 15:52:19 +0100 | [diff] [blame] | 2399 | int local_clock_stable = 1; |
| 2400 | #ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK |
| 2401 | local_clock_stable = sched_clock_stable; |
| 2402 | #endif |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 2403 | WARN_ONCE(delta > (1ULL << 59), |
Jiri Olsa | 31274d7 | 2011-02-18 15:52:19 +0100 | [diff] [blame] | 2404 | KERN_WARNING "Delta way too big! %llu ts=%llu write stamp = %llu\n%s", |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 2405 | (unsigned long long)delta, |
| 2406 | (unsigned long long)ts, |
Jiri Olsa | 31274d7 | 2011-02-18 15:52:19 +0100 | [diff] [blame] | 2407 | (unsigned long long)cpu_buffer->write_stamp, |
| 2408 | local_clock_stable ? "" : |
| 2409 | "If you just came from a suspend/resume,\n" |
| 2410 | "please switch to the trace global clock:\n" |
| 2411 | " echo global > /sys/kernel/debug/tracing/trace_clock\n"); |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 2412 | add_timestamp = 1; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2413 | } |
Steven Rostedt | 168b6b1 | 2009-05-11 22:11:05 -0400 | [diff] [blame] | 2414 | } |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2415 | |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 2416 | event = __rb_reserve_next(cpu_buffer, length, ts, |
| 2417 | delta, add_timestamp); |
Steven Rostedt | 168b6b1 | 2009-05-11 22:11:05 -0400 | [diff] [blame] | 2418 | if (unlikely(PTR_ERR(event) == -EAGAIN)) |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 2419 | goto again; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2420 | |
Steven Rostedt | fa74395 | 2009-06-16 12:37:57 -0400 | [diff] [blame] | 2421 | if (!event) |
| 2422 | goto out_fail; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 2423 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2424 | return event; |
Steven Rostedt | fa74395 | 2009-06-16 12:37:57 -0400 | [diff] [blame] | 2425 | |
| 2426 | out_fail: |
| 2427 | rb_end_commit(cpu_buffer); |
| 2428 | return NULL; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2429 | } |
| 2430 | |
Paul Mundt | 1155de4 | 2009-06-25 14:30:12 +0900 | [diff] [blame] | 2431 | #ifdef CONFIG_TRACING |
| 2432 | |
Steven Rostedt | aa18efb | 2009-04-20 16:16:11 -0400 | [diff] [blame] | 2433 | #define TRACE_RECURSIVE_DEPTH 16 |
Steven Rostedt | 261842b | 2009-04-16 21:41:52 -0400 | [diff] [blame] | 2434 | |
Steven Rostedt | d9abde2 | 2010-10-19 13:17:08 -0400 | [diff] [blame] | 2435 | /* Keep this code out of the fast path cache */ |
| 2436 | static noinline void trace_recursive_fail(void) |
Steven Rostedt | 261842b | 2009-04-16 21:41:52 -0400 | [diff] [blame] | 2437 | { |
Steven Rostedt | aa18efb | 2009-04-20 16:16:11 -0400 | [diff] [blame] | 2438 | /* Disable all tracing before we do anything else */ |
| 2439 | tracing_off_permanent(); |
Frederic Weisbecker | e057a5e | 2009-04-19 23:38:12 +0200 | [diff] [blame] | 2440 | |
Steven Rostedt | 7d7d2b8 | 2009-04-27 12:37:49 -0400 | [diff] [blame] | 2441 | printk_once(KERN_WARNING "Tracing recursion: depth[%ld]:" |
Steven Rostedt | aa18efb | 2009-04-20 16:16:11 -0400 | [diff] [blame] | 2442 | "HC[%lu]:SC[%lu]:NMI[%lu]\n", |
Steven Rostedt | b1cff0a | 2011-05-25 14:27:43 -0400 | [diff] [blame] | 2443 | trace_recursion_buffer(), |
Steven Rostedt | aa18efb | 2009-04-20 16:16:11 -0400 | [diff] [blame] | 2444 | hardirq_count() >> HARDIRQ_SHIFT, |
| 2445 | softirq_count() >> SOFTIRQ_SHIFT, |
| 2446 | in_nmi()); |
Frederic Weisbecker | e057a5e | 2009-04-19 23:38:12 +0200 | [diff] [blame] | 2447 | |
Steven Rostedt | aa18efb | 2009-04-20 16:16:11 -0400 | [diff] [blame] | 2448 | WARN_ON_ONCE(1); |
Steven Rostedt | d9abde2 | 2010-10-19 13:17:08 -0400 | [diff] [blame] | 2449 | } |
| 2450 | |
| 2451 | static inline int trace_recursive_lock(void) |
| 2452 | { |
Steven Rostedt | b1cff0a | 2011-05-25 14:27:43 -0400 | [diff] [blame] | 2453 | trace_recursion_inc(); |
Steven Rostedt | d9abde2 | 2010-10-19 13:17:08 -0400 | [diff] [blame] | 2454 | |
Steven Rostedt | b1cff0a | 2011-05-25 14:27:43 -0400 | [diff] [blame] | 2455 | if (likely(trace_recursion_buffer() < TRACE_RECURSIVE_DEPTH)) |
Steven Rostedt | d9abde2 | 2010-10-19 13:17:08 -0400 | [diff] [blame] | 2456 | return 0; |
| 2457 | |
| 2458 | trace_recursive_fail(); |
| 2459 | |
Steven Rostedt | aa18efb | 2009-04-20 16:16:11 -0400 | [diff] [blame] | 2460 | return -1; |
Steven Rostedt | 261842b | 2009-04-16 21:41:52 -0400 | [diff] [blame] | 2461 | } |
| 2462 | |
Steven Rostedt | d9abde2 | 2010-10-19 13:17:08 -0400 | [diff] [blame] | 2463 | static inline void trace_recursive_unlock(void) |
Steven Rostedt | 261842b | 2009-04-16 21:41:52 -0400 | [diff] [blame] | 2464 | { |
Steven Rostedt | b1cff0a | 2011-05-25 14:27:43 -0400 | [diff] [blame] | 2465 | WARN_ON_ONCE(!trace_recursion_buffer()); |
Steven Rostedt | 261842b | 2009-04-16 21:41:52 -0400 | [diff] [blame] | 2466 | |
Steven Rostedt | b1cff0a | 2011-05-25 14:27:43 -0400 | [diff] [blame] | 2467 | trace_recursion_dec(); |
Steven Rostedt | 261842b | 2009-04-16 21:41:52 -0400 | [diff] [blame] | 2468 | } |
| 2469 | |
Paul Mundt | 1155de4 | 2009-06-25 14:30:12 +0900 | [diff] [blame] | 2470 | #else |
| 2471 | |
| 2472 | #define trace_recursive_lock() (0) |
| 2473 | #define trace_recursive_unlock() do { } while (0) |
| 2474 | |
| 2475 | #endif |
| 2476 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2477 | /** |
| 2478 | * ring_buffer_lock_reserve - reserve a part of the buffer |
| 2479 | * @buffer: the ring buffer to reserve from |
| 2480 | * @length: the length of the data to reserve (excluding event header) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2481 | * |
| 2482 | * Returns a reseverd event on the ring buffer to copy directly to. |
| 2483 | * The user of this interface will need to get the body to write into |
| 2484 | * and can use the ring_buffer_event_data() interface. |
| 2485 | * |
| 2486 | * The length is the length of the data needed, not the event length |
| 2487 | * which also includes the event header. |
| 2488 | * |
| 2489 | * Must be paired with ring_buffer_unlock_commit, unless NULL is returned. |
| 2490 | * If NULL is returned, then nothing has been allocated or locked. |
| 2491 | */ |
| 2492 | struct ring_buffer_event * |
Arnaldo Carvalho de Melo | 0a98775 | 2009-02-05 16:12:56 -0200 | [diff] [blame] | 2493 | ring_buffer_lock_reserve(struct ring_buffer *buffer, unsigned long length) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2494 | { |
| 2495 | struct ring_buffer_per_cpu *cpu_buffer; |
| 2496 | struct ring_buffer_event *event; |
Steven Rostedt | 5168ae5 | 2010-06-03 09:36:50 -0400 | [diff] [blame] | 2497 | int cpu; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2498 | |
Steven Rostedt | 033601a | 2008-11-21 12:41:55 -0500 | [diff] [blame] | 2499 | if (ring_buffer_flags != RB_BUFFERS_ON) |
Steven Rostedt | a358324 | 2008-11-11 15:01:42 -0500 | [diff] [blame] | 2500 | return NULL; |
| 2501 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 2502 | /* If we are tracing schedule, we don't want to recurse */ |
Steven Rostedt | 5168ae5 | 2010-06-03 09:36:50 -0400 | [diff] [blame] | 2503 | preempt_disable_notrace(); |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 2504 | |
Lai Jiangshan | 52fbe9c | 2010-03-08 14:50:43 +0800 | [diff] [blame] | 2505 | if (atomic_read(&buffer->record_disabled)) |
| 2506 | goto out_nocheck; |
| 2507 | |
Steven Rostedt | 261842b | 2009-04-16 21:41:52 -0400 | [diff] [blame] | 2508 | if (trace_recursive_lock()) |
| 2509 | goto out_nocheck; |
| 2510 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2511 | cpu = raw_smp_processor_id(); |
| 2512 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 2513 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 2514 | goto out; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2515 | |
| 2516 | cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2517 | |
| 2518 | if (atomic_read(&cpu_buffer->record_disabled)) |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 2519 | goto out; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2520 | |
Steven Rostedt | be957c4 | 2009-05-11 14:42:53 -0400 | [diff] [blame] | 2521 | if (length > BUF_MAX_DATA_SIZE) |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 2522 | goto out; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2523 | |
Steven Rostedt | 62f0b3e | 2009-09-04 14:11:34 -0400 | [diff] [blame] | 2524 | event = rb_reserve_next_event(buffer, cpu_buffer, length); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2525 | if (!event) |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 2526 | goto out; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2527 | |
| 2528 | return event; |
| 2529 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 2530 | out: |
Steven Rostedt | 261842b | 2009-04-16 21:41:52 -0400 | [diff] [blame] | 2531 | trace_recursive_unlock(); |
| 2532 | |
| 2533 | out_nocheck: |
Steven Rostedt | 5168ae5 | 2010-06-03 09:36:50 -0400 | [diff] [blame] | 2534 | preempt_enable_notrace(); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2535 | return NULL; |
| 2536 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 2537 | EXPORT_SYMBOL_GPL(ring_buffer_lock_reserve); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2538 | |
Steven Rostedt | a1863c2 | 2009-09-03 10:23:58 -0400 | [diff] [blame] | 2539 | static void |
| 2540 | rb_update_write_stamp(struct ring_buffer_per_cpu *cpu_buffer, |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2541 | struct ring_buffer_event *event) |
| 2542 | { |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 2543 | u64 delta; |
| 2544 | |
Steven Rostedt | fa74395 | 2009-06-16 12:37:57 -0400 | [diff] [blame] | 2545 | /* |
| 2546 | * The event first in the commit queue updates the |
| 2547 | * time stamp. |
| 2548 | */ |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 2549 | if (rb_event_is_commit(cpu_buffer, event)) { |
| 2550 | /* |
| 2551 | * A commit event that is first on a page |
| 2552 | * updates the write timestamp with the page stamp |
| 2553 | */ |
| 2554 | if (!rb_event_index(event)) |
| 2555 | cpu_buffer->write_stamp = |
| 2556 | cpu_buffer->commit_page->page->time_stamp; |
| 2557 | else if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) { |
| 2558 | delta = event->array[0]; |
| 2559 | delta <<= TS_SHIFT; |
| 2560 | delta += event->time_delta; |
| 2561 | cpu_buffer->write_stamp += delta; |
| 2562 | } else |
| 2563 | cpu_buffer->write_stamp += event->time_delta; |
| 2564 | } |
Steven Rostedt | a1863c2 | 2009-09-03 10:23:58 -0400 | [diff] [blame] | 2565 | } |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 2566 | |
Steven Rostedt | a1863c2 | 2009-09-03 10:23:58 -0400 | [diff] [blame] | 2567 | static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer, |
| 2568 | struct ring_buffer_event *event) |
| 2569 | { |
| 2570 | local_inc(&cpu_buffer->entries); |
| 2571 | rb_update_write_stamp(cpu_buffer, event); |
Steven Rostedt | fa74395 | 2009-06-16 12:37:57 -0400 | [diff] [blame] | 2572 | rb_end_commit(cpu_buffer); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2573 | } |
| 2574 | |
| 2575 | /** |
| 2576 | * ring_buffer_unlock_commit - commit a reserved |
| 2577 | * @buffer: The buffer to commit to |
| 2578 | * @event: The event pointer to commit. |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2579 | * |
| 2580 | * This commits the data to the ring buffer, and releases any locks held. |
| 2581 | * |
| 2582 | * Must be paired with ring_buffer_lock_reserve. |
| 2583 | */ |
| 2584 | int ring_buffer_unlock_commit(struct ring_buffer *buffer, |
Arnaldo Carvalho de Melo | 0a98775 | 2009-02-05 16:12:56 -0200 | [diff] [blame] | 2585 | struct ring_buffer_event *event) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2586 | { |
| 2587 | struct ring_buffer_per_cpu *cpu_buffer; |
| 2588 | int cpu = raw_smp_processor_id(); |
| 2589 | |
| 2590 | cpu_buffer = buffer->buffers[cpu]; |
| 2591 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2592 | rb_commit(cpu_buffer, event); |
| 2593 | |
Steven Rostedt | 261842b | 2009-04-16 21:41:52 -0400 | [diff] [blame] | 2594 | trace_recursive_unlock(); |
| 2595 | |
Steven Rostedt | 5168ae5 | 2010-06-03 09:36:50 -0400 | [diff] [blame] | 2596 | preempt_enable_notrace(); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2597 | |
| 2598 | return 0; |
| 2599 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 2600 | EXPORT_SYMBOL_GPL(ring_buffer_unlock_commit); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2601 | |
Frederic Weisbecker | f3b9aae | 2009-04-19 23:39:33 +0200 | [diff] [blame] | 2602 | static inline void rb_event_discard(struct ring_buffer_event *event) |
| 2603 | { |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 2604 | if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) |
| 2605 | event = skip_time_extend(event); |
| 2606 | |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 2607 | /* array[0] holds the actual length for the discarded event */ |
| 2608 | event->array[0] = rb_event_data_length(event) - RB_EVNT_HDR_SIZE; |
| 2609 | event->type_len = RINGBUF_TYPE_PADDING; |
Frederic Weisbecker | f3b9aae | 2009-04-19 23:39:33 +0200 | [diff] [blame] | 2610 | /* time delta must be non zero */ |
| 2611 | if (!event->time_delta) |
| 2612 | event->time_delta = 1; |
| 2613 | } |
| 2614 | |
Steven Rostedt | a1863c2 | 2009-09-03 10:23:58 -0400 | [diff] [blame] | 2615 | /* |
| 2616 | * Decrement the entries to the page that an event is on. |
| 2617 | * The event does not even need to exist, only the pointer |
| 2618 | * to the page it is on. This may only be called before the commit |
| 2619 | * takes place. |
| 2620 | */ |
| 2621 | static inline void |
| 2622 | rb_decrement_entry(struct ring_buffer_per_cpu *cpu_buffer, |
| 2623 | struct ring_buffer_event *event) |
| 2624 | { |
| 2625 | unsigned long addr = (unsigned long)event; |
| 2626 | struct buffer_page *bpage = cpu_buffer->commit_page; |
| 2627 | struct buffer_page *start; |
| 2628 | |
| 2629 | addr &= PAGE_MASK; |
| 2630 | |
| 2631 | /* Do the likely case first */ |
| 2632 | if (likely(bpage->page == (void *)addr)) { |
| 2633 | local_dec(&bpage->entries); |
| 2634 | return; |
| 2635 | } |
| 2636 | |
| 2637 | /* |
| 2638 | * Because the commit page may be on the reader page we |
| 2639 | * start with the next page and check the end loop there. |
| 2640 | */ |
| 2641 | rb_inc_page(cpu_buffer, &bpage); |
| 2642 | start = bpage; |
| 2643 | do { |
| 2644 | if (bpage->page == (void *)addr) { |
| 2645 | local_dec(&bpage->entries); |
| 2646 | return; |
| 2647 | } |
| 2648 | rb_inc_page(cpu_buffer, &bpage); |
| 2649 | } while (bpage != start); |
| 2650 | |
| 2651 | /* commit not part of this buffer?? */ |
| 2652 | RB_WARN_ON(cpu_buffer, 1); |
| 2653 | } |
| 2654 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2655 | /** |
Steven Rostedt | fa1b47d | 2009-04-02 00:09:41 -0400 | [diff] [blame] | 2656 | * ring_buffer_commit_discard - discard an event that has not been committed |
| 2657 | * @buffer: the ring buffer |
| 2658 | * @event: non committed event to discard |
| 2659 | * |
Steven Rostedt | dc892f7 | 2009-09-03 15:33:41 -0400 | [diff] [blame] | 2660 | * Sometimes an event that is in the ring buffer needs to be ignored. |
| 2661 | * This function lets the user discard an event in the ring buffer |
| 2662 | * and then that event will not be read later. |
| 2663 | * |
| 2664 | * This function only works if it is called before the the item has been |
| 2665 | * committed. It will try to free the event from the ring buffer |
Steven Rostedt | fa1b47d | 2009-04-02 00:09:41 -0400 | [diff] [blame] | 2666 | * if another event has not been added behind it. |
| 2667 | * |
| 2668 | * If another event has been added behind it, it will set the event |
| 2669 | * up as discarded, and perform the commit. |
| 2670 | * |
| 2671 | * If this function is called, do not call ring_buffer_unlock_commit on |
| 2672 | * the event. |
| 2673 | */ |
| 2674 | void ring_buffer_discard_commit(struct ring_buffer *buffer, |
| 2675 | struct ring_buffer_event *event) |
| 2676 | { |
| 2677 | struct ring_buffer_per_cpu *cpu_buffer; |
Steven Rostedt | fa1b47d | 2009-04-02 00:09:41 -0400 | [diff] [blame] | 2678 | int cpu; |
| 2679 | |
| 2680 | /* The event is discarded regardless */ |
Frederic Weisbecker | f3b9aae | 2009-04-19 23:39:33 +0200 | [diff] [blame] | 2681 | rb_event_discard(event); |
Steven Rostedt | fa1b47d | 2009-04-02 00:09:41 -0400 | [diff] [blame] | 2682 | |
Steven Rostedt | fa74395 | 2009-06-16 12:37:57 -0400 | [diff] [blame] | 2683 | cpu = smp_processor_id(); |
| 2684 | cpu_buffer = buffer->buffers[cpu]; |
| 2685 | |
Steven Rostedt | fa1b47d | 2009-04-02 00:09:41 -0400 | [diff] [blame] | 2686 | /* |
| 2687 | * This must only be called if the event has not been |
| 2688 | * committed yet. Thus we can assume that preemption |
| 2689 | * is still disabled. |
| 2690 | */ |
Steven Rostedt | fa74395 | 2009-06-16 12:37:57 -0400 | [diff] [blame] | 2691 | RB_WARN_ON(buffer, !local_read(&cpu_buffer->committing)); |
Steven Rostedt | fa1b47d | 2009-04-02 00:09:41 -0400 | [diff] [blame] | 2692 | |
Steven Rostedt | a1863c2 | 2009-09-03 10:23:58 -0400 | [diff] [blame] | 2693 | rb_decrement_entry(cpu_buffer, event); |
Steven Rostedt | 0f2541d | 2009-08-05 12:02:48 -0400 | [diff] [blame] | 2694 | if (rb_try_to_discard(cpu_buffer, event)) |
Steven Rostedt | edd813bf | 2009-06-02 23:00:53 -0400 | [diff] [blame] | 2695 | goto out; |
Steven Rostedt | fa1b47d | 2009-04-02 00:09:41 -0400 | [diff] [blame] | 2696 | |
| 2697 | /* |
| 2698 | * The commit is still visible by the reader, so we |
Steven Rostedt | a1863c2 | 2009-09-03 10:23:58 -0400 | [diff] [blame] | 2699 | * must still update the timestamp. |
Steven Rostedt | fa1b47d | 2009-04-02 00:09:41 -0400 | [diff] [blame] | 2700 | */ |
Steven Rostedt | a1863c2 | 2009-09-03 10:23:58 -0400 | [diff] [blame] | 2701 | rb_update_write_stamp(cpu_buffer, event); |
Steven Rostedt | fa1b47d | 2009-04-02 00:09:41 -0400 | [diff] [blame] | 2702 | out: |
Steven Rostedt | fa74395 | 2009-06-16 12:37:57 -0400 | [diff] [blame] | 2703 | rb_end_commit(cpu_buffer); |
Steven Rostedt | fa1b47d | 2009-04-02 00:09:41 -0400 | [diff] [blame] | 2704 | |
Frederic Weisbecker | f3b9aae | 2009-04-19 23:39:33 +0200 | [diff] [blame] | 2705 | trace_recursive_unlock(); |
| 2706 | |
Steven Rostedt | 5168ae5 | 2010-06-03 09:36:50 -0400 | [diff] [blame] | 2707 | preempt_enable_notrace(); |
Steven Rostedt | fa1b47d | 2009-04-02 00:09:41 -0400 | [diff] [blame] | 2708 | |
| 2709 | } |
| 2710 | EXPORT_SYMBOL_GPL(ring_buffer_discard_commit); |
| 2711 | |
| 2712 | /** |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2713 | * ring_buffer_write - write data to the buffer without reserving |
| 2714 | * @buffer: The ring buffer to write to. |
| 2715 | * @length: The length of the data being written (excluding the event header) |
| 2716 | * @data: The data to write to the buffer. |
| 2717 | * |
| 2718 | * This is like ring_buffer_lock_reserve and ring_buffer_unlock_commit as |
| 2719 | * one function. If you already have the data to write to the buffer, it |
| 2720 | * may be easier to simply call this function. |
| 2721 | * |
| 2722 | * Note, like ring_buffer_lock_reserve, the length is the length of the data |
| 2723 | * and not the length of the event which would hold the header. |
| 2724 | */ |
| 2725 | int ring_buffer_write(struct ring_buffer *buffer, |
David Sharp | 01e3e71 | 2012-06-07 16:46:24 -0700 | [diff] [blame] | 2726 | unsigned long length, |
| 2727 | void *data) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2728 | { |
| 2729 | struct ring_buffer_per_cpu *cpu_buffer; |
| 2730 | struct ring_buffer_event *event; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2731 | void *body; |
| 2732 | int ret = -EBUSY; |
Steven Rostedt | 5168ae5 | 2010-06-03 09:36:50 -0400 | [diff] [blame] | 2733 | int cpu; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2734 | |
Steven Rostedt | 033601a | 2008-11-21 12:41:55 -0500 | [diff] [blame] | 2735 | if (ring_buffer_flags != RB_BUFFERS_ON) |
Steven Rostedt | a358324 | 2008-11-11 15:01:42 -0500 | [diff] [blame] | 2736 | return -EBUSY; |
| 2737 | |
Steven Rostedt | 5168ae5 | 2010-06-03 09:36:50 -0400 | [diff] [blame] | 2738 | preempt_disable_notrace(); |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 2739 | |
Lai Jiangshan | 52fbe9c | 2010-03-08 14:50:43 +0800 | [diff] [blame] | 2740 | if (atomic_read(&buffer->record_disabled)) |
| 2741 | goto out; |
| 2742 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2743 | cpu = raw_smp_processor_id(); |
| 2744 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 2745 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 2746 | goto out; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2747 | |
| 2748 | cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2749 | |
| 2750 | if (atomic_read(&cpu_buffer->record_disabled)) |
| 2751 | goto out; |
| 2752 | |
Steven Rostedt | be957c4 | 2009-05-11 14:42:53 -0400 | [diff] [blame] | 2753 | if (length > BUF_MAX_DATA_SIZE) |
| 2754 | goto out; |
| 2755 | |
Steven Rostedt | 62f0b3e | 2009-09-04 14:11:34 -0400 | [diff] [blame] | 2756 | event = rb_reserve_next_event(buffer, cpu_buffer, length); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2757 | if (!event) |
| 2758 | goto out; |
| 2759 | |
| 2760 | body = rb_event_data(event); |
| 2761 | |
| 2762 | memcpy(body, data, length); |
| 2763 | |
| 2764 | rb_commit(cpu_buffer, event); |
| 2765 | |
| 2766 | ret = 0; |
| 2767 | out: |
Steven Rostedt | 5168ae5 | 2010-06-03 09:36:50 -0400 | [diff] [blame] | 2768 | preempt_enable_notrace(); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2769 | |
| 2770 | return ret; |
| 2771 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 2772 | EXPORT_SYMBOL_GPL(ring_buffer_write); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2773 | |
Andrew Morton | 34a148b | 2009-01-09 12:27:09 -0800 | [diff] [blame] | 2774 | static int rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer) |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 2775 | { |
| 2776 | struct buffer_page *reader = cpu_buffer->reader_page; |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 2777 | struct buffer_page *head = rb_set_head_page(cpu_buffer); |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 2778 | struct buffer_page *commit = cpu_buffer->commit_page; |
| 2779 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 2780 | /* In case of error, head will be NULL */ |
| 2781 | if (unlikely(!head)) |
| 2782 | return 1; |
| 2783 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 2784 | return reader->read == rb_page_commit(reader) && |
| 2785 | (commit == reader || |
| 2786 | (commit == head && |
| 2787 | head->read == rb_page_commit(commit))); |
| 2788 | } |
| 2789 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2790 | /** |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2791 | * ring_buffer_record_disable - stop all writes into the buffer |
| 2792 | * @buffer: The ring buffer to stop writes to. |
| 2793 | * |
| 2794 | * This prevents all writes to the buffer. Any attempt to write |
| 2795 | * to the buffer after this will fail and return NULL. |
| 2796 | * |
| 2797 | * The caller should call synchronize_sched() after this. |
| 2798 | */ |
| 2799 | void ring_buffer_record_disable(struct ring_buffer *buffer) |
| 2800 | { |
| 2801 | atomic_inc(&buffer->record_disabled); |
| 2802 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 2803 | EXPORT_SYMBOL_GPL(ring_buffer_record_disable); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2804 | |
| 2805 | /** |
| 2806 | * ring_buffer_record_enable - enable writes to the buffer |
| 2807 | * @buffer: The ring buffer to enable writes |
| 2808 | * |
| 2809 | * Note, multiple disables will need the same number of enables |
Adam Buchbinder | c41b20e | 2009-12-11 16:35:39 -0500 | [diff] [blame] | 2810 | * to truly enable the writing (much like preempt_disable). |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2811 | */ |
| 2812 | void ring_buffer_record_enable(struct ring_buffer *buffer) |
| 2813 | { |
| 2814 | atomic_dec(&buffer->record_disabled); |
| 2815 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 2816 | EXPORT_SYMBOL_GPL(ring_buffer_record_enable); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2817 | |
| 2818 | /** |
Steven Rostedt | 499e547 | 2012-02-22 15:50:28 -0500 | [diff] [blame] | 2819 | * ring_buffer_record_off - stop all writes into the buffer |
| 2820 | * @buffer: The ring buffer to stop writes to. |
| 2821 | * |
| 2822 | * This prevents all writes to the buffer. Any attempt to write |
| 2823 | * to the buffer after this will fail and return NULL. |
| 2824 | * |
| 2825 | * This is different than ring_buffer_record_disable() as |
Wang Tianhong | 87abb3b | 2012-08-02 14:02:00 +0800 | [diff] [blame] | 2826 | * it works like an on/off switch, where as the disable() version |
Steven Rostedt | 499e547 | 2012-02-22 15:50:28 -0500 | [diff] [blame] | 2827 | * must be paired with a enable(). |
| 2828 | */ |
| 2829 | void ring_buffer_record_off(struct ring_buffer *buffer) |
| 2830 | { |
| 2831 | unsigned int rd; |
| 2832 | unsigned int new_rd; |
| 2833 | |
| 2834 | do { |
| 2835 | rd = atomic_read(&buffer->record_disabled); |
| 2836 | new_rd = rd | RB_BUFFER_OFF; |
| 2837 | } while (atomic_cmpxchg(&buffer->record_disabled, rd, new_rd) != rd); |
| 2838 | } |
| 2839 | EXPORT_SYMBOL_GPL(ring_buffer_record_off); |
| 2840 | |
| 2841 | /** |
| 2842 | * ring_buffer_record_on - restart writes into the buffer |
| 2843 | * @buffer: The ring buffer to start writes to. |
| 2844 | * |
| 2845 | * This enables all writes to the buffer that was disabled by |
| 2846 | * ring_buffer_record_off(). |
| 2847 | * |
| 2848 | * This is different than ring_buffer_record_enable() as |
Wang Tianhong | 87abb3b | 2012-08-02 14:02:00 +0800 | [diff] [blame] | 2849 | * it works like an on/off switch, where as the enable() version |
Steven Rostedt | 499e547 | 2012-02-22 15:50:28 -0500 | [diff] [blame] | 2850 | * must be paired with a disable(). |
| 2851 | */ |
| 2852 | void ring_buffer_record_on(struct ring_buffer *buffer) |
| 2853 | { |
| 2854 | unsigned int rd; |
| 2855 | unsigned int new_rd; |
| 2856 | |
| 2857 | do { |
| 2858 | rd = atomic_read(&buffer->record_disabled); |
| 2859 | new_rd = rd & ~RB_BUFFER_OFF; |
| 2860 | } while (atomic_cmpxchg(&buffer->record_disabled, rd, new_rd) != rd); |
| 2861 | } |
| 2862 | EXPORT_SYMBOL_GPL(ring_buffer_record_on); |
| 2863 | |
| 2864 | /** |
| 2865 | * ring_buffer_record_is_on - return true if the ring buffer can write |
| 2866 | * @buffer: The ring buffer to see if write is enabled |
| 2867 | * |
| 2868 | * Returns true if the ring buffer is in a state that it accepts writes. |
| 2869 | */ |
| 2870 | int ring_buffer_record_is_on(struct ring_buffer *buffer) |
| 2871 | { |
| 2872 | return !atomic_read(&buffer->record_disabled); |
| 2873 | } |
| 2874 | |
| 2875 | /** |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2876 | * ring_buffer_record_disable_cpu - stop all writes into the cpu_buffer |
| 2877 | * @buffer: The ring buffer to stop writes to. |
| 2878 | * @cpu: The CPU buffer to stop |
| 2879 | * |
| 2880 | * This prevents all writes to the buffer. Any attempt to write |
| 2881 | * to the buffer after this will fail and return NULL. |
| 2882 | * |
| 2883 | * The caller should call synchronize_sched() after this. |
| 2884 | */ |
| 2885 | void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu) |
| 2886 | { |
| 2887 | struct ring_buffer_per_cpu *cpu_buffer; |
| 2888 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 2889 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 2890 | return; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2891 | |
| 2892 | cpu_buffer = buffer->buffers[cpu]; |
| 2893 | atomic_inc(&cpu_buffer->record_disabled); |
| 2894 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 2895 | EXPORT_SYMBOL_GPL(ring_buffer_record_disable_cpu); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2896 | |
| 2897 | /** |
| 2898 | * ring_buffer_record_enable_cpu - enable writes to the buffer |
| 2899 | * @buffer: The ring buffer to enable writes |
| 2900 | * @cpu: The CPU to enable. |
| 2901 | * |
| 2902 | * Note, multiple disables will need the same number of enables |
Adam Buchbinder | c41b20e | 2009-12-11 16:35:39 -0500 | [diff] [blame] | 2903 | * to truly enable the writing (much like preempt_disable). |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2904 | */ |
| 2905 | void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu) |
| 2906 | { |
| 2907 | struct ring_buffer_per_cpu *cpu_buffer; |
| 2908 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 2909 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 2910 | return; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2911 | |
| 2912 | cpu_buffer = buffer->buffers[cpu]; |
| 2913 | atomic_dec(&cpu_buffer->record_disabled); |
| 2914 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 2915 | EXPORT_SYMBOL_GPL(ring_buffer_record_enable_cpu); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2916 | |
Steven Rostedt | f6195aa | 2010-09-01 12:23:12 -0400 | [diff] [blame] | 2917 | /* |
| 2918 | * The total entries in the ring buffer is the running counter |
| 2919 | * of entries entered into the ring buffer, minus the sum of |
| 2920 | * the entries read from the ring buffer and the number of |
| 2921 | * entries that were overwritten. |
| 2922 | */ |
| 2923 | static inline unsigned long |
| 2924 | rb_num_of_entries(struct ring_buffer_per_cpu *cpu_buffer) |
| 2925 | { |
| 2926 | return local_read(&cpu_buffer->entries) - |
| 2927 | (local_read(&cpu_buffer->overrun) + cpu_buffer->read); |
| 2928 | } |
| 2929 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2930 | /** |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 2931 | * ring_buffer_oldest_event_ts - get the oldest event timestamp from the buffer |
| 2932 | * @buffer: The ring buffer |
| 2933 | * @cpu: The per CPU buffer to read from. |
| 2934 | */ |
Yoshihiro YUNOMAE | 50ecf2c | 2012-10-11 16:27:54 -0700 | [diff] [blame^] | 2935 | u64 ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu) |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 2936 | { |
| 2937 | unsigned long flags; |
| 2938 | struct ring_buffer_per_cpu *cpu_buffer; |
| 2939 | struct buffer_page *bpage; |
Yoshihiro YUNOMAE | 50ecf2c | 2012-10-11 16:27:54 -0700 | [diff] [blame^] | 2940 | u64 ret; |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 2941 | |
| 2942 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
| 2943 | return 0; |
| 2944 | |
| 2945 | cpu_buffer = buffer->buffers[cpu]; |
Linus Torvalds | 7115e3f | 2011-10-26 17:03:38 +0200 | [diff] [blame] | 2946 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 2947 | /* |
| 2948 | * if the tail is on reader_page, oldest time stamp is on the reader |
| 2949 | * page |
| 2950 | */ |
| 2951 | if (cpu_buffer->tail_page == cpu_buffer->reader_page) |
| 2952 | bpage = cpu_buffer->reader_page; |
| 2953 | else |
| 2954 | bpage = rb_set_head_page(cpu_buffer); |
| 2955 | ret = bpage->page->time_stamp; |
Linus Torvalds | 7115e3f | 2011-10-26 17:03:38 +0200 | [diff] [blame] | 2956 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 2957 | |
| 2958 | return ret; |
| 2959 | } |
| 2960 | EXPORT_SYMBOL_GPL(ring_buffer_oldest_event_ts); |
| 2961 | |
| 2962 | /** |
| 2963 | * ring_buffer_bytes_cpu - get the number of bytes consumed in a cpu buffer |
| 2964 | * @buffer: The ring buffer |
| 2965 | * @cpu: The per CPU buffer to read from. |
| 2966 | */ |
| 2967 | unsigned long ring_buffer_bytes_cpu(struct ring_buffer *buffer, int cpu) |
| 2968 | { |
| 2969 | struct ring_buffer_per_cpu *cpu_buffer; |
| 2970 | unsigned long ret; |
| 2971 | |
| 2972 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
| 2973 | return 0; |
| 2974 | |
| 2975 | cpu_buffer = buffer->buffers[cpu]; |
| 2976 | ret = local_read(&cpu_buffer->entries_bytes) - cpu_buffer->read_bytes; |
| 2977 | |
| 2978 | return ret; |
| 2979 | } |
| 2980 | EXPORT_SYMBOL_GPL(ring_buffer_bytes_cpu); |
| 2981 | |
| 2982 | /** |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2983 | * ring_buffer_entries_cpu - get the number of entries in a cpu buffer |
| 2984 | * @buffer: The ring buffer |
| 2985 | * @cpu: The per CPU buffer to get the entries from. |
| 2986 | */ |
| 2987 | unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu) |
| 2988 | { |
| 2989 | struct ring_buffer_per_cpu *cpu_buffer; |
| 2990 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 2991 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 2992 | return 0; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2993 | |
| 2994 | cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 2995 | |
Steven Rostedt | f6195aa | 2010-09-01 12:23:12 -0400 | [diff] [blame] | 2996 | return rb_num_of_entries(cpu_buffer); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2997 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 2998 | EXPORT_SYMBOL_GPL(ring_buffer_entries_cpu); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 2999 | |
| 3000 | /** |
Slava Pestov | 884bfe8 | 2011-07-15 14:23:58 -0700 | [diff] [blame] | 3001 | * ring_buffer_overrun_cpu - get the number of overruns caused by the ring |
| 3002 | * buffer wrapping around (only if RB_FL_OVERWRITE is on). |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3003 | * @buffer: The ring buffer |
| 3004 | * @cpu: The per CPU buffer to get the number of overruns from |
| 3005 | */ |
| 3006 | unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu) |
| 3007 | { |
| 3008 | struct ring_buffer_per_cpu *cpu_buffer; |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 3009 | unsigned long ret; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3010 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 3011 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 3012 | return 0; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3013 | |
| 3014 | cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 3015 | ret = local_read(&cpu_buffer->overrun); |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 3016 | |
| 3017 | return ret; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3018 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 3019 | EXPORT_SYMBOL_GPL(ring_buffer_overrun_cpu); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3020 | |
| 3021 | /** |
Slava Pestov | 884bfe8 | 2011-07-15 14:23:58 -0700 | [diff] [blame] | 3022 | * ring_buffer_commit_overrun_cpu - get the number of overruns caused by |
| 3023 | * commits failing due to the buffer wrapping around while there are uncommitted |
| 3024 | * events, such as during an interrupt storm. |
Steven Rostedt | f0d2c68 | 2009-04-29 13:43:37 -0400 | [diff] [blame] | 3025 | * @buffer: The ring buffer |
| 3026 | * @cpu: The per CPU buffer to get the number of overruns from |
| 3027 | */ |
| 3028 | unsigned long |
| 3029 | ring_buffer_commit_overrun_cpu(struct ring_buffer *buffer, int cpu) |
| 3030 | { |
| 3031 | struct ring_buffer_per_cpu *cpu_buffer; |
| 3032 | unsigned long ret; |
| 3033 | |
| 3034 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
| 3035 | return 0; |
| 3036 | |
| 3037 | cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 3038 | ret = local_read(&cpu_buffer->commit_overrun); |
Steven Rostedt | f0d2c68 | 2009-04-29 13:43:37 -0400 | [diff] [blame] | 3039 | |
| 3040 | return ret; |
| 3041 | } |
| 3042 | EXPORT_SYMBOL_GPL(ring_buffer_commit_overrun_cpu); |
| 3043 | |
| 3044 | /** |
Slava Pestov | 884bfe8 | 2011-07-15 14:23:58 -0700 | [diff] [blame] | 3045 | * ring_buffer_dropped_events_cpu - get the number of dropped events caused by |
| 3046 | * the ring buffer filling up (only if RB_FL_OVERWRITE is off). |
| 3047 | * @buffer: The ring buffer |
| 3048 | * @cpu: The per CPU buffer to get the number of overruns from |
| 3049 | */ |
| 3050 | unsigned long |
| 3051 | ring_buffer_dropped_events_cpu(struct ring_buffer *buffer, int cpu) |
| 3052 | { |
| 3053 | struct ring_buffer_per_cpu *cpu_buffer; |
| 3054 | unsigned long ret; |
| 3055 | |
| 3056 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
| 3057 | return 0; |
| 3058 | |
| 3059 | cpu_buffer = buffer->buffers[cpu]; |
| 3060 | ret = local_read(&cpu_buffer->dropped_events); |
| 3061 | |
| 3062 | return ret; |
| 3063 | } |
| 3064 | EXPORT_SYMBOL_GPL(ring_buffer_dropped_events_cpu); |
| 3065 | |
| 3066 | /** |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3067 | * ring_buffer_entries - get the number of entries in a buffer |
| 3068 | * @buffer: The ring buffer |
| 3069 | * |
| 3070 | * Returns the total number of entries in the ring buffer |
| 3071 | * (all CPU entries) |
| 3072 | */ |
| 3073 | unsigned long ring_buffer_entries(struct ring_buffer *buffer) |
| 3074 | { |
| 3075 | struct ring_buffer_per_cpu *cpu_buffer; |
| 3076 | unsigned long entries = 0; |
| 3077 | int cpu; |
| 3078 | |
| 3079 | /* if you care about this being correct, lock the buffer */ |
| 3080 | for_each_buffer_cpu(buffer, cpu) { |
| 3081 | cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | f6195aa | 2010-09-01 12:23:12 -0400 | [diff] [blame] | 3082 | entries += rb_num_of_entries(cpu_buffer); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3083 | } |
| 3084 | |
| 3085 | return entries; |
| 3086 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 3087 | EXPORT_SYMBOL_GPL(ring_buffer_entries); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3088 | |
| 3089 | /** |
Jiri Olsa | 67b394f | 2009-10-23 19:36:18 -0400 | [diff] [blame] | 3090 | * ring_buffer_overruns - get the number of overruns in buffer |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3091 | * @buffer: The ring buffer |
| 3092 | * |
| 3093 | * Returns the total number of overruns in the ring buffer |
| 3094 | * (all CPU entries) |
| 3095 | */ |
| 3096 | unsigned long ring_buffer_overruns(struct ring_buffer *buffer) |
| 3097 | { |
| 3098 | struct ring_buffer_per_cpu *cpu_buffer; |
| 3099 | unsigned long overruns = 0; |
| 3100 | int cpu; |
| 3101 | |
| 3102 | /* if you care about this being correct, lock the buffer */ |
| 3103 | for_each_buffer_cpu(buffer, cpu) { |
| 3104 | cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 3105 | overruns += local_read(&cpu_buffer->overrun); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3106 | } |
| 3107 | |
| 3108 | return overruns; |
| 3109 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 3110 | EXPORT_SYMBOL_GPL(ring_buffer_overruns); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3111 | |
Steven Rostedt | 642edba | 2008-11-12 00:01:26 -0500 | [diff] [blame] | 3112 | static void rb_iter_reset(struct ring_buffer_iter *iter) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3113 | { |
| 3114 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; |
| 3115 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3116 | /* Iterator usage is expected to have record disabled */ |
| 3117 | if (list_empty(&cpu_buffer->reader_page->list)) { |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 3118 | iter->head_page = rb_set_head_page(cpu_buffer); |
| 3119 | if (unlikely(!iter->head_page)) |
| 3120 | return; |
| 3121 | iter->head = iter->head_page->read; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3122 | } else { |
| 3123 | iter->head_page = cpu_buffer->reader_page; |
Steven Rostedt | 6f807ac | 2008-10-04 02:00:58 -0400 | [diff] [blame] | 3124 | iter->head = cpu_buffer->reader_page->read; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3125 | } |
| 3126 | if (iter->head) |
| 3127 | iter->read_stamp = cpu_buffer->read_stamp; |
| 3128 | else |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 3129 | iter->read_stamp = iter->head_page->page->time_stamp; |
Steven Rostedt | 492a74f | 2010-01-25 15:17:47 -0500 | [diff] [blame] | 3130 | iter->cache_reader_page = cpu_buffer->reader_page; |
| 3131 | iter->cache_read = cpu_buffer->read; |
Steven Rostedt | 642edba | 2008-11-12 00:01:26 -0500 | [diff] [blame] | 3132 | } |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3133 | |
Steven Rostedt | 642edba | 2008-11-12 00:01:26 -0500 | [diff] [blame] | 3134 | /** |
| 3135 | * ring_buffer_iter_reset - reset an iterator |
| 3136 | * @iter: The iterator to reset |
| 3137 | * |
| 3138 | * Resets the iterator, so that it will start from the beginning |
| 3139 | * again. |
| 3140 | */ |
| 3141 | void ring_buffer_iter_reset(struct ring_buffer_iter *iter) |
| 3142 | { |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 3143 | struct ring_buffer_per_cpu *cpu_buffer; |
Steven Rostedt | 642edba | 2008-11-12 00:01:26 -0500 | [diff] [blame] | 3144 | unsigned long flags; |
| 3145 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 3146 | if (!iter) |
| 3147 | return; |
| 3148 | |
| 3149 | cpu_buffer = iter->cpu_buffer; |
| 3150 | |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 3151 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | 642edba | 2008-11-12 00:01:26 -0500 | [diff] [blame] | 3152 | rb_iter_reset(iter); |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 3153 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3154 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 3155 | EXPORT_SYMBOL_GPL(ring_buffer_iter_reset); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3156 | |
| 3157 | /** |
| 3158 | * ring_buffer_iter_empty - check if an iterator has no more to read |
| 3159 | * @iter: The iterator to check |
| 3160 | */ |
| 3161 | int ring_buffer_iter_empty(struct ring_buffer_iter *iter) |
| 3162 | { |
| 3163 | struct ring_buffer_per_cpu *cpu_buffer; |
| 3164 | |
| 3165 | cpu_buffer = iter->cpu_buffer; |
| 3166 | |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 3167 | return iter->head_page == cpu_buffer->commit_page && |
| 3168 | iter->head == rb_commit_index(cpu_buffer); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3169 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 3170 | EXPORT_SYMBOL_GPL(ring_buffer_iter_empty); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3171 | |
| 3172 | static void |
| 3173 | rb_update_read_stamp(struct ring_buffer_per_cpu *cpu_buffer, |
| 3174 | struct ring_buffer_event *event) |
| 3175 | { |
| 3176 | u64 delta; |
| 3177 | |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 3178 | switch (event->type_len) { |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3179 | case RINGBUF_TYPE_PADDING: |
| 3180 | return; |
| 3181 | |
| 3182 | case RINGBUF_TYPE_TIME_EXTEND: |
| 3183 | delta = event->array[0]; |
| 3184 | delta <<= TS_SHIFT; |
| 3185 | delta += event->time_delta; |
| 3186 | cpu_buffer->read_stamp += delta; |
| 3187 | return; |
| 3188 | |
| 3189 | case RINGBUF_TYPE_TIME_STAMP: |
| 3190 | /* FIXME: not implemented */ |
| 3191 | return; |
| 3192 | |
| 3193 | case RINGBUF_TYPE_DATA: |
| 3194 | cpu_buffer->read_stamp += event->time_delta; |
| 3195 | return; |
| 3196 | |
| 3197 | default: |
| 3198 | BUG(); |
| 3199 | } |
| 3200 | return; |
| 3201 | } |
| 3202 | |
| 3203 | static void |
| 3204 | rb_update_iter_read_stamp(struct ring_buffer_iter *iter, |
| 3205 | struct ring_buffer_event *event) |
| 3206 | { |
| 3207 | u64 delta; |
| 3208 | |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 3209 | switch (event->type_len) { |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3210 | case RINGBUF_TYPE_PADDING: |
| 3211 | return; |
| 3212 | |
| 3213 | case RINGBUF_TYPE_TIME_EXTEND: |
| 3214 | delta = event->array[0]; |
| 3215 | delta <<= TS_SHIFT; |
| 3216 | delta += event->time_delta; |
| 3217 | iter->read_stamp += delta; |
| 3218 | return; |
| 3219 | |
| 3220 | case RINGBUF_TYPE_TIME_STAMP: |
| 3221 | /* FIXME: not implemented */ |
| 3222 | return; |
| 3223 | |
| 3224 | case RINGBUF_TYPE_DATA: |
| 3225 | iter->read_stamp += event->time_delta; |
| 3226 | return; |
| 3227 | |
| 3228 | default: |
| 3229 | BUG(); |
| 3230 | } |
| 3231 | return; |
| 3232 | } |
| 3233 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3234 | static struct buffer_page * |
| 3235 | rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3236 | { |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3237 | struct buffer_page *reader = NULL; |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 3238 | unsigned long overwrite; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3239 | unsigned long flags; |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 3240 | int nr_loops = 0; |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 3241 | int ret; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3242 | |
Steven Rostedt | 3e03fb7 | 2008-11-06 00:09:43 -0500 | [diff] [blame] | 3243 | local_irq_save(flags); |
Thomas Gleixner | 0199c4e | 2009-12-02 20:01:25 +0100 | [diff] [blame] | 3244 | arch_spin_lock(&cpu_buffer->lock); |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3245 | |
| 3246 | again: |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 3247 | /* |
| 3248 | * This should normally only loop twice. But because the |
| 3249 | * start of the reader inserts an empty page, it causes |
| 3250 | * a case where we will loop three times. There should be no |
| 3251 | * reason to loop four times (that I know of). |
| 3252 | */ |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 3253 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 3)) { |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 3254 | reader = NULL; |
| 3255 | goto out; |
| 3256 | } |
| 3257 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3258 | reader = cpu_buffer->reader_page; |
| 3259 | |
| 3260 | /* If there's more to read, return this page */ |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 3261 | if (cpu_buffer->reader_page->read < rb_page_size(reader)) |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3262 | goto out; |
| 3263 | |
| 3264 | /* Never should we have an index greater than the size */ |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 3265 | if (RB_WARN_ON(cpu_buffer, |
| 3266 | cpu_buffer->reader_page->read > rb_page_size(reader))) |
| 3267 | goto out; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3268 | |
| 3269 | /* check if we caught up to the tail */ |
| 3270 | reader = NULL; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 3271 | if (cpu_buffer->commit_page == cpu_buffer->reader_page) |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3272 | goto out; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3273 | |
Steven Rostedt | a5fb833 | 2012-06-28 13:35:04 -0400 | [diff] [blame] | 3274 | /* Don't bother swapping if the ring buffer is empty */ |
| 3275 | if (rb_num_of_entries(cpu_buffer) == 0) |
| 3276 | goto out; |
| 3277 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3278 | /* |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3279 | * Reset the reader page to size zero. |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3280 | */ |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 3281 | local_set(&cpu_buffer->reader_page->write, 0); |
| 3282 | local_set(&cpu_buffer->reader_page->entries, 0); |
| 3283 | local_set(&cpu_buffer->reader_page->page->commit, 0); |
Steven Rostedt | ff0ff84 | 2010-03-31 22:11:42 -0400 | [diff] [blame] | 3284 | cpu_buffer->reader_page->real_end = 0; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3285 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 3286 | spin: |
| 3287 | /* |
| 3288 | * Splice the empty reader page into the list around the head. |
| 3289 | */ |
| 3290 | reader = rb_set_head_page(cpu_buffer); |
Steven Rostedt | 0e1ff5d | 2010-01-06 20:40:44 -0500 | [diff] [blame] | 3291 | cpu_buffer->reader_page->list.next = rb_list_head(reader->list.next); |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3292 | cpu_buffer->reader_page->list.prev = reader->list.prev; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 3293 | |
Steven Rostedt | 3adc54f | 2009-03-30 15:32:01 -0400 | [diff] [blame] | 3294 | /* |
| 3295 | * cpu_buffer->pages just needs to point to the buffer, it |
| 3296 | * has no specific buffer page to point to. Lets move it out |
Lucas De Marchi | 25985ed | 2011-03-30 22:57:33 -0300 | [diff] [blame] | 3297 | * of our way so we don't accidentally swap it. |
Steven Rostedt | 3adc54f | 2009-03-30 15:32:01 -0400 | [diff] [blame] | 3298 | */ |
| 3299 | cpu_buffer->pages = reader->list.prev; |
| 3300 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 3301 | /* The reader page will be pointing to the new head */ |
| 3302 | rb_set_list_to_head(cpu_buffer, &cpu_buffer->reader_page->list); |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3303 | |
| 3304 | /* |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 3305 | * We want to make sure we read the overruns after we set up our |
| 3306 | * pointers to the next object. The writer side does a |
| 3307 | * cmpxchg to cross pages which acts as the mb on the writer |
| 3308 | * side. Note, the reader will constantly fail the swap |
| 3309 | * while the writer is updating the pointers, so this |
| 3310 | * guarantees that the overwrite recorded here is the one we |
| 3311 | * want to compare with the last_overrun. |
| 3312 | */ |
| 3313 | smp_mb(); |
| 3314 | overwrite = local_read(&(cpu_buffer->overrun)); |
| 3315 | |
| 3316 | /* |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 3317 | * Here's the tricky part. |
| 3318 | * |
| 3319 | * We need to move the pointer past the header page. |
| 3320 | * But we can only do that if a writer is not currently |
| 3321 | * moving it. The page before the header page has the |
| 3322 | * flag bit '1' set if it is pointing to the page we want. |
| 3323 | * but if the writer is in the process of moving it |
| 3324 | * than it will be '2' or already moved '0'. |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3325 | */ |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3326 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 3327 | ret = rb_head_page_replace(reader, cpu_buffer->reader_page); |
| 3328 | |
| 3329 | /* |
| 3330 | * If we did not convert it, then we must try again. |
| 3331 | */ |
| 3332 | if (!ret) |
| 3333 | goto spin; |
| 3334 | |
| 3335 | /* |
| 3336 | * Yeah! We succeeded in replacing the page. |
| 3337 | * |
| 3338 | * Now make the new head point back to the reader page. |
| 3339 | */ |
David Sharp | 5ded3dc6 | 2010-01-06 17:12:07 -0800 | [diff] [blame] | 3340 | rb_list_head(reader->list.next)->prev = &cpu_buffer->reader_page->list; |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 3341 | rb_inc_page(cpu_buffer, &cpu_buffer->head_page); |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3342 | |
| 3343 | /* Finally update the reader page to the new head */ |
| 3344 | cpu_buffer->reader_page = reader; |
| 3345 | rb_reset_reader_page(cpu_buffer); |
| 3346 | |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 3347 | if (overwrite != cpu_buffer->last_overrun) { |
| 3348 | cpu_buffer->lost_events = overwrite - cpu_buffer->last_overrun; |
| 3349 | cpu_buffer->last_overrun = overwrite; |
| 3350 | } |
| 3351 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3352 | goto again; |
| 3353 | |
| 3354 | out: |
Thomas Gleixner | 0199c4e | 2009-12-02 20:01:25 +0100 | [diff] [blame] | 3355 | arch_spin_unlock(&cpu_buffer->lock); |
Steven Rostedt | 3e03fb7 | 2008-11-06 00:09:43 -0500 | [diff] [blame] | 3356 | local_irq_restore(flags); |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3357 | |
| 3358 | return reader; |
| 3359 | } |
| 3360 | |
| 3361 | static void rb_advance_reader(struct ring_buffer_per_cpu *cpu_buffer) |
| 3362 | { |
| 3363 | struct ring_buffer_event *event; |
| 3364 | struct buffer_page *reader; |
| 3365 | unsigned length; |
| 3366 | |
| 3367 | reader = rb_get_reader_page(cpu_buffer); |
| 3368 | |
| 3369 | /* This function should not be called when buffer is empty */ |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 3370 | if (RB_WARN_ON(cpu_buffer, !reader)) |
| 3371 | return; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3372 | |
| 3373 | event = rb_reader_event(cpu_buffer); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3374 | |
Steven Rostedt | a1863c2 | 2009-09-03 10:23:58 -0400 | [diff] [blame] | 3375 | if (event->type_len <= RINGBUF_TYPE_DATA_TYPE_LEN_MAX) |
Steven Rostedt | e4906ef | 2009-04-30 20:49:44 -0400 | [diff] [blame] | 3376 | cpu_buffer->read++; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3377 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3378 | rb_update_read_stamp(cpu_buffer, event); |
| 3379 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3380 | length = rb_event_length(event); |
Steven Rostedt | 6f807ac | 2008-10-04 02:00:58 -0400 | [diff] [blame] | 3381 | cpu_buffer->reader_page->read += length; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3382 | } |
| 3383 | |
| 3384 | static void rb_advance_iter(struct ring_buffer_iter *iter) |
| 3385 | { |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3386 | struct ring_buffer_per_cpu *cpu_buffer; |
| 3387 | struct ring_buffer_event *event; |
| 3388 | unsigned length; |
| 3389 | |
| 3390 | cpu_buffer = iter->cpu_buffer; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3391 | |
| 3392 | /* |
| 3393 | * Check if we are at the end of the buffer. |
| 3394 | */ |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 3395 | if (iter->head >= rb_page_size(iter->head_page)) { |
Steven Rostedt | ea05b57 | 2009-06-03 09:30:10 -0400 | [diff] [blame] | 3396 | /* discarded commits can make the page empty */ |
| 3397 | if (iter->head_page == cpu_buffer->commit_page) |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 3398 | return; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3399 | rb_inc_iter(iter); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3400 | return; |
| 3401 | } |
| 3402 | |
| 3403 | event = rb_iter_head_event(iter); |
| 3404 | |
| 3405 | length = rb_event_length(event); |
| 3406 | |
| 3407 | /* |
| 3408 | * This should not be called to advance the header if we are |
| 3409 | * at the tail of the buffer. |
| 3410 | */ |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 3411 | if (RB_WARN_ON(cpu_buffer, |
Steven Rostedt | f536aaf | 2008-11-10 23:07:30 -0500 | [diff] [blame] | 3412 | (iter->head_page == cpu_buffer->commit_page) && |
Steven Rostedt | 3e89c7b | 2008-11-11 15:28:41 -0500 | [diff] [blame] | 3413 | (iter->head + length > rb_commit_index(cpu_buffer)))) |
| 3414 | return; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3415 | |
| 3416 | rb_update_iter_read_stamp(iter, event); |
| 3417 | |
| 3418 | iter->head += length; |
| 3419 | |
| 3420 | /* check for end of page padding */ |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 3421 | if ((iter->head >= rb_page_size(iter->head_page)) && |
| 3422 | (iter->head_page != cpu_buffer->commit_page)) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3423 | rb_advance_iter(iter); |
| 3424 | } |
| 3425 | |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 3426 | static int rb_lost_events(struct ring_buffer_per_cpu *cpu_buffer) |
| 3427 | { |
| 3428 | return cpu_buffer->lost_events; |
| 3429 | } |
| 3430 | |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3431 | static struct ring_buffer_event * |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 3432 | rb_buffer_peek(struct ring_buffer_per_cpu *cpu_buffer, u64 *ts, |
| 3433 | unsigned long *lost_events) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3434 | { |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3435 | struct ring_buffer_event *event; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3436 | struct buffer_page *reader; |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 3437 | int nr_loops = 0; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3438 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3439 | again: |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 3440 | /* |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 3441 | * We repeat when a time extend is encountered. |
| 3442 | * Since the time extend is always attached to a data event, |
| 3443 | * we should never loop more than once. |
| 3444 | * (We never hit the following condition more than twice). |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 3445 | */ |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 3446 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 2)) |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 3447 | return NULL; |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 3448 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3449 | reader = rb_get_reader_page(cpu_buffer); |
| 3450 | if (!reader) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3451 | return NULL; |
| 3452 | |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3453 | event = rb_reader_event(cpu_buffer); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3454 | |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 3455 | switch (event->type_len) { |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3456 | case RINGBUF_TYPE_PADDING: |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 3457 | if (rb_null_event(event)) |
| 3458 | RB_WARN_ON(cpu_buffer, 1); |
| 3459 | /* |
| 3460 | * Because the writer could be discarding every |
| 3461 | * event it creates (which would probably be bad) |
| 3462 | * if we were to go back to "again" then we may never |
| 3463 | * catch up, and will trigger the warn on, or lock |
| 3464 | * the box. Return the padding, and we will release |
| 3465 | * the current locks, and try again. |
| 3466 | */ |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 3467 | return event; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3468 | |
| 3469 | case RINGBUF_TYPE_TIME_EXTEND: |
| 3470 | /* Internal data, OK to advance */ |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3471 | rb_advance_reader(cpu_buffer); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3472 | goto again; |
| 3473 | |
| 3474 | case RINGBUF_TYPE_TIME_STAMP: |
| 3475 | /* FIXME: not implemented */ |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3476 | rb_advance_reader(cpu_buffer); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3477 | goto again; |
| 3478 | |
| 3479 | case RINGBUF_TYPE_DATA: |
| 3480 | if (ts) { |
| 3481 | *ts = cpu_buffer->read_stamp + event->time_delta; |
Robert Richter | d8eeb2d | 2009-07-31 14:58:04 +0200 | [diff] [blame] | 3482 | ring_buffer_normalize_time_stamp(cpu_buffer->buffer, |
Steven Rostedt | 37886f6 | 2009-03-17 17:22:06 -0400 | [diff] [blame] | 3483 | cpu_buffer->cpu, ts); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3484 | } |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 3485 | if (lost_events) |
| 3486 | *lost_events = rb_lost_events(cpu_buffer); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3487 | return event; |
| 3488 | |
| 3489 | default: |
| 3490 | BUG(); |
| 3491 | } |
| 3492 | |
| 3493 | return NULL; |
| 3494 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 3495 | EXPORT_SYMBOL_GPL(ring_buffer_peek); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3496 | |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3497 | static struct ring_buffer_event * |
| 3498 | rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3499 | { |
| 3500 | struct ring_buffer *buffer; |
| 3501 | struct ring_buffer_per_cpu *cpu_buffer; |
| 3502 | struct ring_buffer_event *event; |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 3503 | int nr_loops = 0; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3504 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3505 | cpu_buffer = iter->cpu_buffer; |
| 3506 | buffer = cpu_buffer->buffer; |
| 3507 | |
Steven Rostedt | 492a74f | 2010-01-25 15:17:47 -0500 | [diff] [blame] | 3508 | /* |
| 3509 | * Check if someone performed a consuming read to |
| 3510 | * the buffer. A consuming read invalidates the iterator |
| 3511 | * and we need to reset the iterator in this case. |
| 3512 | */ |
| 3513 | if (unlikely(iter->cache_read != cpu_buffer->read || |
| 3514 | iter->cache_reader_page != cpu_buffer->reader_page)) |
| 3515 | rb_iter_reset(iter); |
| 3516 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3517 | again: |
Steven Rostedt | 3c05d74 | 2010-01-26 16:14:08 -0500 | [diff] [blame] | 3518 | if (ring_buffer_iter_empty(iter)) |
| 3519 | return NULL; |
| 3520 | |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 3521 | /* |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 3522 | * We repeat when a time extend is encountered. |
| 3523 | * Since the time extend is always attached to a data event, |
| 3524 | * we should never loop more than once. |
| 3525 | * (We never hit the following condition more than twice). |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 3526 | */ |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 3527 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 2)) |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 3528 | return NULL; |
Steven Rostedt | 818e3dd | 2008-10-31 09:58:35 -0400 | [diff] [blame] | 3529 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3530 | if (rb_per_cpu_empty(cpu_buffer)) |
| 3531 | return NULL; |
| 3532 | |
Steven Rostedt | 3c05d74 | 2010-01-26 16:14:08 -0500 | [diff] [blame] | 3533 | if (iter->head >= local_read(&iter->head_page->page->commit)) { |
| 3534 | rb_inc_iter(iter); |
| 3535 | goto again; |
| 3536 | } |
| 3537 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3538 | event = rb_iter_head_event(iter); |
| 3539 | |
Lai Jiangshan | 334d416 | 2009-04-24 11:27:05 +0800 | [diff] [blame] | 3540 | switch (event->type_len) { |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3541 | case RINGBUF_TYPE_PADDING: |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 3542 | if (rb_null_event(event)) { |
| 3543 | rb_inc_iter(iter); |
| 3544 | goto again; |
| 3545 | } |
| 3546 | rb_advance_iter(iter); |
| 3547 | return event; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3548 | |
| 3549 | case RINGBUF_TYPE_TIME_EXTEND: |
| 3550 | /* Internal data, OK to advance */ |
| 3551 | rb_advance_iter(iter); |
| 3552 | goto again; |
| 3553 | |
| 3554 | case RINGBUF_TYPE_TIME_STAMP: |
| 3555 | /* FIXME: not implemented */ |
| 3556 | rb_advance_iter(iter); |
| 3557 | goto again; |
| 3558 | |
| 3559 | case RINGBUF_TYPE_DATA: |
| 3560 | if (ts) { |
| 3561 | *ts = iter->read_stamp + event->time_delta; |
Steven Rostedt | 37886f6 | 2009-03-17 17:22:06 -0400 | [diff] [blame] | 3562 | ring_buffer_normalize_time_stamp(buffer, |
| 3563 | cpu_buffer->cpu, ts); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3564 | } |
| 3565 | return event; |
| 3566 | |
| 3567 | default: |
| 3568 | BUG(); |
| 3569 | } |
| 3570 | |
| 3571 | return NULL; |
| 3572 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 3573 | EXPORT_SYMBOL_GPL(ring_buffer_iter_peek); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3574 | |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 3575 | static inline int rb_ok_to_lock(void) |
| 3576 | { |
| 3577 | /* |
| 3578 | * If an NMI die dumps out the content of the ring buffer |
| 3579 | * do not grab locks. We also permanently disable the ring |
| 3580 | * buffer too. A one time deal is all you get from reading |
| 3581 | * the ring buffer from an NMI. |
| 3582 | */ |
Steven Rostedt | 464e85e | 2009-08-05 15:26:37 -0400 | [diff] [blame] | 3583 | if (likely(!in_nmi())) |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 3584 | return 1; |
| 3585 | |
| 3586 | tracing_off_permanent(); |
| 3587 | return 0; |
| 3588 | } |
| 3589 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3590 | /** |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3591 | * ring_buffer_peek - peek at the next event to be read |
| 3592 | * @buffer: The ring buffer to read |
| 3593 | * @cpu: The cpu to peak at |
| 3594 | * @ts: The timestamp counter of this event. |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 3595 | * @lost_events: a variable to store if events were lost (may be NULL) |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3596 | * |
| 3597 | * This will return the event that will be read next, but does |
| 3598 | * not consume the data. |
| 3599 | */ |
| 3600 | struct ring_buffer_event * |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 3601 | ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts, |
| 3602 | unsigned long *lost_events) |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3603 | { |
| 3604 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 3605 | struct ring_buffer_event *event; |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3606 | unsigned long flags; |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 3607 | int dolock; |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3608 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 3609 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 3610 | return NULL; |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 3611 | |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 3612 | dolock = rb_ok_to_lock(); |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 3613 | again: |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 3614 | local_irq_save(flags); |
| 3615 | if (dolock) |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 3616 | raw_spin_lock(&cpu_buffer->reader_lock); |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 3617 | event = rb_buffer_peek(cpu_buffer, ts, lost_events); |
Robert Richter | 469535a | 2009-07-30 19:19:18 +0200 | [diff] [blame] | 3618 | if (event && event->type_len == RINGBUF_TYPE_PADDING) |
| 3619 | rb_advance_reader(cpu_buffer); |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 3620 | if (dolock) |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 3621 | raw_spin_unlock(&cpu_buffer->reader_lock); |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 3622 | local_irq_restore(flags); |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3623 | |
Steven Rostedt | 1b959e1 | 2009-09-03 10:12:13 -0400 | [diff] [blame] | 3624 | if (event && event->type_len == RINGBUF_TYPE_PADDING) |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 3625 | goto again; |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 3626 | |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3627 | return event; |
| 3628 | } |
| 3629 | |
| 3630 | /** |
| 3631 | * ring_buffer_iter_peek - peek at the next event to be read |
| 3632 | * @iter: The ring buffer iterator |
| 3633 | * @ts: The timestamp counter of this event. |
| 3634 | * |
| 3635 | * This will return the event that will be read next, but does |
| 3636 | * not increment the iterator. |
| 3637 | */ |
| 3638 | struct ring_buffer_event * |
| 3639 | ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts) |
| 3640 | { |
| 3641 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; |
| 3642 | struct ring_buffer_event *event; |
| 3643 | unsigned long flags; |
| 3644 | |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 3645 | again: |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 3646 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3647 | event = rb_iter_peek(iter, ts); |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 3648 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3649 | |
Steven Rostedt | 1b959e1 | 2009-09-03 10:12:13 -0400 | [diff] [blame] | 3650 | if (event && event->type_len == RINGBUF_TYPE_PADDING) |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 3651 | goto again; |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 3652 | |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3653 | return event; |
| 3654 | } |
| 3655 | |
| 3656 | /** |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3657 | * ring_buffer_consume - return an event and consume it |
| 3658 | * @buffer: The ring buffer to get the next event from |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 3659 | * @cpu: the cpu to read the buffer from |
| 3660 | * @ts: a variable to store the timestamp (may be NULL) |
| 3661 | * @lost_events: a variable to store if events were lost (may be NULL) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3662 | * |
| 3663 | * Returns the next event in the ring buffer, and that event is consumed. |
| 3664 | * Meaning, that sequential reads will keep returning a different event, |
| 3665 | * and eventually empty the ring buffer if the producer is slower. |
| 3666 | */ |
| 3667 | struct ring_buffer_event * |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 3668 | ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts, |
| 3669 | unsigned long *lost_events) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3670 | { |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 3671 | struct ring_buffer_per_cpu *cpu_buffer; |
| 3672 | struct ring_buffer_event *event = NULL; |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3673 | unsigned long flags; |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 3674 | int dolock; |
| 3675 | |
| 3676 | dolock = rb_ok_to_lock(); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3677 | |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 3678 | again: |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 3679 | /* might be called in atomic */ |
| 3680 | preempt_disable(); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3681 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 3682 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
| 3683 | goto out; |
| 3684 | |
| 3685 | cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 3686 | local_irq_save(flags); |
| 3687 | if (dolock) |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 3688 | raw_spin_lock(&cpu_buffer->reader_lock); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3689 | |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 3690 | event = rb_buffer_peek(cpu_buffer, ts, lost_events); |
| 3691 | if (event) { |
| 3692 | cpu_buffer->lost_events = 0; |
Robert Richter | 469535a | 2009-07-30 19:19:18 +0200 | [diff] [blame] | 3693 | rb_advance_reader(cpu_buffer); |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 3694 | } |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3695 | |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 3696 | if (dolock) |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 3697 | raw_spin_unlock(&cpu_buffer->reader_lock); |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 3698 | local_irq_restore(flags); |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3699 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 3700 | out: |
| 3701 | preempt_enable(); |
| 3702 | |
Steven Rostedt | 1b959e1 | 2009-09-03 10:12:13 -0400 | [diff] [blame] | 3703 | if (event && event->type_len == RINGBUF_TYPE_PADDING) |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 3704 | goto again; |
Tom Zanussi | 2d62271 | 2009-03-22 03:30:49 -0500 | [diff] [blame] | 3705 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3706 | return event; |
| 3707 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 3708 | EXPORT_SYMBOL_GPL(ring_buffer_consume); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3709 | |
| 3710 | /** |
David Miller | 72c9ddf | 2010-04-20 15:47:11 -0700 | [diff] [blame] | 3711 | * ring_buffer_read_prepare - Prepare for a non consuming read of the buffer |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3712 | * @buffer: The ring buffer to read from |
| 3713 | * @cpu: The cpu buffer to iterate over |
| 3714 | * |
David Miller | 72c9ddf | 2010-04-20 15:47:11 -0700 | [diff] [blame] | 3715 | * This performs the initial preparations necessary to iterate |
| 3716 | * through the buffer. Memory is allocated, buffer recording |
| 3717 | * is disabled, and the iterator pointer is returned to the caller. |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3718 | * |
David Miller | 72c9ddf | 2010-04-20 15:47:11 -0700 | [diff] [blame] | 3719 | * Disabling buffer recordng prevents the reading from being |
| 3720 | * corrupted. This is not a consuming read, so a producer is not |
| 3721 | * expected. |
| 3722 | * |
| 3723 | * After a sequence of ring_buffer_read_prepare calls, the user is |
| 3724 | * expected to make at least one call to ring_buffer_prepare_sync. |
| 3725 | * Afterwards, ring_buffer_read_start is invoked to get things going |
| 3726 | * for real. |
| 3727 | * |
| 3728 | * This overall must be paired with ring_buffer_finish. |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3729 | */ |
| 3730 | struct ring_buffer_iter * |
David Miller | 72c9ddf | 2010-04-20 15:47:11 -0700 | [diff] [blame] | 3731 | ring_buffer_read_prepare(struct ring_buffer *buffer, int cpu) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3732 | { |
| 3733 | struct ring_buffer_per_cpu *cpu_buffer; |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 3734 | struct ring_buffer_iter *iter; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3735 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 3736 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 3737 | return NULL; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3738 | |
| 3739 | iter = kmalloc(sizeof(*iter), GFP_KERNEL); |
| 3740 | if (!iter) |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 3741 | return NULL; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3742 | |
| 3743 | cpu_buffer = buffer->buffers[cpu]; |
| 3744 | |
| 3745 | iter->cpu_buffer = cpu_buffer; |
| 3746 | |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 3747 | atomic_inc(&buffer->resize_disabled); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3748 | atomic_inc(&cpu_buffer->record_disabled); |
David Miller | 72c9ddf | 2010-04-20 15:47:11 -0700 | [diff] [blame] | 3749 | |
| 3750 | return iter; |
| 3751 | } |
| 3752 | EXPORT_SYMBOL_GPL(ring_buffer_read_prepare); |
| 3753 | |
| 3754 | /** |
| 3755 | * ring_buffer_read_prepare_sync - Synchronize a set of prepare calls |
| 3756 | * |
| 3757 | * All previously invoked ring_buffer_read_prepare calls to prepare |
| 3758 | * iterators will be synchronized. Afterwards, read_buffer_read_start |
| 3759 | * calls on those iterators are allowed. |
| 3760 | */ |
| 3761 | void |
| 3762 | ring_buffer_read_prepare_sync(void) |
| 3763 | { |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3764 | synchronize_sched(); |
David Miller | 72c9ddf | 2010-04-20 15:47:11 -0700 | [diff] [blame] | 3765 | } |
| 3766 | EXPORT_SYMBOL_GPL(ring_buffer_read_prepare_sync); |
| 3767 | |
| 3768 | /** |
| 3769 | * ring_buffer_read_start - start a non consuming read of the buffer |
| 3770 | * @iter: The iterator returned by ring_buffer_read_prepare |
| 3771 | * |
| 3772 | * This finalizes the startup of an iteration through the buffer. |
| 3773 | * The iterator comes from a call to ring_buffer_read_prepare and |
| 3774 | * an intervening ring_buffer_read_prepare_sync must have been |
| 3775 | * performed. |
| 3776 | * |
| 3777 | * Must be paired with ring_buffer_finish. |
| 3778 | */ |
| 3779 | void |
| 3780 | ring_buffer_read_start(struct ring_buffer_iter *iter) |
| 3781 | { |
| 3782 | struct ring_buffer_per_cpu *cpu_buffer; |
| 3783 | unsigned long flags; |
| 3784 | |
| 3785 | if (!iter) |
| 3786 | return; |
| 3787 | |
| 3788 | cpu_buffer = iter->cpu_buffer; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3789 | |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 3790 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
Thomas Gleixner | 0199c4e | 2009-12-02 20:01:25 +0100 | [diff] [blame] | 3791 | arch_spin_lock(&cpu_buffer->lock); |
Steven Rostedt | 642edba | 2008-11-12 00:01:26 -0500 | [diff] [blame] | 3792 | rb_iter_reset(iter); |
Thomas Gleixner | 0199c4e | 2009-12-02 20:01:25 +0100 | [diff] [blame] | 3793 | arch_spin_unlock(&cpu_buffer->lock); |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 3794 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3795 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 3796 | EXPORT_SYMBOL_GPL(ring_buffer_read_start); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3797 | |
| 3798 | /** |
| 3799 | * ring_buffer_finish - finish reading the iterator of the buffer |
| 3800 | * @iter: The iterator retrieved by ring_buffer_start |
| 3801 | * |
| 3802 | * This re-enables the recording to the buffer, and frees the |
| 3803 | * iterator. |
| 3804 | */ |
| 3805 | void |
| 3806 | ring_buffer_read_finish(struct ring_buffer_iter *iter) |
| 3807 | { |
| 3808 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; |
| 3809 | |
Steven Rostedt | 659f451 | 2012-05-14 17:02:33 -0400 | [diff] [blame] | 3810 | /* |
| 3811 | * Ring buffer is disabled from recording, here's a good place |
| 3812 | * to check the integrity of the ring buffer. |
| 3813 | */ |
| 3814 | rb_check_pages(cpu_buffer); |
| 3815 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3816 | atomic_dec(&cpu_buffer->record_disabled); |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 3817 | atomic_dec(&cpu_buffer->buffer->resize_disabled); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3818 | kfree(iter); |
| 3819 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 3820 | EXPORT_SYMBOL_GPL(ring_buffer_read_finish); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3821 | |
| 3822 | /** |
| 3823 | * ring_buffer_read - read the next item in the ring buffer by the iterator |
| 3824 | * @iter: The ring buffer iterator |
| 3825 | * @ts: The time stamp of the event read. |
| 3826 | * |
| 3827 | * This reads the next event in the ring buffer and increments the iterator. |
| 3828 | */ |
| 3829 | struct ring_buffer_event * |
| 3830 | ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts) |
| 3831 | { |
| 3832 | struct ring_buffer_event *event; |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3833 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; |
| 3834 | unsigned long flags; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3835 | |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 3836 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | 7e9391c | 2009-09-03 10:02:09 -0400 | [diff] [blame] | 3837 | again: |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3838 | event = rb_iter_peek(iter, ts); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3839 | if (!event) |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3840 | goto out; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3841 | |
Steven Rostedt | 7e9391c | 2009-09-03 10:02:09 -0400 | [diff] [blame] | 3842 | if (event->type_len == RINGBUF_TYPE_PADDING) |
| 3843 | goto again; |
| 3844 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3845 | rb_advance_iter(iter); |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3846 | out: |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 3847 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3848 | |
| 3849 | return event; |
| 3850 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 3851 | EXPORT_SYMBOL_GPL(ring_buffer_read); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3852 | |
| 3853 | /** |
| 3854 | * ring_buffer_size - return the size of the ring buffer (in bytes) |
| 3855 | * @buffer: The ring buffer. |
| 3856 | */ |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 3857 | unsigned long ring_buffer_size(struct ring_buffer *buffer, int cpu) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3858 | { |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 3859 | /* |
| 3860 | * Earlier, this method returned |
| 3861 | * BUF_PAGE_SIZE * buffer->nr_pages |
| 3862 | * Since the nr_pages field is now removed, we have converted this to |
| 3863 | * return the per cpu buffer value. |
| 3864 | */ |
| 3865 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
| 3866 | return 0; |
| 3867 | |
| 3868 | return BUF_PAGE_SIZE * buffer->buffers[cpu]->nr_pages; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3869 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 3870 | EXPORT_SYMBOL_GPL(ring_buffer_size); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3871 | |
| 3872 | static void |
| 3873 | rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer) |
| 3874 | { |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 3875 | rb_head_page_deactivate(cpu_buffer); |
| 3876 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3877 | cpu_buffer->head_page |
Steven Rostedt | 3adc54f | 2009-03-30 15:32:01 -0400 | [diff] [blame] | 3878 | = list_entry(cpu_buffer->pages, struct buffer_page, list); |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 3879 | local_set(&cpu_buffer->head_page->write, 0); |
Steven Rostedt | 778c55d | 2009-05-01 18:44:45 -0400 | [diff] [blame] | 3880 | local_set(&cpu_buffer->head_page->entries, 0); |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 3881 | local_set(&cpu_buffer->head_page->page->commit, 0); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3882 | |
Steven Rostedt | 6f807ac | 2008-10-04 02:00:58 -0400 | [diff] [blame] | 3883 | cpu_buffer->head_page->read = 0; |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 3884 | |
| 3885 | cpu_buffer->tail_page = cpu_buffer->head_page; |
| 3886 | cpu_buffer->commit_page = cpu_buffer->head_page; |
| 3887 | |
| 3888 | INIT_LIST_HEAD(&cpu_buffer->reader_page->list); |
Vaibhav Nagarnaik | 5040b4b | 2012-05-03 18:59:51 -0700 | [diff] [blame] | 3889 | INIT_LIST_HEAD(&cpu_buffer->new_pages); |
Steven Rostedt | bf41a15 | 2008-10-04 02:00:59 -0400 | [diff] [blame] | 3890 | local_set(&cpu_buffer->reader_page->write, 0); |
Steven Rostedt | 778c55d | 2009-05-01 18:44:45 -0400 | [diff] [blame] | 3891 | local_set(&cpu_buffer->reader_page->entries, 0); |
Steven Rostedt | abc9b56 | 2008-12-02 15:34:06 -0500 | [diff] [blame] | 3892 | local_set(&cpu_buffer->reader_page->page->commit, 0); |
Steven Rostedt | 6f807ac | 2008-10-04 02:00:58 -0400 | [diff] [blame] | 3893 | cpu_buffer->reader_page->read = 0; |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3894 | |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 3895 | local_set(&cpu_buffer->entries_bytes, 0); |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 3896 | local_set(&cpu_buffer->overrun, 0); |
Slava Pestov | 884bfe8 | 2011-07-15 14:23:58 -0700 | [diff] [blame] | 3897 | local_set(&cpu_buffer->commit_overrun, 0); |
| 3898 | local_set(&cpu_buffer->dropped_events, 0); |
Steven Rostedt | e4906ef | 2009-04-30 20:49:44 -0400 | [diff] [blame] | 3899 | local_set(&cpu_buffer->entries, 0); |
Steven Rostedt | fa74395 | 2009-06-16 12:37:57 -0400 | [diff] [blame] | 3900 | local_set(&cpu_buffer->committing, 0); |
| 3901 | local_set(&cpu_buffer->commits, 0); |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 3902 | cpu_buffer->read = 0; |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 3903 | cpu_buffer->read_bytes = 0; |
Steven Rostedt | 69507c0 | 2009-01-21 18:45:57 -0500 | [diff] [blame] | 3904 | |
| 3905 | cpu_buffer->write_stamp = 0; |
| 3906 | cpu_buffer->read_stamp = 0; |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 3907 | |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 3908 | cpu_buffer->lost_events = 0; |
| 3909 | cpu_buffer->last_overrun = 0; |
| 3910 | |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 3911 | rb_head_page_activate(cpu_buffer); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3912 | } |
| 3913 | |
| 3914 | /** |
| 3915 | * ring_buffer_reset_cpu - reset a ring buffer per CPU buffer |
| 3916 | * @buffer: The ring buffer to reset a per cpu buffer of |
| 3917 | * @cpu: The CPU buffer to be reset |
| 3918 | */ |
| 3919 | void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu) |
| 3920 | { |
| 3921 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; |
| 3922 | unsigned long flags; |
| 3923 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 3924 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 3925 | return; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3926 | |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 3927 | atomic_inc(&buffer->resize_disabled); |
Steven Rostedt | 41ede23 | 2009-05-01 20:26:54 -0400 | [diff] [blame] | 3928 | atomic_inc(&cpu_buffer->record_disabled); |
| 3929 | |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 3930 | /* Make sure all commits have finished */ |
| 3931 | synchronize_sched(); |
| 3932 | |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 3933 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3934 | |
Steven Rostedt | 41b6a95 | 2009-09-02 09:59:48 -0400 | [diff] [blame] | 3935 | if (RB_WARN_ON(cpu_buffer, local_read(&cpu_buffer->committing))) |
| 3936 | goto out; |
| 3937 | |
Thomas Gleixner | 0199c4e | 2009-12-02 20:01:25 +0100 | [diff] [blame] | 3938 | arch_spin_lock(&cpu_buffer->lock); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3939 | |
| 3940 | rb_reset_cpu(cpu_buffer); |
| 3941 | |
Thomas Gleixner | 0199c4e | 2009-12-02 20:01:25 +0100 | [diff] [blame] | 3942 | arch_spin_unlock(&cpu_buffer->lock); |
Steven Rostedt | f83c9d0 | 2008-11-11 18:47:44 +0100 | [diff] [blame] | 3943 | |
Steven Rostedt | 41b6a95 | 2009-09-02 09:59:48 -0400 | [diff] [blame] | 3944 | out: |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 3945 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | 41ede23 | 2009-05-01 20:26:54 -0400 | [diff] [blame] | 3946 | |
| 3947 | atomic_dec(&cpu_buffer->record_disabled); |
Vaibhav Nagarnaik | 83f4031 | 2012-05-03 18:59:50 -0700 | [diff] [blame] | 3948 | atomic_dec(&buffer->resize_disabled); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3949 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 3950 | EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3951 | |
| 3952 | /** |
| 3953 | * ring_buffer_reset - reset a ring buffer |
| 3954 | * @buffer: The ring buffer to reset all cpu buffers |
| 3955 | */ |
| 3956 | void ring_buffer_reset(struct ring_buffer *buffer) |
| 3957 | { |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3958 | int cpu; |
| 3959 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3960 | for_each_buffer_cpu(buffer, cpu) |
Steven Rostedt | d769041 | 2008-10-01 00:29:53 -0400 | [diff] [blame] | 3961 | ring_buffer_reset_cpu(buffer, cpu); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3962 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 3963 | EXPORT_SYMBOL_GPL(ring_buffer_reset); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3964 | |
| 3965 | /** |
| 3966 | * rind_buffer_empty - is the ring buffer empty? |
| 3967 | * @buffer: The ring buffer to test |
| 3968 | */ |
| 3969 | int ring_buffer_empty(struct ring_buffer *buffer) |
| 3970 | { |
| 3971 | struct ring_buffer_per_cpu *cpu_buffer; |
Steven Rostedt | d478820 | 2009-06-17 00:39:43 -0400 | [diff] [blame] | 3972 | unsigned long flags; |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 3973 | int dolock; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3974 | int cpu; |
Steven Rostedt | d478820 | 2009-06-17 00:39:43 -0400 | [diff] [blame] | 3975 | int ret; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3976 | |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 3977 | dolock = rb_ok_to_lock(); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3978 | |
| 3979 | /* yes this is racy, but if you don't like the race, lock the buffer */ |
| 3980 | for_each_buffer_cpu(buffer, cpu) { |
| 3981 | cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 3982 | local_irq_save(flags); |
| 3983 | if (dolock) |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 3984 | raw_spin_lock(&cpu_buffer->reader_lock); |
Steven Rostedt | d478820 | 2009-06-17 00:39:43 -0400 | [diff] [blame] | 3985 | ret = rb_per_cpu_empty(cpu_buffer); |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 3986 | if (dolock) |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 3987 | raw_spin_unlock(&cpu_buffer->reader_lock); |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 3988 | local_irq_restore(flags); |
| 3989 | |
Steven Rostedt | d478820 | 2009-06-17 00:39:43 -0400 | [diff] [blame] | 3990 | if (!ret) |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3991 | return 0; |
| 3992 | } |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 3993 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3994 | return 1; |
| 3995 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 3996 | EXPORT_SYMBOL_GPL(ring_buffer_empty); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 3997 | |
| 3998 | /** |
| 3999 | * ring_buffer_empty_cpu - is a cpu buffer of a ring buffer empty? |
| 4000 | * @buffer: The ring buffer |
| 4001 | * @cpu: The CPU buffer to test |
| 4002 | */ |
| 4003 | int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu) |
| 4004 | { |
| 4005 | struct ring_buffer_per_cpu *cpu_buffer; |
Steven Rostedt | d478820 | 2009-06-17 00:39:43 -0400 | [diff] [blame] | 4006 | unsigned long flags; |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 4007 | int dolock; |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 4008 | int ret; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4009 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 4010 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | 8aabee5 | 2009-03-12 13:13:49 -0400 | [diff] [blame] | 4011 | return 1; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4012 | |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 4013 | dolock = rb_ok_to_lock(); |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4014 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4015 | cpu_buffer = buffer->buffers[cpu]; |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 4016 | local_irq_save(flags); |
| 4017 | if (dolock) |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 4018 | raw_spin_lock(&cpu_buffer->reader_lock); |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4019 | ret = rb_per_cpu_empty(cpu_buffer); |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 4020 | if (dolock) |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 4021 | raw_spin_unlock(&cpu_buffer->reader_lock); |
Steven Rostedt | 8d707e8 | 2009-06-16 21:22:48 -0400 | [diff] [blame] | 4022 | local_irq_restore(flags); |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4023 | |
| 4024 | return ret; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4025 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 4026 | EXPORT_SYMBOL_GPL(ring_buffer_empty_cpu); |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4027 | |
Steven Rostedt | 85bac32 | 2009-09-04 14:24:40 -0400 | [diff] [blame] | 4028 | #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4029 | /** |
| 4030 | * ring_buffer_swap_cpu - swap a CPU buffer between two ring buffers |
| 4031 | * @buffer_a: One buffer to swap with |
| 4032 | * @buffer_b: The other buffer to swap with |
| 4033 | * |
| 4034 | * This function is useful for tracers that want to take a "snapshot" |
| 4035 | * of a CPU buffer and has another back up buffer lying around. |
| 4036 | * it is expected that the tracer handles the cpu buffer not being |
| 4037 | * used at the moment. |
| 4038 | */ |
| 4039 | int ring_buffer_swap_cpu(struct ring_buffer *buffer_a, |
| 4040 | struct ring_buffer *buffer_b, int cpu) |
| 4041 | { |
| 4042 | struct ring_buffer_per_cpu *cpu_buffer_a; |
| 4043 | struct ring_buffer_per_cpu *cpu_buffer_b; |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4044 | int ret = -EINVAL; |
| 4045 | |
Rusty Russell | 9e01c1b | 2009-01-01 10:12:22 +1030 | [diff] [blame] | 4046 | if (!cpumask_test_cpu(cpu, buffer_a->cpumask) || |
| 4047 | !cpumask_test_cpu(cpu, buffer_b->cpumask)) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4048 | goto out; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4049 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 4050 | cpu_buffer_a = buffer_a->buffers[cpu]; |
| 4051 | cpu_buffer_b = buffer_b->buffers[cpu]; |
| 4052 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4053 | /* At least make sure the two buffers are somewhat the same */ |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 4054 | if (cpu_buffer_a->nr_pages != cpu_buffer_b->nr_pages) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4055 | goto out; |
| 4056 | |
| 4057 | ret = -EAGAIN; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4058 | |
Steven Rostedt | 97b17ef | 2009-01-21 15:24:56 -0500 | [diff] [blame] | 4059 | if (ring_buffer_flags != RB_BUFFERS_ON) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4060 | goto out; |
Steven Rostedt | 97b17ef | 2009-01-21 15:24:56 -0500 | [diff] [blame] | 4061 | |
| 4062 | if (atomic_read(&buffer_a->record_disabled)) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4063 | goto out; |
Steven Rostedt | 97b17ef | 2009-01-21 15:24:56 -0500 | [diff] [blame] | 4064 | |
| 4065 | if (atomic_read(&buffer_b->record_disabled)) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4066 | goto out; |
Steven Rostedt | 97b17ef | 2009-01-21 15:24:56 -0500 | [diff] [blame] | 4067 | |
Steven Rostedt | 97b17ef | 2009-01-21 15:24:56 -0500 | [diff] [blame] | 4068 | if (atomic_read(&cpu_buffer_a->record_disabled)) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4069 | goto out; |
Steven Rostedt | 97b17ef | 2009-01-21 15:24:56 -0500 | [diff] [blame] | 4070 | |
| 4071 | if (atomic_read(&cpu_buffer_b->record_disabled)) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4072 | goto out; |
Steven Rostedt | 97b17ef | 2009-01-21 15:24:56 -0500 | [diff] [blame] | 4073 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4074 | /* |
| 4075 | * We can't do a synchronize_sched here because this |
| 4076 | * function can be called in atomic context. |
| 4077 | * Normally this will be called from the same CPU as cpu. |
| 4078 | * If not it's up to the caller to protect this. |
| 4079 | */ |
| 4080 | atomic_inc(&cpu_buffer_a->record_disabled); |
| 4081 | atomic_inc(&cpu_buffer_b->record_disabled); |
| 4082 | |
Steven Rostedt | 9827799 | 2009-09-02 10:56:15 -0400 | [diff] [blame] | 4083 | ret = -EBUSY; |
| 4084 | if (local_read(&cpu_buffer_a->committing)) |
| 4085 | goto out_dec; |
| 4086 | if (local_read(&cpu_buffer_b->committing)) |
| 4087 | goto out_dec; |
| 4088 | |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4089 | buffer_a->buffers[cpu] = cpu_buffer_b; |
| 4090 | buffer_b->buffers[cpu] = cpu_buffer_a; |
| 4091 | |
| 4092 | cpu_buffer_b->buffer = buffer_a; |
| 4093 | cpu_buffer_a->buffer = buffer_b; |
| 4094 | |
Steven Rostedt | 9827799 | 2009-09-02 10:56:15 -0400 | [diff] [blame] | 4095 | ret = 0; |
| 4096 | |
| 4097 | out_dec: |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4098 | atomic_dec(&cpu_buffer_a->record_disabled); |
| 4099 | atomic_dec(&cpu_buffer_b->record_disabled); |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4100 | out: |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4101 | return ret; |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4102 | } |
Robert Richter | c4f5018 | 2008-12-11 16:49:22 +0100 | [diff] [blame] | 4103 | EXPORT_SYMBOL_GPL(ring_buffer_swap_cpu); |
Steven Rostedt | 85bac32 | 2009-09-04 14:24:40 -0400 | [diff] [blame] | 4104 | #endif /* CONFIG_RING_BUFFER_ALLOW_SWAP */ |
Steven Rostedt | 7a8e76a | 2008-09-29 23:02:38 -0400 | [diff] [blame] | 4105 | |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4106 | /** |
| 4107 | * ring_buffer_alloc_read_page - allocate a page to read from buffer |
| 4108 | * @buffer: the buffer to allocate for. |
| 4109 | * |
| 4110 | * This function is used in conjunction with ring_buffer_read_page. |
| 4111 | * When reading a full page from the ring buffer, these functions |
| 4112 | * can be used to speed up the process. The calling function should |
| 4113 | * allocate a few pages first with this function. Then when it |
| 4114 | * needs to get pages from the ring buffer, it passes the result |
| 4115 | * of this function into ring_buffer_read_page, which will swap |
| 4116 | * the page that was allocated, with the read page of the buffer. |
| 4117 | * |
| 4118 | * Returns: |
| 4119 | * The page allocated, or NULL on error. |
| 4120 | */ |
Vaibhav Nagarnaik | 7ea5906 | 2011-05-03 17:56:42 -0700 | [diff] [blame] | 4121 | void *ring_buffer_alloc_read_page(struct ring_buffer *buffer, int cpu) |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4122 | { |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 4123 | struct buffer_data_page *bpage; |
Vaibhav Nagarnaik | 7ea5906 | 2011-05-03 17:56:42 -0700 | [diff] [blame] | 4124 | struct page *page; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4125 | |
Vaibhav Nagarnaik | d7ec4bf | 2011-06-07 17:01:42 -0700 | [diff] [blame] | 4126 | page = alloc_pages_node(cpu_to_node(cpu), |
| 4127 | GFP_KERNEL | __GFP_NORETRY, 0); |
Vaibhav Nagarnaik | 7ea5906 | 2011-05-03 17:56:42 -0700 | [diff] [blame] | 4128 | if (!page) |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4129 | return NULL; |
| 4130 | |
Vaibhav Nagarnaik | 7ea5906 | 2011-05-03 17:56:42 -0700 | [diff] [blame] | 4131 | bpage = page_address(page); |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4132 | |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4133 | rb_init_page(bpage); |
| 4134 | |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 4135 | return bpage; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4136 | } |
Steven Rostedt | d6ce96d | 2009-05-05 01:15:24 -0400 | [diff] [blame] | 4137 | EXPORT_SYMBOL_GPL(ring_buffer_alloc_read_page); |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4138 | |
| 4139 | /** |
| 4140 | * ring_buffer_free_read_page - free an allocated read page |
| 4141 | * @buffer: the buffer the page was allocate for |
| 4142 | * @data: the page to free |
| 4143 | * |
| 4144 | * Free a page allocated from ring_buffer_alloc_read_page. |
| 4145 | */ |
| 4146 | void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data) |
| 4147 | { |
| 4148 | free_page((unsigned long)data); |
| 4149 | } |
Steven Rostedt | d6ce96d | 2009-05-05 01:15:24 -0400 | [diff] [blame] | 4150 | EXPORT_SYMBOL_GPL(ring_buffer_free_read_page); |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4151 | |
| 4152 | /** |
| 4153 | * ring_buffer_read_page - extract a page from the ring buffer |
| 4154 | * @buffer: buffer to extract from |
| 4155 | * @data_page: the page to use allocated from ring_buffer_alloc_read_page |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4156 | * @len: amount to extract |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4157 | * @cpu: the cpu of the buffer to extract |
| 4158 | * @full: should the extraction only happen when the page is full. |
| 4159 | * |
| 4160 | * This function will pull out a page from the ring buffer and consume it. |
| 4161 | * @data_page must be the address of the variable that was returned |
| 4162 | * from ring_buffer_alloc_read_page. This is because the page might be used |
| 4163 | * to swap with a page in the ring buffer. |
| 4164 | * |
| 4165 | * for example: |
Lai Jiangshan | b85fa01 | 2009-02-09 14:21:14 +0800 | [diff] [blame] | 4166 | * rpage = ring_buffer_alloc_read_page(buffer); |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4167 | * if (!rpage) |
| 4168 | * return error; |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4169 | * ret = ring_buffer_read_page(buffer, &rpage, len, cpu, 0); |
Lai Jiangshan | 667d241 | 2009-02-09 14:21:17 +0800 | [diff] [blame] | 4170 | * if (ret >= 0) |
| 4171 | * process_page(rpage, ret); |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4172 | * |
| 4173 | * When @full is set, the function will not return true unless |
| 4174 | * the writer is off the reader page. |
| 4175 | * |
| 4176 | * Note: it is up to the calling functions to handle sleeps and wakeups. |
| 4177 | * The ring buffer can be used anywhere in the kernel and can not |
| 4178 | * blindly call wake_up. The layer that uses the ring buffer must be |
| 4179 | * responsible for that. |
| 4180 | * |
| 4181 | * Returns: |
Lai Jiangshan | 667d241 | 2009-02-09 14:21:17 +0800 | [diff] [blame] | 4182 | * >=0 if data has been transferred, returns the offset of consumed data. |
| 4183 | * <0 if no data has been transferred. |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4184 | */ |
| 4185 | int ring_buffer_read_page(struct ring_buffer *buffer, |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4186 | void **data_page, size_t len, int cpu, int full) |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4187 | { |
| 4188 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; |
| 4189 | struct ring_buffer_event *event; |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 4190 | struct buffer_data_page *bpage; |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4191 | struct buffer_page *reader; |
Steven Rostedt | ff0ff84 | 2010-03-31 22:11:42 -0400 | [diff] [blame] | 4192 | unsigned long missed_events; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4193 | unsigned long flags; |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4194 | unsigned int commit; |
Lai Jiangshan | 667d241 | 2009-02-09 14:21:17 +0800 | [diff] [blame] | 4195 | unsigned int read; |
Steven Rostedt | 4f3640f | 2009-03-03 23:52:42 -0500 | [diff] [blame] | 4196 | u64 save_timestamp; |
Lai Jiangshan | 667d241 | 2009-02-09 14:21:17 +0800 | [diff] [blame] | 4197 | int ret = -1; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4198 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4199 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
| 4200 | goto out; |
| 4201 | |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 4202 | /* |
| 4203 | * If len is not big enough to hold the page header, then |
| 4204 | * we can not copy anything. |
| 4205 | */ |
| 4206 | if (len <= BUF_PAGE_HDR_SIZE) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4207 | goto out; |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 4208 | |
| 4209 | len -= BUF_PAGE_HDR_SIZE; |
| 4210 | |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4211 | if (!data_page) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4212 | goto out; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4213 | |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 4214 | bpage = *data_page; |
| 4215 | if (!bpage) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4216 | goto out; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4217 | |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 4218 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4219 | |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4220 | reader = rb_get_reader_page(cpu_buffer); |
| 4221 | if (!reader) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4222 | goto out_unlock; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4223 | |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4224 | event = rb_reader_event(cpu_buffer); |
Lai Jiangshan | 667d241 | 2009-02-09 14:21:17 +0800 | [diff] [blame] | 4225 | |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4226 | read = reader->read; |
| 4227 | commit = rb_page_commit(reader); |
| 4228 | |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 4229 | /* Check if any events were dropped */ |
Steven Rostedt | ff0ff84 | 2010-03-31 22:11:42 -0400 | [diff] [blame] | 4230 | missed_events = cpu_buffer->lost_events; |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 4231 | |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4232 | /* |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 4233 | * If this page has been partially read or |
| 4234 | * if len is not big enough to read the rest of the page or |
| 4235 | * a writer is still on the page, then |
| 4236 | * we must copy the data from the page to the buffer. |
| 4237 | * Otherwise, we can simply swap the page with the one passed in. |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4238 | */ |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 4239 | if (read || (len < (commit - read)) || |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4240 | cpu_buffer->reader_page == cpu_buffer->commit_page) { |
Lai Jiangshan | 667d241 | 2009-02-09 14:21:17 +0800 | [diff] [blame] | 4241 | struct buffer_data_page *rpage = cpu_buffer->reader_page->page; |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 4242 | unsigned int rpos = read; |
| 4243 | unsigned int pos = 0; |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4244 | unsigned int size; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4245 | |
| 4246 | if (full) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4247 | goto out_unlock; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4248 | |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4249 | if (len > (commit - read)) |
| 4250 | len = (commit - read); |
| 4251 | |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 4252 | /* Always keep the time extend and data together */ |
| 4253 | size = rb_event_ts_length(event); |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4254 | |
| 4255 | if (len < size) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4256 | goto out_unlock; |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4257 | |
Steven Rostedt | 4f3640f | 2009-03-03 23:52:42 -0500 | [diff] [blame] | 4258 | /* save the current timestamp, since the user will need it */ |
| 4259 | save_timestamp = cpu_buffer->read_stamp; |
| 4260 | |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4261 | /* Need to copy one event at a time */ |
| 4262 | do { |
David Sharp | e1e3592 | 2010-12-22 16:38:24 -0800 | [diff] [blame] | 4263 | /* We need the size of one event, because |
| 4264 | * rb_advance_reader only advances by one event, |
| 4265 | * whereas rb_event_ts_length may include the size of |
| 4266 | * one or two events. |
| 4267 | * We have already ensured there's enough space if this |
| 4268 | * is a time extend. */ |
| 4269 | size = rb_event_length(event); |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 4270 | memcpy(bpage->data + pos, rpage->data + rpos, size); |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4271 | |
| 4272 | len -= size; |
| 4273 | |
| 4274 | rb_advance_reader(cpu_buffer); |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 4275 | rpos = reader->read; |
| 4276 | pos += size; |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4277 | |
Huang Ying | 18fab91 | 2010-07-28 14:14:01 +0800 | [diff] [blame] | 4278 | if (rpos >= commit) |
| 4279 | break; |
| 4280 | |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4281 | event = rb_reader_event(cpu_buffer); |
Steven Rostedt | 69d1b83 | 2010-10-07 18:18:05 -0400 | [diff] [blame] | 4282 | /* Always keep the time extend and data together */ |
| 4283 | size = rb_event_ts_length(event); |
David Sharp | e1e3592 | 2010-12-22 16:38:24 -0800 | [diff] [blame] | 4284 | } while (len >= size); |
Lai Jiangshan | 667d241 | 2009-02-09 14:21:17 +0800 | [diff] [blame] | 4285 | |
| 4286 | /* update bpage */ |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4287 | local_set(&bpage->commit, pos); |
Steven Rostedt | 4f3640f | 2009-03-03 23:52:42 -0500 | [diff] [blame] | 4288 | bpage->time_stamp = save_timestamp; |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4289 | |
Steven Rostedt | 474d32b | 2009-03-03 19:51:40 -0500 | [diff] [blame] | 4290 | /* we copied everything to the beginning */ |
| 4291 | read = 0; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4292 | } else { |
Steven Rostedt | afbab76 | 2009-05-01 19:40:05 -0400 | [diff] [blame] | 4293 | /* update the entry counter */ |
Steven Rostedt | 77ae365 | 2009-03-27 11:00:29 -0400 | [diff] [blame] | 4294 | cpu_buffer->read += rb_page_entries(reader); |
Vaibhav Nagarnaik | c64e148 | 2011-08-16 14:46:16 -0700 | [diff] [blame] | 4295 | cpu_buffer->read_bytes += BUF_PAGE_SIZE; |
Steven Rostedt | afbab76 | 2009-05-01 19:40:05 -0400 | [diff] [blame] | 4296 | |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4297 | /* swap the pages */ |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 4298 | rb_init_page(bpage); |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4299 | bpage = reader->page; |
| 4300 | reader->page = *data_page; |
| 4301 | local_set(&reader->write, 0); |
Steven Rostedt | 778c55d | 2009-05-01 18:44:45 -0400 | [diff] [blame] | 4302 | local_set(&reader->entries, 0); |
Steven Rostedt | ef7a4a1 | 2009-03-03 00:27:49 -0500 | [diff] [blame] | 4303 | reader->read = 0; |
Steven Rostedt | 044fa78 | 2008-12-02 23:50:03 -0500 | [diff] [blame] | 4304 | *data_page = bpage; |
Steven Rostedt | ff0ff84 | 2010-03-31 22:11:42 -0400 | [diff] [blame] | 4305 | |
| 4306 | /* |
| 4307 | * Use the real_end for the data size, |
| 4308 | * This gives us a chance to store the lost events |
| 4309 | * on the page. |
| 4310 | */ |
| 4311 | if (reader->real_end) |
| 4312 | local_set(&bpage->commit, reader->real_end); |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4313 | } |
Lai Jiangshan | 667d241 | 2009-02-09 14:21:17 +0800 | [diff] [blame] | 4314 | ret = read; |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4315 | |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 4316 | cpu_buffer->lost_events = 0; |
Steven Rostedt | 2711ca2 | 2010-05-21 13:32:26 -0400 | [diff] [blame] | 4317 | |
| 4318 | commit = local_read(&bpage->commit); |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 4319 | /* |
| 4320 | * Set a flag in the commit field if we lost events |
| 4321 | */ |
Steven Rostedt | ff0ff84 | 2010-03-31 22:11:42 -0400 | [diff] [blame] | 4322 | if (missed_events) { |
Steven Rostedt | ff0ff84 | 2010-03-31 22:11:42 -0400 | [diff] [blame] | 4323 | /* If there is room at the end of the page to save the |
| 4324 | * missed events, then record it there. |
| 4325 | */ |
| 4326 | if (BUF_PAGE_SIZE - commit >= sizeof(missed_events)) { |
| 4327 | memcpy(&bpage->data[commit], &missed_events, |
| 4328 | sizeof(missed_events)); |
| 4329 | local_add(RB_MISSED_STORED, &bpage->commit); |
Steven Rostedt | 2711ca2 | 2010-05-21 13:32:26 -0400 | [diff] [blame] | 4330 | commit += sizeof(missed_events); |
Steven Rostedt | ff0ff84 | 2010-03-31 22:11:42 -0400 | [diff] [blame] | 4331 | } |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 4332 | local_add(RB_MISSED_EVENTS, &bpage->commit); |
Steven Rostedt | ff0ff84 | 2010-03-31 22:11:42 -0400 | [diff] [blame] | 4333 | } |
Steven Rostedt | 66a8cb9 | 2010-03-31 13:21:56 -0400 | [diff] [blame] | 4334 | |
Steven Rostedt | 2711ca2 | 2010-05-21 13:32:26 -0400 | [diff] [blame] | 4335 | /* |
| 4336 | * This page may be off to user land. Zero it out here. |
| 4337 | */ |
| 4338 | if (commit < BUF_PAGE_SIZE) |
| 4339 | memset(&bpage->data[commit], 0, BUF_PAGE_SIZE - commit); |
| 4340 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4341 | out_unlock: |
Thomas Gleixner | 5389f6f | 2009-07-25 17:13:33 +0200 | [diff] [blame] | 4342 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4343 | |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4344 | out: |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4345 | return ret; |
| 4346 | } |
Steven Rostedt | d6ce96d | 2009-05-05 01:15:24 -0400 | [diff] [blame] | 4347 | EXPORT_SYMBOL_GPL(ring_buffer_read_page); |
Steven Rostedt | 8789a9e | 2008-12-02 15:34:07 -0500 | [diff] [blame] | 4348 | |
Steven Rostedt | 59222ef | 2009-03-12 11:46:03 -0400 | [diff] [blame] | 4349 | #ifdef CONFIG_HOTPLUG_CPU |
Frederic Weisbecker | 09c9e84 | 2009-03-21 04:33:36 +0100 | [diff] [blame] | 4350 | static int rb_cpu_notify(struct notifier_block *self, |
| 4351 | unsigned long action, void *hcpu) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4352 | { |
| 4353 | struct ring_buffer *buffer = |
| 4354 | container_of(self, struct ring_buffer, cpu_notify); |
| 4355 | long cpu = (long)hcpu; |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 4356 | int cpu_i, nr_pages_same; |
| 4357 | unsigned int nr_pages; |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4358 | |
| 4359 | switch (action) { |
| 4360 | case CPU_UP_PREPARE: |
| 4361 | case CPU_UP_PREPARE_FROZEN: |
Rusty Russell | 3f237a7 | 2009-06-12 21:15:30 +0930 | [diff] [blame] | 4362 | if (cpumask_test_cpu(cpu, buffer->cpumask)) |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4363 | return NOTIFY_OK; |
| 4364 | |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 4365 | nr_pages = 0; |
| 4366 | nr_pages_same = 1; |
| 4367 | /* check if all cpu sizes are same */ |
| 4368 | for_each_buffer_cpu(buffer, cpu_i) { |
| 4369 | /* fill in the size from first enabled cpu */ |
| 4370 | if (nr_pages == 0) |
| 4371 | nr_pages = buffer->buffers[cpu_i]->nr_pages; |
| 4372 | if (nr_pages != buffer->buffers[cpu_i]->nr_pages) { |
| 4373 | nr_pages_same = 0; |
| 4374 | break; |
| 4375 | } |
| 4376 | } |
| 4377 | /* allocate minimum pages, user can later expand it */ |
| 4378 | if (!nr_pages_same) |
| 4379 | nr_pages = 2; |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4380 | buffer->buffers[cpu] = |
Vaibhav Nagarnaik | 438ced1 | 2012-02-02 12:00:41 -0800 | [diff] [blame] | 4381 | rb_allocate_cpu_buffer(buffer, nr_pages, cpu); |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4382 | if (!buffer->buffers[cpu]) { |
| 4383 | WARN(1, "failed to allocate ring buffer on CPU %ld\n", |
| 4384 | cpu); |
| 4385 | return NOTIFY_OK; |
| 4386 | } |
| 4387 | smp_wmb(); |
Rusty Russell | 3f237a7 | 2009-06-12 21:15:30 +0930 | [diff] [blame] | 4388 | cpumask_set_cpu(cpu, buffer->cpumask); |
Steven Rostedt | 554f786 | 2009-03-11 22:00:13 -0400 | [diff] [blame] | 4389 | break; |
| 4390 | case CPU_DOWN_PREPARE: |
| 4391 | case CPU_DOWN_PREPARE_FROZEN: |
| 4392 | /* |
| 4393 | * Do nothing. |
| 4394 | * If we were to free the buffer, then the user would |
| 4395 | * lose any trace that was in the buffer. |
| 4396 | */ |
| 4397 | break; |
| 4398 | default: |
| 4399 | break; |
| 4400 | } |
| 4401 | return NOTIFY_OK; |
| 4402 | } |
| 4403 | #endif |