drivers/scsi/fnic/fnic_trace.c

/*
 * Copyright 2012 Cisco Systems, Inc.  All rights reserved.
 *
 * This program is free software; you may redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include <linux/module.h>
#include <linux/mempool.h>
#include <linux/errno.h>
#include <linux/spinlock.h>
#include <linux/kallsyms.h>
#include "fnic_io.h"
#include "fnic.h"

unsigned int trace_max_pages;
static int fnic_max_trace_entries;

static unsigned long fnic_trace_buf_p;
static DEFINE_SPINLOCK(fnic_trace_lock);

static fnic_trace_dbg_t fnic_trace_entries;
int fnic_tracing_enabled = 1;

/*
 * fnic_trace_get_buf - Give buffer pointer to user to fill up trace information
 *
 * Description:
 * This routine gets next available trace buffer entry location @wr_idx
 * from allocated trace buffer pages and give that memory location
 * to user to store the trace information.
 *
 * Return Value:
 * This routine returns pointer to next available trace entry
 * @fnic_buf_head for user to fill trace information.
 */
fnic_trace_data_t *fnic_trace_get_buf(void)
{
	unsigned long fnic_buf_head;
	unsigned long flags;

	spin_lock_irqsave(&fnic_trace_lock, flags);

	/*
	 * Get next available memory location for writing trace information
	 * at @wr_idx and increment @wr_idx
	 */
	fnic_buf_head =
		fnic_trace_entries.page_offset[fnic_trace_entries.wr_idx];
	fnic_trace_entries.wr_idx++;

	/*
	 * Verify if trace buffer is full then change wd_idx to
	 * start from zero
	 */
	if (fnic_trace_entries.wr_idx >= fnic_max_trace_entries)
		fnic_trace_entries.wr_idx = 0;

	/*
	 * Verify if write index @wr_idx and read index @rd_idx are same then
	 * increment @rd_idx to move to next entry in trace buffer
	 */
	if (fnic_trace_entries.wr_idx == fnic_trace_entries.rd_idx) {
		fnic_trace_entries.rd_idx++;
		if (fnic_trace_entries.rd_idx >= fnic_max_trace_entries)
			fnic_trace_entries.rd_idx = 0;
	}
	spin_unlock_irqrestore(&fnic_trace_lock, flags);
	return (fnic_trace_data_t *)fnic_buf_head;
}

/*
 * fnic_get_trace_data - Copy trace buffer to a memory file
 * @fnic_dbgfs_t: pointer to debugfs trace buffer
 *
 * Description:
 * This routine gathers the fnic trace debugfs data from the fnic_trace_data_t
 * buffer and dumps it to fnic_dbgfs_t. It will start at the rd_idx entry in
 * the log and process the log until the end of the buffer. Then it will gather
 * from the beginning of the log and process until the current entry @wr_idx.
 *
 * Return Value:
 * This routine returns the amount of bytes that were dumped into fnic_dbgfs_t
 */
int fnic_get_trace_data(fnic_dbgfs_t *fnic_dbgfs_prt)
{
	int rd_idx;
	int wr_idx;
	int len = 0;
	unsigned long flags;
	char str[KSYM_SYMBOL_LEN];
	struct timespec val;
	fnic_trace_data_t *tbp;

	spin_lock_irqsave(&fnic_trace_lock, flags);
	rd_idx = fnic_trace_entries.rd_idx;
	wr_idx = fnic_trace_entries.wr_idx;
	if (wr_idx < rd_idx) {
		while (1) {
			/* Start from read index @rd_idx */
			tbp = (fnic_trace_data_t *)
				  fnic_trace_entries.page_offset[rd_idx];
			if (!tbp) {
				spin_unlock_irqrestore(&fnic_trace_lock, flags);
				return 0;
			}
			/* Convert function pointer to function name */
			if (sizeof(unsigned long) < 8) {
				sprint_symbol(str, tbp->fnaddr.low);
				jiffies_to_timespec(tbp->timestamp.low, &val);
			} else {
				sprint_symbol(str, tbp->fnaddr.val);
				jiffies_to_timespec(tbp->timestamp.val, &val);
			}
			/*
			 * Dump trace buffer entry to memory file
			 * and increment read index @rd_idx
			 */
			len += snprintf(fnic_dbgfs_prt->buffer + len,
				  (trace_max_pages * PAGE_SIZE * 3) - len,
				  "%16lu.%16lu %-50s %8x %8x %16llx %16llx "
				  "%16llx %16llx %16llx\n", val.tv_sec,
				  val.tv_nsec, str, tbp->host_no, tbp->tag,
				  tbp->data[0], tbp->data[1], tbp->data[2],
				  tbp->data[3], tbp->data[4]);
			rd_idx++;
			/*
			 * If rd_idx is reached to maximum trace entries
			 * then move rd_idx to zero
			 */
			if (rd_idx > (fnic_max_trace_entries-1))
				rd_idx = 0;
			/*
			 * Continure dumpping trace buffer entries into
			 * memory file till rd_idx reaches write index
			 */
			if (rd_idx == wr_idx)
				break;
		}
	} else if (wr_idx > rd_idx) {
		while (1) {
			/* Start from read index @rd_idx */
			tbp = (fnic_trace_data_t *)
				  fnic_trace_entries.page_offset[rd_idx];
			if (!tbp) {
				spin_unlock_irqrestore(&fnic_trace_lock, flags);
				return 0;
			}
			/* Convert function pointer to function name */
			if (sizeof(unsigned long) < 8) {
				sprint_symbol(str, tbp->fnaddr.low);
				jiffies_to_timespec(tbp->timestamp.low, &val);
			} else {
				sprint_symbol(str, tbp->fnaddr.val);
				jiffies_to_timespec(tbp->timestamp.val, &val);
			}
			/*
			 * Dump trace buffer entry to memory file
			 * and increment read index @rd_idx
			 */
			len += snprintf(fnic_dbgfs_prt->buffer + len,
				  (trace_max_pages * PAGE_SIZE * 3) - len,
				  "%16lu.%16lu %-50s %8x %8x %16llx %16llx "
				  "%16llx %16llx %16llx\n", val.tv_sec,
				  val.tv_nsec, str, tbp->host_no, tbp->tag,
				  tbp->data[0], tbp->data[1], tbp->data[2],
				  tbp->data[3], tbp->data[4]);
			rd_idx++;
			/*
			 * Continue dumpping trace buffer entries into
			 * memory file till rd_idx reaches write index
			 */
			if (rd_idx == wr_idx)
				break;
		}
	}
	spin_unlock_irqrestore(&fnic_trace_lock, flags);
	return len;
}

/*
 * fnic_trace_buf_init - Initialize fnic trace buffer logging facility
 *
 * Description:
 * Initialize trace buffer data structure by allocating required memory and
 * setting page_offset information for every trace entry by adding trace entry
 * length to previous page_offset value.
 */
int fnic_trace_buf_init(void)
{
	unsigned long fnic_buf_head;
	int i;
	int err = 0;

	trace_max_pages = fnic_trace_max_pages;
	fnic_max_trace_entries = (trace_max_pages * PAGE_SIZE)/
					  FNIC_ENTRY_SIZE_BYTES;

	fnic_trace_buf_p = (unsigned long)vmalloc((trace_max_pages * PAGE_SIZE));
	if (!fnic_trace_buf_p) {
		printk(KERN_ERR PFX "Failed to allocate memory "
				  "for fnic_trace_buf_p\n");
		err = -ENOMEM;
		goto err_fnic_trace_buf_init;
	}
	memset((void *)fnic_trace_buf_p, 0, (trace_max_pages * PAGE_SIZE));

	fnic_trace_entries.page_offset = vmalloc(fnic_max_trace_entries *
						  sizeof(unsigned long));
	if (!fnic_trace_entries.page_offset) {
		printk(KERN_ERR PFX "Failed to allocate memory for"
				  " page_offset\n");
		if (fnic_trace_buf_p) {
			vfree((void *)fnic_trace_buf_p);
			fnic_trace_buf_p = 0;
		}
		err = -ENOMEM;
		goto err_fnic_trace_buf_init;
	}
	memset((void *)fnic_trace_entries.page_offset, 0,
		  (fnic_max_trace_entries * sizeof(unsigned long)));
	fnic_trace_entries.wr_idx = fnic_trace_entries.rd_idx = 0;
	fnic_buf_head = fnic_trace_buf_p;

	/*
	 * Set page_offset field of fnic_trace_entries struct by
	 * calculating memory location for every trace entry using
	 * length of each trace entry
	 */
	for (i = 0; i < fnic_max_trace_entries; i++) {
		fnic_trace_entries.page_offset[i] = fnic_buf_head;
		fnic_buf_head += FNIC_ENTRY_SIZE_BYTES;
	}
	err = fnic_trace_debugfs_init();
	if (err < 0) {
		printk(KERN_ERR PFX "Failed to initialize debugfs for tracing\n");
		goto err_fnic_trace_debugfs_init;
	}
	printk(KERN_INFO PFX "Successfully Initialized Trace Buffer\n");
	return err;
err_fnic_trace_debugfs_init:
	fnic_trace_free();
err_fnic_trace_buf_init:
	return err;
}

/*
 * fnic_trace_free - Free memory of fnic trace data structures.
 */
void fnic_trace_free(void)
{
	fnic_tracing_enabled = 0;
	fnic_trace_debugfs_terminate();
	if (fnic_trace_entries.page_offset) {
		vfree((void *)fnic_trace_entries.page_offset);
		fnic_trace_entries.page_offset = NULL;
	}
	if (fnic_trace_buf_p) {
		vfree((void *)fnic_trace_buf_p);
		fnic_trace_buf_p = 0;
	}
	printk(KERN_INFO PFX "Successfully Freed Trace Buffer\n");
}