[PATCH] ppc32: fix last_jiffy time comparison
This fixes a hang on ppc32.
The problem was that I was comparing a 32-bit quantity with a 64-bit
quantity, and consequently time wasn't advancing. This makes us use a
64-bit quantity on all platforms, which ends up simplifying the code
since we can now get rid of the tb_last_stamp variable (which actually
fixes another bug that Ben H and I noticed while going carefully through
the code).
This works fine on my G4 tibook. Let me know how it goes on your
machines.
Acked-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Mikael Pettersson <mikpe@it.uu.se>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 18e59e4..a124499 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -125,15 +125,8 @@
unsigned long ppc_proc_freq;
unsigned long ppc_tb_freq;
-u64 tb_last_jiffy __cacheline_aligned_in_smp;
-unsigned long tb_last_stamp;
-
-/*
- * Note that on ppc32 this only stores the bottom 32 bits of
- * the timebase value, but that's enough to tell when a jiffy
- * has passed.
- */
-DEFINE_PER_CPU(unsigned long, last_jiffy);
+static u64 tb_last_jiffy __cacheline_aligned_in_smp;
+static DEFINE_PER_CPU(u64, last_jiffy);
#ifdef CONFIG_VIRT_CPU_ACCOUNTING
/*
@@ -458,7 +451,7 @@
do {
seq = read_seqbegin_irqsave(&xtime_lock, flags);
sec = xtime.tv_sec;
- nsec = xtime.tv_nsec + tb_ticks_since(tb_last_stamp);
+ nsec = xtime.tv_nsec + tb_ticks_since(tb_last_jiffy);
} while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
usec = nsec / 1000;
while (usec >= 1000000) {
@@ -700,7 +693,6 @@
tb_next_jiffy = tb_last_jiffy + tb_ticks_per_jiffy;
if (per_cpu(last_jiffy, cpu) >= tb_next_jiffy) {
tb_last_jiffy = tb_next_jiffy;
- tb_last_stamp = per_cpu(last_jiffy, cpu);
do_timer(regs);
timer_recalc_offset(tb_last_jiffy);
timer_check_rtc();
@@ -749,7 +741,7 @@
int i;
unsigned long half = tb_ticks_per_jiffy / 2;
unsigned long offset = tb_ticks_per_jiffy / max_cpus;
- unsigned long previous_tb = per_cpu(last_jiffy, boot_cpuid);
+ u64 previous_tb = per_cpu(last_jiffy, boot_cpuid);
/* make sure tb > per_cpu(last_jiffy, cpu) for all cpus always */
previous_tb -= tb_ticks_per_jiffy;
@@ -830,7 +822,7 @@
* and therefore the (jiffies - wall_jiffies) computation
* has been removed.
*/
- tb_delta = tb_ticks_since(tb_last_stamp);
+ tb_delta = tb_ticks_since(tb_last_jiffy);
tb_delta = mulhdu(tb_delta, do_gtod.varp->tb_to_xs); /* in xsec */
new_nsec -= SCALE_XSEC(tb_delta, 1000000000);
@@ -950,8 +942,7 @@
if (__USE_RTC()) {
/* 601 processor: dec counts down by 128 every 128ns */
ppc_tb_freq = 1000000000;
- tb_last_stamp = get_rtcl();
- tb_last_jiffy = tb_last_stamp;
+ tb_last_jiffy = get_rtcl();
} else {
/* Normal PowerPC with timebase register */
ppc_md.calibrate_decr();
@@ -959,7 +950,7 @@
ppc_tb_freq / 1000000, ppc_tb_freq % 1000000);
printk(KERN_DEBUG "time_init: processor frequency = %lu.%.6lu MHz\n",
ppc_proc_freq / 1000000, ppc_proc_freq % 1000000);
- tb_last_stamp = tb_last_jiffy = get_tb();
+ tb_last_jiffy = get_tb();
}
tb_ticks_per_jiffy = ppc_tb_freq / HZ;
@@ -1036,7 +1027,7 @@
do_gtod.varp = &do_gtod.vars[0];
do_gtod.var_idx = 0;
do_gtod.varp->tb_orig_stamp = tb_last_jiffy;
- __get_cpu_var(last_jiffy) = tb_last_stamp;
+ __get_cpu_var(last_jiffy) = tb_last_jiffy;
do_gtod.varp->stamp_xsec = (u64) xtime.tv_sec * XSEC_PER_SEC;
do_gtod.tb_ticks_per_sec = tb_ticks_per_sec;
do_gtod.varp->tb_to_xs = tb_to_xs;