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[PATCH] improve timekeeping resume robustness 

Resolve problems seen w/ APM suspend.

Due to resume initialization ordering, its possible we could get a timer
interrupt before the timekeeping resume() function is called.  This patch
ensures we don't do any timekeeping accounting before we're fully resumed.

(akpm: fixes the machine-freezes-on-APM-resume bug)

Signed-off-by: John Stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
john stultz 2006-07-14 00:24:17 -07:00 committed by Linus Torvalds
parent 635adb6cd2
commit 3e143475c2
1 changed files with 18 additions and 1 deletions
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19
kernel/timer.c
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@ -969,6 +969,7 @@ void __init timekeeping_init(void)
}
static int timekeeping_suspended;
/*
* timekeeping_resume - Resumes the generic timekeeping subsystem.
* @dev: unused
@ -984,6 +985,18 @@ static int timekeeping_resume(struct sys_device *dev)
write_seqlock_irqsave(&xtime_lock, flags);
/* restart the last cycle value */
clock->cycle_last = clocksource_read(clock);
clock->error = 0;
timekeeping_suspended = 0;
write_sequnlock_irqrestore(&xtime_lock, flags);
return 0;
}
static int timekeeping_suspend(struct sys_device *dev, pm_message_t state)
{
unsigned long flags;
write_seqlock_irqsave(&xtime_lock, flags);
timekeeping_suspended = 1;
write_sequnlock_irqrestore(&xtime_lock, flags);
return 0;
}
@ -991,6 +1004,7 @@ static int timekeeping_resume(struct sys_device *dev)
/* sysfs resume/suspend bits for timekeeping */
static struct sysdev_class timekeeping_sysclass = {
.resume = timekeeping_resume,
.suspend = timekeeping_suspend,
set_kset_name("timekeeping"),
};
@ -1101,13 +1115,16 @@ static void update_wall_time(void)
{
cycle_t offset;
clock->xtime_nsec += (s64)xtime.tv_nsec << clock->shift;
/* Make sure we're fully resumed: */
if (unlikely(timekeeping_suspended))
return;
#ifdef CONFIG_GENERIC_TIME
offset = (clocksource_read(clock) - clock->cycle_last) & clock->mask;
#else
offset = clock->cycle_interval;
#endif
clock->xtime_nsec += (s64)xtime.tv_nsec << clock->shift;
/* normally this loop will run just once, however in the
* case of lost or late ticks, it will accumulate correctly.