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Subject[PATCH] improve timekeeping resume robustness
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On Tue, 2006-07-11 at 01:36 +0200, Mikael Pettersson wrote:
> With this patch my Latitude resumes OK from APM suspend again.

This patch (against current git tree) resolves 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.

Signed-off-by: John Stultz <johnstul@us.ibm.com>

diff --git a/kernel/timer.c b/kernel/timer.c
index 2a87430..6ffff03 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -968,6 +968,7 @@ void __init timekeeping_init(void)
}


+static int timekeeping_suspended;
/*
* timekeeping_resume - Resumes the generic timekeeping subsystem.
* @dev: unused
@@ -983,6 +984,18 @@ static int timekeeping_resume(struct sys
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;
}
@@ -990,6 +1003,7 @@ static int timekeeping_resume(struct sys
/* sysfs resume/suspend bits for timekeeping */
static struct sysdev_class timekeeping_sysclass = {
.resume = timekeeping_resume,
+ .suspend = timekeeping_suspend,
set_kset_name("timekeeping"),
};

@@ -1099,14 +1113,17 @@ static void clocksource_adjust(struct cl
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.

-
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