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Commit 3e143475 authored by John Stultz's avatar John Stultz Committed by Linus Torvalds
Browse files

[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: default avatarJohn Stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 635adb6c

kernel/timer.c

+18 −1
Original line number Diff line number Diff line
@@ -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.