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Commit cd05a1f8 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Linus Torvalds
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[PATCH] clockevents: Fix suspend/resume to disk hangs 



I finally found a dual core box, which survives suspend/resume without
crashing in the middle of nowhere. Sigh, I never figured out from the
code and the bug reports what's going on.

The observed hangs are caused by a stale state transition of the clock
event devices, which keeps the RCU synchronization away from completion,
when the non boot CPU is brought back up.

The suspend/resume in oneshot mode needs the similar care as the
periodic mode during suspend to RAM. My assumption that the state
transitions during the different shutdown/bringups of s2disk would go
through the periodic boot phase and then switch over to highres resp.
nohz mode were simply wrong.

Add the appropriate suspend / resume handling for the non periodic
modes.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 24c4ac07

kernel/time/tick-broadcast.c

+22 −5
Original line number Diff line number Diff line
@@ -307,12 +307,19 @@ int tick_resume_broadcast(void) 
	spin_lock_irqsave(&tick_broadcast_lock, flags);



	bc = tick_broadcast_device.evtdev;



	if (bc) {

		if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC &&

		    !cpus_empty(tick_broadcast_mask))

		switch (tick_broadcast_device.mode) {

		case TICKDEV_MODE_PERIODIC:

			if(!cpus_empty(tick_broadcast_mask))

				tick_broadcast_start_periodic(bc);



		broadcast = cpu_isset(smp_processor_id(), tick_broadcast_mask);

			broadcast = cpu_isset(smp_processor_id(),

					      tick_broadcast_mask);

			break;

		case TICKDEV_MODE_ONESHOT:

			broadcast = tick_resume_broadcast_oneshot(bc);

			break;

		}

	}

	spin_unlock_irqrestore(&tick_broadcast_lock, flags);
@@ -347,6 +354,16 @@ static int tick_broadcast_set_event(ktime_t expires, int force) 
	}

}



int tick_resume_broadcast_oneshot(struct clock_event_device *bc)

{

	clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);



	if(!cpus_empty(tick_broadcast_oneshot_mask))

		tick_broadcast_set_event(ktime_get(), 1);



	return cpu_isset(smp_processor_id(), tick_broadcast_oneshot_mask);

}



/*

 * Reprogram the broadcast device:

 *

kernel/time/tick-common.c

+7 −6
Original line number Diff line number Diff line
@@ -298,18 +298,17 @@ static void tick_shutdown(unsigned int *cpup) 
	spin_unlock_irqrestore(&tick_device_lock, flags);

}



static void tick_suspend_periodic(void)

static void tick_suspend(void)

{

	struct tick_device *td = &__get_cpu_var(tick_cpu_device);

	unsigned long flags;



	spin_lock_irqsave(&tick_device_lock, flags);

	if (td->mode == TICKDEV_MODE_PERIODIC)

	clockevents_set_mode(td->evtdev, CLOCK_EVT_MODE_SHUTDOWN);

	spin_unlock_irqrestore(&tick_device_lock, flags);

}



static void tick_resume_periodic(void)

static void tick_resume(void)

{

	struct tick_device *td = &__get_cpu_var(tick_cpu_device);

	unsigned long flags;
@@ -317,6 +316,8 @@ static void tick_resume_periodic(void) 
	spin_lock_irqsave(&tick_device_lock, flags);

	if (td->mode == TICKDEV_MODE_PERIODIC)

		tick_setup_periodic(td->evtdev, 0);

	else

		tick_resume_oneshot();

	spin_unlock_irqrestore(&tick_device_lock, flags);

}
@@ -348,13 +349,13 @@ static int tick_notify(struct notifier_block *nb, unsigned long reason, 
		break;



	case CLOCK_EVT_NOTIFY_SUSPEND:

		tick_suspend_periodic();

		tick_suspend();

		tick_suspend_broadcast();

		break;



	case CLOCK_EVT_NOTIFY_RESUME:

		if (!tick_resume_broadcast())

			tick_resume_periodic();

			tick_resume();

		break;



	default:

kernel/time/tick-internal.h

+10 −1
Original line number Diff line number Diff line
@@ -19,12 +19,13 @@ extern void tick_setup_oneshot(struct clock_event_device *newdev, 
extern int tick_program_event(ktime_t expires, int force);

extern void tick_oneshot_notify(void);

extern int tick_switch_to_oneshot(void (*handler)(struct clock_event_device *));



extern void tick_resume_oneshot(void);

# ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST

extern void tick_broadcast_setup_oneshot(struct clock_event_device *bc);

extern void tick_broadcast_oneshot_control(unsigned long reason);

extern void tick_broadcast_switch_to_oneshot(void);

extern void tick_shutdown_broadcast_oneshot(unsigned int *cpup);

extern int tick_resume_broadcast_oneshot(struct clock_event_device *bc);

# else /* BROADCAST */

static inline void tick_broadcast_setup_oneshot(struct clock_event_device *bc)

{
@@ -43,6 +44,10 @@ void tick_setup_oneshot(struct clock_event_device *newdev, 
{

	BUG();

}

static inline void tick_resume_oneshot(void)

{

	BUG();

}

static inline int tick_program_event(ktime_t expires, int force)

{

	return 0;
@@ -54,6 +59,10 @@ static inline void tick_broadcast_setup_oneshot(struct clock_event_device *bc) 
}

static inline void tick_broadcast_oneshot_control(unsigned long reason) { }

static inline void tick_shutdown_broadcast_oneshot(unsigned int *cpup) { }

static inline int tick_resume_broadcast_oneshot(struct clock_event_device *bc)

{

	return 0;

}

#endif /* !TICK_ONESHOT */



/*

kernel/time/tick-oneshot.c

+12 −0
Original line number Diff line number Diff line
@@ -40,6 +40,18 @@ int tick_program_event(ktime_t expires, int force) 
	}

}



/**

 * tick_resume_onshot - resume oneshot mode

 */

void tick_resume_oneshot(void)

{

	struct tick_device *td = &__get_cpu_var(tick_cpu_device);

	struct clock_event_device *dev = td->evtdev;



	clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);

	tick_program_event(ktime_get(), 1);

}



/**

 * tick_setup_oneshot - setup the event device for oneshot mode (hres or nohz)

 */