[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: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 6 deletions

diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index 43ba1bdec14c..bfda3f7f0716 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -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);
+	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: