Patch "clockevents: Set dummy handler on CPU_DEAD shutdown" has been added to the 3.4-stable tree

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This is a note to let you know that I've just added the patch titled

    clockevents: Set dummy handler on CPU_DEAD shutdown

to the 3.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     clockevents-set-dummy-handler-on-cpu_dead-shutdown.patch
and it can be found in the queue-3.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From 6f7a05d7018de222e40ca003721037a530979974 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Date: Thu, 25 Apr 2013 11:45:53 +0200
Subject: clockevents: Set dummy handler on CPU_DEAD shutdown

From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>

commit 6f7a05d7018de222e40ca003721037a530979974 upstream.

Vitaliy reported that a per cpu HPET timer interrupt crashes the
system during hibernation. What happens is that the per cpu HPET timer
gets shut down when the nonboot cpus are stopped. When the nonboot
cpus are onlined again the HPET code sets up the MSI interrupt which
fires before the clock event device is registered. The event handler
is still set to hrtimer_interrupt, which then crashes the machine due
to highres mode not being active.

See http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=700333

There is no real good way to avoid that in the HPET code. The HPET
code alrady has a mechanism to detect spurious interrupts when event
handler == NULL for a similar reason.

We can handle that in the clockevent/tick layer and replace the
previous functional handler with a dummy handler like we do in
tick_setup_new_device().

The original clockevents code did this in clockevents_exchange_device(),
but that got removed by commit 7c1e76897 (clockevents: prevent
clockevent event_handler ending up handler_noop) which forgot to fix
it up in tick_shutdown(). Same issue with the broadcast device.

Reported-by: Vitaliy Fillipov <vitalif@xxxxxxxxxx>
Cc: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Cc: 700333@xxxxxxxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 kernel/time/tick-broadcast.c |    4 ++++
 kernel/time/tick-common.c    |    1 +
 2 files changed, 5 insertions(+)

--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -66,6 +66,8 @@ static void tick_broadcast_start_periodi
  */
 int tick_check_broadcast_device(struct clock_event_device *dev)
 {
+	struct clock_event_device *cur = tick_broadcast_device.evtdev;
+
 	if ((dev->features & CLOCK_EVT_FEAT_DUMMY) ||
 	    (tick_broadcast_device.evtdev &&
 	     tick_broadcast_device.evtdev->rating >= dev->rating) ||
@@ -73,6 +75,8 @@ int tick_check_broadcast_device(struct c
 		return 0;
 
 	clockevents_exchange_device(tick_broadcast_device.evtdev, dev);
+	if (cur)
+		cur->event_handler = clockevents_handle_noop;
 	tick_broadcast_device.evtdev = dev;
 	if (!cpumask_empty(tick_get_broadcast_mask()))
 		tick_broadcast_start_periodic(dev);
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -323,6 +323,7 @@ static void tick_shutdown(unsigned int *
 		 */
 		dev->mode = CLOCK_EVT_MODE_UNUSED;
 		clockevents_exchange_device(dev, NULL);
+		dev->event_handler = clockevents_handle_noop;
 		td->evtdev = NULL;
 	}
 	raw_spin_unlock_irqrestore(&tick_device_lock, flags);


Patches currently in stable-queue which might be from tglx@xxxxxxxxxxxxx are

queue-3.4/clockevents-set-dummy-handler-on-cpu_dead-shutdown.patch
queue-3.4/drivers-rtc-rtc-cmos.c-don-t-disable-hpet-emulation-on-suspend.patch
queue-3.4/hrtimer-add-expiry-time-overflow-check-in-hrtimer_interrupt.patch
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