clockevents: Set dummy handler on CPU_DEAD shutdown

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@yourcmc.ru>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: stable@vger.kernel.org
Cc: 700333@bugs.debian.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index 6e23fde83dbeb21faeca1d5500003cd7e1a373e0..61d00a8cdf2f2140091f9ece92f004ee34aa273b 100644 (file)
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -66,6 +66,8 @@ static void tick_broadcast_start_periodic(struct clock_event_device *bc)
  */
 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 clock_event_device *dev)
                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_broadcast_mask))
                tick_broadcast_start_periodic(dev);

diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index 74413e396acc7793d424e8d341c5c37dba3c7dbc..6176a3e4570997ea3f5d366416e306ee61b800d0 100644 (file)
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -323,6 +323,7 @@ static void tick_shutdown(unsigned int *cpup)
                 */
                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);