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authorMark Rutland <mark.rutland@arm.com>2013-03-07 15:09:24 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-03-28 12:06:03 -0700
commit611f2aaf1f4de0ab50d0a3dabfb1759d13f65cf9 (patch)
tree7e10f94a06660127db03eb566682d23f4de8eca7 /kernel
parent52bc8dc1e1023ad0a91b3c80d048688d4167b7e5 (diff)
clockevents: Don't allow dummy broadcast timers
commit a7dc19b8652c862d5b7c4d2339bd3c428bd29c4a upstream. Currently tick_check_broadcast_device doesn't reject clock_event_devices with CLOCK_EVT_FEAT_DUMMY, and may select them in preference to real hardware if they have a higher rating value. In this situation, the dummy timer is responsible for broadcasting to itself, and the core clockevents code may attempt to call non-existent callbacks for programming the dummy, eventually leading to a panic. This patch makes tick_check_broadcast_device always reject dummy timers, preventing this problem. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: linux-arm-kernel@lists.infradead.org Cc: Jon Medhurst (Tixy) <tixy@linaro.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/time/tick-broadcast.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index 7a90d021b79a..9e40370c7695 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -66,7 +66,8 @@ static void tick_broadcast_start_periodic(struct clock_event_device *bc)
*/
int tick_check_broadcast_device(struct clock_event_device *dev)
{
- if ((tick_broadcast_device.evtdev &&
+ if ((dev->features & CLOCK_EVT_FEAT_DUMMY) ||
+ (tick_broadcast_device.evtdev &&
tick_broadcast_device.evtdev->rating >= dev->rating) ||
(dev->features & CLOCK_EVT_FEAT_C3STOP))
return 0;