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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 12:12:26 -0700
commit8d96fcec68c30196fca01a75a911835c7b89a50d (patch)
parent3d2e7424b3e18dc851a4b0efdc6676c09573f55f (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>
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index f113755695e2..a13987af44fd 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;