| From | Luis Henriques <> | Subject | [PATCH 001/102] clockevents: Don't allow dummy broadcast timers | Date | Mon, 8 Apr 2013 10:49:16 +0100 |
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3.5.7.10 -stable review patch. If anyone has any objections, please let me know.
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From: Mark Rutland <mark.rutland@arm.com>
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: Luis Henriques <luis.henriques@canonical.com> --- kernel/time/tick-broadcast.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c index f113755..a13987a 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; -- 1.8.1.2
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