This is a note to let you know that I've just added the patch titled
clockevents: Don't allow dummy broadcast timers
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-don-t-allow-dummy-broadcast-timers.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 a7dc19b8652c862d5b7c4d2339bd3c428bd29c4a Mon Sep 17 00:00:00 2001
From: Mark Rutland <mark.rutland@xxxxxxx>
Date: Thu, 7 Mar 2013 15:09:24 +0000
Subject: clockevents: Don't allow dummy broadcast timers
From: Mark Rutland <mark.rutland@xxxxxxx>
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@xxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: Jon Medhurst (Tixy) <tixy@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/time/tick-broadcast.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -66,7 +66,8 @@ static void tick_broadcast_start_periodi
*/
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;
Patches currently in stable-queue which might be from mark.rutland@xxxxxxx are
queue-3.4/clockevents-don-t-allow-dummy-broadcast-timers.patch
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