This is a note to let you know that I've just added the patch titled
hrtimer: Set expiry time before switch_hrtimer_base()
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:
hrtimer-set-expiry-time-before-switch_hrtimer_base.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 84ea7fe37908254c3bd90910921f6e1045c1747a Mon Sep 17 00:00:00 2001
From: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
Date: Mon, 12 May 2014 13:42:29 +0530
Subject: hrtimer: Set expiry time before switch_hrtimer_base()
From: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
commit 84ea7fe37908254c3bd90910921f6e1045c1747a upstream.
switch_hrtimer_base() calls hrtimer_check_target() which ensures that
we do not migrate a timer to a remote cpu if the timer expires before
the current programmed expiry time on that remote cpu.
But __hrtimer_start_range_ns() calls switch_hrtimer_base() before the
new expiry time is set. So the sanity check in hrtimer_check_target()
is operating on stale or even uninitialized data.
Update expiry time before calling switch_hrtimer_base().
[ tglx: Rewrote changelog once again ]
Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
Cc: linaro-kernel@xxxxxxxxxxxxxxxx
Cc: linaro-networking@xxxxxxxxxx
Cc: fweisbec@xxxxxxxxx
Cc: arvind.chauhan@xxxxxxx
Link: http://lkml.kernel.org/r/81999e148745fc51bbcd0615823fbab9b2e87e23.1399882253.git.viresh.kumar@xxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/hrtimer.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -985,11 +985,8 @@ int __hrtimer_start_range_ns(struct hrti
/* Remove an active timer from the queue: */
ret = remove_hrtimer(timer, base);
- /* Switch the timer base, if necessary: */
- new_base = switch_hrtimer_base(timer, base, mode & HRTIMER_MODE_PINNED);
-
if (mode & HRTIMER_MODE_REL) {
- tim = ktime_add_safe(tim, new_base->get_time());
+ tim = ktime_add_safe(tim, base->get_time());
/*
* CONFIG_TIME_LOW_RES is a temporary way for architectures
* to signal that they simply return xtime in
@@ -1004,6 +1001,9 @@ int __hrtimer_start_range_ns(struct hrti
hrtimer_set_expires_range_ns(timer, tim, delta_ns);
+ /* Switch the timer base, if necessary: */
+ new_base = switch_hrtimer_base(timer, base, mode & HRTIMER_MODE_PINNED);
+
timer_stats_hrtimer_set_start_info(timer);
leftmost = enqueue_hrtimer(timer, new_base);
Patches currently in stable-queue which might be from viresh.kumar@xxxxxxxxxx are
queue-3.4/hrtimer-set-expiry-time-before-switch_hrtimer_base.patch
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