This is a note to let you know that I have just added a patch titled

hrtimer: Set expiry time before switch_hrtimer_base()

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree which can be found at:

http://kernel.ubuntu.com/git?p=ubuntu/linux.git%3Ba=shortlog%3Bh=refs/heads/...

If you, or anyone else, feels it should not be added to this tree, please reply to this email.

For more information about the 3.11.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks. -Luis

------

From bbe1a6ec07f62a0a8990187a0dd7622cce772ed5 Mon Sep 17 00:00:00 2001

From: Viresh Kumar viresh.kumar@linaro.org Date: Mon, 12 May 2014 13:42:29 +0530 Subject: hrtimer: Set expiry time before switch_hrtimer_base()

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@linaro.org Cc: linaro-kernel@lists.linaro.org Cc: linaro-networking@linaro.org Cc: fweisbec@gmail.com Cc: arvind.chauhan@arm.com Link: http://lkml.kernel.org/r/81999e148745fc51bbcd0615823fbab9b2e87e23.1399882253... Signed-off-by: Thomas Gleixner tglx@linutronix.de Signed-off-by: Luis Henriques luis.henriques@canonical.com --- kernel/hrtimer.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index 6de65d8a70e2..aa149222cd8e 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -1002,11 +1002,8 @@ int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim, /* 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 @@ -1021,6 +1018,9 @@ int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,

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); -- 1.9.1