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-3.8.y-queue branch of the 3.8.y.z extended stable tree which can be found at:

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

This patch is scheduled to be released in version 3.8.13.25.

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

For more information about the 3.8.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks. -Kamal

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From aa47826370c46dcfda97623f9ec636228401a869 Mon Sep 17 00:00:00 2001

From: Viresh Kumar viresh.kumar@linaro.org Date: Mon, 12 May 2014 13:42:29 +0530 Subject: [PATCH 13/66] 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: Kamal Mostafa kamal@canonical.com --- kernel/hrtimer.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index 9873816..20e88af 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -980,11 +980,8 @@ 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 @@ -999,6 +996,9 @@ 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