This is a note to let you know that I've just added the patch titled
sched_clock: Avoid corrupting hrtimer tree during suspend
to the 3.15-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:
sched_clock-avoid-corrupting-hrtimer-tree-during-suspend.patch
and it can be found in the queue-3.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From f723aa1817dd8f4fe005aab52ba70c8ab0ef9457 Mon Sep 17 00:00:00 2001
From: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>
Date: Wed, 23 Jul 2014 21:03:50 -0700
Subject: sched_clock: Avoid corrupting hrtimer tree during suspend
From: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>
commit f723aa1817dd8f4fe005aab52ba70c8ab0ef9457 upstream.
During suspend we call sched_clock_poll() to update the epoch and
accumulated time and reprogram the sched_clock_timer to fire
before the next wrap-around time. Unfortunately,
sched_clock_poll() doesn't restart the timer, instead it relies
on the hrtimer layer to do that and during suspend we aren't
calling that function from the hrtimer layer. Instead, we're
reprogramming the expires time while the hrtimer is enqueued,
which can cause the hrtimer tree to be corrupted. Furthermore, we
restart the timer during suspend but we update the epoch during
resume which seems counter-intuitive.
Let's fix this by saving the accumulated state and canceling the
timer during suspend. On resume we can update the epoch and
restart the timer similar to what we would do if we were starting
the clock for the first time.
Fixes: a08ca5d1089d "sched_clock: Use an hrtimer instead of timer"
Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>
Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/1406174630-23458-1-git-send-email-john.stultz@xxxxxxxxxx
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/time/sched_clock.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/kernel/time/sched_clock.c
+++ b/kernel/time/sched_clock.c
@@ -204,7 +204,8 @@ void __init sched_clock_postinit(void)
static int sched_clock_suspend(void)
{
- sched_clock_poll(&sched_clock_timer);
+ update_sched_clock();
+ hrtimer_cancel(&sched_clock_timer);
cd.suspended = true;
return 0;
}
@@ -212,6 +213,7 @@ static int sched_clock_suspend(void)
static void sched_clock_resume(void)
{
cd.epoch_cyc = read_sched_clock();
+ hrtimer_start(&sched_clock_timer, cd.wrap_kt, HRTIMER_MODE_REL);
cd.suspended = false;
}
Patches currently in stable-queue which might be from sboyd@xxxxxxxxxxxxxx are
queue-3.15/sched_clock-avoid-corrupting-hrtimer-tree-during-suspend.patch
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