This is a note to let you know that I've just added the patch titled
timers, sched_clock: Update timeout for clock wrap
to the 3.18-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:
timers-sched_clock-update-timeout-for-clock-wrap.patch
and it can be found in the queue-3.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Mon Mar 19 10:11:52 CET 2018
From: David Engraf <david.engraf@xxxxxxxxx>
Date: Fri, 17 Feb 2017 08:51:03 +0100
Subject: timers, sched_clock: Update timeout for clock wrap
From: David Engraf <david.engraf@xxxxxxxxx>
[ Upstream commit 1b8955bc5ac575009835e371ae55e7f3af2197a9 ]
The scheduler clock framework may not use the correct timeout for the clock
wrap. This happens when a new clock driver calls sched_clock_register()
after the kernel called sched_clock_postinit(). In this case the clock wrap
timeout is too long thus sched_clock_poll() is called too late and the clock
already wrapped.
On my ARM system the scheduler was no longer scheduling any other task than
the idle task because the sched_clock() wrapped.
Signed-off-by: David Engraf <david.engraf@xxxxxxxxx>
Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/time/sched_clock.c | 5 +++++
1 file changed, 5 insertions(+)
--- a/kernel/time/sched_clock.c
+++ b/kernel/time/sched_clock.c
@@ -146,6 +146,11 @@ void __init sched_clock_register(u64 (*r
cd.epoch_ns = ns;
raw_write_seqcount_end(&cd.seq);
+ if (sched_clock_timer.function != NULL) {
+ /* update timeout for clock wrap */
+ hrtimer_start(&sched_clock_timer, cd.wrap_kt, HRTIMER_MODE_REL);
+ }
+
r = rate;
if (r >= 4000000) {
r /= 1000000;
Patches currently in stable-queue which might be from david.engraf@xxxxxxxxx are
queue-3.18/timers-sched_clock-update-timeout-for-clock-wrap.patch