3.18-stable review patch. If anyone has any objections, please let me know.
------------------
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;