Messages in this thread Patch in this message | | | From | Sasha Levin <> | Subject | [PATCH AUTOSEL for 3.18 17/63] timers, sched_clock: Update timeout for clock wrap | Date | Sat, 3 Mar 2018 22:33:19 +0000 |
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From: David Engraf <david.engraf@sysgo.com>
[ 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@sysgo.com> Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> --- kernel/time/sched_clock.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c index 01d2d15aa662..830e214f372c 100644 --- a/kernel/time/sched_clock.c +++ b/kernel/time/sched_clock.c @@ -146,6 +146,11 @@ void __init sched_clock_register(u64 (*read)(void), int bits, 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; -- 2.14.1
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