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| author | Peter Zijlstra <peterz@infradead.org> | 2017-03-13 13:46:21 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2017-03-23 07:31:48 +0100 |
| commit | 71fdb70eb48784c1f28cdf2e67c4c587dd7f2594 (patch) | |
| tree | 4df2510a131df21ac31d649fd792b5acae47c78b | |
| parent | mm, swap: Remove WARN_ON_ONCE() in free_swap_slot() (diff) | |
| download | linux-71fdb70eb48784c1f28cdf2e67c4c587dd7f2594.tar.xz linux-71fdb70eb48784c1f28cdf2e67c4c587dd7f2594.zip | |
sched/clock: Fix clear_sched_clock_stable() preempt wobbly
Paul reported a problems with clear_sched_clock_stable(). Since we run
all of __clear_sched_clock_stable() from workqueue context, there's a
preempt problem.
Solve it by only running the static_key_disable() from workqueue.
Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: fweisbec@gmail.com
Link: http://lkml.kernel.org/r/20170313124621.GA3328@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | kernel/sched/clock.c | 17 |
1 files changed, 12 insertions, 5 deletions
diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c index a08795e21628..fec0f58c8dee 100644 --- a/kernel/sched/clock.c +++ b/kernel/sched/clock.c @@ -141,7 +141,14 @@ static void __set_sched_clock_stable(void) tick_dep_clear(TICK_DEP_BIT_CLOCK_UNSTABLE); } -static void __clear_sched_clock_stable(struct work_struct *work) +static void __sched_clock_work(struct work_struct *work) +{ + static_branch_disable(&__sched_clock_stable); +} + +static DECLARE_WORK(sched_clock_work, __sched_clock_work); + +static void __clear_sched_clock_stable(void) { struct sched_clock_data *scd = this_scd(); @@ -160,11 +167,11 @@ static void __clear_sched_clock_stable(struct work_struct *work) scd->tick_gtod, gtod_offset, scd->tick_raw, raw_offset); - static_branch_disable(&__sched_clock_stable); tick_dep_set(TICK_DEP_BIT_CLOCK_UNSTABLE); -} -static DECLARE_WORK(sched_clock_work, __clear_sched_clock_stable); + if (sched_clock_stable()) + schedule_work(&sched_clock_work); +} void clear_sched_clock_stable(void) { @@ -173,7 +180,7 @@ void clear_sched_clock_stable(void) smp_mb(); /* matches sched_clock_init_late() */ if (sched_clock_running == 2) - schedule_work(&sched_clock_work); + __clear_sched_clock_stable(); } void sched_clock_init_late(void) |