Commit-ID: 71fdb70eb48784c1f28cdf2e67c4c587dd7f2594 Gitweb: http://git.kernel.org/tip/71fdb70eb48784c1f28cdf2e67c4c587dd7f2594 Author: Peter Zijlstra <pet...@infradead.org> AuthorDate: Mon, 13 Mar 2017 13:46:21 +0100 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Thu, 23 Mar 2017 07:31:48 +0100
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 <paul...@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Mike Galbraith <efa...@gmx.de> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: fweis...@gmail.com Link: http://lkml.kernel.org/r/20170313124621.ga3...@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mi...@kernel.org> --- kernel/sched/clock.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c index a08795e..fec0f58 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)
