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authorPeter Zijlstra <peterz@infradead.org>2017-03-13 13:46:21 +0100
committerIngo Molnar <mingo@kernel.org>2017-03-23 07:31:48 +0100
commit71fdb70eb48784c1f28cdf2e67c4c587dd7f2594 (patch)
tree4df2510a131df21ac31d649fd792b5acae47c78b /kernel/sched/clock.c
parent093b995e3b55a0ae0670226ddfcb05bfbf0099ae (diff)
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>
Diffstat (limited to 'kernel/sched/clock.c')
-rw-r--r--kernel/sched/clock.c17
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)