Commit-ID: 71fdb70eb48784c1f28cdf2e67c4c587dd7f2594
Gitweb: http://git.kernel.org/tip/71fdb70eb48784c1f28cdf2e67c4c587dd7f2594
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Mon, 13 Mar 2017 13:46:21 +0100
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
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 <paulmck@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: fweisbec@xxxxxxxxx
Link: http://lkml.kernel.org/r/20170313124621.GA3328@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
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)
--
To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
|