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>
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@ -141,7 +141,14 @@ static void __set_sched_clock_stable(void)
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tick_dep_clear(TICK_DEP_BIT_CLOCK_UNSTABLE);
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}
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static void __clear_sched_clock_stable(struct work_struct *work)
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static void __sched_clock_work(struct work_struct *work)
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{
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static_branch_disable(&__sched_clock_stable);
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}
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static DECLARE_WORK(sched_clock_work, __sched_clock_work);
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static void __clear_sched_clock_stable(void)
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{
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struct sched_clock_data *scd = this_scd();
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@ -160,11 +167,11 @@ static void __clear_sched_clock_stable(struct work_struct *work)
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scd->tick_gtod, gtod_offset,
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scd->tick_raw, raw_offset);
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static_branch_disable(&__sched_clock_stable);
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tick_dep_set(TICK_DEP_BIT_CLOCK_UNSTABLE);
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}
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static DECLARE_WORK(sched_clock_work, __clear_sched_clock_stable);
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if (sched_clock_stable())
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schedule_work(&sched_clock_work);
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}
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void clear_sched_clock_stable(void)
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{
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@ -173,7 +180,7 @@ void clear_sched_clock_stable(void)
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smp_mb(); /* matches sched_clock_init_late() */
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if (sched_clock_running == 2)
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schedule_work(&sched_clock_work);
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__clear_sched_clock_stable();
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}
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void sched_clock_init_late(void)
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