I picked up the patch; will drop it if Ingo also does ;-)
On Thu, Jan 22, 2015 at 06:08:04PM +0100, Frederic Weisbecker wrote:
> +++ b/kernel/sched/core.c
> @@ -2877,6 +2877,21 @@ void __sched schedule_preempt_disabled(void)
> preempt_disable();
> }
>
> +static void preempt_schedule_common(void)
> +{
> + do {
> + __preempt_count_add(PREEMPT_ACTIVE);
> + __schedule();
> + __preempt_count_sub(PREEMPT_ACTIVE);
> +
> + /*
> + * Check again in case we missed a preemption opportunity
> + * between schedule and now.
> + */
> + barrier();
I do however wonder about this barrier() here; why do we think we need
it?
Is that because test_bit() it 'broken'? The bitops are typically atomic
ops and atomic reads should be through a volatile cast (x86
constant_test_bit doesn't seem to do this).
Should we go audit and fix that?
> + } while (need_resched());
> +}
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