Re: [PATCH 3/3] nohz: Use IPI implicit full barrier against rq->nr_running r/w

From: Peter Zijlstra
Date: Wed May 14 2014 - 05:09:17 EST


On Wed, May 14, 2014 at 12:25:56AM +0200, Frederic Weisbecker wrote:
> @@ -670,10 +670,11 @@ bool sched_can_stop_tick(void)
>
> rq = this_rq();
>
> - /* Make sure rq->nr_running update is visible after the IPI */
> - smp_rmb();
> -
> - /* More than one running task need preemption */
> + /*
> + * More than one running task need preemption.
> + * nr_running update is assumed to be visible
> + * after IPI is sent from wakers.
> + */
> if (rq->nr_running > 1)
> return false;

Looks like whitespace damage on that comment's indenting.

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