Re: [PATCH 04/14] sched: SCHED_DEADLINE SMP-related data structures& logic.

From: Peter Zijlstra
Date: Mon Oct 14 2013 - 08:03:30 EST


On Mon, Oct 14, 2013 at 12:43:36PM +0200, Juri Lelli wrote:
> +static inline void dl_set_overload(struct rq *rq)
> +{
> + if (!rq->online)
> + return;
> +
> + cpumask_set_cpu(rq->cpu, rq->rd->dlo_mask);
> + /*
> + * Must be visible before the overload count is
> + * set (as in sched_rt.c).
> + */
> + wmb();
> + atomic_inc(&rq->rd->dlo_count);
> +}

Please, make that smp_wmb() and modify the comment to point to the
matching barrier ; I couldn't find one! Which suggests something is
amiss.

Ideally we'd have something like smp_wmb__after_set_bit() but alas.
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