On Wed, Oct 07, 2009 at 05:15:36PM +0800, Peter Zijlstra wrote:
> On Wed, 2009-10-07 at 17:07 +0800, Wu Fengguang wrote:
> >
> > > wakeup implies a full memory barrier.
> >
> > If so, this smp_mb__after_clear_bit() line is also not necessary?
> >
> > void clear_bdi_congested(struct backing_dev_info *bdi, int sync)
> > {
> > //...
> > clear_bit(bit, &bdi->state);
> > smp_mb__after_clear_bit();
> > if (waitqueue_active(wqh))
> > wake_up(wqh);
>
> Depends on if the barrier is needed even when the wakeup doesn't happen
> I guess ;-)
I see. Thanks!
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