Re: [PATCH] io stalls (was: -rc7 Re: Linux 2.4.21-rc6)

Andrea Arcangeli
2003-06-11T00:20:38Z

On Mon, Jun 09, 2003 at 05:39:23PM -0400, Chris Mason wrote:
> + if (!waitqueue_active(&q->wait_for_requests[rw]))
> + clear_queue_full(q, rw);

you've an smp race above, the smp safe implementation is this:

if (!waitqueue_active(&q->wait_for_requests[rw])) {
clear_queue_full(q, rw);
mb();
if (unlikely(waitqueue_active(&q->wait_for_requests[rw])))
wake_up(&q->wait_for_requests[rw]);
}

I'm also unsure what the "waited" logic does, it doesn't seem necessary.

Andrea