Re: 2.4.20: Proccess stuck in __lock_page ...

[Marc-Christian Petersen (m.c.p@wolk-project.de)]

On Wednesday 28 May 2003 12:59, Andrew Morton wrote:

Hi Andrew,

> umm, I'd like confirmation of that.
>
> The waitqueue_active() test is wrong because of a missing barrier, but only
> on SMP.  And if it does make a mistake it will surely correct itself when
> the next request is put back. (That's why I left it there...)
> More testing, please.
Does the attached one make sense?

ciao, Marc


--- old/drivers/block/ll_rw_blk.c	2003-05-14 23:11:08.000000000 +0200
+++ new/drivers/block/ll_rw_blk.c	2003-05-28 13:04:34.000000000 +0200
@@ -829,9 +829,10 @@ void blkdev_release_request(struct reque
 	 */
 	if (q) {
 		list_add(&req->queue, &q->rq[rw].free);
-		if (++q->rq[rw].count >= q->batch_requests &&
-				waitqueue_active(&q->wait_for_requests[rw]))
+		if (++q->rq[rw].count >= q->batch_requests) {
+			smp_mb();
 			wake_up(&q->wait_for_requests[rw]);
+		}
 	}
 }