Attachment 150775 Details for Bug 233653 – patch #2

[patch] patch #2

nbd-fix-tx-rx-race-condition-update.patch (text/plain), 1.85 KB, created by Paul Clements on 2007-03-23 16:28:26 UTC

(hide)

Description:

Filename:

MIME Type:

Creator: Paul Clements

Created: 2007-03-23 16:28:26 UTC

Size: 1.85 KB

patch

obsolete

>The patch titled
>
>     nbd-fix-tx-rx-race-condition update
>
>has been added to the -mm tree.  Its filename is
>
>     nbd-fix-tx-rx-race-condition-update.patch
>
>
>From: Herbert Xu <herbert@gondor.apana.org.au>
>
>Here is an updated patch which removes the active_req wait in
>nbd_clear_queue and the associated memory barrier.
>
>I've also clarified this in the comment.
>
>Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
>Cc: <djani22@dynamicweb.hu>
>Cc: Paul Clements <Paul.Clements@SteelEye.com>
>Signed-off-by: Andrew Morton <akpm@osdl.org>
>---
>
> drivers/block/nbd.c |   11 +++++++----
> linux/nbd.h         |    0 
> 2 files changed, 7 insertions(+), 4 deletions(-)
>
>diff -puN drivers/block/nbd.c~nbd-fix-tx-rx-race-condition-update drivers/block/nbd.c
>--- devel/drivers/block/nbd.c~nbd-fix-tx-rx-race-condition-update	2005-11-19 16:25:04.000000000 -0800
>+++ devel-akpm/drivers/block/nbd.c	2005-11-19 16:25:04.000000000 -0800
>@@ -403,12 +403,15 @@ static void nbd_clear_que(struct nbd_dev
> 	BUG_ON(lo->magic != LO_MAGIC);
> 
> 	/*
>-	 * lo->sock == NULL guarantees that the queue will not grow beyond the
>-	 * current active request.
>+	 * Because we have set lo->sock to NULL under the tx_lock, all
>+	 * modifications to the list must have completed by now.  For
>+	 * the same reason, the active_req must be NULL.
>+	 *
>+	 * As a consequence, we don't need to take the spin lock while
>+	 * purging the list here.
> 	 */
> 	BUG_ON(lo->sock);
>-	wait_event(lo->active_wq, !lo->active_req);
>-	smp_rmb();
>+	BUG_ON(lo->active_req);
> 
> 	while (!list_empty(&lo->queue_head)) {
> 		req = list_entry(lo->queue_head.next, struct request,
>diff -puN include/linux/nbd.h~nbd-fix-tx-rx-race-condition-update include/linux/nbd.h
>_
>
>Patches currently in -mm which might be from herbert@gondor.apana.org.au are
>
>linus.patch
>nbd-fix-tx-rx-race-condition.patch
>nbd-fix-tx-rx-race-condition-update.patch
>git-cryptodev.patch
>

Actions: View | Diff

Attachments on bug 233653: 150774 | 150775