From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=53615 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OZ058-0006bs-Pd for qemu-devel@nongnu.org; Wed, 14 Jul 2010 07:24:55 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OZ057-0001Vj-KL for qemu-devel@nongnu.org; Wed, 14 Jul 2010 07:24:54 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36671) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OZ057-0001VU-9J for qemu-devel@nongnu.org; Wed, 14 Jul 2010 07:24:53 -0400 From: Kevin Wolf Date: Wed, 14 Jul 2010 13:24:13 +0200 Message-Id: <1279106653-24351-15-git-send-email-kwolf@redhat.com> In-Reply-To: <1279106653-24351-1-git-send-email-kwolf@redhat.com> References: <1279106653-24351-1-git-send-email-kwolf@redhat.com> Subject: [Qemu-devel] [STABLE][PATCH 14/14] block: Handle multiwrite errors only when all requests have completed List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: aurelien@aurel32.net Cc: kwolf@redhat.com, qemu-devel@nongnu.org Don't try to be clever by freeing all temporary data and calling all callbacks when the return value (an error) is certain. Doing so has at least two important problems: * The temporary data that is freed (qiov, possibly zero buffer) is still used by the requests that have not yet completed. * Calling the callbacks for all requests in the multiwrite means for the caller that it may free buffers etc. which are still in use. Just remember the error value and do the cleanup when all requests have completed. Signed-off-by: Kevin Wolf (cherry picked from commit de189a1b4a471d37a2909e97646654fc9751b52f) --- block.c | 5 +---- 1 files changed, 1 insertions(+), 4 deletions(-) diff --git a/block.c b/block.c index 80f2fae..1694780 100644 --- a/block.c +++ b/block.c @@ -1661,14 +1661,11 @@ static void multiwrite_cb(void *opaque, int ret) if (ret < 0 && !mcb->error) { mcb->error = ret; - multiwrite_user_cb(mcb); } mcb->num_requests--; if (mcb->num_requests == 0) { - if (mcb->error == 0) { - multiwrite_user_cb(mcb); - } + multiwrite_user_cb(mcb); qemu_free(mcb); } } -- 1.7.1.1