From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=48185 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OUKoC-0003N9-Ek for qemu-devel@nongnu.org; Thu, 01 Jul 2010 10:32:09 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OUKoB-0008E3-Fx for qemu-devel@nongnu.org; Thu, 01 Jul 2010 10:32:08 -0400 Received: from mx1.redhat.com ([209.132.183.28]:20244) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OUKoB-0008Dp-8b for qemu-devel@nongnu.org; Thu, 01 Jul 2010 10:32:07 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o61EW6iF016438 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Thu, 1 Jul 2010 10:32:06 -0400 From: Kevin Wolf Date: Thu, 1 Jul 2010 16:31:58 +0200 Message-Id: <1277994718-14443-3-git-send-email-kwolf@redhat.com> In-Reply-To: <1277994718-14443-1-git-send-email-kwolf@redhat.com> References: <1277994718-14443-1-git-send-email-kwolf@redhat.com> Subject: [Qemu-devel] [PATCH 2/2] 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: qemu-devel@nongnu.org Cc: kwolf@redhat.com 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 --- block.c | 5 +---- 1 files changed, 1 insertions(+), 4 deletions(-) diff --git a/block.c b/block.c index 9719649..bff7d5a 100644 --- a/block.c +++ b/block.c @@ -2056,14 +2056,11 @@ 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); } } -- 1.6.6.1