From patchwork Wed Jul 14 11:24:13 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 58878 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [199.232.76.165]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 73548B6F15 for ; Wed, 14 Jul 2010 21:46:13 +1000 (EST) Received: from localhost ([127.0.0.1]:34908 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OZ0Li-0001HA-CI for incoming@patchwork.ozlabs.org; Wed, 14 Jul 2010 07:42:02 -0400 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 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 o6EBOmLS001749 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Wed, 14 Jul 2010 07:24:48 -0400 Received: from dhcp-5-188.str.redhat.com (vpn2-8-54.ams2.redhat.com [10.36.8.54]) by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id o6EBOFBr023208; Wed, 14 Jul 2010 07:24:46 -0400 From: Kevin Wolf To: aurelien@aurel32.net 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> X-Scanned-By: MIMEDefang 2.67 on 10.5.11.11 X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. Cc: kwolf@redhat.com, qemu-devel@nongnu.org Subject: [Qemu-devel] [STABLE][PATCH 14/14] block: Handle multiwrite errors only when all requests have completed X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@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); } }