From patchwork Thu Jul 1 14:31:58 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 57552 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 5A09AB6EEB for ; Fri, 2 Jul 2010 00:33:31 +1000 (EST) Received: from localhost ([127.0.0.1]:59581 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OUKpT-0003OF-9S for incoming@patchwork.ozlabs.org; Thu, 01 Jul 2010 10:33:27 -0400 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 Received: from localhost.localdomain (dhcp-5-217.str.redhat.com [10.32.5.217]) by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id o61EW3tR012444; Thu, 1 Jul 2010 10:32:05 -0400 From: Kevin Wolf To: qemu-devel@nongnu.org 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> 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 Subject: [Qemu-devel] [PATCH 2/2] 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 --- 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); } }