From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=44340 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OUjH4-0004bd-7d for qemu-devel@nongnu.org; Fri, 02 Jul 2010 12:39:35 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OUjH1-0001fT-WC for qemu-devel@nongnu.org; Fri, 02 Jul 2010 12:39:33 -0400 Received: from mx1.redhat.com ([209.132.183.28]:2413) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OUjH1-0001fB-Pc for qemu-devel@nongnu.org; Fri, 02 Jul 2010 12:39:31 -0400 From: Kevin Wolf Date: Fri, 2 Jul 2010 18:38:32 +0200 Message-Id: <1278088712-12302-24-git-send-email-kwolf@redhat.com> In-Reply-To: <1278088712-12302-1-git-send-email-kwolf@redhat.com> References: <1278088712-12302-1-git-send-email-kwolf@redhat.com> Subject: [Qemu-devel] [PATCH 23/23] 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: anthony@codemonkey.ws 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 --- block.c | 5 +---- 1 files changed, 1 insertions(+), 4 deletions(-) diff --git a/block.c b/block.c index e65971c..dd6dd76 100644 --- a/block.c +++ b/block.c @@ -2042,14 +2042,11 @@ 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