From patchwork Fri Jul 2 12:07:37 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [v2, 2/2] block: Handle multiwrite errors only when all requests have completed From: Kevin Wolf X-Patchwork-Id: 57653 Message-Id: <1278072457-8156-3-git-send-email-kwolf@redhat.com> To: qemu-devel@nongnu.org Cc: kwolf@redhat.com, stefanha@gmail.com Date: Fri, 2 Jul 2010 14:07:37 +0200 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); } }