From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50356) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fEXPb-0000Ol-QC for qemu-devel@nongnu.org; Fri, 04 May 2018 05:54:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fEXPW-0003p3-VV for qemu-devel@nongnu.org; Fri, 04 May 2018 05:53:59 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:34930 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fEXPW-0003oB-RB for qemu-devel@nongnu.org; Fri, 04 May 2018 05:53:54 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id CE25240858CD for ; Fri, 4 May 2018 09:53:50 +0000 (UTC) From: "Dr. David Alan Gilbert (git)" Date: Fri, 4 May 2018 10:53:46 +0100 Message-Id: <20180504095346.14159-1-dgilbert@redhat.com> Subject: [Qemu-devel] [PATCH] libvhost-user: Send messages with no data List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org, mst@redhat.com, marcandre.lureau@redhat.com From: "Dr. David Alan Gilbert" The response to a VHOST_USER_POSTCOPY_ADVISE contains a fd but doesn't actually contain any data. FIx vu_message_write so that it doesn't do a 0-byte write() call, since this was ending up with rc=0 that was confusing the error handling code. Signed-off-by: Dr. David Alan Gilbert --- contrib/libvhost-user/libvhost-user.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c index beeed0c43f..54e643d871 100644 --- a/contrib/libvhost-user/libvhost-user.c +++ b/contrib/libvhost-user/libvhost-user.c @@ -323,13 +323,15 @@ vu_message_write(VuDev *dev, int conn_fd, VhostUserMsg *vmsg) rc = sendmsg(conn_fd, &msg, 0); } while (rc < 0 && (errno == EINTR || errno == EAGAIN)); - do { - if (vmsg->data) { - rc = write(conn_fd, vmsg->data, vmsg->size); - } else { - rc = write(conn_fd, p + VHOST_USER_HDR_SIZE, vmsg->size); - } - } while (rc < 0 && (errno == EINTR || errno == EAGAIN)); + if (vmsg->size) { + do { + if (vmsg->data) { + rc = write(conn_fd, vmsg->data, vmsg->size); + } else { + rc = write(conn_fd, p + VHOST_USER_HDR_SIZE, vmsg->size); + } + } while (rc < 0 && (errno == EINTR || errno == EAGAIN)); + } if (rc <= 0) { vu_panic(dev, "Error while writing: %s", strerror(errno)); -- 2.17.0