From patchwork Mon Mar 20 23:08:28 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michael Roth X-Patchwork-Id: 9635607 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id BE4AD60132 for ; Mon, 20 Mar 2017 23:55:59 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id AE8AE26E3A for ; Mon, 20 Mar 2017 23:55:59 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A17EA27031; Mon, 20 Mar 2017 23:55:59 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 41B4426E3A for ; Mon, 20 Mar 2017 23:55:58 +0000 (UTC) Received: from localhost ([::1]:35749 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cq79Z-0007g2-9Z for patchwork-qemu-devel@patchwork.kernel.org; Mon, 20 Mar 2017 19:55:57 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41771) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cq6R3-00026A-TO for qemu-devel@nongnu.org; Mon, 20 Mar 2017 19:10:07 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cq6Qt-0005E8-Uu for qemu-devel@nongnu.org; Mon, 20 Mar 2017 19:09:57 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:35241) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cq6Qt-0005Cp-LT for qemu-devel@nongnu.org; Mon, 20 Mar 2017 19:09:47 -0400 Received: from pps.filterd (m0098394.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v2KN8jXT025524 for ; Mon, 20 Mar 2017 19:09:46 -0400 Received: from e34.co.us.ibm.com (e34.co.us.ibm.com [32.97.110.152]) by mx0a-001b2d01.pphosted.com with ESMTP id 29ae098une-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 20 Mar 2017 19:09:46 -0400 Received: from localhost by e34.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Mon, 20 Mar 2017 17:09:41 -0600 Received: from b03ledav005.gho.boulder.ibm.com (b03ledav005.gho.boulder.ibm.com [9.17.130.236]) by b03cxnp08026.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v2KN9f3S6488554; Mon, 20 Mar 2017 16:09:41 -0700 Received: from b03ledav005.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 05480BE03B; Mon, 20 Mar 2017 17:09:41 -0600 (MDT) Received: from localhost (unknown [9.53.92.194]) by b03ledav005.gho.boulder.ibm.com (Postfix) with ESMTP id E1317BE039; Mon, 20 Mar 2017 17:09:40 -0600 (MDT) From: Michael Roth To: qemu-devel@nongnu.org Date: Mon, 20 Mar 2017 18:08:28 -0500 X-Mailer: git-send-email 2.7.4 In-Reply-To: <1490051325-3770-1-git-send-email-mdroth@linux.vnet.ibm.com> References: <1490051325-3770-1-git-send-email-mdroth@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 17032023-0016-0000-0000-00000668D4D8 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00006819; HX=3.00000240; KW=3.00000007; PH=3.00000004; SC=3.00000206; SDB=6.00836553; UDB=6.00411162; IPR=6.00614322; BA=6.00005224; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00014732; XFM=3.00000013; UTC=2017-03-20 23:09:43 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17032023-0017-0000-0000-00003852967D Message-Id: <1490051325-3770-65-git-send-email-mdroth@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2017-03-20_16:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=62 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1702020001 definitions=main-1703200196 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [generic] [fuzzy] X-Received-From: 148.163.156.1 Subject: [Qemu-devel] [PATCH 64/81] vnc: do not disconnect on EAGAIN X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Michael Tokarev , qemu-stable@nongnu.org, Gerd Hoffmann Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP From: Michael Tokarev When qemu vnc server is trying to send large update to clients, there might be a situation when system responds with something like EAGAIN, indicating that there's no system memory to send that much data (depending on the network speed, client and server and what is happening). In this case, something like this happens on qemu side (from strace): sendmsg(16, {msg_name(0)=NULL, msg_iov(1)=[{"\244\"..., 729186}], msg_controllen=0, msg_flags=0}, 0) = 103950 sendmsg(16, {msg_name(0)=NULL, msg_iov(1)=[{"lz\346"..., 1559618}], msg_controllen=0, msg_flags=0}, 0) = -1 EAGAIN sendmsg(-1, {msg_name(0)=NULL, msg_iov(1)=[{"lz\346"..., 1559618}], msg_controllen=0, msg_flags=0}, 0) = -1 EBADF qemu closes the socket before the retry, and obviously it gets EBADF when trying to send to -1. This is because there WAS a special handling for EAGAIN, but now it doesn't work anymore, after commit 04d2529da27db512dcbd5e99d0e26d333f16efcc, because now in all error-like cases we initiate vnc disconnect. This change were introduced in qemu 2.6, and caused numerous grief for many people, resulting in their vnc clients reporting sporadic random disconnects from vnc server. Fix that by doing the disconnect only when necessary, i.e. omitting this very case of EAGAIN. Hopefully the existing condition (comparing with QIO_CHANNEL_ERR_BLOCK) is sufficient, as the original code (before the above commit) were checking for other errno values too. Apparently there's another (semi?)bug exist somewhere here, since the code tries to write to fd# -1, it probably should check if the connection is open before. But this isn't important. Signed-off-by: Michael Tokarev Reviewed-by: Daniel P. Berrange Message-id: 1486115549-9398-1-git-send-email-mjt@msgid.tls.msk.ru Fixes: 04d2529da27db512dcbd5e99d0e26d333f16efcc Cc: Daniel P. Berrange Cc: Gerd Hoffmann Cc: qemu-stable@nongnu.org Signed-off-by: Gerd Hoffmann (cherry picked from commit 537848ee62195fc06c328b1cd64f4218f404a7f1) Signed-off-by: Michael Roth --- ui/vnc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/ui/vnc.c b/ui/vnc.c index 29aa9c4..552f1da 100644 --- a/ui/vnc.c +++ b/ui/vnc.c @@ -1258,12 +1258,13 @@ ssize_t vnc_client_io_error(VncState *vs, ssize_t ret, Error **errp) if (ret <= 0) { if (ret == 0) { VNC_DEBUG("Closing down client sock: EOF\n"); + vnc_disconnect_start(vs); } else if (ret != QIO_CHANNEL_ERR_BLOCK) { VNC_DEBUG("Closing down client sock: ret %d (%s)\n", ret, errp ? error_get_pretty(*errp) : "Unknown"); + vnc_disconnect_start(vs); } - vnc_disconnect_start(vs); if (errp) { error_free(*errp); *errp = NULL;