From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by dpdk.org (Postfix) with ESMTP id 4D8553237 for ; Thu, 21 Jul 2016 11:33:09 +0200 (CEST) Received: from orsmga003.jf.intel.com ([10.7.209.27]) by fmsmga101.fm.intel.com with ESMTP; 21 Jul 2016 02:33:08 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.28,398,1464678000"; d="scan'208";a="850479060" Received: from yliu-dev.sh.intel.com (HELO yliu-dev) ([10.239.67.162]) by orsmga003.jf.intel.com with ESMTP; 21 Jul 2016 02:33:06 -0700 Date: Thu, 21 Jul 2016 17:37:14 +0800 From: Yuanhan Liu To: Ilya Maximets Cc: dev@dpdk.org, Huawei Xie , Dyasly Sergey , Heetae Ahn , Thomas Monjalon Message-ID: <20160721093714.GD28708@yliu-dev.sh.intel.com> References: <1469089275-15209-1-git-send-email-i.maximets@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1469089275-15209-1-git-send-email-i.maximets@samsung.com> User-Agent: Mutt/1.5.23 (2014-03-12) Subject: Re: [dpdk-dev] [PATCH] vhost: fix connect hang in client mode X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 21 Jul 2016 09:33:09 -0000 On Thu, Jul 21, 2016 at 11:21:15AM +0300, Ilya Maximets wrote: > If something abnormal happened to QEMU, 'connect()' can block calling > thread (e.g. main thread of OVS) forever or for a really long time. > This can break whole application or block the reconnection thread. > > Example with OVS: > > ovs_rcu(urcu2)|WARN|blocked 512000 ms waiting for main to quiesce > (gdb) bt > #0 connect () from /lib64/libpthread.so.0 > #1 vhost_user_create_client (vsocket=0xa816e0) > #2 rte_vhost_driver_register > #3 netdev_dpdk_vhost_user_construct > #4 netdev_open (name=0xa664b0 "vhost1") > [...] > #11 main > > Fix that by setting non-blocking mode for client sockets for connection. > > Fixes: 64ab701c3d1e ("vhost: add vhost-user client mode") Thanks for spotting and fixing yet another bug! > > +static int > +vhost_user_connect_nonblock(int fd, struct sockaddr *un, size_t sz) I don't quite understand why this is needed: connect() with O_NONBLOCK flag set is not enough? --yliu