From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) by dpdk.org (Postfix) with ESMTP id D2AF01D9E for ; Wed, 28 Feb 2018 11:19:47 +0100 (CET) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 28 Feb 2018 02:19:46 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.47,405,1515484800"; d="scan'208";a="178698709" Received: from aburakov-mobl.ger.corp.intel.com (HELO [10.237.220.78]) ([10.237.220.78]) by orsmga004.jf.intel.com with ESMTP; 28 Feb 2018 02:19:45 -0800 To: "Tan, Jianfeng" , "dev@dpdk.org" References: <31f6d9ef676fb1eb0a664c06d62d66f32876dcb6.1519672713.git.anatoly.burakov@intel.com> <4be9dbc2f5751e9584f69997d4ef0077992eae52.1519740527.git.anatoly.burakov@intel.com> From: "Burakov, Anatoly" Message-ID: <78e91c1c-2f7f-e93b-4e4b-ef1d77aa1140@intel.com> Date: Wed, 28 Feb 2018 10:19:45 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [dpdk-dev] [PATCH v3 4/5] eal: prevent secondary process init while sending messages X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 28 Feb 2018 10:19:48 -0000 On 28-Feb-18 1:58 AM, Tan, Jianfeng wrote: > Hi Anatoly, > >> -----Original Message----- >> From: Burakov, Anatoly >> Sent: Tuesday, February 27, 2018 10:36 PM >> To: dev@dpdk.org >> Cc: Tan, Jianfeng >> Subject: [PATCH v3 4/5] eal: prevent secondary process init while sending >> messages >> >> Currently, it is possible to spin up a secondary process while >> either sendmsg or request is in progress. Fix this by adding >> directory locks during init, sendmsg and requests. > > Could you give a more detailed example for this issue? > > And why locking the directory can help? > > Thanks, > Jianfeng > Consider this. You start a request. Since sending this out takes non-zero amount of time, and you're waiting for process to reply each time you send a message, there's a non-zero chance where contents of /var/run may change and another socket file may appear that wasn't there when we started sending out those messages. This is simply making sending requests atomic, if you will. Honestly, i can't think of a situation where this might be a problem, but it just doesn't feel right, so i fixed it :) -- Thanks, Anatoly