From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754787AbeDBWtx (ORCPT ); Mon, 2 Apr 2018 18:49:53 -0400 Received: from esa1.hgst.iphmx.com ([68.232.141.245]:35300 "EHLO esa1.hgst.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754535AbeDBWtr (ORCPT ); Mon, 2 Apr 2018 18:49:47 -0400 X-IronPort-AV: E=Sophos;i="5.48,397,1517846400"; d="scan'208";a="178126564" From: Bart Van Assche To: "tj@kernel.org" CC: "kernel-team@fb.com" , "linux-kernel@vger.kernel.org" , "linux-block@vger.kernel.org" , "axboe@kernel.dk" Subject: Re: [PATCH 2/2] blk-mq: Fix request handover from timeout path to normal execution Thread-Topic: [PATCH 2/2] blk-mq: Fix request handover from timeout path to normal execution Thread-Index: AQHTyrUNkNkjnUv7yk+FmjLOLTu6JKPt+B6AgAAAm4CAAAzSAIAAAWEAgAACJYCAAAIlgIAACSYA Date: Mon, 2 Apr 2018 22:49:43 +0000 Message-ID: References: <20180402190053.GC388343@devbig577.frc2.facebook.com> <20180402190120.GD388343@devbig577.frc2.facebook.com> <20180402211047.GF388343@devbig577.frc2.facebook.com> <20180402220136.GI388343@devbig577.frc2.facebook.com> <6d6985b8d95317aa5572809f1b987c45e932c5b2.camel@wdc.com> <20180402221657.GL388343@devbig577.frc2.facebook.com> In-Reply-To: <20180402221657.GL388343@devbig577.frc2.facebook.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: spf=none (sender IP is ) smtp.mailfrom=Bart.VanAssche@wdc.com; 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x-microsoft-antispam-message-info: 1afFipC/t0ps82WmmzwVsOGs8shW8rELcd1Nd4l+0EPACTwK0E4Zn1j1zo/O6VnFRNj6BKINe7HfMBMGr8Jwy19RbXdTBfEWqa1S9+JQSn71JuzRAPwyraQQkR/raZEqo5P/fPYIbfbK/kFApDvNggwevhAAItBx2NOfVuwo5L0ayz59pwyYHw8bp3MI8HjlrT8Sox+NYKj/5SdOCgZk32hkATJiSRohC7qFPi/uCjKd6w7jzz+GblzcS6slCNEXV96roS7NbQUkf0z5JLCtasrvIBytTNIOyOrf+0HrP+ehJw5g07eukIwNtv14mynmTOqxTbC7STGeJNm0K0HpeSdwR4/aEBuIBRCwEpYaP16DFIqBm69/8r7mGMiJUYEHMTzgoNWtqJA9QwKq+1sePCZRWr3O0cBMmVRvBzTAff4= spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="utf-8" Content-ID: MIME-Version: 1.0 X-OriginatorOrg: wdc.com X-MS-Exchange-CrossTenant-Network-Message-Id: bead1b59-ee05-4c7e-1bff-08d598ec06db X-MS-Exchange-CrossTenant-originalarrivaltime: 02 Apr 2018 22:49:43.6582 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: b61c8803-16f3-4c35-9b17-6f65f441df86 X-MS-Exchange-Transport-CrossTenantHeadersStamped: MWHPR04MB0751 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by mail.home.local id w32MnxEu025240 On Mon, 2018-04-02 at 15:16 -0700, tj@kernel.org wrote: > AFAIK, > there's one non-critical race condition which has always been there. > We have a larger race window for that case but don't yet know whether > that's problematic or not. If that actually is problematic, we can > figure out a way to solve that but such effort / added complexity > doesn't seem justified yet. No? Hello Tejun, Some important block drivers systematically return BLK_EH_RESET_TIMER from their timeout handler, e.g. the virtio-scsi initiator driver. What will the consequence be for these drivers if a blk_mq_complete_request() call is ignored? Will the request for which the completion was ignored get stuck? Thanks, Bart.