From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8C3B8CE7A8A for ; Sun, 24 Sep 2023 06:37:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229788AbjIXGhP (ORCPT ); Sun, 24 Sep 2023 02:37:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41058 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229437AbjIXGhO (ORCPT ); Sun, 24 Sep 2023 02:37:14 -0400 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 99B7E107; Sat, 23 Sep 2023 23:37:07 -0700 (PDT) Received: from kwepemm000012.china.huawei.com (unknown [172.30.72.53]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4RtbpP15LZz15NRG; Sun, 24 Sep 2023 14:34:53 +0800 (CST) Received: from [10.174.178.220] (10.174.178.220) by kwepemm000012.china.huawei.com (7.193.23.142) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.31; Sun, 24 Sep 2023 14:37:03 +0800 Message-ID: <407be945-9fd2-8e00-e72b-82e2f311dbeb@huawei.com> Date: Sun, 24 Sep 2023 14:37:02 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [PATCH 1/2] scsi: core: scsi_device_online() return false if state is SDEV_CANCEL Content-Language: en-US To: Bart Van Assche , "James E . J . Bottomley" , "Martin K . Petersen" CC: , , References: <20230922093636.2645961-1-haowenchao2@huawei.com> <20230922093636.2645961-2-haowenchao2@huawei.com> <50b20a3e-e264-4788-8e52-f7b57cf944f0@acm.org> From: Wenchao Hao In-Reply-To: <50b20a3e-e264-4788-8e52-f7b57cf944f0@acm.org> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.178.220] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To kwepemm000012.china.huawei.com (7.193.23.142) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2023/9/22 23:23, Bart Van Assche wrote: > On 9/22/23 02:36, Wenchao Hao wrote: >> SDEV_CANCEL is set when removing device and scsi_device_online() should >> return false if sdev_state is SDEV_CANCEL. >> >> IO hang would be caused if return true when state is SDEV_CANCEL with >> following order: >> >> T1:                        T2:scsi_error_handler >> __scsi_remove_device() >>    scsi_device_set_state(sdev, SDEV_CANCEL) >>                            scsi_eh_flush_done_q() >>                         if (scsi_device_online(sdev)) >>                           scsi_queue_insert(scmd,...) >> >> The command added by scsi_queue_insert() would never be handled any >> more. > > Why not? I think the blk_mq_destroy_queue() call in __scsi_remove_device() will cause it to fail. > > Thanks, > > Bart. > Sorry, I did not describe in detail, the __scsi_remove_device() would be blocked in blk_mq_freeze_queue_wait() to wait all block requests finished, so blk_mq_destroy_queue() would not be called, and the task which try to remove scsi_device would be hung.