From patchwork Thu Aug 5 14:32:31 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Li Jinlin X-Patchwork-Id: 492568 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 29FCAC4338F for ; Thu, 5 Aug 2021 14:02:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 024156113B for ; Thu, 5 Aug 2021 14:02:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241399AbhHEOCa (ORCPT ); Thu, 5 Aug 2021 10:02:30 -0400 Received: from szxga08-in.huawei.com ([45.249.212.255]:13238 "EHLO szxga08-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233088AbhHEOC3 (ORCPT ); Thu, 5 Aug 2021 10:02:29 -0400 Received: from dggemv703-chm.china.huawei.com (unknown [172.30.72.53]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4GgVfM2l6cz1CRvV; Thu, 5 Aug 2021 22:02:03 +0800 (CST) Received: from dggema773-chm.china.huawei.com (10.1.198.217) by dggemv703-chm.china.huawei.com (10.3.19.46) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2176.2; Thu, 5 Aug 2021 22:02:10 +0800 Received: from localhost.huawei.com (10.175.124.27) by dggema773-chm.china.huawei.com (10.1.198.217) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2176.2; Thu, 5 Aug 2021 22:02:09 +0800 From: To: , , , CC: , , , , , Subject: [PATCH] scsi: core: Run queue first after running device. Date: Thu, 5 Aug 2021 22:32:31 +0800 Message-ID: <20210805143231.1713299-1-lijinlin3@huawei.com> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 X-Originating-IP: [10.175.124.27] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggema773-chm.china.huawei.com (10.1.198.217) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org From: Li Jinlin We found a hang issue, the test steps are as follows: 1. echo "blocked" >/sys/block/sda/device/state 2. dd if=/dev/sda of=/mnt/t.log bs=1M count=10 3. echo none > /sys/block/sda/queue/scheduler 4. echo "running" >/sys/block/sda/device/state Step3 and Step4 should finish this work after Step4, but them hangs. CPU#0 CPU#1 CPU#2 --------------- ---------------- ---------------- Step1: blocking device Step2: dd xxxx ^^^^^^ get request q_usage_counter++ Step3: switching scheculer elv_iosched_store elevator_switch blk_mq_freeze_queue blk_freeze_queue > blk_freeze_queue_start ^^^^^^ mq_freeze_depth++ > blk_mq_run_hw_queues ^^^^^^ can't run queue when dev blocked > blk_mq_freeze_queue_wait ^^^^^^ Hang here!!! wait q_usage_counter==0 Step4: running device store_state_field scsi_rescan_device scsi_attach_vpd scsi_vpd_inquiry __scsi_execute blk_get_request blk_mq_alloc_request blk_queue_enter ^^^^^^ Hang here!!! wait mq_freeze_depth==0 blk_mq_run_hw_queues ^^^^^^ dispatch IO, q_usage_counter will reduce to zero blk_mq_unfreeze_queue ^^^^^ mq_freeze_depth-- Step3 and Step4 wait for each other, caused hangs. This requires run queue frist to fix this issue when the device state changes to SDEV_RUNNING. Fixes: f0f82e2476f6 ("scsi: core: Fix capacity set to zero after offlinining device") Signed-off-by: Li Jinlin Signed-off-by: Qiu Laibin Signed-off-by: Wu Bo --- drivers/scsi/scsi_sysfs.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c index c3a710bceba0..aa701582c950 100644 --- a/drivers/scsi/scsi_sysfs.c +++ b/drivers/scsi/scsi_sysfs.c @@ -809,12 +809,12 @@ store_state_field(struct device *dev, struct device_attribute *attr, ret = scsi_device_set_state(sdev, state); /* * If the device state changes to SDEV_RUNNING, we need to - * rescan the device to revalidate it, and run the queue to - * avoid I/O hang. + * run the queue to avoid I/O hang, and rescan the device + * to revalidate it. */ if (ret == 0 && state == SDEV_RUNNING) { - scsi_rescan_device(dev); blk_mq_run_hw_queues(sdev->request_queue, true); + scsi_rescan_device(dev); } mutex_unlock(&sdev->state_mutex);