From patchwork Wed Sep 27 05:48:53 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ming Lei X-Patchwork-Id: 9973085 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 5B32E60375 for ; Wed, 27 Sep 2017 05:52:09 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4D5092909D for ; Wed, 27 Sep 2017 05:52:09 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 420A2290A1; Wed, 27 Sep 2017 05:52:09 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id F0276290A6 for ; Wed, 27 Sep 2017 05:52:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752189AbdI0FwH (ORCPT ); Wed, 27 Sep 2017 01:52:07 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51876 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751396AbdI0FwG (ORCPT ); Wed, 27 Sep 2017 01:52:06 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9D017C00B6E5; Wed, 27 Sep 2017 05:52:06 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 9D017C00B6E5 Authentication-Results: ext-mx07.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx07.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=ming.lei@redhat.com Received: from localhost (ovpn-12-112.pek2.redhat.com [10.72.12.112]) by smtp.corp.redhat.com (Postfix) with ESMTP id 432336FE70; Wed, 27 Sep 2017 05:51:55 +0000 (UTC) From: Ming Lei To: Jens Axboe , linux-block@vger.kernel.org, Christoph Hellwig , linux-scsi@vger.kernel.org, "Martin K . Petersen" , "James E . J . Bottomley" Cc: Bart Van Assche , Oleksandr Natalenko , Johannes Thumshirn , Cathy Avery , Martin Steigerwald , Ming Lei Subject: [PATCH V6 6/6] SCSI: set block queue at preempt only when SCSI device is put into quiesce Date: Wed, 27 Sep 2017 13:48:53 +0800 Message-Id: <20170927054853.6647-7-ming.lei@redhat.com> In-Reply-To: <20170927054853.6647-1-ming.lei@redhat.com> References: <20170927054853.6647-1-ming.lei@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Wed, 27 Sep 2017 05:52:06 +0000 (UTC) Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Simply quiesing SCSI device and waiting for completeion of IO dispatched to SCSI queue isn't safe, it is easy to use up request pool because all allocated requests before can't be dispatched when device is put in QIUESCE. Then no request can be allocated for RQF_PREEMPT, and system may hang somewhere, such as When sending commands of sync_cache or start_stop during system suspend path. Before quiesing SCSI, this patch sets block queue in preempt mode first, so no new normal request can enter queue any more, and all pending requests are drained too once blk_set_preempt_only(true) is returned. Then RQF_PREEMPT can be allocated successfully duirng preempt freeze. Signed-off-by: Ming Lei --- drivers/scsi/scsi_lib.c | 25 ++++++++++++++++++++++--- 1 file changed, 22 insertions(+), 3 deletions(-) diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 9cf6a80fe297..82c51619f1b7 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -252,9 +252,10 @@ int scsi_execute(struct scsi_device *sdev, const unsigned char *cmd, struct scsi_request *rq; int ret = DRIVER_ERROR << 24; - req = blk_get_request(sdev->request_queue, + req = __blk_get_request(sdev->request_queue, data_direction == DMA_TO_DEVICE ? - REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN, __GFP_RECLAIM); + REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN, __GFP_RECLAIM, + BLK_REQ_PREEMPT); if (IS_ERR(req)) return ret; rq = scsi_req(req); @@ -2928,12 +2929,28 @@ scsi_device_quiesce(struct scsi_device *sdev) { int err; + /* + * Simply quiesing SCSI device isn't safe, it is easy + * to use up requests because all these allocated requests + * can't be dispatched when device is put in QIUESCE. + * Then no request can be allocated and we may hang + * somewhere, such as system suspend/resume. + * + * So we set block queue in preempt only first, no new + * normal request can enter queue any more, and all pending + * requests are drained once blk_set_preempt_only() + * returns. Only RQF_PREEMPT is allowed in preempt only mode. + */ + blk_set_preempt_only(sdev->request_queue, true); + mutex_lock(&sdev->state_mutex); err = scsi_device_set_state(sdev, SDEV_QUIESCE); mutex_unlock(&sdev->state_mutex); - if (err) + if (err) { + blk_set_preempt_only(sdev->request_queue, false); return err; + } scsi_run_queue(sdev->request_queue); while (atomic_read(&sdev->device_busy)) { @@ -2964,6 +2981,8 @@ void scsi_device_resume(struct scsi_device *sdev) scsi_device_set_state(sdev, SDEV_RUNNING) == 0) scsi_run_queue(sdev->request_queue); mutex_unlock(&sdev->state_mutex); + + blk_set_preempt_only(sdev->request_queue, false); } EXPORT_SYMBOL(scsi_device_resume);