From patchwork Fri May 26 03:07:39 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ming Lei X-Patchwork-Id: 9749925 X-Patchwork-Delegate: snitzer@redhat.com 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 B18E860390 for ; Fri, 26 May 2017 08:08:51 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A0A35283BB for ; Fri, 26 May 2017 08:08:51 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 95B08283FF; Fri, 26 May 2017 08:08:51 +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=ham version=3.3.1 Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 4C8DC283BB for ; Fri, 26 May 2017 08:08:51 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 3282B7F3E1; Fri, 26 May 2017 08:08:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 3282B7F3E1 Authentication-Results: ext-mx01.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx01.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=dm-devel-bounces@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 3282B7F3E1 Received: from colo-mx.corp.redhat.com (colo-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.20]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 0B8AA17981; Fri, 26 May 2017 08:08:50 +0000 (UTC) Received: from lists01.pubmisc.prod.ext.phx2.redhat.com (lists01.pubmisc.prod.ext.phx2.redhat.com [10.5.19.33]) by colo-mx.corp.redhat.com (Postfix) with ESMTP id CCD85180BAF9; Fri, 26 May 2017 08:08:49 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) by lists01.pubmisc.prod.ext.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id v4Q38o64005131 for ; Thu, 25 May 2017 23:08:50 -0400 Received: by smtp.corp.redhat.com (Postfix) id 46B5C79288; Fri, 26 May 2017 03:08:50 +0000 (UTC) Delivered-To: dm-devel@redhat.com Received: from localhost (ovpn-12-44.pek2.redhat.com [10.72.12.44]) by smtp.corp.redhat.com (Postfix) with ESMTP id 98E4F7BB56; Fri, 26 May 2017 03:08:40 +0000 (UTC) From: Ming Lei To: Jens Axboe , linux-block@vger.kernel.org, Christoph Hellwig Date: Fri, 26 May 2017 11:07:39 +0800 Message-Id: <20170526030740.26959-7-ming.lei@redhat.com> In-Reply-To: <20170526030740.26959-1-ming.lei@redhat.com> References: <20170526030740.26959-1-ming.lei@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-loop: dm-devel@redhat.com X-Mailman-Approved-At: Fri, 26 May 2017 04:07:24 -0400 Cc: Bart Van Assche , dm-devel@redhat.com, linux-scsi@vger.kernel.org, linux-nvme@lists.infradead.org Subject: [dm-devel] [PATCH 6/6] blk-mq: clarify dispatching may not be drained/blocked by stopping queue X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Fri, 26 May 2017 08:08:50 +0000 (UTC) X-Virus-Scanned: ClamAV using ClamSMTP BLK_MQ_S_STOPPED may be not observed in other concurrent I/O paths, we can't guarantee that dispatching won't happen after queue is stopped. So clarify the fact and avoid potential misuse. Signed-off-by: Ming Lei --- block/blk-mq.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/block/blk-mq.c b/block/blk-mq.c index 900eb91e0ece..32bed5bac7da 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1240,6 +1240,11 @@ static void __blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx, bool sync) set_bit(BLK_MQ_S_STOPPED, &hctx->state); } +/* + * Do not expect that dispatching or .queue_rq() can be blocked + * after blk_mq_stop_hw_queue() returns. Please use + * blk_mq_quiesce_queue() for that requirement. + */ void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx) { __blk_mq_stop_hw_queue(hctx, false); @@ -1255,6 +1260,11 @@ static void __blk_mq_stop_hw_queues(struct request_queue *q, bool sync) __blk_mq_stop_hw_queue(hctx, sync); } +/* + * Do not expect that dispatching or .queue_rq() can be blocked + * after blk_mq_stop_hw_queues() returns. Please use + * blk_mq_quiesce_queue() for that requirement. + */ void blk_mq_stop_hw_queues(struct request_queue *q) { __blk_mq_stop_hw_queues(q, false);