From patchwork Fri May 26 03:07:37 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ming Lei X-Patchwork-Id: 9749659 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 A2E6360388 for ; Fri, 26 May 2017 03:08:31 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9E6892833C for ; Fri, 26 May 2017 03:08:31 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 92EE02836F; Fri, 26 May 2017 03:08:31 +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 vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4B8332833C for ; Fri, 26 May 2017 03:08:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936098AbdEZDIa (ORCPT ); Thu, 25 May 2017 23:08:30 -0400 Received: from mx1.redhat.com ([209.132.183.28]:40232 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934477AbdEZDIa (ORCPT ); Thu, 25 May 2017 23:08:30 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 885514E03F; Fri, 26 May 2017 03:08:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 885514E03F Authentication-Results: ext-mx09.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx09.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=ming.lei@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 885514E03F Received: from localhost (ovpn-12-44.pek2.redhat.com [10.72.12.44]) by smtp.corp.redhat.com (Postfix) with ESMTP id B8E865DD60; Fri, 26 May 2017 03:08:20 +0000 (UTC) From: Ming Lei To: Jens Axboe , linux-block@vger.kernel.org, Christoph Hellwig Cc: Bart Van Assche , linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org, dm-devel@redhat.com Subject: [PATCH 4/6] blk-mq: update comments on blk_mq_quiesce_queue() Date: Fri, 26 May 2017 11:07:37 +0800 Message-Id: <20170526030740.26959-5-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 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Fri, 26 May 2017 03:08:29 +0000 (UTC) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Actually what we want to get from blk_mq_quiesce_queue() isn't only to wait for completion of all ongooing .queue_rq(). In the typical context of canceling requests, we need to make sure that the following is done in the dispatch path before starting to cancel requests: - failed dispatched request is freeed - busy dispatched request is requeued, and the STARTED flag is cleared Signed-off-by: Ming Lei --- block/blk-mq.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 864709453c90..e1fc9ab50c87 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -155,12 +155,12 @@ void blk_mq_unfreeze_queue(struct request_queue *q) EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue); /** - * blk_mq_quiesce_queue() - wait until all ongoing queue_rq calls have finished + * blk_mq_quiesce_queue() - wait until all ongoing dispatching have finished * @q: request queue. * * Note: this function does not prevent that the struct request end_io() - * callback function is invoked. Additionally, it is not prevented that - * new queue_rq() calls occur unless the queue has been stopped first. + * callback function is invoked. Once this function is returned, we make + * sure no dispatching can happen. */ void blk_mq_quiesce_queue(struct request_queue *q) {