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Tue, 08 Sep 2020 21:19:29 -0400 X-MC-Unique: Ceczz7n6PMSNJVVC4SLU4A-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D8B7D109106A; Wed, 9 Sep 2020 01:19:27 +0000 (UTC) Received: from T590 (ovpn-12-76.pek2.redhat.com [10.72.12.76]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 5EDF91002D5A; Wed, 9 Sep 2020 01:19:19 +0000 (UTC) Date: Wed, 9 Sep 2020 09:19:16 +0800 From: Ming Lei To: Keith Busch Subject: Re: [PATCH V3 2/4] blk-mq: implement queue quiesce via percpu_ref for BLK_MQ_F_BLOCKING Message-ID: <20200909011916.GB1465199@T590> References: <20200908081538.1434936-1-ming.lei@redhat.com> <20200908081538.1434936-3-ming.lei@redhat.com> <20200908153108.GA3341002@dhcp-10-100-145-180.wdl.wdc.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200908153108.GA3341002@dhcp-10-100-145-180.wdl.wdc.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200908_211934_207180_2F94DEB5 X-CRM114-Status: GOOD ( 15.19 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jens Axboe , Bart Van Assche , Johannes Thumshirn , linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, Chao Leng , Christoph Hellwig , Sagi Grimberg Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Tue, Sep 08, 2020 at 08:31:08AM -0700, Keith Busch wrote: > On Tue, Sep 08, 2020 at 04:15:36PM +0800, Ming Lei wrote: > > void blk_mq_quiesce_queue(struct request_queue *q) > > { > > - struct blk_mq_hw_ctx *hctx; > > - unsigned int i; > > - bool rcu = false; > > + bool blocking = !!(q->tag_set->flags & BLK_MQ_F_BLOCKING); > > > > mutex_lock(&q->mq_quiesce_lock); > > > > - if (blk_queue_quiesced(q)) > > - goto exit; > > Why remove the 'goto exit' on this condition? There shouldn't be a need > to synchronize dispatch again if a previous quiesce already did so. Hammm, this change is supposed to be done in next patch of 'blk-mq: add tagset quiesce interface'. The tagset quiesce interface starts to apply async quiesce, so synchronize dispatch has to be done in blk_mq_quiesce_queue(). thanks, Ming _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme