From mboxrd@z Thu Jan 1 00:00:00 1970 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=-3.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 667B1C433E2 for ; Wed, 9 Sep 2020 01:19:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 17F26218AC for ; Wed, 9 Sep 2020 01:19:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="eJq9fp+n" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726369AbgIIBTe (ORCPT ); Tue, 8 Sep 2020 21:19:34 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:40669 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726002AbgIIBTe (ORCPT ); Tue, 8 Sep 2020 21:19:34 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1599614373; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Gf75B6Udqf9iPOzPF2w9rijRVVDFIq7lsR+ojBwz+4k=; b=eJq9fp+nYhAbk4mR9vYT/DT1bs8snBCuFGPKatk+mbC3WMaEk+obb1wSmrPYRRyeG095HZ WCdDIkRGptirKDyhwthGwJn2k3gBBG0P60J7rlug7vwlbBfs2jkOXoHOitZYqJ6daYAWHm V76qoD45U3nEE7VQMs7gLM2ocgyA94k= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-458-Ceczz7n6PMSNJVVC4SLU4A-1; 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 Cc: Jens Axboe , linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, Christoph Hellwig , Sagi Grimberg , Bart Van Assche , Johannes Thumshirn , Chao Leng 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-Type: text/plain; charset=us-ascii 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 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.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