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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 E4BD5C433E0 for ; Sat, 6 Mar 2021 04:33:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 98FCE64FBD for ; Sat, 6 Mar 2021 04:33:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229898AbhCFEcj (ORCPT ); Fri, 5 Mar 2021 23:32:39 -0500 Received: from mail-pj1-f41.google.com ([209.85.216.41]:33788 "EHLO mail-pj1-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229714AbhCFEc1 (ORCPT ); Fri, 5 Mar 2021 23:32:27 -0500 Received: by mail-pj1-f41.google.com with SMTP id j14-20020a17090a588eb02900cefe2daa2cso151487pji.0; Fri, 05 Mar 2021 20:32:27 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=0FLdb7WRYyetMAGeVkmVyaxyT94n1/im6YgyjkPRT3E=; b=CGCJrIPfnZ7Mgz/1f6l55lxDaAjW9oRsxkl9RmG4YzHZqO5MzkjqVmWevj5B3eKirb X9we6corwSdoP2XxUcYWO1kQX3hBFjvxXjRJnCO3IJU49qcTENl9R3RVkZ2PjAR3+fuI DAFRTb303F02N7+uCq6y0RmxdoHFzoVaZEcWxMuwQbfRPYATXNzYmBZk428BTkt4OsMS G6tDxzElikvAhrJO4qUYL2/FndpxSUpxyOkyaBGial9nWpqd73hBtMNPEC56Uk33sizM rUQUQ6PD6hLUocHV9YxVGxnBa6X5TBq6IGf9s0p3LK9zUOu1xKIYoj6VnSWBx2CwWk90 gvjA== X-Gm-Message-State: AOAM533fyeUmVKntMeeY/xlZIRBvs9TyoFk7YcYyM5Ctxj8MyzlY+yvD gqIelo7BLo2Pud+ExThDJeTafsagqKk= X-Google-Smtp-Source: ABdhPJywIhgawDTlWs6vOPCOvxkKzRxO0NIFJq96trJk5+cU+UtxNV74qZdVpuhUal9m/JelfZChkg== X-Received: by 2002:a17:90a:4381:: with SMTP id r1mr14325348pjg.20.1615005146889; Fri, 05 Mar 2021 20:32:26 -0800 (PST) Received: from ?IPv6:2601:647:4000:d7:508e:d398:f4d5:3d44? ([2601:647:4000:d7:508e:d398:f4d5:3d44]) by smtp.gmail.com with ESMTPSA id z3sm3233394pff.40.2021.03.05.20.32.25 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 05 Mar 2021 20:32:26 -0800 (PST) Subject: Re: [RFC PATCH v3 2/3] blk-mq: Freeze and quiesce all queues for tagset in elevator_exit() To: John Garry , hare@suse.de, ming.lei@redhat.com, axboe@kernel.dk, hch@lst.de Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, pragalla@codeaurora.org, kashyap.desai@broadcom.com, yuyufen@huawei.com References: <1614957294-188540-1-git-send-email-john.garry@huawei.com> <1614957294-188540-3-git-send-email-john.garry@huawei.com> From: Bart Van Assche Message-ID: <52618092-07ca-ecb5-320f-957af26ab146@acm.org> Date: Fri, 5 Mar 2021 20:32:24 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: <1614957294-188540-3-git-send-email-john.garry@huawei.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 3/5/21 7:14 AM, John Garry wrote: > diff --git a/block/blk.h b/block/blk.h > index 3b53e44b967e..1a948bfd91e4 100644 > --- a/block/blk.h > +++ b/block/blk.h > @@ -201,10 +201,29 @@ void elv_unregister_queue(struct request_queue *q); > static inline void elevator_exit(struct request_queue *q, > struct elevator_queue *e) > { > + struct blk_mq_tag_set *set = q->tag_set; > + struct request_queue *tmp; > + > lockdep_assert_held(&q->sysfs_lock); > > + mutex_lock(&set->tag_list_lock); > + list_for_each_entry(tmp, &set->tag_list, tag_set_list) { > + if (tmp == q) > + continue; > + blk_mq_freeze_queue(tmp); > + blk_mq_quiesce_queue(tmp); > + } > + > blk_mq_sched_free_requests(q); > __elevator_exit(q, e); > + > + list_for_each_entry(tmp, &set->tag_list, tag_set_list) { > + if (tmp == q) > + continue; > + blk_mq_unquiesce_queue(tmp); > + blk_mq_unfreeze_queue(tmp); > + } > + mutex_unlock(&set->tag_list_lock); > } This patch introduces nesting of tag_list_lock inside sysfs_lock. The latter is per request queue while the former can be shared across multiple request queues. Has it been analyzed whether this is safe? Thanks, Bart.