From patchwork Thu Feb 11 15:02:55 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 381741 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=-19.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT 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 280EEC433DB for ; Thu, 11 Feb 2021 15:26:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D8DAD64D87 for ; Thu, 11 Feb 2021 15:26:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230147AbhBKP0X (ORCPT ); Thu, 11 Feb 2021 10:26:23 -0500 Received: from mail.kernel.org ([198.145.29.99]:53510 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230418AbhBKPWh (ORCPT ); Thu, 11 Feb 2021 10:22:37 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 0E74E64F32; Thu, 11 Feb 2021 15:07:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1613056028; bh=/nF6qPipkgNN+AGt8o6n3NFN/weCxFIubucELHp2D2I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fsYiuLuNcYkl289j+cDte0rnXPiqpYjWyQffiQH46wIQjPeHa479gA74qKWz9pBRS zAm1CxKQzDbAOWVxjJFw2+b4JqQ88QDMa97mLTAz5aOsTP45EimiYN11aKRVdxRnhp 1mK6aLnwUEcK4CMVLKSS70m6A9rCYM2bcvDXR8pY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Christoph Hellwig , Hannes Reinecke , Mike Snitzer , Bart Van Assche , Ming Lei , Jens Axboe , Jack Wang Subject: [PATCH 4.19 21/24] blk-mq: dont hold q->sysfs_lock in blk_mq_map_swqueue Date: Thu, 11 Feb 2021 16:02:55 +0100 Message-Id: <20210211150148.681811267@linuxfoundation.org> X-Mailer: git-send-email 2.30.1 In-Reply-To: <20210211150147.743660073@linuxfoundation.org> References: <20210211150147.743660073@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Ming Lei commit c6ba933358f0d7a6a042b894dba20cc70396a6d3 upstream. blk_mq_map_swqueue() is called from blk_mq_init_allocated_queue() and blk_mq_update_nr_hw_queues(). For the former caller, the kobject isn't exposed to userspace yet. For the latter caller, hctx sysfs entries and debugfs are un-registered before updating nr_hw_queues. On the other hand, commit 2f8f1336a48b ("blk-mq: always free hctx after request queue is freed") moves freeing hctx into queue's release handler, so there won't be race with queue release path too. So don't hold q->sysfs_lock in blk_mq_map_swqueue(). Cc: Christoph Hellwig Cc: Hannes Reinecke Cc: Greg KH Cc: Mike Snitzer Cc: Bart Van Assche Reviewed-by: Bart Van Assche Signed-off-by: Ming Lei Signed-off-by: Jens Axboe Signed-off-by: Jack Wang Signed-off-by: Greg Kroah-Hartman --- block/blk-mq.c | 7 ------- 1 file changed, 7 deletions(-) --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2324,11 +2324,6 @@ static void blk_mq_map_swqueue(struct re struct blk_mq_ctx *ctx; struct blk_mq_tag_set *set = q->tag_set; - /* - * Avoid others reading imcomplete hctx->cpumask through sysfs - */ - mutex_lock(&q->sysfs_lock); - queue_for_each_hw_ctx(q, hctx, i) { cpumask_clear(hctx->cpumask); hctx->nr_ctx = 0; @@ -2362,8 +2357,6 @@ static void blk_mq_map_swqueue(struct re hctx->ctxs[hctx->nr_ctx++] = ctx; } - mutex_unlock(&q->sysfs_lock); - queue_for_each_hw_ctx(q, hctx, i) { /* * If no software queues are mapped to this hardware queue,