From patchwork Mon Nov 30 02:46:07 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bart Van Assche X-Patchwork-Id: 11939567 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 085B8C71155 for ; Mon, 30 Nov 2020 02:47:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CD7A22076C for ; Mon, 30 Nov 2020 02:47:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726630AbgK3CrF (ORCPT ); Sun, 29 Nov 2020 21:47:05 -0500 Received: from mail-pf1-f195.google.com ([209.85.210.195]:43647 "EHLO mail-pf1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726000AbgK3CrF (ORCPT ); Sun, 29 Nov 2020 21:47:05 -0500 Received: by mail-pf1-f195.google.com with SMTP id w202so9466589pff.10; Sun, 29 Nov 2020 18:46:50 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=uo+5W/VFPGcdmJas5S5VfCp+uberliRJhse/5+5MoEs=; b=qC61DSU/aPZp9pg6ENHHnPGjj6lw3YpEG30S34AQpfSjFzWTMX5vyvFbPQtShjD5VH d3EqRuYApoI5LmuvsOt4lNd/Sx5vb21lpTMfC3g4qyRxVj1jYoHXxlGn7hy6MgwxcqeE zbzYd2RYc9liI2/AzkjdgE5jCoLRvl38W7anitPhsaUD6khgjOfrDOaO5nb7higStKS6 Wty77cnbi9Qo/GQ+L8hjBC2RTD762fYIynY0vr3FLWuTfc6kq88KkPHEGqd9gTArY03s XzyAY8+DHXFxHFHrDakC5EiQc6FfSrvFYQNcNmrcwNh1S37DHrSCVwvEc60RFRKbgmlJ s/4w== X-Gm-Message-State: AOAM5335BwA45V38LNS2GJcvJqzlLelDe3iGlhroUmYSy4nbLFE4dKTV jqZF0cdtP/PWdi1cxybQ18M+5g5DX5Q= X-Google-Smtp-Source: ABdhPJxUa/UG3UwhIngJplELaSW0y1y3pJsgxmzZ8dl+JDG+y+xzN7Oy+mlGhCRyxdCtwHLs6dP98A== X-Received: by 2002:aa7:82c5:0:b029:19a:aaac:9b4c with SMTP id f5-20020aa782c50000b029019aaaac9b4cmr14034095pfn.75.1606704384660; Sun, 29 Nov 2020 18:46:24 -0800 (PST) Received: from asus.hsd1.ca.comcast.net (c-73-241-217-19.hsd1.ca.comcast.net. [73.241.217.19]) by smtp.gmail.com with ESMTPSA id n127sm14734659pfd.143.2020.11.29.18.46.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 29 Nov 2020 18:46:23 -0800 (PST) From: Bart Van Assche To: "Martin K . Petersen" Cc: "James E . J . Bottomley" , Jens Axboe , Christoph Hellwig , Ming Lei , linux-scsi@vger.kernel.org, linux-block@vger.kernel.org, Bart Van Assche , Alan Stern , Stanley Chu , Hannes Reinecke , "Rafael J . Wysocki" , stable , Can Guo Subject: [PATCH v4 1/9] block: Fix a race in the runtime power management code Date: Sun, 29 Nov 2020 18:46:07 -0800 Message-Id: <20201130024615.29171-2-bvanassche@acm.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201130024615.29171-1-bvanassche@acm.org> References: <20201130024615.29171-1-bvanassche@acm.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org With the current implementation the following race can happen: * blk_pre_runtime_suspend() calls blk_freeze_queue_start() and blk_mq_unfreeze_queue(). * blk_queue_enter() calls blk_queue_pm_only() and that function returns true. * blk_queue_enter() calls blk_pm_request_resume() and that function does not call pm_request_resume() because the queue runtime status is RPM_ACTIVE. * blk_pre_runtime_suspend() changes the queue status into RPM_SUSPENDING. Fix this race by changing the queue runtime status into RPM_SUSPENDING before switching q_usage_counter to atomic mode. Acked-by: Alan Stern Acked-by: Stanley Chu Reviewed-by: Christoph Hellwig Reviewed-by: Hannes Reinecke Cc: Ming Lei Cc: Rafael J. Wysocki Cc: stable Fixes: 986d413b7c15 ("blk-mq: Enable support for runtime power management") Signed-off-by: Can Guo Signed-off-by: Bart Van Assche --- block/blk-pm.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/block/blk-pm.c b/block/blk-pm.c index b85234d758f7..17bd020268d4 100644 --- a/block/blk-pm.c +++ b/block/blk-pm.c @@ -67,6 +67,10 @@ int blk_pre_runtime_suspend(struct request_queue *q) WARN_ON_ONCE(q->rpm_status != RPM_ACTIVE); + spin_lock_irq(&q->queue_lock); + q->rpm_status = RPM_SUSPENDING; + spin_unlock_irq(&q->queue_lock); + /* * Increase the pm_only counter before checking whether any * non-PM blk_queue_enter() calls are in progress to avoid that any @@ -89,15 +93,14 @@ int blk_pre_runtime_suspend(struct request_queue *q) /* Switch q_usage_counter back to per-cpu mode. */ blk_mq_unfreeze_queue(q); - spin_lock_irq(&q->queue_lock); - if (ret < 0) + if (ret < 0) { + spin_lock_irq(&q->queue_lock); + q->rpm_status = RPM_ACTIVE; pm_runtime_mark_last_busy(q->dev); - else - q->rpm_status = RPM_SUSPENDING; - spin_unlock_irq(&q->queue_lock); + spin_unlock_irq(&q->queue_lock); - if (ret) blk_clear_pm_only(q); + } return ret; }