From patchwork Fri Apr 23 20:01:09 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bart Van Assche X-Patchwork-Id: 12221641 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=-16.7 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=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 A892DC433B4 for ; Fri, 23 Apr 2021 20:01:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6FAFD6144A for ; Fri, 23 Apr 2021 20:01:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231337AbhDWUBy (ORCPT ); Fri, 23 Apr 2021 16:01:54 -0400 Received: from mail-pf1-f180.google.com ([209.85.210.180]:33752 "EHLO mail-pf1-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230028AbhDWUBx (ORCPT ); Fri, 23 Apr 2021 16:01:53 -0400 Received: by mail-pf1-f180.google.com with SMTP id h11so3725557pfn.0 for ; Fri, 23 Apr 2021 13:01:16 -0700 (PDT) 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:mime-version :content-transfer-encoding; bh=65ztGkUjmMwJn+e+QOQva4w/D+JwPNVGsneM6eljFAI=; b=KP19ek7mhSMJ6sd+7v+yU1CH30z1CaGt9VXCjxMFrGIfbrouHZUIhNvLeSx6Ky2107 aNvyEdkYMiyTrXj3ohg5THdkU0LIskWskaBtHbWf6QsIwQ6tFPOakvI+2UiLAAfdqrBa sd1nAHbitWYdrnSo5O4trKROlOtalMFu11dqfG4VlP0Z1LZOz2ETzesnUDz3QsuMEGTg g0FyXTzChNKOBWxG60sWgiTVwfbxURKqInpp1c27GC6o7kVVv8wMdTSjLDIZ1GQPDKoO ODl9pSUdmFqSm404JDA9Vvt88kyLkRNvRkeBPSom9UJ4ifYZNs5MxtBI5Zd7dgmqO34S c0Iw== X-Gm-Message-State: AOAM530OmJHgQ52eshwXP4TjxCFm3D7NFEe6QCxihp4cq5v8di6pqpag gJfLKEGCzRT4Tkb8ondX9p86qhNOWtU= X-Google-Smtp-Source: ABdhPJy8cG5EfKGeIZwM6SKIfiPS5CAUi9EKzRv6HJOIx3gj+jeImxckpmmvvu7gkRbbTM3qyO6VRA== X-Received: by 2002:aa7:88c6:0:b029:250:bf78:a4a3 with SMTP id k6-20020aa788c60000b0290250bf78a4a3mr5270599pff.70.1619208076485; Fri, 23 Apr 2021 13:01:16 -0700 (PDT) Received: from asus.hsd1.ca.comcast.net ([2601:647:4000:d7:a976:f332:ee26:584f]) by smtp.gmail.com with ESMTPSA id m7sm5502129pfd.52.2021.04.23.13.01.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 23 Apr 2021 13:01:15 -0700 (PDT) From: Bart Van Assche To: Jens Axboe Cc: linux-block@vger.kernel.org, Christoph Hellwig , Bart Van Assche , Ming Lei , Hannes Reinecke , John Garry Subject: [PATCH] blk-mq: Fix two racy hctx->tags->rqs[] assignments Date: Fri, 23 Apr 2021 13:01:09 -0700 Message-Id: <20210423200109.18430-1-bvanassche@acm.org> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org hctx->tags->rqs[] must be cleared before releasing a request tag because otherwise clearing that pointer races with the following assignment in blk_mq_get_driver_tag(): rcu_assign_pointer(hctx->tags->rqs[rq->tag], rq); Reported-by: Ming Lei Cc: Christoph Hellwig Cc: Ming Lei Cc: Hannes Reinecke Cc: John Garry Signed-off-by: Bart Van Assche --- block/blk-mq.c | 2 +- block/blk-mq.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 06d204796c43..1ffaab7c9b11 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -501,8 +501,8 @@ static void __blk_mq_free_request(struct request *rq) blk_pm_mark_last_busy(rq); rq->mq_hctx = NULL; if (rq->tag != BLK_MQ_NO_TAG) { - blk_mq_put_tag(hctx->tags, ctx, rq->tag); rcu_assign_pointer(hctx->tags->rqs[rq->tag], NULL); + blk_mq_put_tag(hctx->tags, ctx, rq->tag); } if (sched_tag != BLK_MQ_NO_TAG) blk_mq_put_tag(hctx->sched_tags, ctx, sched_tag); diff --git a/block/blk-mq.h b/block/blk-mq.h index 9ccb1818303b..f73cd659eb81 100644 --- a/block/blk-mq.h +++ b/block/blk-mq.h @@ -225,8 +225,8 @@ static inline int __blk_mq_active_requests(struct blk_mq_hw_ctx *hctx) static inline void __blk_mq_put_driver_tag(struct blk_mq_hw_ctx *hctx, struct request *rq) { - blk_mq_put_tag(hctx->tags, rq->mq_ctx, rq->tag); rcu_assign_pointer(hctx->tags->rqs[rq->tag], NULL); + blk_mq_put_tag(hctx->tags, rq->mq_ctx, rq->tag); rq->tag = BLK_MQ_NO_TAG; if (rq->rq_flags & RQF_MQ_INFLIGHT) {