From patchwork Tue Jul 30 18:17:56 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bart Van Assche X-Patchwork-Id: 11066441 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 95B1E174A for ; Tue, 30 Jul 2019 18:18:13 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7D3E928880 for ; Tue, 30 Jul 2019 18:18:13 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 446C42888B; Tue, 30 Jul 2019 18:18:13 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8DB0B28870 for ; Tue, 30 Jul 2019 18:18:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726535AbfG3SSH (ORCPT ); Tue, 30 Jul 2019 14:18:07 -0400 Received: from mail-pf1-f196.google.com ([209.85.210.196]:36409 "EHLO mail-pf1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729160AbfG3SSG (ORCPT ); Tue, 30 Jul 2019 14:18:06 -0400 Received: by mail-pf1-f196.google.com with SMTP id r7so30267884pfl.3 for ; Tue, 30 Jul 2019 11:18:06 -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:in-reply-to :references:mime-version:content-transfer-encoding; bh=FFf7FfipKf4YjMmj4Z92Pfv4esvoZUAtr/L6dGQBO9E=; b=pKsAoO6r7u3yhcl3ITY7bxNq6D+E4urfI0+dnnUTkObQCMr/ccbnkn4JSYjt2Tc497 Jnd9FFH1esKDDhRBHx395R38uxv+O6tXBE+uufvISt4Qs6vm20Wr+oAzGyo3brLsPt9B zhH+fnu6mkGZtas7dQ9SO1cVlcfGRslSjSLcp4oMxh1HKljj9hJgTpBDPfieokkHvP9d sGLuGSDzuV2RBQjb2s7GGNtif5UU5lrj0MFwn6e/wHFcekwpNFl4Xbmt2BzSFxVmWHXI LoSaoEtUSKeiYOQvVq6oZS8PDdEZ2PbvJMwJE172OMBZvkzAZ+T0fbiTEH38vtLjSCaP QXSw== X-Gm-Message-State: APjAAAUpTtPDmD9GB2EVTgKEayuZvkiZxArmiuTz/UnydJ/OCwDW3GPw 7HQ08+2K0faFQoHLitwd38E= X-Google-Smtp-Source: APXvYqzrBt5ufTV6Ie1bjQLWU4GGIWm3eCei3tp5Me7h0lIl0hix25rGQhVJsYx5DSMBIjwohQnX+g== X-Received: by 2002:a63:7a01:: with SMTP id v1mr112578233pgc.310.1564510685887; Tue, 30 Jul 2019 11:18:05 -0700 (PDT) Received: from desktop-bart.svl.corp.google.com ([2620:15c:2cd:202:4308:52a3:24b6:2c60]) by smtp.gmail.com with ESMTPSA id 32sm12165895pgt.43.2019.07.30.11.18.04 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Tue, 30 Jul 2019 11:18:05 -0700 (PDT) From: Bart Van Assche To: Jens Axboe Cc: linux-block@vger.kernel.org, Christoph Hellwig , Bart Van Assche , Tejun Heo , Ming Lei , Hannes Reinecke , Johannes Thumshirn , Alexandru Moise <00moses.alexander00@gmail.com>, Joseph Qi Subject: [PATCH 1/2] block: Verify whether blk_queue_enter() is used when necessary Date: Tue, 30 Jul 2019 11:17:56 -0700 Message-Id: <20190730181757.248832-2-bvanassche@acm.org> X-Mailer: git-send-email 2.22.0.709.g102302147b-goog In-Reply-To: <20190730181757.248832-1-bvanassche@acm.org> References: <20190730181757.248832-1-bvanassche@acm.org> MIME-Version: 1.0 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP It is required to protect blkg_lookup() calls with a blk_queue_enter() / blk_queue_exit() pair. Since it is nontrivial to verify whether this is the case, verify this at runtime. Only perform this verification if CONFIG_LOCKDEP=y to avoid that unnecessary runtime overhead is added. Note: using lock_acquire()/lock_release() to verify whether blkg_lookup() is protected correctly is not possible since lock_acquire() and lock_release() must be called from the same task and since blk_queue_enter() and blk_queue_exit() can be called from different tasks. Suggested-by: Tejun Heo Cc: Tejun Heo Cc: Christoph Hellwig Cc: Ming Lei Cc: Hannes Reinecke Cc: Johannes Thumshirn Cc: Alexandru Moise <00moses.alexander00@gmail.com> Cc: Joseph Qi Signed-off-by: Bart Van Assche --- block/blk-cgroup.c | 2 ++ block/blk-core.c | 21 +++++++++++++++++++++ include/linux/blk-cgroup.h | 2 ++ include/linux/blkdev.h | 8 ++++++++ 4 files changed, 33 insertions(+) diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 24ed26957367..04b6e962eefb 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -196,6 +196,8 @@ struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg, { struct blkcg_gq *blkg; + WARN_ON_ONCE(!blk_entered_queue(q)); + /* * Hint didn't match. Look up from the radix tree. Note that the * hint can only be updated under queue_lock as otherwise @blkg diff --git a/block/blk-core.c b/block/blk-core.c index 5878504a29af..ff27c3080348 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -389,6 +389,25 @@ struct request_queue *blk_alloc_queue(gfp_t gfp_mask) } EXPORT_SYMBOL(blk_alloc_queue); +#ifdef CONFIG_PROVE_LOCKING +/** + * blk_entered_queue() - whether or not it is safe to access cgroup information + * @q: request queue pointer + * + * In order to avoid races between accessing cgroup information and the cgroup + * information removal from inside __blk_release_queue(), any code that accesses + * cgroup information must be protected by a blk_queue_enter()/blk_queue_exit() + * pair or must be called after queue cleanup progressed to a stage in which + * only the cleanup code accesses the queue. + */ +bool blk_entered_queue(struct request_queue *q) +{ + return percpu_ref_is_dying(&q->q_usage_counter) || + !percpu_ref_is_zero(&q->q_usage_counter); +} +EXPORT_SYMBOL(blk_entered_queue); +#endif + /** * blk_queue_enter() - try to increase q->q_usage_counter * @q: request queue pointer @@ -878,6 +897,8 @@ generic_make_request_checks(struct bio *bio) goto end_io; } + WARN_ON_ONCE(!blk_entered_queue(q)); + /* * For a REQ_NOWAIT based request, return -EOPNOTSUPP * if queue is not a request based queue. diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h index 689a58231288..397df0719bda 100644 --- a/include/linux/blk-cgroup.h +++ b/include/linux/blk-cgroup.h @@ -358,6 +358,8 @@ static inline struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, { struct blkcg_gq *blkg; + WARN_ON_ONCE(!blk_entered_queue(q)); + if (blkcg == &blkcg_root) return q->root_blkg; diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 96a29a72fd4a..e57651888450 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -856,6 +856,14 @@ extern int sg_scsi_ioctl(struct request_queue *, struct gendisk *, fmode_t, extern int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags); extern void blk_queue_exit(struct request_queue *q); +#ifdef CONFIG_PROVE_LOCKING +extern bool blk_entered_queue(struct request_queue *q); +#else +static inline bool blk_entered_queue(struct request_queue *q) +{ + return true; +} +#endif extern void blk_sync_queue(struct request_queue *q); extern int blk_rq_map_user(struct request_queue *, struct request *, struct rq_map_data *, void __user *, unsigned long,