From patchwork Wed Jan 4 08:53:53 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Kuai X-Patchwork-Id: 13088279 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6581FC4332F for ; Wed, 4 Jan 2023 08:29:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233329AbjADI3d (ORCPT ); Wed, 4 Jan 2023 03:29:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59508 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234041AbjADI3Z (ORCPT ); Wed, 4 Jan 2023 03:29:25 -0500 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CE96E192BA; Wed, 4 Jan 2023 00:29:24 -0800 (PST) Received: from mail02.huawei.com (unknown [172.30.67.169]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4Nn2nq0Qy6z4f42p3; Wed, 4 Jan 2023 16:29:19 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.127.227]) by APP2 (Coremail) with SMTP id Syh0CgBnW+ndOLVjwys+BA--.58806S7; Wed, 04 Jan 2023 16:29:21 +0800 (CST) From: Yu Kuai To: tj@kernel.org, hch@infradead.org, josef@toxicpanda.com, axboe@kernel.dk Cc: cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, yukuai3@huawei.com, yukuai1@huaweicloud.com, yi.zhang@huawei.com, yangerkun@huawei.com Subject: [PATCH -next 3/4] block/rq_qos: use a global mutex to protect rq_qos apis Date: Wed, 4 Jan 2023 16:53:53 +0800 Message-Id: <20230104085354.2343590-4-yukuai1@huaweicloud.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20230104085354.2343590-1-yukuai1@huaweicloud.com> References: <20230104085354.2343590-1-yukuai1@huaweicloud.com> MIME-Version: 1.0 X-CM-TRANSID: Syh0CgBnW+ndOLVjwys+BA--.58806S7 X-Coremail-Antispam: 1UD129KBjvJXoWxAryftw1DGrW7ZFy8Cw1Utrb_yoWrGr4Dpa 1fKrWay3yqgrs7Was8Gw48ZasxKw1rKryUJF4xJrWfArWvvF1jvF10yFyxWFWrZF9rJrs3 Ary5trs5Ar1UXwUanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUBE14x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_JrWl82xGYIkIc2 x26xkF7I0E14v26ryj6s0DM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2z4x0 Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F4UJw A2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oVCq3wAS 0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2 IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0 Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwACI402YVCY1x02628vn2kIc2 xKxwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v2 6r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_Jw0_GFylIxkGc2 Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7CjxVAFwI0_ Gr0_Cr1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r1j6r4UMI IF0xvEx4A2jsIEc7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x0JUd8n5UUUUU = X-CM-SenderInfo: 51xn3trlr6x35dzhxuhorxvhhfrp/ X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org From: Yu Kuai This patch fix following problems: 1) rq_qos_add() and rq_qos_del() is protected, while rq_qos_exit() is not. 2) rq_qos_add() and blkcg_activate_policy() is not atomic, if rq_qos_exit() is done before blkcg_activate_policy(), null-ptr-deference can be triggered. rq_qos_add(), rq_qos_del() and rq_qos_exit() are super cold path, hence fix the problems by using a global mutex to protect them. Signed-off-by: Yu Kuai --- block/blk-rq-qos.c | 50 ++++++++++++++++++++++++++++++---------------- 1 file changed, 33 insertions(+), 17 deletions(-) diff --git a/block/blk-rq-qos.c b/block/blk-rq-qos.c index 50544bfb12f1..5f7ccc249c11 100644 --- a/block/blk-rq-qos.c +++ b/block/blk-rq-qos.c @@ -2,6 +2,8 @@ #include "blk-rq-qos.h" +static DEFINE_MUTEX(rq_qos_lock); + /* * Increment 'v', if 'v' is below 'below'. Returns true if we succeeded, * false if 'v' + 1 would be bigger than 'below'. @@ -286,23 +288,18 @@ void rq_qos_wait(struct rq_wait *rqw, void *private_data, finish_wait(&rqw->wait, &data.wq); } -int rq_qos_add(struct request_queue *q, struct rq_qos *rqos) +static int __rq_qos_add(struct request_queue *q, struct rq_qos *rqos) { /* * No IO can be in-flight when adding rqos, so freeze queue, which * is fine since we only support rq_qos for blk-mq queue. - * - * Reuse ->queue_lock for protecting against other concurrent - * rq_qos adding/deleting */ blk_mq_freeze_queue(q); - spin_lock_irq(&q->queue_lock); if (rq_qos_id(q, rqos->id)) goto ebusy; rqos->next = q->rq_qos; q->rq_qos = rqos; - spin_unlock_irq(&q->queue_lock); blk_mq_unfreeze_queue(q); @@ -314,29 +311,23 @@ int rq_qos_add(struct request_queue *q, struct rq_qos *rqos) return 0; ebusy: - spin_unlock_irq(&q->queue_lock); blk_mq_unfreeze_queue(q); return -EBUSY; } -void rq_qos_del(struct request_queue *q, struct rq_qos *rqos) +static void __rq_qos_del(struct request_queue *q, struct rq_qos *rqos) { struct rq_qos **cur; - /* - * See comment in rq_qos_add() about freezing queue & using - * ->queue_lock. - */ + /* See comment in __rq_qos_add() about freezing queue */ blk_mq_freeze_queue(q); - spin_lock_irq(&q->queue_lock); for (cur = &q->rq_qos; *cur; cur = &(*cur)->next) { if (*cur == rqos) { *cur = rqos->next; break; } } - spin_unlock_irq(&q->queue_lock); blk_mq_unfreeze_queue(q); @@ -345,13 +336,33 @@ void rq_qos_del(struct request_queue *q, struct rq_qos *rqos) mutex_unlock(&q->debugfs_mutex); } +int rq_qos_add(struct request_queue *q, struct rq_qos *rqos) +{ + int ret; + + mutex_lock(&rq_qos_lock); + ret = __rq_qos_add(q, rqos); + mutex_unlock(&rq_qos_lock); + + return ret; +} + +void rq_qos_del(struct request_queue *q, struct rq_qos *rqos) +{ + mutex_lock(&rq_qos_lock); + __rq_qos_del(q, rqos); + mutex_unlock(&rq_qos_lock); +} + void rq_qos_exit(struct request_queue *q) { + mutex_lock(&rq_qos_lock); while (q->rq_qos) { struct rq_qos *rqos = q->rq_qos; q->rq_qos = rqos->next; rqos->ops->exit(rqos); } + mutex_unlock(&rq_qos_lock); } #ifdef CONFIG_BLK_CGROUP @@ -364,15 +375,20 @@ int rq_qos_add_and_activate_policy(struct request_queue *q, struct rq_qos *rqos, * may get called before policy activation completion, can't assume that * the target bio has an pd associated and need to test for NULL. */ - int ret = rq_qos_add(q, rqos); + int ret; - if (ret) + mutex_lock(&rq_qos_lock); + ret = __rq_qos_add(q, rqos); + if (ret) { + mutex_unlock(&rq_qos_lock); return ret; + } ret = blkcg_activate_policy(q, pol); if (ret) - rq_qos_del(q, rqos); + __rq_qos_del(q, rqos); + mutex_unlock(&rq_qos_lock); return ret; } #endif