linux-kernel - [PATCH 2/4] blk-mq-debugfs: factor out a helper blk_mq_debugfs_register_rq

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20251014022149.947800-3-yukuai3@huawei.com>
Date: Tue, 14 Oct 2025 10:21:47 +0800
From: Yu Kuai <yukuai3@...wei.com>
To: <nilay@...ux.ibm.com>, <ming.lei@...hat.com>, <tj@...nel.org>,
	<josef@...icpanda.com>, <axboe@...nel.dk>
CC: <cgroups@...r.kernel.org>, <linux-block@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <yukuai3@...wei.com>,
	<yukuai1@...weicloud.com>, <yi.zhang@...wei.com>, <yangerkun@...wei.com>,
	<johnny.chenyi@...wei.com>
Subject: [PATCH 2/4] blk-mq-debugfs: factor out a helper blk_mq_debugfs_register_rq_qos()

Prepare to fix possible deadlock to create blk-mq debugfs entries while
queue is still freezed.

Signed-off-by: Yu Kuai <yukuai3@...wei.com>
---
 block/blk-mq-debugfs.c | 23 +++++++++++++++--------
 block/blk-mq-debugfs.h |  5 +++++
 2 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 66864ed0b77f..1de9bab7ba80 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -633,6 +633,20 @@ static void debugfs_create_files(struct request_queue *q, struct dentry *parent,
 				    (void *)attr, data, &blk_mq_debugfs_fops);
 }
 
+void blk_mq_debugfs_register_rq_qos(struct request_queue *q)
+{
+	lockdep_assert_held(&q->debugfs_mutex);
+
+	if (q->rq_qos) {
+		struct rq_qos *rqos = q->rq_qos;
+
+		while (rqos) {
+			blk_mq_debugfs_register_rqos(rqos);
+			rqos = rqos->next;
+		}
+	}
+}
+
 void blk_mq_debugfs_register(struct request_queue *q)
 {
 	struct blk_mq_hw_ctx *hctx;
@@ -645,14 +659,7 @@ void blk_mq_debugfs_register(struct request_queue *q)
 			blk_mq_debugfs_register_hctx(q, hctx);
 	}
 
-	if (q->rq_qos) {
-		struct rq_qos *rqos = q->rq_qos;
-
-		while (rqos) {
-			blk_mq_debugfs_register_rqos(rqos);
-			rqos = rqos->next;
-		}
-	}
+	blk_mq_debugfs_register_rq_qos(q);
 }
 
 static void blk_mq_debugfs_register_ctx(struct blk_mq_hw_ctx *hctx,
diff --git a/block/blk-mq-debugfs.h b/block/blk-mq-debugfs.h
index c80e453e3014..9f76603792fe 100644
--- a/block/blk-mq-debugfs.h
+++ b/block/blk-mq-debugfs.h
@@ -34,6 +34,7 @@ void blk_mq_debugfs_register_sched_hctx(struct request_queue *q,
 void blk_mq_debugfs_unregister_sched_hctx(struct blk_mq_hw_ctx *hctx);
 
 void blk_mq_debugfs_register_rqos(struct rq_qos *rqos);
+void blk_mq_debugfs_register_rq_qos(struct request_queue *q);
 void blk_mq_debugfs_unregister_rqos(struct rq_qos *rqos);
 #else
 static inline void blk_mq_debugfs_register(struct request_queue *q)
@@ -78,6 +79,10 @@ static inline void blk_mq_debugfs_register_rqos(struct rq_qos *rqos)
 {
 }
 
+static inline void blk_mq_debugfs_register_rq_qos(struct request_queue *q)
+{
+}
+
 static inline void blk_mq_debugfs_unregister_rqos(struct rq_qos *rqos)
 {
 }
-- 
2.39.2