[PATCH 4/4] blk-mq: use blk_queue_enter/exit to protect debugfs file creation
From: Yu Kuai <hidden>
Date: 2026-02-09 08:30:14
Also in:
asahi, linux-block, linux-nvme
Subsystem:
block layer, the rest · Maintainers:
Jens Axboe, Linus Torvalds
Replace the freeze depth check with blk_queue_enter()/blk_queue_exit() which properly waits for the queue to be unfrozen and prevents new freezes while creating debugfs files. This provides correct synchronization without false warnings. If the queue is dying (blk_queue_enter returns error), skip creating the debugfs files as the queue is being torn down anyway. Reported-by: Shinichiro Kawasaki <redacted> Closes: https://lore.kernel.org/all/aYWQR7CtYdk3K39g@shinmob/ (local) Signed-off-by: Yu Kuai <redacted> --- block/blk-mq-debugfs.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index faeaa1fc86a7..03583d0d3972 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c@@ -613,11 +613,6 @@ static void debugfs_create_files(struct request_queue *q, struct dentry *parent, const struct blk_mq_debugfs_attr *attr) { lockdep_assert_held(&q->debugfs_mutex); - /* - * Creating new debugfs entries with queue freezed has the risk of - * deadlock. - */ - WARN_ON_ONCE(q->mq_freeze_depth != 0); /* * debugfs_mutex should not be nested under other locks that can be * grabbed while queue is frozen.
@@ -628,9 +623,19 @@ static void debugfs_create_files(struct request_queue *q, struct dentry *parent, if (IS_ERR_OR_NULL(parent)) return; + /* + * Avoid creating debugfs files while the queue is frozen, wait for + * the queue to be unfrozen and prevent new freeze while creating + * debugfs files. + */ + if (blk_queue_enter(q, 0)) + return; + for (; attr->name; attr++) debugfs_create_file_aux(attr->name, attr->mode, parent, (void *)attr, data, &blk_mq_debugfs_fops); + + blk_queue_exit(q); } void blk_mq_debugfs_register(struct request_queue *q)
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2.51.0