This is a note to let you know that I've just added the patch titled
blk-mq: don't create hctx debugfs dir until q->debugfs_dir is created
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
blk-mq-don-t-create-hctx-debugfs-dir-until-q-debugfs.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit a49e2a610c21b02fe6616903e1b490c1d7d02b1b
Author: Ming Lei <ming.lei@xxxxxxxxxx>
Date: Mon Jul 11 17:08:08 2022 +0800
blk-mq: don't create hctx debugfs dir until q->debugfs_dir is created
[ Upstream commit f3ec5d11554778c24ac8915e847223ed71d104fc ]
blk_mq_debugfs_register_hctx() can be called by blk_mq_update_nr_hw_queues
when gendisk isn't added yet, such as nvme tcp.
Fixes the warning of 'debugfs: Directory 'hctx0' with parent '/' already present!'
which can be observed reliably when running blktests nvme/005.
Fixes: 6cfc0081b046 ("blk-mq: no need to check return value of debugfs_create functions")
Reported-by: Yi Zhang <yi.zhang@xxxxxxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
Tested-by: Yi Zhang <yi.zhang@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Link: https://lore.kernel.org/r/20220711090808.259682-1-ming.lei@xxxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 121f4c1e0697..772a6c6b1634 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -883,6 +883,9 @@ void blk_mq_debugfs_register_hctx(struct request_queue *q,
char name[20];
int i;
+ if (!q->debugfs_dir)
+ return;
+
snprintf(name, sizeof(name), "hctx%u", hctx->queue_num);
hctx->debugfs_dir = debugfs_create_dir(name, q->debugfs_dir);
