'q->debugfs_dir' is created in blk_register_queue(), however, it's not
removed in blk_unregister_queue() and is delayed to blk_release_queue().
Thus it's possible that del_gendisk() is done and blk_release_queue()
is not called yet, and in the mean time blk_register_queue() is called
for the new device with the same name. In this case, kernel will
compalin about creation failure for 'debugfs_dir' like following:
debugfs: Directory 'nullb1' with parent 'block' already present!
Fix the problem by moving forward the removal of 'debgfs_dir' to
blk_unregister_queue().
Signed-off-by: Yu Kuai <[email protected]>
---
block/blk-sysfs.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 88bd41d4cb59..15fc3f0786e3 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -779,11 +779,6 @@ static void blk_release_queue(struct kobject *kobj)
if (queue_is_mq(q))
blk_mq_release(q);
- blk_trace_shutdown(q);
- mutex_lock(&q->debugfs_mutex);
- debugfs_remove_recursive(q->debugfs_dir);
- mutex_unlock(&q->debugfs_mutex);
-
if (queue_is_mq(q))
blk_mq_debugfs_unregister(q);
@@ -951,5 +946,11 @@ void blk_unregister_queue(struct gendisk *disk)
mutex_unlock(&q->sysfs_dir_lock);
+ blk_trace_shutdown(q);
+ mutex_lock(&q->debugfs_mutex);
+ blk_mq_debugfs_unregister_hctxs(q);
+ debugfs_remove_recursive(q->debugfs_dir);
+ mutex_unlock(&q->debugfs_mutex);
+
kobject_put(&disk_to_dev(disk)->kobj);
}
--
2.31.1
On Fri, 15 Apr 2022 11:56:07 +0800, Yu Kuai wrote:
> 'q->debugfs_dir' is created in blk_register_queue(), however, it's not
> removed in blk_unregister_queue() and is delayed to blk_release_queue().
> Thus it's possible that del_gendisk() is done and blk_release_queue()
> is not called yet, and in the mean time blk_register_queue() is called
> for the new device with the same name. In this case, kernel will
> compalin about creation failure for 'debugfs_dir' like following:
>
> [...]
Applied, thanks!
[1/1] blk-mq: fix possible creation failure for 'debugfs_dir'
commit: a87c29e1a85e64b28445bb1e80505230bf2e3b4b
Best regards,
--
Jens Axboe
On Fri, 2022-04-15 at 11:56 +0800, Yu Kuai wrote:
> 'q->debugfs_dir' is created in blk_register_queue(), however, it's not
> removed in blk_unregister_queue() and is delayed to blk_release_queue().
> Thus it's possible that del_gendisk() is done and blk_release_queue()
> is not called yet, and in the mean time blk_register_queue() is called
> for the new device with the same name. In this case, kernel will
> compalin about creation failure for 'debugfs_dir' like following:
>
> debugfs: Directory 'nullb1' with parent 'block' already present!
>
> Fix the problem by moving forward the removal of 'debgfs_dir' to
> blk_unregister_queue().
>
> Signed-off-by: Yu Kuai <[email protected]>
Looks like I'm late to the party, but for what its worth:
Tested-by: Dan Williams <[email protected]>
Thanks!