linux-kernel - Re: [PATCH RESEND] blk-mq: fix possible creation failure for 'debugfs

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Date:   Wed, 20 Apr 2022 03:40:02 +0000
From:   "Williams, Dan J" <dan.j.williams@...el.com>
To:     "yukuai3@...wei.com" <yukuai3@...wei.com>,
        "axboe@...nel.dk" <axboe@...nel.dk>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
        "yi.zhang@...wei.com" <yi.zhang@...wei.com>
Subject: Re: [PATCH RESEND] blk-mq: fix possible creation failure for
 'debugfs_dir'

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 <yukuai3@...wei.com>

Looks like I'm late to the party, but for what its worth:

Tested-by: Dan Williams <dan.j.williams@...el.com>

Thanks!