linux-kernel - Re: [PATCH] blk-mq: Fix spurious debugfs directory creation during initialization

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Date:   Fri, 16 Apr 2021 15:17:24 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     Saravanan D <saravanand@...com>, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     tj@...nel.org, kernel-team@...com
Subject: Re: [PATCH] blk-mq: Fix spurious debugfs directory creation during
 initialization

On 4/7/21 11:59 AM, Saravanan D wrote:
> blk_mq_debugfs_register_sched_hctx() called from
> device_add_disk()->elevator_init_mq()->blk_mq_init_sched()
> initialization sequence does not have relevant parent directory
> setup and thus spuriously attempts "sched" directory creation
> from root mount of debugfs for every hw queue detected on the
> block device
> 
> dmesg
> ...
> debugfs: Directory 'sched' with parent '/' already present!
> debugfs: Directory 'sched' with parent '/' already present!
> .
> .
> debugfs: Directory 'sched' with parent '/' already present!
> ...
> 
> The parent debugfs directory for hw queues get properly setup
> device_add_disk()->blk_register_queue()->blk_mq_debugfs_register()
> ->blk_mq_debugfs_register_hctx() later in the block device
> initialization sequence.
> 
> A simple check for debugfs_dir has been added to thwart premature
> debugfs directory/file creation attempts.

Applied, thanks.

-- 
Jens Axboe