Re: [PATCH v2 01/14] NTB: ntb_transport: Remove the device debugfs directory

[Frank Li <Frank.li@oss.nxp.com>]

On Thu, Sep 10, 2026 at 01:08:23PM +0900, Koichiro Den wrote:
> ntb_transport_free() removes QP debugfs directories but leaves the
> device directory. On rebind, debugfs_create_dir() fails with -EEXIST
> and QP statistics files are not recreated. Module unload masks this
> by removing the entire debugfs tree.
>
> To reproduce:
>
>   # ls /sys/kernel/debug/ntb_transport/0001:10:00.0/
>   qp0
>   # echo 0001:10:00.0 > /sys/bus/ntb/drivers/ntb_transport/unbind
>   # ls /sys/kernel/debug/ntb_transport/
>   0001:10:00.0   <-- should not remain
>   # echo 0001:10:00.0 > /sys/bus/ntb/drivers/ntb_transport/bind
>
>   .. and then dmesg shows:
>   debugfs: '0001:10:00.0' already exists in 'ntb_transport'
>
>   # ls /sys/kernel/debug/ntb_transport/0001:10:00.0/
>   (nothing)      <-- should be 'qp0'
>
> Remove the device debugfs tree on teardown and probe failure.
>
> Verified that unbind removes the directory and rebind recreates qp0.
>
> Fixes: c8650fd03d32 ("NTB: Fix transport stats for multiple devices")
> Cc: stable@vger.kernel.org
> Signed-off-by: Koichiro Den <den@valinux.co.jp>
> ---

Reviewed-by: Frank Li <Frank.Li@nxp.com>

> Changes in v2:
>   - No changes.
>
>  drivers/ntb/ntb_transport.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/ntb/ntb_transport.c b/drivers/ntb/ntb_transport.c
> index f9caa1a653c5..3389d6ca9ebd 100644
> --- a/drivers/ntb/ntb_transport.c
> +++ b/drivers/ntb/ntb_transport.c
> @@ -1382,6 +1382,7 @@ static int ntb_transport_probe(struct ntb_client *self, struct ntb_dev *ndev)
>  err3:
>  	ntb_clear_ctx(ndev);
>  err2:
> +	debugfs_remove_recursive(nt->debugfs_node_dir);
>  	kfree(nt->qp_vec);
>  err1:
>  	while (i--) {
> @@ -1401,6 +1402,8 @@ static void ntb_transport_free(struct ntb_client *self, struct ntb_dev *ndev)
>  	u64 qp_bitmap_alloc;
>  	int i;
>
> +	debugfs_remove_recursive(nt->debugfs_node_dir);
> +
>  	ntb_transport_link_cleanup(nt);
>  	cancel_work_sync(&nt->link_cleanup);
>  	cancel_delayed_work_sync(&nt->link_work);
> @@ -1412,7 +1415,6 @@ static void ntb_transport_free(struct ntb_client *self, struct ntb_dev *ndev)
>  		qp = &nt->qp_vec[i];
>  		if (qp_bitmap_alloc & BIT_ULL(i))
>  			ntb_transport_free_queue(qp);
> -		debugfs_remove_recursive(qp->debugfs_dir);
>  	}
>
>  	ntb_link_disable(ndev);
> --
> 2.51.0
>