Re: [PATCH 2/2] mailbox: arm_mhu_db: Remove redundant mbox_controller_unregister() on probe failure

[Mukesh Ojha]

On Tue, Oct 06, 2026 at 02:44:15PM +0530, Anup Vishwakarma wrote:
> mhu_db_probe() registers the mailbox controller via
> devm_mbox_controller_register(), which automatically calls
> mbox_controller_unregister() through devres when the device is removed
> or probe fails. If devm_request_threaded_irq() subsequently fails in
> the channel setup loop, the error path also manually calls
> mbox_controller_unregister(), resulting in a double call that corrupts
> the global mailbox controller list and causes a kernel panic.
> 
> Remove the redundant manual call and rely on devres for cleanup.
> 
> Fixes: 7002ca237b21 ("mailbox: arm_mhu: Add ARM MHU doorbell driver")
> Signed-off-by: Anup Vishwakarma <anup.vishwakarma@xxxxxxxxxxxxxxxx>
> ---
>  drivers/mailbox/arm_mhu_db.c | 8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/mailbox/arm_mhu_db.c b/drivers/mailbox/arm_mhu_db.c
> index a39239e38a47..9668dfdedc78 100644
> --- a/drivers/mailbox/arm_mhu_db.c
> +++ b/drivers/mailbox/arm_mhu_db.c
> @@ -315,12 +315,10 @@ static int mhu_db_probe(struct amba_device *adev, const struct amba_id *id)
>  		mhu->mlink[i].tx_reg = mhu->mlink[i].rx_reg + TX_REG_OFFSET;
>  
>  		err = devm_request_threaded_irq(dev, irq, NULL,
> -						mhu_db_mbox_rx_handler,
> -						IRQF_ONESHOT, "mhu_db_link", mhu);
> -		if (err) {
> -			mbox_controller_unregister(&mhu->mbox);
> +					mhu_db_mbox_rx_handler,
> +					IRQF_ONESHOT, "mhu_db_link", mhu);

It looks like alignment/indentation is unnecessary changing.

> +		if (err)
>  			return err;
> -		}
>  	}

with the above fix.

Reviewed-by: Mukesh Ojha <mukesh.ojha@xxxxxxxxxxxxxxxx>

-- 
-Mukesh Ojha