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

[Anup Vishwakarma <anup.vishwakarma@oss.qualcomm.com>]

On 10/6/2026 3:00 PM, Mukesh Ojha wrote:
> 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@oss.qualcomm.com>
>> ---
>>   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@oss.qualcomm.com>

Thanks for the review, Mukesh. Addressed both comments in v2: - Removed 
the now-empty err_req_irq: label in qcom-ipcc.c - Restored original 
alignment of devm_request_threaded_irq() arguments in arm_mhu_db.c

Best Regards, Anup Vishwakarma