linux-kernel - Re: [PATCH] mcb: Fix incorrect sanity check

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Message-ID: <07831c5f-7cc1-41f5-b88e-ca3ece325e87@gmail.com>
Date: Fri, 21 Nov 2025 11:54:08 +0100
From: Johannes Thumshirn <morbidrsa@...il.com>
To: Jose Javier Rodriguez Barbarin <dev-josejavier.rodriguez@...gon.com>
Cc: gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mcb: Fix incorrect sanity check

On 11/21/25 11:33 AM, Jose Javier Rodriguez Barbarin wrote:
> On Thu, Nov 20, 2025 at 12:48:45PM +0100, Johannes Thumshirn wrote:
>> On 11/20/25 12:37 PM, Jose Javier Rodriguez Barbarin wrote:
>>> __mcb_register_driver() makes some sanity checks over mcb_driver
>>> to check if .probe and .remove callbacks are set. However, not all
>>> mcb device drivers implement .remove callback.
>>>
>>> Remove .remove check to ensure all mcb device drivers can be loaded.
>> The only driver I can see that doesn't implement a .remove method is
>> gpio-menz127.c.
> Yes. In the past gpio-menz127.c also implemented .remove method, however in
>
> 3bd13ae04ccc ("gpio: menz127: simplify error path and remove remove()")
>
> The driver changed, using now devm_* functions so .remove was no longer necessary.
>
>> Is this safe?
>>
>  From the point of view of mcb bus it should be safe becase I protected the call
> of .remove on mcb_remove(), preventing possible crashes when the driver is removed
> from the bus.
>
> I'm afraid I'm lossing something because I cannot understand why these changes are or
> not safe. Could you explain me why you understand that these changes are unsafe?


Thanks this is the information I was missing from the changelog. I'll 
change the commit message to:

__mcb_register_driver() makes some sanity checks over mcb_driver
to check if .probe and .remove callbacks are set. However, since commit
3bd13ae04ccc ("gpio: menz127: simplify error path and remove remove()")
removed the .remove callback from menz127-gpio.c, not all mcb device
drivers implement .remove callback.

Remove .remove check to ensure all mcb device drivers can be loaded.

I'll also add

Fixes: 3bd13ae04ccc ("gpio: menz127: simplify error path and remove remove()")


Thanks,

     Johannes