linux-kernel - Re: [PATCH v2 01/10] devm-helpers: introduce devm_mutex

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Message-ID: <6381d523-8f49-48e2-8576-b74a14eead30@redhat.com>
Date:   Wed, 6 Dec 2023 15:58:23 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     George Stark <gnstark@...utedevices.com>,
        Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     pavel@....cz, lee@...nel.org, vadimp@...dia.com,
        mpe@...erman.id.au, npiggin@...il.com, christophe.leroy@...roup.eu,
        mazziesaccount@...il.com, jic23@...nel.org,
        linux-leds@...r.kernel.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, kernel@...utedevices.com
Subject: Re: [PATCH v2 01/10] devm-helpers: introduce devm_mutex_init

Hi,

On 12/6/23 08:56, George Stark wrote:
> Hello Andy
> 
> Thanks for the review.
> 
> On 12/4/23 21:11, Andy Shevchenko wrote:
>> On Mon, Dec 4, 2023 at 8:07 PM George Stark <gnstark@...utedevices.com> wrote:
>>>
>>> Using of devm API leads to certain order of releasing resources.
>>> So all dependent resources which are not devm-wrapped should be deleted
>>> with respect to devm-release order. Mutex is one of such objects that
>>> often is bound to other resources and has no own devm wrapping.
>>> Since mutex_destroy() actually does nothing in non-debug builds
>>> frequently calling mutex_destroy() is just ignored which is safe for now
>>> but wrong formally and can lead to a problem if mutex_destroy() is
>>> extended so introduce devm_mutex_init().
>>
>> ...
>>
>> Do you need to include mutex.h?
> It's already included in linux/device.h which is included in devm-helpers. Should I include mutex.h explicitly?

Yes you must explicitly include all headers you use definitions
from. Relying on other headers to do this for you is error prone.

Regards,

Hans