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References: <20231213223020.2713164-1-gnstark@salutedevices.com> <20231213223020.2713164-4-gnstark@salutedevices.com>
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From:   Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Thu, 14 Dec 2023 00:36:31 +0200
Message-ID: <CAHp75Vc1zZFWB8PPrg8oeAKz9aHnQrrSjdGyGd8mWcmeZdJ9qA@mail.gmail.com>
Subject: Re: [PATCH v3 03/11] devm-helpers: introduce devm_mutex_init
To:     George Stark <gnstark@salutedevices.com>
Cc:     pavel@ucw.cz, lee@kernel.org, vadimp@nvidia.com,
        mpe@ellerman.id.au, npiggin@gmail.com, christophe.leroy@csgroup.eu,
        hdegoede@redhat.com, mazziesaccount@gmail.com,
        peterz@infradead.org, mingo@redhat.com, will@kernel.org,
        longman@redhat.com, boqun.feng@gmail.com, nikitos.tr@gmail.com,
        linux-leds@vger.kernel.org, linux-kernel@vger.kernel.org,
        linuxppc-dev@lists.ozlabs.org, kernel@salutedevices.com
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On Thu, Dec 14, 2023 at 12:30=E2=80=AFAM George Stark <gnstark@salutedevice=
s.com> wrote:
>
> Using of devm API leads to a 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 wrapper.
> 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().

...

> +#ifdef mutex_destroy
> +static inline void devm_mutex_release(void *res)
> +{
> +       mutex_destroy(res);
> +}
> +#endif
> +
> +/**
> + * devm_mutex_init - Resource-managed mutex initialization
> + * @dev:       Device which lifetime mutex is bound to
> + * @lock:      Pointer to a mutex
> + *
> + * Initialize mutex which is automatically destroyed when the driver is =
detached.
> + *
> + * Returns: 0 on success or a negative error code on failure.
> + */
> +static inline int devm_mutex_init(struct device *dev, struct mutex *lock=
)
> +{
> +       mutex_init(lock);
> +#ifdef mutex_destroy
> +       return devm_add_action_or_reset(dev, devm_mutex_release, lock);
> +#else
> +       return 0;
> +#endif
> +}

If this is going to be accepted, you may decrease the amount of ifdeffery.

#ifdef ...
#else
#define devm_mutex_init(dev, lock)  mutex_init(lock)
#endif


--=20
With Best Regards,
Andy Shevchenko