Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.37 as permitted sender) client-ip=23.128.96.37;
MIME-Version: 1.0
References: <20231213223020.2713164-1-gnstark@salutedevices.com>
 <20231213223020.2713164-4-gnstark@salutedevices.com> <CAHp75Vc1zZFWB8PPrg8oeAKz9aHnQrrSjdGyGd8mWcmeZdJ9qA@mail.gmail.com>
In-Reply-To: <CAHp75Vc1zZFWB8PPrg8oeAKz9aHnQrrSjdGyGd8mWcmeZdJ9qA@mail.gmail.com>
From:   Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Thu, 14 Dec 2023 00:38:13 +0200
Message-ID: <CAHp75Vdxa5k-CLhL+PmK0iTPTNSpP77DA6ooWnxfViwSKiEOSw@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
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

On Thu, Dec 14, 2023 at 12:36=E2=80=AFAM Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
> On Thu, Dec 14, 2023 at 12:30=E2=80=AFAM George Stark <gnstark@salutedevi=
ces.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 no=
w
> > 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 i=
s detached.
> > + *
> > + * Returns: 0 on success or a negative error code on failure.
> > + */
> > +static inline int devm_mutex_init(struct device *dev, struct mutex *lo=
ck)
> > +{
> > +       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)

More precisely ({ mutex_init(lock); 0; }) or as a static inline...

> #endif

--=20
With Best Regards,
Andy Shevchenko