MIME-Version: 1.0
References: <20230307165432.25484-1-afd@ti.com> <20230307165432.25484-4-afd@ti.com>
 <ZAd35D4C96MP5Qrm@smile.fi.intel.com> <b6e4ae3f-a3ff-b118-43ce-a45d007ae2e9@ti.com>
In-Reply-To: <b6e4ae3f-a3ff-b118-43ce-a45d007ae2e9@ti.com>
From:   Bartosz Golaszewski <brgl@bgdev.pl>
Date:   Wed, 8 Mar 2023 11:27:50 +0100
Message-ID: <CAMRc=McBp6DQvYTQXwC8hNjpcuOe_TAnj4S__Q79b6wjgYkK8g@mail.gmail.com>
Subject: Re: [PATCH 4/6] gpio: pisosr: Use devm_gpiochip_add_data() to
 simplify remove path
To:     Andrew Davis <afd@ti.com>
Cc:     Andy Shevchenko <andy@kernel.org>,
        Peter Tyser <ptyser@xes-inc.com>,
        Linus Walleij <linus.walleij@linaro.org>,
        linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

On Tue, Mar 7, 2023 at 6:55=E2=80=AFPM Andrew Davis <afd@ti.com> wrote:
>
> On 3/7/23 11:44 AM, Andy Shevchenko wrote:
> > On Tue, Mar 07, 2023 at 10:54:30AM -0600, Andrew Davis wrote:
> >> Use devm version of gpiochip add function to handle removal for us.
> >>
> >> While here update copyright and module author.
> >
> > ...
> >
> >> -    mutex_destroy(&gpio->lock);
> >
> > You need to wrap this into devm.
> >
>
> I was thinking that but it seems there is no such thing. Most drivers
> just ignore unwinding mutex_init() since it doesn't allocate anything.
>
> mutex_destroy() is a NOP unless you are doing DEBUG builds were
> it sets a magic value to check for use-after-free issues.
>
> Andrew

And this is precisely why it's useful to destroy it. :)

Bart