linux-kernel - Re: [PATCH 4/6] gpio: pisosr: Use devm_gpiochip_add

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Message-ID: <ZAd9A+waCS88zDZj@smile.fi.intel.com>
Date:   Tue, 7 Mar 2023 20:05:55 +0200
From:   Andy Shevchenko <andy@...nel.org>
To:     Andrew Davis <afd@...com>
Cc:     Peter Tyser <ptyser@...-inc.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/6] gpio: pisosr: Use devm_gpiochip_add_data() to
 simplify remove path

On Tue, Mar 07, 2023 at 11:55:11AM -0600, Andrew Davis 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.

In any case it's correct to destroy it.

See, how it's done, for example, here a82c7cf803d9 ("leds: is31fl319x: Wrap
mutex_destroy() for devm_add_action_or_rest()").

-- 
With Best Regards,
Andy Shevchenko