linux-kernel - Re: [PATCH v2 2/2] gpiolib: use a mutex to protect the list of GPIO devices

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Date:   Thu, 14 Dec 2023 15:18:48 +0100
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Kent Gibson <warthog618@...il.com>, linux-gpio@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH v2 2/2] gpiolib: use a mutex to protect the list of GPIO devices

On Thu, Dec 14, 2023 at 3:04 PM Andy Shevchenko
<andriy.shevchenko@...ux.intel.com> wrote:
>
> On Thu, Dec 14, 2023 at 02:59:28PM +0100, Bartosz Golaszewski wrote:
> > On Thu, Dec 14, 2023 at 2:53 PM Andy Shevchenko
> > <andriy.shevchenko@...ux.intel.com> wrote:
> > >
> > > On Fri, Dec 08, 2023 at 11:20:20AM +0100, Bartosz Golaszewski wrote:
> > > > From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> > > >
> > > > The global list of GPIO devices is never modified or accessed from
> > > > atomic context so it's fine to protect it using a mutex. Add a new
> > > > global lock dedicated to the gpio_devices list and use it whenever
> > > > accessing or modifying it.
>
> ...
>
> > > > While at it: fold the sysfs registering of existing devices into
> > > > gpiolib.c and make gpio_devices static within its compilation unit.
> > >
> > > TBH I do not like injecting sysfs (legacy!) code into gpiolib.
> > > It makes things at very least confusing.
> > >
> > > That _ugly_ ifdeffery and sysfs in the function name are not okay.
> > >
> > > If you want do that, please create a separate change and explain the rationale
> > > behind with answering to the Q "Why do we need all that and why is it better
> > > than any alternatives?".
> >
> > I can move it back to gpiolib-sysfs.c but this way we'll have to keep
> > the GPIO device mutex public in gpiolib.h.
>
> And I'm fine with that. Again, we can discuss this in a separate change that
> will do that (make that mutex local with the explanation why).
>

No, I won't be sending one. I'll send another iteration of this with
sysfs stuff contained to gpiolib-sysfs.c.

Bart

> --
> With Best Regards,
> Andy Shevchenko
>
>