linux-kernel - Re: [PATCH 2/2] gpio: sim: simplify code with cleanup helpers

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Date:   Thu, 10 Aug 2023 21:04:12 +0200
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 2/2] gpio: sim: simplify code with cleanup helpers

On Thu, Aug 10, 2023 at 4:42 PM Andy Shevchenko
<andriy.shevchenko@...ux.intel.com> wrote:
>
> On Wed, Aug 09, 2023 at 03:14:42PM +0200, Bartosz Golaszewski wrote:
> > From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> >
> > Use macros defined in linux/cleanup.h to automate resource lifetime
> > control in the gpio-simulator.
>
> gpio-sim ?
>

Meh, if you insist...

> ...
>
> > -     mutex_lock(&chip->lock);
> > +     guard(mutex)(&chip->lock);
>
> I hoped to see somehing like
>
>         guard_mutex(...);
>
> But looking into cleanup.h it seems to me that the lock itself on GPIO library
> can be defined with respective class, no?
>

Why though? This is perfectly clear and concise as it is. It's similar
to going bare mutex_lock() everywhere instead of wrapping it with
foo_lock() which requires you to go and check what you're locking.

> ...
>
> > +     scoped_guard(mutex, &chip->lock)
> > +             bitmap_replace(chip->value_map, chip->value_map, bits, mask,
> > +                            gc->ngpio);
>
> Perhaps with {} ?
>

This scoped_guard() thing is in essence a for loop, so I believe
kernel coding style applies and a single statement doesn't require a
{}.

> ...
>
> >       int ret;
> >
> > -     mutex_lock(&dev->lock);
> > +     guard(mutex)(&dev->lock);
> > +
> >       pdev = dev->pdev;
> >       if (pdev)
> >               ret = sprintf(page, "%s\n", dev_name(&pdev->dev));
> >       else
> >               ret = sprintf(page, "gpio-sim.%d\n", dev->id);
> > -     mutex_unlock(&dev->lock);
> >
> >       return ret;
>
> Now can be
>
>         if (...)
>                 return ...
>         else // if you wish (not needed)
>                 return ...
>
> ...
>
> >       int ret;
> >
> > -     mutex_lock(&dev->lock);
> > +     guard(mutex)(&dev->lock);
> > +
> >       if (gpio_sim_device_is_live_unlocked(dev))
> >               ret = device_for_each_child(&dev->pdev->dev, &ctx,
> >                                           gpio_sim_emit_chip_name);
> >       else
> >               ret = sprintf(page, "none\n");
> > -     mutex_unlock(&dev->lock);
> >
> >       return ret;
>
> As per above. And may be other functions as well.
>

Sure.

> ...
>
> >       int ret;
> >
> > -     mutex_lock(&dev->lock);
> > -     ret = sprintf(page, "%s\n", line->name ?: "");
> > -     mutex_unlock(&dev->lock);
> > +     scoped_guard(mutex, &dev->lock)
> > +             ret = sprintf(page, "%s\n", line->name ?: "");
> >
> >       return ret;
>
> Why not
>
>         guard(...);
>         return sprintf(...);
>
> ?

I'll change that too.

Bart

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