linux-kernel - Re: [PATCH v2 09/10] gpiolib: use gpiochip_dup_line_label() in for

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Message-ID: <CAMRc=MfC9sxgvaigtP5=MMZwbzaSkUukfH61QBf+r_eTJh5fJA@mail.gmail.com>
Date:   Thu, 30 Nov 2023 18:42:37 +0100
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH v2 09/10] gpiolib: use gpiochip_dup_line_label() in
 for_each helpers

On Thu, Nov 30, 2023 at 5:40 PM Andy Shevchenko
<andriy.shevchenko@...ux.intel.com> wrote:
>
> On Thu, Nov 30, 2023 at 02:46:29PM +0100, Bartosz Golaszewski wrote:
> > From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> >
> > Rework for_each_requested_gpio_in_range() to use the new helper to
> > retrieve a dynamically allocated copy of the descriptor label and free
> > it at the end of each iteration. We need to leverage the CLASS()'
> > destructor to make sure that the label is freed even when breaking out
> > of the loop.
>
> ...
>
> >  const char *gpiochip_is_requested(struct gpio_chip *gc, unsigned int offset);
> >  char *gpiochip_dup_line_label(struct gpio_chip *gc, unsigned int offset);
> >
> > +
>
> One blank line is enough.
>
> > +struct _gpiochip_for_each_data {
> > +     const char **label;
> > +     int *i;
>
> Why is this a signed?
>

Some users use signed, others use unsigned. It doesn't matter as we
can't overflow it with the limit on the lines we have.

Bart

> > +};
>
> ...
>
> > +DEFINE_CLASS(_gpiochip_for_each_data,
> > +          struct _gpiochip_for_each_data,
> > +          if (*_T.label) kfree(*_T.label),
> > +          ({ struct _gpiochip_for_each_data _data = { label, i };
> > +             *_data.i = 0;
> > +             _data; }),
>
> To me indentation of ({}) is quite weird. Where is this style being used
> instead of more readable
>

There are no guidelines for this type of C abuse AFAIK. The macro may
be ugly but at least it hides the details from users which look nice
instead.

Bart

>         ({
>            ...
>         })
>
> ?
>
> --
> With Best Regards,
> Andy Shevchenko
>
>