linux-kernel - Re: [PATCH v4 03/11] gpiolib: provide gpio_device

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Date:   Mon, 2 Oct 2023 11:52:52 +0200
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-acpi@...r.kernel.org,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH v4 03/11] gpiolib: provide gpio_device_find()

On Mon, Oct 2, 2023 at 11:42 AM Andy Shevchenko
<andriy.shevchenko@...ux.intel.com> wrote:
>
> On Wed, Sep 27, 2023 at 04:29:23PM +0200, Bartosz Golaszewski wrote:
> > From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> >
> > gpiochip_find() is wrong and its kernel doc is misleading as the
> > function doesn't return a reference to the gpio_chip but just a raw
> > pointer. The chip itself is not guaranteed to stay alive, in fact it can
> > be deleted at any point. Also: other than GPIO drivers themselves,
> > nobody else has any business accessing gpio_chip structs.
> >
> > Provide a new gpio_device_find() function that returns a real reference
> > to the opaque gpio_device structure that is guaranteed to stay alive for
> > as long as there are active users of it.
>
> ...
>
> >  struct gpio_chip *gpiochip_find(void *data,
> >                               int (*match)(struct gpio_chip *gc,
>
> > +struct gpio_device *gpio_device_find(void *data,
> > +                                  int (*match)(struct gpio_chip *gc,
> > +                                               void *data))
>
> Why not
>
> typedef int (*gpio_chip_match_fn)(struct gpio_chip *gc, void *data);
>

Because gpiochip_find() will go away as soon as we convert all users.

Bart

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