linux-kernel - Re: [PATCH v2 03/11] gpiolib: convert the type of hwnum to unsigned int in gpiochip_get

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Message-ID: <CAHp75VfL95BXuj=bhEjh0zbwoiaj3bQb0HEGfx8RqGppHDCyHQ@mail.gmail.com>
Date:   Thu, 5 Dec 2019 00:19:11 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Bartosz Golaszewski <brgl@...ev.pl>
Cc:     Kent Gibson <warthog618@...il.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>
Subject: Re: [PATCH v2 03/11] gpiolib: convert the type of hwnum to unsigned
 int in gpiochip_get_desc()

On Wed, Dec 4, 2019 at 6:04 PM Bartosz Golaszewski <brgl@...ev.pl> wrote:
>
> From: Bartosz Golaszewski <bgolaszewski@...libre.com>
>
> gpiochip_get_desc() takes a u16 hwnum, but it turns out most users don't
> respect that and usually pass an unsigned int. Since implicit casting to
> a smaller type is dangerous - let's change the type of hwnum to unsigned
> int in gpiochip_get_desc() and in gpiochip_request_own_desc() where the
> size of hwnum is not respected either and who's a user of the former.
>
> This is safe as we then check the hwnum against the number of lines
> before proceeding in gpiochip_get_desc().
>

Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>

> Signed-off-by: Bartosz Golaszewski <bgolaszewski@...libre.com>
> ---
>  drivers/gpio/gpiolib.c      | 5 +++--
>  drivers/gpio/gpiolib.h      | 3 ++-
>  include/linux/gpio/driver.h | 3 ++-
>  3 files changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index 72211407469f..b3ffb079e323 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -140,7 +140,7 @@ EXPORT_SYMBOL_GPL(gpio_to_desc);
>   * in the given chip for the specified hardware number.
>   */
>  struct gpio_desc *gpiochip_get_desc(struct gpio_chip *chip,
> -                                   u16 hwnum)
> +                                   unsigned int hwnum)
>  {
>         struct gpio_device *gdev = chip->gpiodev;
>
> @@ -2990,7 +2990,8 @@ EXPORT_SYMBOL_GPL(gpiochip_is_requested);
>   * A pointer to the GPIO descriptor, or an ERR_PTR()-encoded negative error
>   * code on failure.
>   */
> -struct gpio_desc *gpiochip_request_own_desc(struct gpio_chip *chip, u16 hwnum,
> +struct gpio_desc *gpiochip_request_own_desc(struct gpio_chip *chip,
> +                                           unsigned int hwnum,
>                                             const char *label,
>                                             enum gpio_lookup_flags lflags,
>                                             enum gpiod_flags dflags)
> diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
> index ca9bc1e4803c..a1cbeabadc69 100644
> --- a/drivers/gpio/gpiolib.h
> +++ b/drivers/gpio/gpiolib.h
> @@ -78,7 +78,8 @@ struct gpio_array {
>         unsigned long           invert_mask[];
>  };
>
> -struct gpio_desc *gpiochip_get_desc(struct gpio_chip *chip, u16 hwnum);
> +struct gpio_desc *gpiochip_get_desc(struct gpio_chip *chip,
> +                                   unsigned int hwnum);
>  int gpiod_get_array_value_complex(bool raw, bool can_sleep,
>                                   unsigned int array_size,
>                                   struct gpio_desc **desc_array,
> diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
> index e2480ef94c55..4f032de10bae 100644
> --- a/include/linux/gpio/driver.h
> +++ b/include/linux/gpio/driver.h
> @@ -715,7 +715,8 @@ gpiochip_remove_pin_ranges(struct gpio_chip *chip)
>
>  #endif /* CONFIG_PINCTRL */
>
> -struct gpio_desc *gpiochip_request_own_desc(struct gpio_chip *chip, u16 hwnum,
> +struct gpio_desc *gpiochip_request_own_desc(struct gpio_chip *chip,
> +                                           unsigned int hwnum,
>                                             const char *label,
>                                             enum gpio_lookup_flags lflags,
>                                             enum gpiod_flags dflags);
> --
> 2.23.0
>


-- 
With Best Regards,
Andy Shevchenko