linux-kernel - Re: [PATCH] gpio: gpiolib: set gpiochip

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Date:	Sun, 25 May 2014 16:46:26 +0900
From:	Alexandre Courbot <gnurou@...il.com>
To:	abdoulaye berthe <berthe.ab@...il.com>
Cc:	Linus Walleij <linus.walleij@...aro.org>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Stephen Rothwell <sfr@...b.auug.org.au>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] gpio: gpiolib: set gpiochip_remove retval to void

On Sat, May 24, 2014 at 2:12 AM, abdoulaye berthe <berthe.ab@...il.com> wrote:
> This avoids handling gpiochip remove error in device
> remove handler.

Be aware that at the moment many callers of gpiochip_remove() read its
return value. So applying your patch as-is would break compilation.

This patch should therefore be the last of a series that first
modifies all callers of gpiochip_remove() to ignore its return value,
then neutralizes the function itself.

I am not sure whether the world would really be a better place after
this though. Callers that don't need the return value of
gpiochip_remove() can simply ignore it...

>
> Signed-off-by: abdoulaye berthe <berthe.ab@...il.com>
> ---
>  drivers/gpio/gpiolib.c      | 24 +++++++-----------------
>  include/linux/gpio/driver.h |  2 +-
>  2 files changed, 8 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index f48817d..4878980 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -1263,10 +1263,9 @@ static void gpiochip_irqchip_remove(struct gpio_chip *gpiochip);
>   *
>   * A gpio_chip with any GPIOs still requested may not be removed.
>   */
> -int gpiochip_remove(struct gpio_chip *chip)
> +void gpiochip_remove(struct gpio_chip *chip)
>  {
>         unsigned long   flags;
> -       int             status = 0;
>         unsigned        id;
>
>         acpi_gpiochip_remove(chip);
> @@ -1278,24 +1277,15 @@ int gpiochip_remove(struct gpio_chip *chip)
>         of_gpiochip_remove(chip);
>
>         for (id = 0; id < chip->ngpio; id++) {
> -               if (test_bit(FLAG_REQUESTED, &chip->desc[id].flags)) {
> -                       status = -EBUSY;
> -                       break;
> -               }
> -       }
> -       if (status == 0) {
> -               for (id = 0; id < chip->ngpio; id++)
> -                       chip->desc[id].chip = NULL;
> -
> -               list_del(&chip->list);
> +               if (test_bit(FLAG_REQUESTED, &chip->desc[id].flags))
> +                       panic("gpiolib.c: gpiochip is still requested\n");

panic() sounds a little harsh here. Maybe a dev_err() would be enough?

>         }
> +       for (id = 0; id < chip->ngpio; id++)
> +               chip->desc[id].chip = NULL;
>
> +       list_del(&chip->list);
>         spin_unlock_irqrestore(&gpio_lock, flags);
> -
> -       if (status == 0)
> -               gpiochip_unexport(chip);
> -
> -       return status;
> +       gpiochip_unexport(chip);
>  }
>  EXPORT_SYMBOL_GPL(gpiochip_remove);
>
> diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
> index 1827b43..72ed256 100644
> --- a/include/linux/gpio/driver.h
> +++ b/include/linux/gpio/driver.h
> @@ -138,7 +138,7 @@ extern const char *gpiochip_is_requested(struct gpio_chip *chip,
>
>  /* add/remove chips */
>  extern int gpiochip_add(struct gpio_chip *chip);
> -extern int __must_check gpiochip_remove(struct gpio_chip *chip);
> +void gpiochip_remove(struct gpio_chip *chip);

"extern" should be preserved here for style consistency.
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