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

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Message-ID: <CABprBybqJvXU0dbXiq15GtUTjeLsxDyvyKmCEbZPJwq4sgcyZA@mail.gmail.com>
Date:	Sun, 25 May 2014 18:40:45 +0200
From:	abdoulaye berthe <berthe.ab@...il.com>
To:	Alexandre Courbot <gnurou@...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

Well, ignoring the return value as it is done in gpio-bt8xx makes the
compiler complain and display a warning message. The problem with
false warning is that it might distract you. I think that the patch
will makes things consistent once completed
Thanks a lot for the review.

On Sun, May 25, 2014 at 9:46 AM, Alexandre Courbot <gnurou@...il.com> wrote:
> 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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