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SubjectRe: [PATCH 2/2] gpio: gpiolib: set gpiochip_remove retval to void
On 05/30/2014 07:33 PM, David Daney wrote:
> On 05/30/2014 04:39 AM, Geert Uytterhoeven wrote:
>> On Fri, May 30, 2014 at 1:30 PM, abdoulaye berthe <berthe.ab@gmail.com>
>> wrote:
>>> --- 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("gpio: removing gpiochip with gpios still
>>> requested\n");
>>
>> panic?
>
> NACK to the patch for this reason. The strongest thing you should do here
> is WARN.
>
> That said, I am not sure why we need this whole patch set in the first place.

Well, what currently happens when you remove a device that is a provider of
a gpio_chip which is still in use, is that the kernel crashes. Probably with
a rather cryptic error message. So this patch doesn't really change the
behavior, but makes it more explicit what is actually wrong. And even if you
replace the panic() by a WARN() it will again just crash slightly later.

This is a design flaw in the GPIO subsystem that needs to be fixed.

- Lars


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