Re: [PATCH 2/2] gpio: gpiolib: set gpiochip_remove retval to void

[Lars-Peter Clausen]

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@xxxxxxxxx>
> > 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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