From mboxrd@z Thu Jan  1 00:00:00 1970
From: greg@kroah.com (Greg KH)
Date: Fri, 30 May 2014 16:29:22 -0700
Subject: [PATCH 2/2] gpio: gpiolib: set gpiochip_remove retval to void
In-Reply-To: <5388CB1B.3090802@metafoo.de>
References: <20140530094025.3b78301e@canb.auug.org.au>
 <1401449454-30895-1-git-send-email-berthe.ab@gmail.com>
 <1401449454-30895-2-git-send-email-berthe.ab@gmail.com>
 <CAMuHMdV6AtjD2aqO3buzj8Eo7A7xc_+ROYnxEi2sdjMaqFiAuA@mail.gmail.com>
 <5388C0F1.90503@gmail.com> <5388CB1B.3090802@metafoo.de>
Message-ID: <20140530232922.GD25854@kroah.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Fri, May 30, 2014 at 08:16:59PM +0200, Lars-Peter Clausen wrote:
> 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.

Then fix the GPIO code properly, don't add a new panic() to the kernel.

greg k-h