On 05/31/2014 01:29 AM, Greg KH wrote:

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

quoted

On 05/30/2014 07:33 PM, David Daney wrote:

quoted

On 05/30/2014 04:39 AM, Geert Uytterhoeven wrote:

quoted

On Fri, May 30, 2014 at 1:30 PM, abdoulaye berthe [off-list ref]
wrote:

quoted

--- 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.

Until somebody comes up with a patch that fixes this for good I think that 
patch is still an improvement over the current situation. Rather than 
keeping the kernel running in a inconsistent state, which might cause all 
kinds of undefined behavior and which will lead to a crash eventually, we 
might as well just crash the kernel at the cause of the inconsistent state. 
This will make it obvious why it crashed (compared to a random stacktrace) 
and will also prevent the kernel from running in a undefined state.

- Lars