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