I got this on an RPi and I can't find anything specific to that.
Besides, it's clearly wrong to try to access desc->chip when we have
just tested that it may be NULL at drivers/gpio/gpiolib.c:1409:
chip = desc->chip;
if (chip == NULL)
goto done;
....
done:
if (status)
pr_debug("_gpio_request: gpio-%d (%s) status %d\n",
desc_to_gpio(desc), label ? : "?", status);
To reproduce, just pick an invalid gpio nubmer and:
echo -n 248 > /sys/class/gpio/export
However, I wasn't able to reproduce it on my laptop, maybe because I
don't have any real gpio chips there, not sure. More info on RPi bug
report: https://github.com/raspberrypi/linux/issues/364
[ 222.961384] Unable to handle kernel NULL pointer dereference at
virtual address 00000044
[ 222.969486] pgd = d97d0000
[ 222.972190] [00000044] *pgd=1aaca831, *pte=00000000, *ppte=00000000
[ 222.978483] Internal error: Oops: 17 [#1] PREEMPT ARM
---
drivers/gpio/gpiolib.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index d6413b2..e547f75f8b 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -136,7 +136,7 @@ static struct gpio_desc *gpio_to_desc(unsigned gpio)
*/
static int desc_to_gpio(const struct gpio_desc *desc)
{
- return desc->chip->base + gpio_chip_hwgpio(desc);
+ return desc->chip ? desc->chip->base + gpio_chip_hwgpio(desc) : -1;
}
--
1.8.1.5
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