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gpiolib: Fix irq_disable() semantics 

The implementation if .irq_disable() which kicks in between
the gpiolib and the driver is not properly mimicking the
expected semantics of the irqchip core: the irqchip will
call .irq_disable() if that exists, else it will call
mask_irq() which first checks if .irq_mask() is defined
before calling it.

Since we are calling it unconditionally, we get this bug
from drivers/pinctrl/qcom/pinctrl-ssbi-gpio.c, as it only
defines .irq_mask_ack and not .irq_mask:

  Unable to handle kernel NULL pointer dereference at virtual address 00000000
  pgd = (ptrval)
  (...)
  PC is at 0x0
  LR is at gpiochip_irq_disable+0x20/0x30

Fix this by only calling .irq_mask() if it exists.

Cc: Brian Masney <masneyb@onstation.org>
Cc: Hans Verkuil <hans.verkuil@cisco.com>
Cc: stable@vger.kernel.org
Reviewed-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Fixes: 461c1a7d47 ("gpiolib: override irq_enable/disable")
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20200306132326.1329640-1-linus.walleij@linaro.org
alistair/sensors
Linus Walleij 2020-03-06 14:23:26 +01:00
parent f8788d86ab
commit 8959b304c7
1 changed files with 8 additions and 1 deletions
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9
drivers/gpio/gpiolib.c
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@ -2306,9 +2306,16 @@ static void gpiochip_irq_disable(struct irq_data *d)
{
struct gpio_chip *chip = irq_data_get_irq_chip_data(d);
/*
* Since we override .irq_disable() we need to mimic the
* behaviour of __irq_disable() in irq/chip.c.
* First call .irq_disable() if it exists, else mimic the
* behaviour of mask_irq() which calls .irq_mask() if
* it exists.
*/
if (chip->irq.irq_disable)
chip->irq.irq_disable(d);
else
else if (chip->irq.chip->irq_mask)
chip->irq.chip->irq_mask(d);
gpiochip_disable_irq(chip, d->hwirq);
}