gpio: protect the pointer to gpio_chip in gpio_device with SRCU

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Ensure we cannot crash if the GPIO device gets unregistered (and the
chip pointer set to NULL) during any of the API calls.

To that end: wait for all users of gdev->chip to exit their read-only
SRCU critical sections in gpiochip_remove().

For brevity: add a guard class which can be instantiated at the top of
every function requiring read-only access to the chip pointer and use it
in all API calls taking a GPIO descriptor as argument. In places where
we only deal with the GPIO device - use regular guard() helpers and
rcu_dereference() for chip access. Do the same in API calls taking a
const pointer to gpio_desc.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

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This commit is contained in:

Bartosz Golaszewski 2024-01-23 12:01:10 +01:00

parent 47d8b4c1d8

commit d83cee3d2b

4 changed files with 271 additions and 129 deletions

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64

drivers/gpio/gpiolib-cdev.c

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57

drivers/gpio/gpiolib-sysfs.c

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257

drivers/gpio/gpiolib.c

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22

drivers/gpio/gpiolib.h

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