gpio: reference count the gpio device for each desc (33a68e86) · Commits · e / devices / android_kernel_fairphone_FP5

Every time a descriptor is retrieved from the gpiolib, we issue module_get() to reference count the module supplying the GPIOs. We also need to call device_get() and device_put() as we also reference the backing gpio_device when doing this. Since the sysfs GPIO interface is using gpiod_get() this will also reference count the sysfs requests until all GPIOs are unexported. Signed-off-by:

Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpiolib.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -1205,6 +1205,8 @@ int gpiod_request(struct gpio_desc desc, const char label)
		status = __gpiod_request(desc, label);
		if (status < 0)
		module_put(gdev->owner);
		else
		get_device(&gdev->dev);
		}

		if (status)
		@@ -1248,11 +1250,13 @@ static bool __gpiod_free(struct gpio_desc *desc)

		void gpiod_free(struct gpio_desc *desc)
		{
		if (desc && __gpiod_free(desc))
		if (desc && desc->gdev && __gpiod_free(desc)) {
		module_put(desc->gdev->owner);
		else
		put_device(&desc->gdev->dev);
		} else {
		WARN_ON(extra_checks);
		}
		}

		/**
		* gpiochip_is_requested - return string iff signal was requested