Commit 3386fb86 authored Aug 11, 2023 by Bartosz Golaszewski

gpiolib: fix reference leaks when removing GPIO chips still in use



After we remove a GPIO chip that still has some requested descriptors,
gpiod_free_commit() will fail and we will never put the references to the
GPIO device and the owning module in gpiod_free().

Rework this function to:
- not warn on desc == NULL as this is a use-case on which most free
  functions silently return
- put the references to desc->gdev and desc->gdev->owner unconditionally
  so that the release callback actually gets called when the remaining
  references are dropped by external GPIO users

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

parent 20d9b3b5

drivers/gpio/gpiolib.c

+11 −5

Original line number	Diff line number	Diff line
		@@ -2167,12 +2167,18 @@ static bool gpiod_free_commit(struct gpio_desc *desc)

		void gpiod_free(struct gpio_desc *desc)
		{
		if (desc && desc->gdev && gpiod_free_commit(desc)) {
		/*
		* We must not use VALIDATE_DESC_VOID() as the underlying gdev->chip
		* may already be NULL but we still want to put the references.
		*/
		if (!desc)
		return;

		if (!gpiod_free_commit(desc))
		WARN_ON(extra_checks);

		module_put(desc->gdev->owner);
		gpio_device_put(desc->gdev);
		} else {
		WARN_ON(extra_checks);
		}
		}

		/**