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Commit f4833b8c authored by Ricardo Ribalda Delgado's avatar Ricardo Ribalda Delgado Committed by Linus Walleij
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gpiolib: Fix unaligned used of reference counters 



gpiolib relies on the reference counters to clean up the gpio_device
structure.

Although the number of get/put is properly aligned on gpiolib.c
itself, it does not take into consideration how the referece counters
are affected by other external functions such as cdev_add and device_add.

Because of this, after the last call to put_device, the reference counter
has a value of +3, therefore never calling gpiodevice_release.

Due to the fact that some of the device  has already been cleaned on
gpiochip_remove, the library will end up OOPsing the kernel (e.g. a call
to of_gpiochip_find_and_xlate).

Cc: stable@vger.kernel.org
Signed-off-by: default avatarRicardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
parent 11f33a6d

drivers/gpio/gpiolib.c

+2 −2
Original line number Diff line number Diff line
@@ -449,7 +449,6 @@ static void gpiodevice_release(struct device *dev) 
{

	struct gpio_device *gdev = dev_get_drvdata(dev);



	cdev_del(&gdev->chrdev);

	list_del(&gdev->list);

	ida_simple_remove(&gpio_ida, gdev->id);

	kfree(gdev->label);
@@ -482,7 +481,6 @@ static int gpiochip_setup_dev(struct gpio_device *gdev) 


	/* From this point, the .release() function cleans up gpio_device */

	gdev->dev.release = gpiodevice_release;

	get_device(&gdev->dev);

	pr_debug("%s: registered GPIOs %d to %d on device: %s (%s)\n",

		 __func__, gdev->base, gdev->base + gdev->ngpio - 1,

		 dev_name(&gdev->dev), gdev->chip->label ? : "generic");
@@ -770,6 +768,8 @@ void gpiochip_remove(struct gpio_chip *chip) 
	 * be removed, else it will be dangling until the last user is

	 * gone.

	 */

	cdev_del(&gdev->chrdev);

	device_del(&gdev->dev);

	put_device(&gdev->dev);

}

EXPORT_SYMBOL_GPL(gpiochip_remove);