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gpiolib: Fix unaligned used of reference counters

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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: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Ricardo Ribalda Delgado 2016-06-03 19:10:02 +02:00 committed by Linus Walleij
parent 11f33a6d15
commit f4833b8cc7
1 changed files with 2 additions and 2 deletions
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4
drivers/gpio/gpiolib.c
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@ -449,7 +449,6 @@ static void gpiodevice_release(struct device *dev)
{ {
struct gpio_device *gdev = dev_get_drvdata(dev); struct gpio_device *gdev = dev_get_drvdata(dev);
cdev_del(&gdev->chrdev);
list_del(&gdev->list); list_del(&gdev->list);
ida_simple_remove(&gpio_ida, gdev->id); ida_simple_remove(&gpio_ida, gdev->id);
kfree(gdev->label); 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 */ /* From this point, the .release() function cleans up gpio_device */
gdev->dev.release = gpiodevice_release; gdev->dev.release = gpiodevice_release;
get_device(&gdev->dev);
pr_debug("%s: registered GPIOs %d to %d on device: %s (%s)\n", pr_debug("%s: registered GPIOs %d to %d on device: %s (%s)\n",
__func__, gdev->base, gdev->base + gdev->ngpio - 1, __func__, gdev->base, gdev->base + gdev->ngpio - 1,
dev_name(&gdev->dev), gdev->chip->label ? : "generic"); 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 * be removed, else it will be dangling until the last user is
* gone. * gone.
*/ */
cdev_del(&gdev->chrdev);
device_del(&gdev->dev);
put_device(&gdev->dev); put_device(&gdev->dev);
} }
EXPORT_SYMBOL_GPL(gpiochip_remove); EXPORT_SYMBOL_GPL(gpiochip_remove);