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

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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>
This commit is contained in:
Bartosz Golaszewski 2023-08-11 21:30:34 +02:00
parent 20d9b3b5f2
commit 3386fb86ec
1 changed files with 11 additions and 5 deletions
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16
drivers/gpio/gpiolib.c
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@ -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)) {
module_put(desc->gdev->owner);
gpio_device_put(desc->gdev);
} else {
/*
* 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);
}
/**