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gpiolib: remove the GPIO device from the list when it's unregistered

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If we wait until the GPIO device's .release() callback gets invoked
before we remove it from the global device list, then we risk that
someone will look it up using gpio_device_find() between where we
dropped the last reference and before .release() is done taking a
reference again to an object that's being released.

The device must be removed when it's being unregistered - just like how
we remove it from the GPIO bus.

Fixes: ff2b135922 ("gpio: make the gpiochip a real device")
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Bartosz Golaszewski 2024-01-02 16:59:47 +01:00
parent c4f8457d17
commit 48e1b4d369
1 changed files with 3 additions and 3 deletions
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6
drivers/gpio/gpiolib.c
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@ -651,9 +651,6 @@ static void gpiodev_release(struct device *dev)
{
struct gpio_device *gdev = to_gpio_device(dev);
scoped_guard(mutex, &gpio_devices_lock)
list_del(&gdev->list);
ida_free(&gpio_ida, gdev->id);
kfree_const(gdev->label);
kfree(gdev->descs);
@ -1068,6 +1065,9 @@ void gpiochip_remove(struct gpio_chip *gc)
dev_crit(&gdev->dev,
"REMOVING GPIOCHIP WITH GPIOS STILL REQUESTED\n");
scoped_guard(mutex, &gpio_devices_lock)
list_del(&gdev->list);
/*
* The gpiochip side puts its use of the device to rest here:
* if there are no userspace clients, the chardev and device will