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gpio: reference count the gpio device for each desc 

Every time a descriptor is retrieved from the gpiolib, we issue
module_get() to reference count the module supplying the GPIOs.
We also need to call device_get() and device_put() as we also
reference the backing gpio_device when doing this.

Since the sysfs GPIO interface is using gpiod_get() this will
also reference count the sysfs requests until all GPIOs are
unexported.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Linus Walleij 2016-02-11 10:28:44 +01:00
parent fdeb8e1547
commit 33a68e86fd
1 changed files with 6 additions and 2 deletions
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8
drivers/gpio/gpiolib.c
View File

@ -1205,6 +1205,8 @@ int gpiod_request(struct gpio_desc *desc, const char *label)
status = __gpiod_request(desc, label);
if (status < 0)
module_put(gdev->owner);
else
get_device(&gdev->dev);
}
if (status)
@ -1248,10 +1250,12 @@ static bool __gpiod_free(struct gpio_desc *desc)
void gpiod_free(struct gpio_desc *desc)
{
if (desc && __gpiod_free(desc))
if (desc && desc->gdev && __gpiod_free(desc)) {
module_put(desc->gdev->owner);
else
put_device(&desc->gdev->dev);
} else {
WARN_ON(extra_checks);
}
}
/**