From: Dong Aisheng <[email protected]> The module lock will be automatically claimed for gpiochip_find function in case the gpio module is removed during the using of gpiochip instance. Users are responsible to call gpiochip_put to release the lock after the using.
Signed-off-by: Dong Aisheng <[email protected]> --- drivers/gpio/gpiolib-of.c | 5 ++++- drivers/gpio/gpiolib.c | 17 +++++++++++++++++ include/asm-generic/gpio.h | 2 +- 3 files changed, 22 insertions(+), 2 deletions(-) diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c index b8010a9..d521452 100644 --- a/drivers/gpio/gpiolib-of.c +++ b/drivers/gpio/gpiolib-of.c @@ -63,6 +63,7 @@ int of_get_named_gpio_flags(struct device_node *np, const char *propname, int index, enum of_gpio_flags *flags) { struct gg_data gg_data = { .flags = flags, .out_gpio = -ENODEV }; + struct gpio_chip *chip; int ret; /* .of_xlate might decide to not fill in the flags, so clear it. */ @@ -76,7 +77,9 @@ int of_get_named_gpio_flags(struct device_node *np, const char *propname, return -EINVAL; } - gpiochip_find(&gg_data, of_gpiochip_find_and_xlate); + chip = gpiochip_find(&gg_data, of_gpiochip_find_and_xlate); + if (chip) + gpiochip_put(chip); of_node_put(gg_data.gpiospec.np); pr_debug("%s exited with status %d\n", __func__, ret); diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 120b2a0..6453d43 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -1144,6 +1144,18 @@ int gpiochip_remove(struct gpio_chip *chip) EXPORT_SYMBOL_GPL(gpiochip_remove); /** + * gpiochip_put() - release a gpio_chip + * @chip: the chip to release + */ +inline void gpiochip_put(struct gpio_chip *chip) +{ + BUG_ON(!chip); + + module_put(chip->owner); +} +EXPORT_SYMBOL_GPL(gpiochip_put); + +/** * gpiochip_find() - iterator for locating a specific gpio_chip * @data: data to pass to match function * @callback: Callback function to check gpio_chip @@ -1153,6 +1165,9 @@ EXPORT_SYMBOL_GPL(gpiochip_remove); * 0 if the device doesn't match and non-zero if it does. If the callback is * non-zero, this function will return to the caller and not iterate over any * more gpio_chips. + * + * Note the gpio_chip is returned with the module locked, users are responsible + * to release the lock with gpiochip_put(chip) after using it. */ struct gpio_chip *gpiochip_find(void *data, int (*match)(struct gpio_chip *chip, @@ -1169,6 +1184,8 @@ struct gpio_chip *gpiochip_find(void *data, if (match(gpio_desc[i].chip, data)) { chip = gpio_desc[i].chip; + if (!try_module_get(chip->owner)) + chip = NULL; break; } } diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h index 365ea09..af372be 100644 --- a/include/asm-generic/gpio.h +++ b/include/asm-generic/gpio.h @@ -145,7 +145,7 @@ extern int __must_check gpiochip_remove(struct gpio_chip *chip); extern struct gpio_chip *gpiochip_find(void *data, int (*match)(struct gpio_chip *chip, void *data)); - +extern void gpiochip_put(struct gpio_chip *chip); /* Always use the library code for GPIO management calls, * or when sleeping may be involved. -- 1.7.0.4 _______________________________________________ devicetree-discuss mailing list [email protected] https://lists.ozlabs.org/listinfo/devicetree-discuss
