[PATCH 22/22] gpio: mark unsafe gpio_chip manipulators as deprecated

[Bartosz Golaszewski <brgl@bgdev.pl>]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

We still have some functions that return the address of the GPIO chip
associated with the GPIO device. This is dangerous and the users should
find a better solution. Let's add appropriate comments to the kernel
docs.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
 drivers/gpio/gpiolib.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 5741bbfdc178..7ecdd8cc39c5 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -211,6 +211,11 @@ EXPORT_SYMBOL_GPL(desc_to_gpio);
 /**
  * gpiod_to_chip - Return the GPIO chip to which a GPIO descriptor belongs
  * @desc:	descriptor to return the chip of
+ *
+ * *DEPRECATED*
+ * This function is unsafe and should not be used. Using the chip address
+ * without taking the SRCU read lock may result in dereferencing a dangling
+ * pointer.
  */
 struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc)
 {
@@ -275,6 +280,7 @@ EXPORT_SYMBOL(gpio_device_get_label);
  * Returns:
  * Address of the GPIO chip backing this device.
  *
+ * *DEPRECATED*
  * Until we can get rid of all non-driver users of struct gpio_chip, we must
  * provide a way of retrieving the pointer to it from struct gpio_device. This
  * is *NOT* safe as the GPIO API is considered to be hot-unpluggable and the
-- 
2.40.1