gpio: make gpiod_is_equal() arguments stricter

It makes no sense for a GPIO descriptor comparator to return true when
the arguments passed to it are NULL or IS_ERR(). Let's validate both and
return false unless both are valid GPIO descriptors.

Suggested-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Link: https://lore.kernel.org/all/Z_aFBfjb17JxOwyk@black.fi.intel.com/
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Link: https://lore.kernel.org/r/20250620-gpiod-is-equal-improv-v1-2-a75060505d2c@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

1 files changed, 15 insertions, 14 deletions

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 6b4f94c3887f..7b2174b10219 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -279,20 +279,6 @@ struct gpio_device *gpiod_to_gpio_device(struct gpio_desc *desc)
 EXPORT_SYMBOL_GPL(gpiod_to_gpio_device);
 
 /**
- * gpiod_is_equal() - Check if two GPIO descriptors refer to the same pin.
- * @desc: Descriptor to compare.
- * @other: The second descriptor to compare against.
- *
- * Returns:
- * True if the descriptors refer to the same physical pin. False otherwise.
- */
-bool gpiod_is_equal(const struct gpio_desc *desc, const struct gpio_desc *other)
-{
-	return desc == other;
-}
-EXPORT_SYMBOL_GPL(gpiod_is_equal);
-
-/**
  * gpio_device_get_base() - Get the base GPIO number allocated by this device
  * @gdev: GPIO device
  *
@@ -400,6 +386,21 @@ static int validate_desc(const struct gpio_desc *desc, const char *func)
 		return; \
 	} while (0)
 
+/**
+ * gpiod_is_equal() - Check if two GPIO descriptors refer to the same pin.
+ * @desc: Descriptor to compare.
+ * @other: The second descriptor to compare against.
+ *
+ * Returns:
+ * True if the descriptors refer to the same physical pin. False otherwise.
+ */
+bool gpiod_is_equal(const struct gpio_desc *desc, const struct gpio_desc *other)
+{
+	return validate_desc(desc, __func__) > 0 &&
+	       !IS_ERR_OR_NULL(other) && desc == other;
+}
+EXPORT_SYMBOL_GPL(gpiod_is_equal);
+
 static int gpiochip_get_direction(struct gpio_chip *gc, unsigned int offset)
 {
 	int ret;