Commit 92ac7de3 authored by Bartosz Golaszewski's avatar Bartosz Golaszewski
Browse files

gpiolib: don't allow setting values on input lines 



Some drivers as well as the character device and sysfs code check
whether the line actually is in output mode before allowing the user to
set a value.

However, GPIO value setters now return integer values and can indicate
failures. This allows us to move these checks into the core code.

Reviewed-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250311-gpio-set-check-output-v1-1-d971bca9e6fa@linaro.org


Signed-off-by: default avatarBartosz Golaszewski <bartosz.golaszewski@linaro.org>
parent 0af2f6be

drivers/gpio/gpiolib-cdev.c

+0 −3
Original line number Diff line number Diff line
@@ -1366,9 +1366,6 @@ static long linereq_set_values(struct linereq *lr, void __user *ip) 
	/* scan requested lines to determine the subset to be set */

	for (num_set = 0, i = 0; i < lr->num_lines; i++) {

		if (lv.mask & BIT_ULL(i)) {

			/* setting inputs is not allowed */

			if (!test_bit(FLAG_IS_OUT, &lr->lines[i].desc->flags))

				return -EPERM;

			/* add to compacted values */

			if (lv.bits & BIT_ULL(i))

				__set_bit(num_set, vals);

drivers/gpio/gpiolib-sysfs.c

+3 −5
Original line number Diff line number Diff line
@@ -134,17 +134,15 @@ static ssize_t value_store(struct device *dev, 
	long value;



	status = kstrtol(buf, 0, &value);

	if (status)

		return status;



	guard(mutex)(&data->mutex);



	if (!test_bit(FLAG_IS_OUT, &desc->flags))

		return -EPERM;



	status = gpiod_set_value_cansleep(desc, value);

	if (status)

		return status;



	gpiod_set_value_cansleep(desc, value);



	return size;

}

static DEVICE_ATTR_PREALLOC(value, S_IWUSR | S_IRUGO, value_show, value_store);

drivers/gpio/gpiolib.c

+12 −0
Original line number Diff line number Diff line
@@ -3593,6 +3593,9 @@ static int gpio_set_open_source_value_commit(struct gpio_desc *desc, bool value) 


static int gpiod_set_raw_value_commit(struct gpio_desc *desc, bool value)

{

	if (unlikely(!test_bit(FLAG_IS_OUT, &desc->flags)))

		return -EPERM;



	CLASS(gpio_chip_guard, guard)(desc);

	if (!guard.gc)

		return -ENODEV;
@@ -3664,6 +3667,12 @@ int gpiod_set_array_value_complex(bool raw, bool can_sleep, 
		if (!can_sleep)

			WARN_ON(array_info->gdev->can_sleep);



		for (i = 0; i < array_size; i++) {

			if (unlikely(!test_bit(FLAG_IS_OUT,

					       &desc_array[i]->flags)))

				return -EPERM;

		}



		guard(srcu)(&array_info->gdev->srcu);

		gc = srcu_dereference(array_info->gdev->chip,

				      &array_info->gdev->srcu);
@@ -3723,6 +3732,9 @@ int gpiod_set_array_value_complex(bool raw, bool can_sleep, 
			int hwgpio = gpio_chip_hwgpio(desc);

			int value = test_bit(i, value_bitmap);



			if (unlikely(!test_bit(FLAG_IS_OUT, &desc->flags)))

				return -EPERM;



			/*

			 * Pins applicable for fast input but not for

			 * fast output processing may have been already