Commit fc4e2514 authored by Ryan Mallon's avatar Ryan Mallon Committed by Linus Walleij
Browse files

gpiolib: Refactor gpio_export 



The gpio_export function uses nested if statements and the status
variable to handle the failure cases. This makes the function logic
difficult to follow. Refactor the code to abort immediately on failure
using goto. This makes the code slightly longer, but significantly
reduces the nesting and number of split lines and makes the code easier
to read.

Signed-off-by: default avatarRyan Mallon <rmallon@gmail.com>
Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
parent 67a0d499

drivers/gpio/gpiolib.c

+46 −39
Original line number Diff line number Diff line
@@ -702,8 +702,9 @@ int gpio_export(unsigned gpio, bool direction_may_change) 
{

	unsigned long		flags;

	struct gpio_desc	*desc;

	int			status = -EINVAL;

	int			status;

	const char		*ioname = NULL;

	struct device		*dev;



	/* can't export until sysfs is available ... */

	if (!gpio_class.p) {
@@ -711,59 +712,65 @@ int gpio_export(unsigned gpio, bool direction_may_change) 
		return -ENOENT;

	}



	if (!gpio_is_valid(gpio))

		goto done;

	if (!gpio_is_valid(gpio)) {

		pr_debug("%s: gpio %d is not valid\n", __func__, gpio);

		return -EINVAL;

	}



	mutex_lock(&sysfs_lock);



	spin_lock_irqsave(&gpio_lock, flags);

	desc = &gpio_desc[gpio];

	if (test_bit(FLAG_REQUESTED, &desc->flags)

			&& !test_bit(FLAG_EXPORT, &desc->flags)) {

		status = 0;

		if (!desc->chip->direction_input

				|| !desc->chip->direction_output)

			direction_may_change = false;

	if (!test_bit(FLAG_REQUESTED, &desc->flags) ||

	     test_bit(FLAG_EXPORT, &desc->flags)) {

		spin_unlock_irqrestore(&gpio_lock, flags);

		pr_debug("%s: gpio %d unavailable (requested=%d, exported=%d)\n",

				__func__, gpio,

				test_bit(FLAG_REQUESTED, &desc->flags),

				test_bit(FLAG_EXPORT, &desc->flags));

		return -EPERM;

	}



	if (!desc->chip->direction_input || !desc->chip->direction_output)

		direction_may_change = false;

	spin_unlock_irqrestore(&gpio_lock, flags);



	if (desc->chip->names && desc->chip->names[gpio - desc->chip->base])

		ioname = desc->chip->names[gpio - desc->chip->base];



	if (status == 0) {

		struct device	*dev;



	dev = device_create(&gpio_class, desc->chip->dev, MKDEV(0, 0),

			    desc, ioname ? ioname : "gpio%u", gpio);

		if (!IS_ERR(dev)) {

			status = sysfs_create_group(&dev->kobj,

						&gpio_attr_group);

	if (IS_ERR(dev)) {

		status = PTR_ERR(dev);

		goto fail_unlock;

	}



			if (!status && direction_may_change)

				status = device_create_file(dev,

						&dev_attr_direction);

	status = sysfs_create_group(&dev->kobj, &gpio_attr_group);

	if (status)

		goto fail_unregister_device;



			if (!status && gpio_to_irq(gpio) >= 0

					&& (direction_may_change

						|| !test_bit(FLAG_IS_OUT,

							&desc->flags)))

				status = device_create_file(dev,

						&dev_attr_edge);

	if (direction_may_change) {

		status = device_create_file(dev, &dev_attr_direction);

		if (status)

			goto fail_unregister_device;

	}



			if (status != 0)

				device_unregister(dev);

		} else

			status = PTR_ERR(dev);

		if (status == 0)

			set_bit(FLAG_EXPORT, &desc->flags);

	if (gpio_to_irq(gpio) >= 0 && (direction_may_change ||

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

		status = device_create_file(dev, &dev_attr_edge);

		if (status)

			goto fail_unregister_device;

	}



	set_bit(FLAG_EXPORT, &desc->flags);

	mutex_unlock(&sysfs_lock);

	return 0;



done:

	if (status)

fail_unregister_device:

	device_unregister(dev);

fail_unlock:

	mutex_unlock(&sysfs_lock);

	pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);



	return status;

}

EXPORT_SYMBOL_GPL(gpio_export);

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