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gpiolib: Refactor gpio_export

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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: Ryan Mallon <rmallon@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Ryan Mallon 2012-10-22 11:39:12 +11:00 committed by Linus Walleij
parent 67a0d4993d
commit fc4e251499
1 changed files with 46 additions and 39 deletions
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85
drivers/gpio/gpiolib.c
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@ -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 (!status && direction_may_change)
status = device_create_file(dev,
&dev_attr_direction);
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 (status != 0)
device_unregister(dev);
} else
status = PTR_ERR(dev);
if (status == 0)
set_bit(FLAG_EXPORT, &desc->flags);
dev = device_create(&gpio_class, desc->chip->dev, MKDEV(0, 0),
desc, ioname ? ioname : "gpio%u", gpio);
if (IS_ERR(dev)) {
status = PTR_ERR(dev);
goto fail_unlock;
}
mutex_unlock(&sysfs_lock);
done:
status = sysfs_create_group(&dev->kobj, &gpio_attr_group);
if (status)
pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);
goto fail_unregister_device;
if (direction_may_change) {
status = device_create_file(dev, &dev_attr_direction);
if (status)
goto fail_unregister_device;
}
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;
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);