[PATCH 3.13.y-ckt 084/103] gpio: sysfs: fix gpio device-attribute leak

Kamal Mostafa
2015-02-19T00:42:24Z

From: Johan Hovold <johan@kernel.org>

commit 0915e6feb38de8d3601819992a5bd050201a56fa upstream.

The gpio device attributes were never destroyed when the gpio was
unexported (or on export failures).

Use device_create_with_groups() to create the default device attributes
of the gpio class device. Note that this also fixes the
attribute-creation race with userspace for these attributes.

Remove contingent attributes in export error path and on unexport.

Fixes: d8f388d8dc8d ("gpio: sysfs interface")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
[ luis: backported to 3.16:
- file rename: drivers/gpio/gpiolib-sysfs.c -> drivers/gpio/gpiolib.c ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
drivers/gpio/gpiolib.c | 28 +++++++++++++---------------
1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 1c22667..e829dc4 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -390,7 +390,7 @@ static ssize_t gpio_value_store(struct device *dev,
return status;
}

-static const DEVICE_ATTR(value, 0644,
+static DEVICE_ATTR(value, 0644,
gpio_value_show, gpio_value_store);

static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
@@ -615,18 +615,15 @@ static ssize_t gpio_active_low_store(struct device *dev,
return status ? : size;
}

-static const DEVICE_ATTR(active_low, 0644,
+static DEVICE_ATTR(active_low, 0644,
gpio_active_low_show, gpio_active_low_store);

-static const struct attribute *gpio_attrs[] = {
+static struct attribute *gpio_attrs[] = {
&dev_attr_value.attr,
&dev_attr_active_low.attr,
NULL,
};
-
-static const struct attribute_group gpio_attr_group = {
- .attrs = (struct attribute **) gpio_attrs,
-};
+ATTRIBUTE_GROUPS(gpio);

/*
* /sys/class/gpio/gpiochipN/
@@ -823,18 +820,15 @@ int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
if (desc->chip->names && desc->chip->names[offset])
ioname = desc->chip->names[offset];

- dev = device_create(&gpio_class, desc->chip->dev, MKDEV(0, 0),
- desc, ioname ? ioname : "gpio%u",
- desc_to_gpio(desc));
+ dev = device_create_with_groups(&gpio_class, desc->chip->dev,
+ MKDEV(0, 0), desc, gpio_groups,
+ ioname ? ioname : "gpio%u",
+ desc_to_gpio(desc));
if (IS_ERR(dev)) {
status = PTR_ERR(dev);
goto fail_unlock;
}

- status = sysfs_create_group(&dev->kobj, &gpio_attr_group);
- if (status)
- goto fail_unregister_device;
-
if (direction_may_change) {
status = device_create_file(dev, &dev_attr_direction);
if (status)
@@ -845,13 +839,15 @@ int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
!test_bit(FLAG_IS_OUT, &desc->flags))) {
status = device_create_file(dev, &dev_attr_edge);
if (status)
- goto fail_unregister_device;
+ goto fail_remove_attr_direction;
}

set_bit(FLAG_EXPORT, &desc->flags);
mutex_unlock(&sysfs_lock);
return 0;

+fail_remove_attr_direction:
+ device_remove_file(dev, &dev_attr_direction);
fail_unregister_device:
device_unregister(dev);
fail_unlock:
@@ -988,6 +984,8 @@ void gpiod_unexport(struct gpio_desc *desc)
mutex_unlock(&sysfs_lock);

if (dev) {
+ device_remove_file(dev, &dev_attr_edge);
+ device_remove_file(dev, &dev_attr_direction);
device_unregister(dev);
put_device(dev);
}
--
1.9.1