[PATCH 2/2] gpio: sysfs: fix gpio device-attribute leak

Johan Hovold
2015-01-26T18:06:26Z

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")
Cc: stable <stable@vger.kernel.org> # v2.6.27+
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
[johan: fix leaks without device_create_with_groups, which wasn't
introduced until 3.11 ]
Signed-off-by: Johan Hovold <johan@kernel.org>
---
drivers/gpio/gpiolib.c | 19 +++++++++++++------
1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index bc3d59efe80b..4b2a26b62025 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -362,7 +362,7 @@ 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)
@@ -580,17 +580,17 @@ 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,
+ .attrs = gpio_attrs,
};

/*
@@ -806,20 +806,24 @@ static int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
if (direction_may_change) {
status = device_create_file(dev, &dev_attr_direction);
if (status)
- goto fail_unregister_device;
+ goto fail_remove_attr_group;
}

if (gpiod_to_irq(desc) >= 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;
+ 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_remove_attr_group:
+ sysfs_remove_group(&dev->kobj, &gpio_attr_group);
fail_unregister_device:
device_unregister(dev);
fail_unlock:
@@ -962,6 +966,9 @@ static void gpiod_unexport(struct gpio_desc *desc)

dev = class_find_device(&gpio_class, NULL, desc, match_export);
if (dev) {
+ device_remove_file(dev, &dev_attr_edge);
+ device_remove_file(dev, &dev_attr_direction);
+ sysfs_remove_group(&dev->kobj, &gpio_attr_group);
gpio_setup_irq(desc, dev, 0);
clear_bit(FLAG_EXPORT, &desc->flags);
} else
--
2.0.5