linux-kernel - [PATCH 3.2 116/152] gpio: sysfs: fix gpio device-attribute leak

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Date:	Tue, 17 Feb 2015 01:46:53 +0000
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org,
	"Linus Walleij" <linus.walleij@...aro.org>,
	"Johan Hovold" <johan@...nel.org>
Subject: [PATCH 3.2 116/152] gpio: sysfs: fix gpio device-attribute leak

3.2.67-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Johan Hovold <johan@...nel.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@...nel.org>
Signed-off-by: Linus Walleij <linus.walleij@...aro.org>
[bwh: Backported to 3.2: adjust filename, context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/gpio/gpiolib.c | 28 +++++++++++++---------------
 1 file changed, 13 insertions(+), 15 deletions(-)

--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -317,7 +317,7 @@ static ssize_t gpio_value_store(struct d
 	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)
@@ -540,18 +540,15 @@ static ssize_t gpio_active_low_store(str
 	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/
@@ -733,17 +730,14 @@ int gpio_export(unsigned gpio, bool dire
 	if (desc->chip->names && desc->chip->names[gpio - desc->chip->base])
 		ioname = desc->chip->names[gpio - desc->chip->base];
 
-	dev = device_create(&gpio_class, desc->chip->dev, MKDEV(0, 0),
-			    desc, ioname ? ioname : "gpio%u", gpio);
+	dev = device_create_with_groups(&gpio_class, desc->chip->dev,
+					MKDEV(0, 0), desc, gpio_groups,
+					ioname ? ioname : "gpio%u", gpio);
 	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)
@@ -754,13 +748,15 @@ int gpio_export(unsigned gpio, bool dire
 				       !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:
@@ -900,6 +896,8 @@ void gpio_unexport(unsigned gpio)
 
 	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);
 	}

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