gpio: sysfs: fix gpio-chip device-attribute leak

commit 121b6a79 upstream.

The gpio-chip device attributes were never destroyed when the device was
removed.

Fix by using device_create_with_groups() to create the device attributes
of the chip class device.

Note that this also fixes the attribute-creation race with userspace.

Fixes: d8f388d8 ("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>

drivers/gpio/gpiolib.c

@@ -681,16 +681,13 @@ static ssize_t chip_ngpio_show(struct device *dev,
 }
 static DEVICE_ATTR(ngpio, 0444, chip_ngpio_show, NULL);
 
-static const struct attribute *gpiochip_attrs[] = {
+static struct attribute *gpiochip_attrs[] = {
 	&dev_attr_base.attr,
 	&dev_attr_label.attr,
 	&dev_attr_ngpio.attr,
 	NULL,
 };
-
-static const struct attribute_group gpiochip_attr_group = {
-	.attrs = (struct attribute **) gpiochip_attrs,
-};
+ATTRIBUTE_GROUPS(gpiochip);
 
 /*
  * /sys/class/gpio/export ... write-only
@@ -1031,13 +1028,13 @@ static int gpiochip_export(struct gpio_chip *chip)
 
 	/* use chip->base for the ID; it's already known to be unique */
 	mutex_lock(&sysfs_lock);
-	dev = device_create(&gpio_class, chip->dev, MKDEV(0, 0), chip,
+	dev = device_create_with_groups(&gpio_class, chip->dev, MKDEV(0, 0),
+					chip, gpiochip_groups,
 					"gpiochip%d", chip->base);
-	if (!IS_ERR(dev)) {
-		status = sysfs_create_group(&dev->kobj,
-				&gpiochip_attr_group);
-	} else
+	if (IS_ERR(dev))
 		status = PTR_ERR(dev);
+	else
+		status = 0;
 	chip->exported = (status == 0);
 	mutex_unlock(&sysfs_lock);