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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/gpio/gpiolib.c

@@ -627,7 +627,7 @@ 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,
@@ -635,7 +635,7 @@ static const struct attribute *gpiochip_attrs[] = {
 };
 
 static const struct attribute_group gpiochip_attr_group = {
-	.attrs = (struct attribute **) gpiochip_attrs,
+	.attrs = gpiochip_attrs,
 };
 
 /*
@@ -1036,6 +1036,7 @@ static void gpiochip_unexport(struct gpio_chip *chip)
 	mutex_lock(&sysfs_lock);
 	dev = class_find_device(&gpio_class, NULL, chip, match_export);
 	if (dev) {
+		sysfs_remove_group(&dev->kobj, &gpiochip_attr_group);
 		put_device(dev);
 		device_unregister(dev);
 		chip->exported = 0;