[CLASS DEVICE]: add attribute_group creation

Extend the support of attribute groups in class_device's to allow
groups to be created as part of the registration process. This allows
network device's to avoid race between registration and creating
groups.

Note that unlike attributes that are a property of the class object,
the groups are a property of the class_device object. This is done
because there are different types of network devices (wireless for
example).
Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/base/class.c

@@ -456,6 +456,35 @@ static void class_device_remove_attrs(struct class_device * cd)
 	}
 }
 
+static int class_device_add_groups(struct class_device * cd)
+{
+	int i;
+	int error = 0;
+
+	if (cd->groups) {
+		for (i = 0; cd->groups[i]; i++) {
+			error = sysfs_create_group(&cd->kobj, cd->groups[i]);
+			if (error) {
+				while (--i >= 0)
+					sysfs_remove_group(&cd->kobj, cd->groups[i]);
+				goto out;
+			}
+		}
+	}
+out:
+	return error;
+}
+
+static void class_device_remove_groups(struct class_device * cd)
+{
+	int i;
+	if (cd->groups) {
+		for (i = 0; cd->groups[i]; i++) {
+			sysfs_remove_group(&cd->kobj, cd->groups[i]);
+		}
+	}
+}
+
 static ssize_t show_dev(struct class_device *class_dev, char *buf)
 {
 	return print_dev_t(buf, class_dev->devt);
@@ -559,6 +588,8 @@ int class_device_add(struct class_device *class_dev)
 				  class_name);
 	}
 
+	class_device_add_groups(class_dev);
+
 	kobject_uevent(&class_dev->kobj, KOBJ_ADD);
 
 	/* notify any interfaces this device is now here */
@@ -672,6 +703,7 @@ void class_device_del(struct class_device *class_dev)
 	if (class_dev->devt_attr)
 		class_device_remove_file(class_dev, class_dev->devt_attr);
 	class_device_remove_attrs(class_dev);
+	class_device_remove_groups(class_dev);
 
 	kobject_uevent(&class_dev->kobj, KOBJ_REMOVE);
 	kobject_del(&class_dev->kobj);

include/linux/device.h

@@ -200,6 +200,7 @@ extern int class_device_create_file(struct class_device *,
  * @node: for internal use by the driver core only.
  * @kobj: for internal use by the driver core only.
  * @devt_attr: for internal use by the driver core only.
+ * @groups: optional additional groups to be created
  * @dev: if set, a symlink to the struct device is created in the sysfs
  * directory for this struct class device.
  * @class_data: pointer to whatever you want to store here for this struct
@@ -228,6 +229,7 @@ struct class_device {
 	struct device		* dev;		/* not necessary, but nice to have */
 	void			* class_data;	/* class-specific data */
 	struct class_device	*parent;	/* parent of this child device, if there is one */
+	struct attribute_group  ** groups;	/* optional groups */
 
 	void	(*release)(struct class_device *dev);
 	int	(*uevent)(struct class_device *dev, char **envp,