class: Implement support for class attrs in tagged sysfs directories.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/base/class.c

@@ -47,6 +47,18 @@ static ssize_t class_attr_store(struct kobject *kobj, struct attribute *attr,
 	return ret;
 }
 
+static const void *class_attr_namespace(struct kobject *kobj,
+					const struct attribute *attr)
+{
+	struct class_attribute *class_attr = to_class_attr(attr);
+	struct subsys_private *cp = to_subsys_private(kobj);
+	const void *ns = NULL;
+
+	if (class_attr->namespace)
+		ns = class_attr->namespace(cp->class, class_attr);
+	return ns;
+}
+
 static void class_release(struct kobject *kobj)
 {
 	struct subsys_private *cp = to_subsys_private(kobj);
@@ -74,6 +86,7 @@ static const struct kobj_ns_type_operations *class_child_ns_type(struct kobject
 static const struct sysfs_ops class_sysfs_ops = {
 	.show	   = class_attr_show,
 	.store	   = class_attr_store,
+	.namespace = class_attr_namespace,
 };
 
 static struct kobj_type class_ktype = {

include/linux/device.h

@@ -350,6 +350,8 @@ struct class_attribute {
 			char *buf);
 	ssize_t (*store)(struct class *class, struct class_attribute *attr,
 			const char *buf, size_t count);
+	const void *(*namespace)(struct class *class,
+				 const struct class_attribute *attr);
 };
 
 #define CLASS_ATTR(_name, _mode, _show, _store)			\