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>
diff --git a/include/linux/device.h b/include/linux/device.h
index c20dfbf..ea70bb2 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -350,6 +350,8 @@
 			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)			\