diff --git a/include/net/sock.h b/include/net/sock.h
index 5697caf..d24f382 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -312,7 +312,7 @@
 	void			*sk_security;
 #endif
 	__u32			sk_mark;
-	/* XXX 4 bytes hole on 64 bit */
+	u32			sk_classid;
 	void			(*sk_state_change)(struct sock *sk);
 	void			(*sk_data_ready)(struct sock *sk, int bytes);
 	void			(*sk_write_space)(struct sock *sk);
@@ -1074,6 +1074,14 @@
 extern void sock_kfree_s(struct sock *sk, void *mem, int size);
 extern void sk_send_sigurg(struct sock *sk);
 
+#ifdef CONFIG_CGROUPS
+extern void sock_update_classid(struct sock *sk);
+#else
+static inline void sock_update_classid(struct sock *sk)
+{
+}
+#endif
+
 /*
  * Functions to fill in entries in struct proto_ops when a protocol
  * does not implement a particular function.