Subject: [PATCH 1/5] NET : Introduce union in struct dst_entry to hold 'next' pointer

From: Eric Dumazet <[email-masked]>
Date: Thu, 08 Feb 2007 22:33:09 +0100

This patch introduces an anonymous union to nicely express the fact that all 
objects inherited from struct dst_entry should access to the generic 'next' 
pointer but with appropriate type verification.

This patch is a prereq before following patches.

Signed-off-by: Eric Dumazet <[email-masked]>
--- linux-2.6.20/include/net/dst.h	2007-02-08 21:06:15.000000000 +0100
+++ linux-2.6.20-ed/include/net/dst.h	2007-02-08 21:07:21.000000000 +0100
@@ -37,7 +37,12 @@ struct sk_buff;
 
 struct dst_entry
 {
-	struct dst_entry        *next;
+	union {
+		struct dst_entry *next;
+		struct rtable    *rt_next;
+		struct rt6_info   *rt6_next;
+		struct dn_route  *dn_next;
+	};
 	atomic_t		__refcnt;	/* client references	*/
 	int			__use;
 	struct dst_entry	*child;