Question about CONFIG_IPV6_SUBTREES

[Yan Zheng <yanzheng@21cn.com>]

Hi all

In ip6_fib.c, fib6_lookup_1() does't make sense to me with 
CONFIG_IPV6_SUBTREES enable. It seem to only match source address when 
fib6_node has subtree. So I write a patch to show my opinion. 
unfortunately, this changes don't cooperate with  BACKTRACK() in route.c.

Can somebody explain the exact meaning of CONFIG_IPV6_SUBTREES!

Thanks.


--- linux-2.6.14-rc3-git8/net/ipv6/ip6_fib.c    2005-10-10 
08:57:40.000000000 +0800
+++ linux/net/ipv6/ip6_fib.c    2005-10-10 08:53:44.000000000 +0800
@@ -616,21 +616,6 @@
       }

       while ((fn->fn_flags & RTN_ROOT) == 0) {
-#ifdef CONFIG_IPV6_SUBTREES
-               if (fn->subtree) {
-                       struct fib6_node *st;
-                       struct lookup_args *narg;
-
-                       narg = args + 1;
-
-                       if (narg->addr) {
-                               st = fib6_lookup_1(fn->subtree, narg);
-
-                               if (st && !(st->fn_flags & RTN_ROOT))
-                                       return st;
-                       }
-               }
-#endif

               if (fn->fn_flags & RTN_RTINFO) {
                       struct rt6key *key;
@@ -639,7 +624,24 @@
                                       args->offset);

                       if (ipv6_prefix_equal(&key->addr, args->addr, 
key->plen))
-                               return fn;
+#ifdef CONFIG_IPV6_SUBTREES
+                               if (fn->subtree) {
+                                       struct fib6_node *st;
+                                       struct lookup_args *narg;
+
+                                       narg = args + 1;
+
+                                       if (narg->addr) {
+                                               st = 
fib6_lookup_1(fn->subtree, narg);
+
+                                               if (st && !(st->fn_flags 
& RTN_ROOT))
+                                                       return st;
+                                               if (fn->subtree->leaf != 
&ip6_null_entry)
+                                                       return fn->subtree;
+                                       }
+                               } else
+#endif
+                                       return fn;
               }

               fn = fn->parent;