ipv6: prepare fib6_age() for exception table

If all dst cache entries are stored in the exception table under the
main route, we have to go through them during fib6_age() when doing
garbage collecting.
Introduce a new function rt6_age_exception() which goes through all dst
entries in the exception table and remove those entries that are expired.
This function is called in fib6_age() so that all dst caches are also
garbage collected.

Signed-off-by: Wei Wang <weiwan@google.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/ip6_fib.h

@@ -29,6 +29,14 @@
 #define FIB6_TABLE_HASHSZ 1
 #endif
 
+#define RT6_DEBUG 2
+
+#if RT6_DEBUG >= 3
+#define RT6_TRACE(x...) pr_debug(x)
+#else
+#define RT6_TRACE(x...) do { ; } while (0)
+#endif
+
 struct rt6_info;
 
 struct fib6_config {
@@ -75,6 +83,11 @@ struct fib6_node {
 	struct rcu_head		rcu;
 };
 
+struct fib6_gc_args {
+	int			timeout;
+	int			more;
+};
+
 #ifndef CONFIG_IPV6_SUBTREES
 #define FIB6_SUBTREE(fn)	NULL
 #else

include/net/ip6_route.h

@@ -97,6 +97,8 @@ int ip6_del_rt(struct rt6_info *);
 
 void rt6_flush_exceptions(struct rt6_info *rt);
 int rt6_remove_exception_rt(struct rt6_info *rt);
+void rt6_age_exceptions(struct rt6_info *rt, struct fib6_gc_args *gc_args,
+			unsigned long now);
 
 static inline int ip6_route_get_saddr(struct net *net, struct rt6_info *rt,
 				      const struct in6_addr *daddr,