ipv4: Avoid overhead when no custom FIB rules are installed.

If the user hasn't actually installed any custom rules, or fiddled
with the default ones, don't go through the whole FIB rules layer.

It's just pure overhead.

Instead do what we do with CONFIG_IP_MULTIPLE_TABLES disabled, check
the individual tables by hand, one by one.

Also, move fib_num_tclassid_users into the ipv4 network namespace.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 22 insertions, 5 deletions

diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 3e11ea225dad..81f85716a894 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -86,6 +86,24 @@ struct fib_table *fib_new_table(struct net *net, u32 id)
         tb = fib_trie_table(id);
         if (!tb)
                 return NULL;
+
+        switch (id) {
+        case RT_TABLE_LOCAL:
+                net->ipv4.fib_local = tb;
+                break;
+
+        case RT_TABLE_MAIN:
+                net->ipv4.fib_main = tb;
+                break;
+
+        case RT_TABLE_DEFAULT:
+                net->ipv4.fib_default = tb;
+                break;
+
+        default:
+                break;
+        }
+
         h = id & (FIB_TABLE_HASHSZ - 1);
         hlist_add_head_rcu(&tb->tb_hlist, &net->ipv4.fib_table_hash[h]);
         return tb;
@@ -218,10 +236,6 @@ __be32 fib_compute_spec_dst(struct sk_buff *skb)
         return inet_select_addr(dev, ip_hdr(skb)->saddr, scope);
 }
 
-#ifdef CONFIG_IP_ROUTE_CLASSID
-int fib_num_tclassid_users __read_mostly;
-#endif
-
 /* Given (packet source, input interface) and optional (dst, oif, tos):
  * - (main) check, that source is valid i.e. not broadcast or our local
  *   address.
@@ -312,7 +326,7 @@ int fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,
 {
         int r = secpath_exists(skb) ? 0 : IN_DEV_RPFILTER(idev);
 
-        if (!r && !fib_num_tclassid_users) {
+        if (!r && !fib_num_tclassid_users(dev_net(dev))) {
                 *itag = 0;
                 return 0;
         }
@@ -1134,6 +1148,9 @@ static int __net_init fib_net_init(struct net *net)
 {
         int error;
 
+#ifdef CONFIG_IP_ROUTE_CLASSID
+        net->ipv4.fib_num_tclassid_users = 0;
+#endif
         error = ip_fib_net_init(net);
         if (error < 0)
                 goto out;