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>

3 files changed, 33 insertions, 12 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;
diff --git a/net/ipv4/fib_rules.c b/net/ipv4/fib_rules.c
index b23fd952c84f..c06da93b0b70 100644
--- a/net/ipv4/fib_rules.c
+++ b/net/ipv4/fib_rules.c
@@ -54,7 +54,7 @@ u32 fib_rules_tclass(const struct fib_result *res)
 }
 #endif
 
-int fib_lookup(struct net *net, struct flowi4 *flp, struct fib_result *res)
+int __fib_lookup(struct net *net, struct flowi4 *flp, struct fib_result *res)
 {
         struct fib_lookup_arg arg = {
                 .result = res,
@@ -67,7 +67,7 @@ int fib_lookup(struct net *net, struct flowi4 *flp, struct fib_result *res)
 
         return err;
 }
-EXPORT_SYMBOL_GPL(fib_lookup);
+EXPORT_SYMBOL_GPL(__fib_lookup);
 
 static int fib4_rule_action(struct fib_rule *rule, struct flowi *flp,
                             int flags, struct fib_lookup_arg *arg)
@@ -172,7 +172,7 @@ static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
         if (tb[FRA_FLOW]) {
                 rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
                 if (rule4->tclassid)
-                        fib_num_tclassid_users++;
+                        net->ipv4.fib_num_tclassid_users++;
         }
 #endif
 
@@ -182,6 +182,7 @@ static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
         rule4->dstmask = inet_make_mask(rule4->dst_len);
         rule4->tos = frh->tos;
 
+        net->ipv4.fib_has_custom_rules = true;
         err = 0;
 errout:
         return err;
@@ -189,12 +190,14 @@ errout:
 
 static void fib4_rule_delete(struct fib_rule *rule)
 {
+        struct net *net = rule->fr_net;
 #ifdef CONFIG_IP_ROUTE_CLASSID
         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 
         if (rule4->tclassid)
-                fib_num_tclassid_users--;
+                net->ipv4.fib_num_tclassid_users--;
 #endif
+        net->ipv4.fib_has_custom_rules = true;
 }
 
 static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
@@ -309,6 +312,7 @@ int __net_init fib4_rules_init(struct net *net)
         if (err < 0)
                 goto fail;
         net->ipv4.rules_ops = ops;
+        net->ipv4.fib_has_custom_rules = false;
         return 0;
 
 fail:
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index c46c20b6b0b6..ae301c897a19 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -166,7 +166,7 @@ void free_fib_info(struct fib_info *fi)
 #ifdef CONFIG_IP_ROUTE_CLASSID
         change_nexthops(fi) {
                 if (nexthop_nh->nh_tclassid)
-                        fib_num_tclassid_users--;
+                        fi->fib_net->ipv4.fib_num_tclassid_users--;
         } endfor_nexthops(fi);
 #endif
         call_rcu(&fi->rcu, free_fib_info_rcu);
@@ -428,7 +428,7 @@ static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
                         nla = nla_find(attrs, attrlen, RTA_FLOW);
                         nexthop_nh->nh_tclassid = nla ? nla_get_u32(nla) : 0;
                         if (nexthop_nh->nh_tclassid)
-                                fib_num_tclassid_users++;
+                                fi->fib_net->ipv4.fib_num_tclassid_users++;
 #endif
                 }
 
@@ -824,7 +824,7 @@ struct fib_info *fib_create_info(struct fib_config *cfg)
 #ifdef CONFIG_IP_ROUTE_CLASSID
                 nh->nh_tclassid = cfg->fc_flow;
                 if (nh->nh_tclassid)
-                        fib_num_tclassid_users++;
+                        fi->fib_net->ipv4.fib_num_tclassid_users++;
 #endif
 #ifdef CONFIG_IP_ROUTE_MULTIPATH
                 nh->nh_weight = 1;