[NETFILTER]: nf_conntrack: optimize __nf_conntrack_find()

Ignoring specific entries in __nf_conntrack_find() is only needed by NAT
for nf_conntrack_tuple_taken(). Remove it from __nf_conntrack_find()
and make nf_conntrack_tuple_taken() search the hash itself.

Saves 54 bytes of text in the hotpath on x86_64:

  __nf_conntrack_find      |  -54 # 321 -> 267, # inlines: 3 -> 2, size inlines: 181 -> 127
  nf_conntrack_tuple_taken | +305 # 15 -> 320, lexblocks: 0 -> 3, # inlines: 0 -> 3, size inlines: 0 -> 181
  nf_conntrack_find_get    |   -2 # 90 -> 88
 3 functions changed, 305 bytes added, 56 bytes removed, diff: +249

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/netfilter/nf_conntrack.h

@@ -178,8 +178,7 @@ extern void nf_ct_free_hashtable(struct hlist_head *hash, int vmalloced,
 				 unsigned int size);
 
 extern struct nf_conntrack_tuple_hash *
-__nf_conntrack_find(const struct nf_conntrack_tuple *tuple,
-		    const struct nf_conn *ignored_conntrack);
+__nf_conntrack_find(const struct nf_conntrack_tuple *tuple);
 
 extern void nf_conntrack_hash_insert(struct nf_conn *ct);
 

net/netfilter/nf_conntrack_core.c

@@ -246,16 +246,14 @@ static void death_by_timeout(unsigned long ul_conntrack)
 }
 
 struct nf_conntrack_tuple_hash *
-__nf_conntrack_find(const struct nf_conntrack_tuple *tuple,
-		    const struct nf_conn *ignored_conntrack)
+__nf_conntrack_find(const struct nf_conntrack_tuple *tuple)
 {
 	struct nf_conntrack_tuple_hash *h;
 	struct hlist_node *n;
 	unsigned int hash = hash_conntrack(tuple);
 
 	hlist_for_each_entry_rcu(h, n, &nf_conntrack_hash[hash], hnode) {
-		if (nf_ct_tuplehash_to_ctrack(h) != ignored_conntrack &&
-		    nf_ct_tuple_equal(tuple, &h->tuple)) {
+		if (nf_ct_tuple_equal(tuple, &h->tuple)) {
 			NF_CT_STAT_INC(found);
 			return h;
 		}
@@ -274,7 +272,7 @@ nf_conntrack_find_get(const struct nf_conntrack_tuple *tuple)
 	struct nf_conn *ct;
 
 	rcu_read_lock();
-	h = __nf_conntrack_find(tuple, NULL);
+	h = __nf_conntrack_find(tuple);
 	if (h) {
 		ct = nf_ct_tuplehash_to_ctrack(h);
 		if (unlikely(!atomic_inc_not_zero(&ct->ct_general.use)))
@@ -395,12 +393,22 @@ nf_conntrack_tuple_taken(const struct nf_conntrack_tuple *tuple,
 			 const struct nf_conn *ignored_conntrack)
 {
 	struct nf_conntrack_tuple_hash *h;
+	struct hlist_node *n;
+	unsigned int hash = hash_conntrack(tuple);
 
 	rcu_read_lock();
-	h = __nf_conntrack_find(tuple, ignored_conntrack);
+	hlist_for_each_entry_rcu(h, n, &nf_conntrack_hash[hash], hnode) {
+		if (nf_ct_tuplehash_to_ctrack(h) != ignored_conntrack &&
+		    nf_ct_tuple_equal(tuple, &h->tuple)) {
+			NF_CT_STAT_INC(found);
+			rcu_read_unlock();
+			return 1;
+		}
+		NF_CT_STAT_INC(searched);
+	}
 	rcu_read_unlock();
 
-	return h != NULL;
+	return 0;
 }
 EXPORT_SYMBOL_GPL(nf_conntrack_tuple_taken);
 

net/netfilter/nf_conntrack_netlink.c

@@ -1222,9 +1222,9 @@ ctnetlink_new_conntrack(struct sock *ctnl, struct sk_buff *skb,
 
 	spin_lock_bh(&nf_conntrack_lock);
 	if (cda[CTA_TUPLE_ORIG])
-		h = __nf_conntrack_find(&otuple, NULL);
+		h = __nf_conntrack_find(&otuple);
 	else if (cda[CTA_TUPLE_REPLY])
-		h = __nf_conntrack_find(&rtuple, NULL);
+		h = __nf_conntrack_find(&rtuple);
 
 	if (h == NULL) {
 		struct nf_conntrack_tuple master;
@@ -1239,7 +1239,7 @@ ctnetlink_new_conntrack(struct sock *ctnl, struct sk_buff *skb,
 			if (err < 0)
 				goto out_unlock;
 
-			master_h = __nf_conntrack_find(&master, NULL);
+			master_h = __nf_conntrack_find(&master);
 			if (master_h == NULL) {
 				err = -ENOENT;
 				goto out_unlock;

net/netfilter/xt_connlimit.c

@@ -124,7 +124,7 @@ static int count_them(struct xt_connlimit_data *data,
 
 	/* check the saved connections */
 	list_for_each_entry_safe(conn, tmp, hash, list) {
-		found    = __nf_conntrack_find(&conn->tuple, NULL);
+		found    = __nf_conntrack_find(&conn->tuple);
 		found_ct = NULL;
 
 		if (found != NULL)