[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>

3 files changed, 19 insertions, 11 deletions

diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index f284dddfc89..ce4c4ba31cb 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/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);
 
diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index b6a8c089a07..bf86fdd89fd 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/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;
diff --git a/net/netfilter/xt_connlimit.c b/net/netfilter/xt_connlimit.c
index f9b59a6753e..3b0111933f6 100644
--- a/net/netfilter/xt_connlimit.c
+++ b/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)