netfilter: conntrack: use a single hashtable for all namespaces

We already include netns address in the hash and compare the netns pointers
during lookup, so even if namespaces have overlapping addresses entries
will be spread across the table.

Assuming 64k bucket size, this change saves 0.5 mbyte per namespace on a
64bit system.

NAT bysrc and expectation hash is still per namespace, those will
changed too soon.

Future patch will also make conntrack object slab cache global again.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

2 files changed, 5 insertions, 7 deletions

diff --git a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
index e3c46e8e2762..ae1a71a97132 100644
--- a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
+++ b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
@@ -360,7 +360,7 @@ static int ipv4_init_net(struct net *net)
 
 	in->ctl_table[0].data = &nf_conntrack_max;
 	in->ctl_table[1].data = &net->ct.count;
-	in->ctl_table[2].data = &net->ct.htable_size;
+	in->ctl_table[2].data = &nf_conntrack_htable_size;
 	in->ctl_table[3].data = &net->ct.sysctl_checksum;
 	in->ctl_table[4].data = &net->ct.sysctl_log_invalid;
 #endif
diff --git a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4_compat.c b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4_compat.c
index 171aba15c952..f8fc7ab201c9 100644
--- a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4_compat.c
+++ b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4_compat.c
@@ -31,15 +31,14 @@ struct ct_iter_state {
 
 static struct hlist_nulls_node *ct_get_first(struct seq_file *seq)
 {
-	struct net *net = seq_file_net(seq);
 	struct ct_iter_state *st = seq->private;
 	struct hlist_nulls_node *n;
 
 	for (st->bucket = 0;
-	     st->bucket < net->ct.htable_size;
+	     st->bucket < nf_conntrack_htable_size;
 	     st->bucket++) {
 		n = rcu_dereference(
-			hlist_nulls_first_rcu(&net->ct.hash[st->bucket]));
+			hlist_nulls_first_rcu(&nf_conntrack_hash[st->bucket]));
 		if (!is_a_nulls(n))
 			return n;
 	}
@@ -49,17 +48,16 @@ static struct hlist_nulls_node *ct_get_first(struct seq_file *seq)
 static struct hlist_nulls_node *ct_get_next(struct seq_file *seq,
 				      struct hlist_nulls_node *head)
 {
-	struct net *net = seq_file_net(seq);
 	struct ct_iter_state *st = seq->private;
 
 	head = rcu_dereference(hlist_nulls_next_rcu(head));
 	while (is_a_nulls(head)) {
 		if (likely(get_nulls_value(head) == st->bucket)) {
-			if (++st->bucket >= net->ct.htable_size)
+			if (++st->bucket >= nf_conntrack_htable_size)
 				return NULL;
 		}
 		head = rcu_dereference(
-			hlist_nulls_first_rcu(&net->ct.hash[st->bucket]));
+			hlist_nulls_first_rcu(&nf_conntrack_hash[st->bucket]));
 	}
 	return head;
 }