netfilter: helper: avoid extra expectation iterations on unregister

The expectation table is not duplicated per net namespace anymore, so we can move
the expectation table and conntrack table iteration out of the per-net loop.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_conntrack_helper.c

@@ -388,13 +388,40 @@ EXPORT_SYMBOL_GPL(nf_conntrack_helper_register);
 
 static void __nf_conntrack_helper_unregister(struct nf_conntrack_helper *me,
 					     struct net *net)
+{
+	struct nf_conntrack_tuple_hash *h;
+	const struct hlist_nulls_node *nn;
+	int cpu;
+
+	/* Get rid of expecteds, set helpers to NULL. */
+	for_each_possible_cpu(cpu) {
+		struct ct_pcpu *pcpu = per_cpu_ptr(net->ct.pcpu_lists, cpu);
+
+		spin_lock_bh(&pcpu->lock);
+		hlist_nulls_for_each_entry(h, nn, &pcpu->unconfirmed, hnnode)
+			unhelp(h, me);
+		spin_unlock_bh(&pcpu->lock);
+	}
+}
+
+void nf_conntrack_helper_unregister(struct nf_conntrack_helper *me)
 {
 	struct nf_conntrack_tuple_hash *h;
 	struct nf_conntrack_expect *exp;
 	const struct hlist_node *next;
 	const struct hlist_nulls_node *nn;
+	struct net *net;
 	unsigned int i;
-	int cpu;
+
+	mutex_lock(&nf_ct_helper_mutex);
+	hlist_del_rcu(&me->hnode);
+	nf_ct_helper_count--;
+	mutex_unlock(&nf_ct_helper_mutex);
+
+	/* Make sure every nothing is still using the helper unless its a
+	 * connection in the hash.
+	 */
+	synchronize_rcu();
 
 	/* Get rid of expectations */
 	spin_lock_bh(&nf_conntrack_expect_lock);
@@ -414,15 +441,11 @@ static void __nf_conntrack_helper_unregister(struct nf_conntrack_helper *me,
 	}
 	spin_unlock_bh(&nf_conntrack_expect_lock);
 
-	/* Get rid of expecteds, set helpers to NULL. */
-	for_each_possible_cpu(cpu) {
-		struct ct_pcpu *pcpu = per_cpu_ptr(net->ct.pcpu_lists, cpu);
+	rtnl_lock();
+	for_each_net(net)
+		__nf_conntrack_helper_unregister(me, net);
+	rtnl_unlock();
 
-		spin_lock_bh(&pcpu->lock);
-		hlist_nulls_for_each_entry(h, nn, &pcpu->unconfirmed, hnnode)
-			unhelp(h, me);
-		spin_unlock_bh(&pcpu->lock);
-	}
 	local_bh_disable();
 	for (i = 0; i < nf_conntrack_htable_size; i++) {
 		nf_conntrack_lock(&nf_conntrack_locks[i % CONNTRACK_LOCKS]);
@@ -434,26 +457,6 @@ static void __nf_conntrack_helper_unregister(struct nf_conntrack_helper *me,
 	}
 	local_bh_enable();
 }
-
-void nf_conntrack_helper_unregister(struct nf_conntrack_helper *me)
-{
-	struct net *net;
-
-	mutex_lock(&nf_ct_helper_mutex);
-	hlist_del_rcu(&me->hnode);
-	nf_ct_helper_count--;
-	mutex_unlock(&nf_ct_helper_mutex);
-
-	/* Make sure every nothing is still using the helper unless its a
-	 * connection in the hash.
-	 */
-	synchronize_rcu();
-
-	rtnl_lock();
-	for_each_net(net)
-		__nf_conntrack_helper_unregister(me, net);
-	rtnl_unlock();
-}
 EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister);
 
 static struct nf_ct_ext_type helper_extend __read_mostly = {