ipvs: convert app locks

We use locks like tcp_app_lock, udp_app_lock,
sctp_app_lock to protect access to the protocol hash tables
from readers in packet context while the application
instances (inc) are [un]registered under global mutex.

As the hash tables are mostly read when conns are
created and bound to app, use RCU for readers and reclaim
app instance after grace period.

Simplify ip_vs_app_inc_get because we use usecnt
only for statistics and rely on module refcounting.

Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off by: Hans Schillstrom <hans@schillstrom.com>
Signed-off-by: Simon Horman <horms@verge.net.au>

1 files changed, 6 insertions, 12 deletions

diff --git a/net/netfilter/ipvs/ip_vs_proto_tcp.c b/net/netfilter/ipvs/ip_vs_proto_tcp.c
index 9af653a75825..0bbc3feae682 100644
--- a/net/netfilter/ipvs/ip_vs_proto_tcp.c
+++ b/net/netfilter/ipvs/ip_vs_proto_tcp.c
@@ -580,18 +580,16 @@ static int tcp_register_app(struct net *net, struct ip_vs_app *inc)
 
 	hash = tcp_app_hashkey(port);
 
-	spin_lock_bh(&ipvs->tcp_app_lock);
 	list_for_each_entry(i, &ipvs->tcp_apps[hash], p_list) {
 		if (i->port == port) {
 			ret = -EEXIST;
 			goto out;
 		}
 	}
-	list_add(&inc->p_list, &ipvs->tcp_apps[hash]);
+	list_add_rcu(&inc->p_list, &ipvs->tcp_apps[hash]);
 	atomic_inc(&pd->appcnt);
 
   out:
-	spin_unlock_bh(&ipvs->tcp_app_lock);
 	return ret;
 }
 
@@ -599,13 +597,10 @@ static int tcp_register_app(struct net *net, struct ip_vs_app *inc)
 static void
 tcp_unregister_app(struct net *net, struct ip_vs_app *inc)
 {
-	struct netns_ipvs *ipvs = net_ipvs(net);
 	struct ip_vs_proto_data *pd = ip_vs_proto_data_get(net, IPPROTO_TCP);
 
-	spin_lock_bh(&ipvs->tcp_app_lock);
 	atomic_dec(&pd->appcnt);
-	list_del(&inc->p_list);
-	spin_unlock_bh(&ipvs->tcp_app_lock);
+	list_del_rcu(&inc->p_list);
 }
 
 
@@ -624,12 +619,12 @@ tcp_app_conn_bind(struct ip_vs_conn *cp)
 	/* Lookup application incarnations and bind the right one */
 	hash = tcp_app_hashkey(cp->vport);
 
-	spin_lock(&ipvs->tcp_app_lock);
-	list_for_each_entry(inc, &ipvs->tcp_apps[hash], p_list) {
+	rcu_read_lock();
+	list_for_each_entry_rcu(inc, &ipvs->tcp_apps[hash], p_list) {
 		if (inc->port == cp->vport) {
 			if (unlikely(!ip_vs_app_inc_get(inc)))
 				break;
-			spin_unlock(&ipvs->tcp_app_lock);
+			rcu_read_unlock();
 
 			IP_VS_DBG_BUF(9, "%s(): Binding conn %s:%u->"
 				      "%s:%u to app %s on port %u\n",
@@ -646,7 +641,7 @@ tcp_app_conn_bind(struct ip_vs_conn *cp)
 			goto out;
 		}
 	}
-	spin_unlock(&ipvs->tcp_app_lock);
+	rcu_read_unlock();
 
   out:
 	return result;
@@ -676,7 +671,6 @@ static int __ip_vs_tcp_init(struct net *net, struct ip_vs_proto_data *pd)
 	struct netns_ipvs *ipvs = net_ipvs(net);
 
 	ip_vs_init_hash_table(ipvs->tcp_apps, TCP_APP_TAB_SIZE);
-	spin_lock_init(&ipvs->tcp_app_lock);
 	pd->timeout_table = ip_vs_create_timeout_table((int *)tcp_timeouts,
 							sizeof(tcp_timeouts));
 	if (!pd->timeout_table)