llc: use a device based hash table to speed up multicast delivery

This patch adds a per SAP device based hash table to solve the
multicast delivery scalability issue when we have large number of
interfaces and a large number of sockets bound to the same SAP.

Signed-off-by: Octavian Purdila <opurdila@ixiacom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 15 insertions, 3 deletions

diff --git a/net/llc/llc_conn.c b/net/llc/llc_conn.c
index 77bb3816655e..10cdfe2db830 100644
--- a/net/llc/llc_conn.c
+++ b/net/llc/llc_conn.c
@@ -682,10 +682,15 @@ static int llc_find_offset(int state, int ev_type)
  */
 void llc_sap_add_socket(struct llc_sap *sap, struct sock *sk)
 {
+        struct llc_sock *llc = llc_sk(sk);
+        struct hlist_head *dev_hb = llc_sk_dev_hash(sap, llc->dev->ifindex);
+
         llc_sap_hold(sap);
-        spin_lock_bh(&sap->sk_lock);
         llc_sk(sk)->sap = sap;
+
+        spin_lock_bh(&sap->sk_lock);
         sk_nulls_add_node_rcu(sk, &sap->sk_list);
+        hlist_add_head(&llc->dev_hash_node, dev_hb);
         spin_unlock_bh(&sap->sk_lock);
 }
 
@@ -699,8 +704,11 @@ void llc_sap_add_socket(struct llc_sap *sap, struct sock *sk)
  */
 void llc_sap_remove_socket(struct llc_sap *sap, struct sock *sk)
 {
+        struct llc_sock *llc = llc_sk(sk);
+
         spin_lock_bh(&sap->sk_lock);
         sk_nulls_del_node_init_rcu(sk);
+        hlist_del(&llc->dev_hash_node);
         spin_unlock_bh(&sap->sk_lock);
         llc_sap_put(sap);
 }
diff --git a/net/llc/llc_sap.c b/net/llc/llc_sap.c
index 94790e60d072..94cb706f6cc4 100644
--- a/net/llc/llc_sap.c
+++ b/net/llc/llc_sap.c
@@ -387,10 +387,14 @@ static void llc_sap_mcast(struct llc_sap *sap,
 {
         int i = 0, count = 256 / sizeof(struct sock *);
         struct sock *sk, *stack[count];
-        struct hlist_nulls_node *node;
+        struct hlist_node *node;
+        struct llc_sock *llc;
+        struct hlist_head *dev_hb = llc_sk_dev_hash(sap, skb->dev->ifindex);
 
         spin_lock_bh(&sap->sk_lock);
-        sk_nulls_for_each_rcu(sk, node, &sap->sk_list) {
+        hlist_for_each_entry(llc, node, dev_hb, dev_hash_node) {
+
+                sk = &llc->sk;
 
                 if (!llc_mcast_match(sap, laddr, skb, sk))
                         continue;