llc: optimize multicast delivery
Octavian Purdila [Sat, 26 Dec 2009 11:51:03 +0000 (11:51 +0000)]
Optimize multicast delivery by doing the actual delivery without
holding the lock. Based on the same approach used in UDP code.

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

net/llc/llc_sap.c

index 39760d0..94790e6 100644 (file)
@@ -355,6 +355,24 @@ static inline bool llc_mcast_match(const struct llc_sap *sap,
          llc->dev == skb->dev;
 }
 
+static void llc_do_mcast(struct llc_sap *sap, struct sk_buff *skb,
+                        struct sock **stack, int count)
+{
+       struct sk_buff *skb1;
+       int i;
+
+       for (i = 0; i < count; i++) {
+               skb1 = skb_clone(skb, GFP_ATOMIC);
+               if (!skb1) {
+                       sock_put(stack[i]);
+                       continue;
+               }
+
+               llc_sap_rcv(sap, skb1, stack[i]);
+               sock_put(stack[i]);
+       }
+}
+
 /**
  *     llc_sap_mcast - Deliver multicast PDU's to all matching datagram sockets.
  *     @sap: SAP
@@ -367,25 +385,27 @@ static void llc_sap_mcast(struct llc_sap *sap,
                          const struct llc_addr *laddr,
                          struct sk_buff *skb)
 {
-       struct sock *sk;
+       int i = 0, count = 256 / sizeof(struct sock *);
+       struct sock *sk, *stack[count];
        struct hlist_nulls_node *node;
 
        spin_lock_bh(&sap->sk_lock);
        sk_nulls_for_each_rcu(sk, node, &sap->sk_list) {
-               struct sk_buff *skb1;
 
                if (!llc_mcast_match(sap, laddr, skb, sk))
                        continue;
 
-               skb1 = skb_clone(skb, GFP_ATOMIC);
-               if (!skb1)
-                       break;
-
                sock_hold(sk);
-               llc_sap_rcv(sap, skb1, sk);
-               sock_put(sk);
+               if (i < count)
+                       stack[i++] = sk;
+               else {
+                       llc_do_mcast(sap, skb, stack, i);
+                       i = 0;
+               }
        }
        spin_unlock_bh(&sap->sk_lock);
+
+       llc_do_mcast(sap, skb, stack, i);
 }