llc: optimize multicast delivery

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>

1 files changed, 28 insertions, 8 deletions

diff --git a/net/llc/llc_sap.c b/net/llc/llc_sap.c
index 39760d013ce2..94790e60d072 100644
--- a/net/llc/llc_sap.c
+++ b/net/llc/llc_sap.c
@@ -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);
 }