udp: RCU handling for Unicast packets.

[mv-sheeva.git] / net / ipv6 / udp.c

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index ccee7244ca0ffe4c7429f22e12d52e0b262db77a..1d9790e43dfcb977bc28ec22093b62b64c5f52df 100644 (file)
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -97,24 +97,40 @@ static struct sock *__udp6_lib_lookup(struct net *net,
                                      struct in6_addr *daddr, __be16 dport,
                                      int dif, struct udp_table *udptable)
 {
-       struct sock *sk, *result = NULL;
+       struct sock *sk, *result;
        struct hlist_node *node;
        unsigned short hnum = ntohs(dport);
        unsigned int hash = udp_hashfn(net, hnum);
        struct udp_hslot *hslot = &udptable->hash[hash];
-       int score, badness = -1;
+       int score, badness;
 
-       spin_lock(&hslot->lock);
-       sk_for_each(sk, node, &hslot->head) {
+       rcu_read_lock();
+begin:
+       result = NULL;
+       badness = -1;
+       sk_for_each_rcu(sk, node, &hslot->head) {
+               /*
+                * lockless reader, and SLAB_DESTROY_BY_RCU items:
+                * We must check this item was not moved to another chain
+                */
+               if (udp_hashfn(net, sk->sk_hash) != hash)
+                       goto begin;
                score = compute_score(sk, net, hnum, saddr, sport, daddr, dport, dif);
                if (score > badness) {
                        result = sk;
                        badness = score;
                }
        }
-       if (result)
-               sock_hold(result);
-       spin_unlock(&hslot->lock);
+       if (result) {
+               if (unlikely(!atomic_inc_not_zero(&result->sk_refcnt)))
+                       result = NULL;
+               else if (unlikely(compute_score(result, net, hnum, saddr, sport,
+                                       daddr, dport, dif) < badness)) {
+                       sock_put(result);
+                       goto begin;
+               }
+       }
+       rcu_read_unlock();
        return result;
 }
 
@@ -1062,6 +1078,7 @@ struct proto udpv6_prot = {
        .sysctl_wmem       = &sysctl_udp_wmem_min,
        .sysctl_rmem       = &sysctl_udp_rmem_min,
        .obj_size          = sizeof(struct udp6_sock),
+       .slab_flags        = SLAB_DESTROY_BY_RCU,
        .h.udp_table       = &udp_table,
 #ifdef CONFIG_COMPAT
        .compat_setsockopt = compat_udpv6_setsockopt,