udp: secondary hash on (local port, local address)

Extends udp_table to contain a secondary hash table.

socket anchor for this second hash is free, because UDP
doesnt use skc_bind_node : We define an union to hold
both skc_bind_node & a new hlist_nulls_node udp_portaddr_node

udp_lib_get_port() inserts sockets into second hash chain
(additional cost of one atomic op)

udp_lib_unhash() deletes socket from second hash chain
(additional cost of one atomic op)

Note : No spinlock lockdep annotation is needed, because
lock for the secondary hash chain is always get after
lock for primary hash chain.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 26 insertions, 5 deletions

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index af72de1c8690..5f04216f35ce 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -163,7 +163,7 @@ int udp_lib_get_port(struct sock *sk, unsigned short snum,
                        int (*saddr_comp)(const struct sock *sk1,
                                          const struct sock *sk2))
 {
-        struct udp_hslot *hslot;
+        struct udp_hslot *hslot, *hslot2;
         struct udp_table *udptable = sk->sk_prot->h.udp_table;
         int    error = 1;
         struct net *net = sock_net(sk);
@@ -222,6 +222,13 @@ found:
                 sk_nulls_add_node_rcu(sk, &hslot->head);
                 hslot->count++;
                 sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
+
+                hslot2 = udp_hashslot2(udptable, udp_sk(sk)->udp_portaddr_hash);
+                spin_lock(&hslot2->lock);
+                hlist_nulls_add_head_rcu(&udp_sk(sk)->udp_portaddr_node,
+                                         &hslot2->head);
+                hslot2->count++;
+                spin_unlock(&hslot2->lock);
         }
         error = 0;
 fail_unlock:
@@ -1062,14 +1069,22 @@ void udp_lib_unhash(struct sock *sk)
 {
         if (sk_hashed(sk)) {
                 struct udp_table *udptable = sk->sk_prot->h.udp_table;
-                struct udp_hslot *hslot = udp_hashslot(udptable, sock_net(sk),
-                                                       udp_sk(sk)->udp_port_hash);
+                struct udp_hslot *hslot, *hslot2;
+
+                hslot  = udp_hashslot(udptable, sock_net(sk),
+                                      udp_sk(sk)->udp_port_hash);
+                hslot2 = udp_hashslot2(udptable, udp_sk(sk)->udp_portaddr_hash);
 
                 spin_lock_bh(&hslot->lock);
                 if (sk_nulls_del_node_init_rcu(sk)) {
                         hslot->count--;
                         inet_sk(sk)->inet_num = 0;
                         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
+
+                        spin_lock(&hslot2->lock);
+                        hlist_nulls_del_init_rcu(&udp_sk(sk)->udp_portaddr_node);
+                        hslot2->count--;
+                        spin_unlock(&hslot2->lock);
                 }
                 spin_unlock_bh(&hslot->lock);
         }
@@ -1857,7 +1872,7 @@ void __init udp_table_init(struct udp_table *table, const char *name)
 
         if (!CONFIG_BASE_SMALL)
                 table->hash = alloc_large_system_hash(name,
-                        sizeof(struct udp_hslot),
+                        2 * sizeof(struct udp_hslot),
                         uhash_entries,
                         21, /* one slot per 2 MB */
                         0,
@@ -1869,17 +1884,23 @@ void __init udp_table_init(struct udp_table *table, const char *name)
          */
         if (CONFIG_BASE_SMALL || table->mask < UDP_HTABLE_SIZE_MIN - 1) {
                 table->hash = kmalloc(UDP_HTABLE_SIZE_MIN *
-                                      sizeof(struct udp_hslot), GFP_KERNEL);
+                                      2 * sizeof(struct udp_hslot), GFP_KERNEL);
                 if (!table->hash)
                         panic(name);
                 table->log = ilog2(UDP_HTABLE_SIZE_MIN);
                 table->mask = UDP_HTABLE_SIZE_MIN - 1;
         }
+        table->hash2 = table->hash + (table->mask + 1);
         for (i = 0; i <= table->mask; i++) {
                 INIT_HLIST_NULLS_HEAD(&table->hash[i].head, i);
                 table->hash[i].count = 0;
                 spin_lock_init(&table->hash[i].lock);
         }
+        for (i = 0; i <= table->mask; i++) {
+                INIT_HLIST_NULLS_HEAD(&table->hash2[i].head, i);
+                table->hash2[i].count = 0;
+                spin_lock_init(&table->hash2[i].lock);
+        }
 }
 
 void __init udp_init(void)