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>

4 files changed, 53 insertions, 9 deletions

diff --git a/include/linux/udp.h b/include/linux/udp.h
index 5b4b5274e683..59f0ddf2d284 100644
--- a/include/linux/udp.h
+++ b/include/linux/udp.h
@@ -57,6 +57,7 @@ struct udp_sock {
         struct inet_sock inet;
 #define udp_port_hash           inet.sk.__sk_common.skc_u16hashes[0]
 #define udp_portaddr_hash       inet.sk.__sk_common.skc_u16hashes[1]
+#define udp_portaddr_node       inet.sk.__sk_common.skc_portaddr_node
         int              pending;       /* Any pending frames ? */
         unsigned int     corkflag;      /* Cork is required */
         __u16            encap_type;    /* Is this an Encapsulation socket? */
diff --git a/include/net/sock.h b/include/net/sock.h
index 827366b62680..3f1a4804bb3f 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -105,7 +105,7 @@ struct net;
 /**
  *      struct sock_common - minimal network layer representation of sockets
  *      @skc_node: main hash linkage for various protocol lookup tables
- *      @skc_nulls_node: main hash linkage for UDP/UDP-Lite protocol
+ *      @skc_nulls_node: main hash linkage for TCP/UDP/UDP-Lite protocol
  *      @skc_refcnt: reference count
  *      @skc_tx_queue_mapping: tx queue number for this connection
  *      @skc_hash: hash value used with various protocol lookup tables
@@ -115,6 +115,7 @@ struct net;
  *      @skc_reuse: %SO_REUSEADDR setting
  *      @skc_bound_dev_if: bound device index if != 0
  *      @skc_bind_node: bind hash linkage for various protocol lookup tables
+ *      @skc_portaddr_node: second hash linkage for UDP/UDP-Lite protocol
  *      @skc_prot: protocol handlers inside a network family
  *      @skc_net: reference to the network namespace of this socket
  *
@@ -140,7 +141,10 @@ struct sock_common {
         volatile unsigned char  skc_state;
         unsigned char           skc_reuse;
         int                     skc_bound_dev_if;
-        struct hlist_node       skc_bind_node;
+        union {
+                struct hlist_node       skc_bind_node;
+                struct hlist_nulls_node skc_portaddr_node;
+        };
         struct proto            *skc_prot;
 #ifdef CONFIG_NET_NS
         struct net              *skc_net;
diff --git a/include/net/udp.h b/include/net/udp.h
index 9167281e47dc..af41850f742a 100644
--- a/include/net/udp.h
+++ b/include/net/udp.h
@@ -63,10 +63,19 @@ struct udp_hslot {
         spinlock_t              lock;
 } __attribute__((aligned(2 * sizeof(long))));
 
+/**
+ *      struct udp_table - UDP table
+ *
+ *      @hash:  hash table, sockets are hashed on (local port)
+ *      @hash2: hash table, sockets are hashed on (local port, local address)
+ *      @mask:  number of slots in hash tables, minus 1
+ *      @log:   log2(number of slots in hash table)
+ */
 struct udp_table {
         struct udp_hslot        *hash;
-        unsigned int mask;
-        unsigned int log;
+        struct udp_hslot        *hash2;
+        unsigned int            mask;
+        unsigned int            log;
 };
 extern struct udp_table udp_table;
 extern void udp_table_init(struct udp_table *, const char *);
@@ -75,6 +84,15 @@ static inline struct udp_hslot *udp_hashslot(struct udp_table *table,
 {
         return &table->hash[udp_hashfn(net, num, table->mask)];
 }
+/*
+ * For secondary hash, net_hash_mix() is performed before calling
+ * udp_hashslot2(), this explains difference with udp_hashslot()
+ */
+static inline struct udp_hslot *udp_hashslot2(struct udp_table *table,
+                                              unsigned int hash)
+{
+        return &table->hash2[hash & table->mask];
+}
 
 /* Note: this must match 'valbool' in sock_setsockopt */
 #define UDP_CSUM_NOXMIT         1
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)