net: listening_hash get a spinlock per bucket

This patch prepares RCU migration of listening_hash table for
TCP/DCCP protocols.

listening_hash table being small (32 slots per protocol), we add
a spinlock for each slot, instead of a single rwlock for whole table.

This should reduce hold time of readers, and writers concurrency.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 12 insertions, 11 deletions

diff --git a/net/ipv6/inet6_hashtables.c b/net/ipv6/inet6_hashtables.c
index c1b4d401fd95..21544b9be259 100644
--- a/net/ipv6/inet6_hashtables.c
+++ b/net/ipv6/inet6_hashtables.c
@@ -25,30 +25,30 @@
 void __inet6_hash(struct sock *sk)
 {
         struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
-        rwlock_t *lock;
 
         WARN_ON(!sk_unhashed(sk));
 
         if (sk->sk_state == TCP_LISTEN) {
-                struct hlist_head *list;
+                struct inet_listen_hashbucket *ilb;
 
-                list = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
-                lock = &hashinfo->lhash_lock;
-                inet_listen_wlock(hashinfo);
-                __sk_add_node(sk, list);
+                ilb = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
+                spin_lock(&ilb->lock);
+                __sk_add_node(sk, &ilb->head);
+                spin_unlock(&ilb->lock);
         } else {
                 unsigned int hash;
                 struct hlist_nulls_head *list;
+                rwlock_t *lock;
 
                 sk->sk_hash = hash = inet6_sk_ehashfn(sk);
                 list = &inet_ehash_bucket(hashinfo, hash)->chain;
                 lock = inet_ehash_lockp(hashinfo, hash);
                 write_lock(lock);
                 __sk_nulls_add_node_rcu(sk, list);
+                write_unlock(lock);
         }
 
         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
-        write_unlock(lock);
 }
 EXPORT_SYMBOL(__inet6_hash);
 
@@ -126,10 +126,11 @@ struct sock *inet6_lookup_listener(struct net *net,
         const struct hlist_node *node;
         struct sock *result = NULL;
         int score, hiscore = 0;
+        struct inet_listen_hashbucket *ilb;
 
-        read_lock(&hashinfo->lhash_lock);
-        sk_for_each(sk, node,
-                        &hashinfo->listening_hash[inet_lhashfn(net, hnum)]) {
+        ilb = &hashinfo->listening_hash[inet_lhashfn(net, hnum)];
+        spin_lock(&ilb->lock);
+        sk_for_each(sk, node, &ilb->head) {
                 if (net_eq(sock_net(sk), net) && inet_sk(sk)->num == hnum &&
                                 sk->sk_family == PF_INET6) {
                         const struct ipv6_pinfo *np = inet6_sk(sk);
@@ -157,7 +158,7 @@ struct sock *inet6_lookup_listener(struct net *net,
         }
         if (result)
                 sock_hold(result);
-        read_unlock(&hashinfo->lhash_lock);
+        spin_unlock(&ilb->lock);
         return result;
 }