[PATCH RFC net-next 1/4] inet: Add a count to struct inet_listen_hashbucket

[Martin KaFai Lau]

This patch adds a count to the 'struct inet_listen_hashbucket'.
It counts how many sk is hashed to a bucket.  It will be
used to decide if the (to-be-added) portaddr listener's hashtable
should be used during inet[6]_lookup_listener().

Signed-off-by: Martin KaFai Lau <ka...@fb.com>
---
 include/net/inet_hashtables.h |  1 +
 net/ipv4/inet_hashtables.c    | 11 +++++++++--
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h
index 2dbbbff5e1e3..4cce516c41ac 100644
--- a/include/net/inet_hashtables.h
+++ b/include/net/inet_hashtables.h
@@ -111,6 +111,7 @@ struct inet_bind_hashbucket {
  */
 struct inet_listen_hashbucket {
        spinlock_t              lock;
+       unsigned int            count;
        struct hlist_head       head;
 };
 
diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index e7d15fb0d94d..bf16aa852aa3 100644
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -483,6 +483,7 @@ int __inet_hash(struct sock *sk, struct sock *osk)
                hlist_add_tail_rcu(&sk->sk_node, &ilb->head);
        else
                hlist_add_head_rcu(&sk->sk_node, &ilb->head);
+       ilb->count++;
        sock_set_flag(sk, SOCK_RCU_FREE);
        sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
 unlock:
@@ -509,6 +510,7 @@ EXPORT_SYMBOL_GPL(inet_hash);
 void inet_unhash(struct sock *sk)
 {
        struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
+       struct inet_listen_hashbucket *ilb;
        spinlock_t *lock;
        bool listener = false;
        int done;
@@ -517,7 +519,8 @@ void inet_unhash(struct sock *sk)
                return;
 
        if (sk->sk_state == TCP_LISTEN) {
-               lock = 
&hashinfo->listening_hash[inet_sk_listen_hashfn(sk)].lock;
+               ilb = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
+               lock = &ilb->lock;
                listener = true;
        } else {
                lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
@@ -529,8 +532,11 @@ void inet_unhash(struct sock *sk)
                done = __sk_del_node_init(sk);
        else
                done = __sk_nulls_del_node_init_rcu(sk);
-       if (done)
+       if (done) {
+               if (listener)
+                       ilb->count--;
                sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
+       }
        spin_unlock_bh(lock);
 }
 EXPORT_SYMBOL_GPL(inet_unhash);
@@ -665,6 +671,7 @@ void inet_hashinfo_init(struct inet_hashinfo *h)
        for (i = 0; i < INET_LHTABLE_SIZE; i++) {
                spin_lock_init(&h->listening_hash[i].lock);
                INIT_HLIST_HEAD(&h->listening_hash[i].head);
+               h->listening_hash[i].count = 0;
        }
 }
 EXPORT_SYMBOL_GPL(inet_hashinfo_init);
-- 
2.9.5