inet: don't check for bind conflicts twice when searching for a port

This is just wasted time, we've already found a tb that doesn't have a bind
conflict, and we don't drop the head lock so scanning again isn't going to give
us a different answer.  Instead move the tb->reuse setting logic outside of the
found_tb path and put it in the success: path.  Then make it so that we don't
goto again if we find a bind conflict in the found_tb path as we won't reach
this anymore when we are scanning for an ephemeral port.

Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index d3523661c9057828ed763df07459747431cb8cd3..f7e844d84836088d7f7969e118f30e2de98ecf3c 100644 (file)
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -164,7 +164,7 @@ int inet_csk_get_port(struct sock *sk, unsigned short snum)
 {
        bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
        struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo;
-       int ret = 1, attempts = 5, port = snum;
+       int ret = 1, port = snum;
        struct inet_bind_hashbucket *head;
        struct net *net = sock_net(sk);
        int i, low, high, attempt_half;
@@ -183,7 +183,6 @@ int inet_csk_get_port(struct sock *sk, unsigned short snum)
 
                goto tb_not_found;
        }
-again:
        attempt_half = (sk->sk_reuse == SK_CAN_REUSE) ? 1 : 0;
 other_half_scan:
        inet_get_local_port_range(net, &low, &high);
@@ -221,7 +220,7 @@ other_parity_scan:
                inet_bind_bucket_for_each(tb, &head->chain)
                        if (net_eq(ib_net(tb), net) && tb->port == port) {
                                if (!inet_csk_bind_conflict(sk, tb, false, reuseport_ok))
-                                       goto tb_found;
+                                       goto success;
                                goto next_port;
                        }
                goto tb_not_found;
@@ -256,23 +255,11 @@ tb_found:
                      !rcu_access_pointer(sk->sk_reuseport_cb) &&
                      sk->sk_reuseport && uid_eq(tb->fastuid, uid)))
                        goto success;
-               if (inet_csk_bind_conflict(sk, tb, true, reuseport_ok)) {
-                       if ((reuse ||
-                            (tb->fastreuseport > 0 &&
-                             sk->sk_reuseport &&
-                             !rcu_access_pointer(sk->sk_reuseport_cb) &&
-                             uid_eq(tb->fastuid, uid))) && !snum &&
-                           --attempts >= 0) {
-                               spin_unlock_bh(&head->lock);
-                               goto again;
-                       }
+               if (inet_csk_bind_conflict(sk, tb, true, reuseport_ok))
                        goto fail_unlock;
-               }
-               if (!reuse)
-                       tb->fastreuse = 0;
-               if (!sk->sk_reuseport || !uid_eq(tb->fastuid, uid))
-                       tb->fastreuseport = 0;
-       } else {
+       }
+success:
+       if (!hlist_empty(&tb->owners)) {
                tb->fastreuse = reuse;
                if (sk->sk_reuseport) {
                        tb->fastreuseport = 1;
@@ -280,8 +267,12 @@ tb_found:
                } else {
                        tb->fastreuseport = 0;
                }
+       } else {
+               if (!reuse)
+                       tb->fastreuse = 0;
+               if (!sk->sk_reuseport || !uid_eq(tb->fastuid, uid))
+                       tb->fastreuseport = 0;
        }
-success:
        if (!inet_csk(sk)->icsk_bind_hash)
                inet_bind_hash(sk, tb, port);
        WARN_ON(inet_csk(sk)->icsk_bind_hash != tb);