net: refactor bind_bucket fastreuse into helper

Refactor the fastreuse update code in inet_csk_get_port into a small
helper function that can be called from other places.

Acked-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Tim Froidcoeur <tim.froidcoeur@tessares.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/inet_connection_sock.h

@@ -304,6 +304,10 @@ void inet_csk_listen_stop(struct sock *sk);
 
 void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr);
 
+/* update the fast reuse flag when adding a socket */
+void inet_csk_update_fastreuse(struct inet_bind_bucket *tb,
+			       struct sock *sk);
+
 struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu);
 
 #define TCP_PINGPONG_THRESH	3

net/ipv4/inet_connection_sock.c

@@ -296,6 +296,57 @@ static inline int sk_reuseport_match(struct inet_bind_bucket *tb,
 				    ipv6_only_sock(sk), true, false);
 }
 
+void inet_csk_update_fastreuse(struct inet_bind_bucket *tb,
+			       struct sock *sk)
+{
+	kuid_t uid = sock_i_uid(sk);
+	bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
+
+	if (hlist_empty(&tb->owners)) {
+		tb->fastreuse = reuse;
+		if (sk->sk_reuseport) {
+			tb->fastreuseport = FASTREUSEPORT_ANY;
+			tb->fastuid = uid;
+			tb->fast_rcv_saddr = sk->sk_rcv_saddr;
+			tb->fast_ipv6_only = ipv6_only_sock(sk);
+			tb->fast_sk_family = sk->sk_family;
+#if IS_ENABLED(CONFIG_IPV6)
+			tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
+#endif
+		} else {
+			tb->fastreuseport = 0;
+		}
+	} else {
+		if (!reuse)
+			tb->fastreuse = 0;
+		if (sk->sk_reuseport) {
+			/* We didn't match or we don't have fastreuseport set on
+			 * the tb, but we have sk_reuseport set on this socket
+			 * and we know that there are no bind conflicts with
+			 * this socket in this tb, so reset our tb's reuseport
+			 * settings so that any subsequent sockets that match
+			 * our current socket will be put on the fast path.
+			 *
+			 * If we reset we need to set FASTREUSEPORT_STRICT so we
+			 * do extra checking for all subsequent sk_reuseport
+			 * socks.
+			 */
+			if (!sk_reuseport_match(tb, sk)) {
+				tb->fastreuseport = FASTREUSEPORT_STRICT;
+				tb->fastuid = uid;
+				tb->fast_rcv_saddr = sk->sk_rcv_saddr;
+				tb->fast_ipv6_only = ipv6_only_sock(sk);
+				tb->fast_sk_family = sk->sk_family;
+#if IS_ENABLED(CONFIG_IPV6)
+				tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
+#endif
+			}
+		} else {
+			tb->fastreuseport = 0;
+		}
+	}
+}
+
 /* Obtain a reference to a local port for the given sock,
  * if snum is zero it means select any available local port.
  * We try to allocate an odd port (and leave even ports for connect())
@@ -308,7 +359,6 @@ int inet_csk_get_port(struct sock *sk, unsigned short snum)
 	struct inet_bind_hashbucket *head;
 	struct net *net = sock_net(sk);
 	struct inet_bind_bucket *tb = NULL;
-	kuid_t uid = sock_i_uid(sk);
 	int l3mdev;
 
 	l3mdev = inet_sk_bound_l3mdev(sk);
@@ -345,49 +395,8 @@ int inet_csk_get_port(struct sock *sk, unsigned short snum)
 			goto fail_unlock;
 	}
 success:
-	if (hlist_empty(&tb->owners)) {
-		tb->fastreuse = reuse;
-		if (sk->sk_reuseport) {
-			tb->fastreuseport = FASTREUSEPORT_ANY;
-			tb->fastuid = uid;
-			tb->fast_rcv_saddr = sk->sk_rcv_saddr;
-			tb->fast_ipv6_only = ipv6_only_sock(sk);
-			tb->fast_sk_family = sk->sk_family;
-#if IS_ENABLED(CONFIG_IPV6)
-			tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
-#endif
-		} else {
-			tb->fastreuseport = 0;
-		}
-	} else {
-		if (!reuse)
-			tb->fastreuse = 0;
-		if (sk->sk_reuseport) {
-			/* We didn't match or we don't have fastreuseport set on
-			 * the tb, but we have sk_reuseport set on this socket
-			 * and we know that there are no bind conflicts with
-			 * this socket in this tb, so reset our tb's reuseport
-			 * settings so that any subsequent sockets that match
-			 * our current socket will be put on the fast path.
-			 *
-			 * If we reset we need to set FASTREUSEPORT_STRICT so we
-			 * do extra checking for all subsequent sk_reuseport
-			 * socks.
-			 */
-			if (!sk_reuseport_match(tb, sk)) {
-				tb->fastreuseport = FASTREUSEPORT_STRICT;
-				tb->fastuid = uid;
-				tb->fast_rcv_saddr = sk->sk_rcv_saddr;
-				tb->fast_ipv6_only = ipv6_only_sock(sk);
-				tb->fast_sk_family = sk->sk_family;
-#if IS_ENABLED(CONFIG_IPV6)
-				tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
-#endif
-			}
-		} else {
-			tb->fastreuseport = 0;
-		}
-	}
+	inet_csk_update_fastreuse(tb, sk);
+
 	if (!inet_csk(sk)->icsk_bind_hash)
 		inet_bind_hash(sk, tb, port);
 	WARN_ON(inet_csk(sk)->icsk_bind_hash != tb);