tcp: tcp_mtu_probing() cleanup

Reduce one indentation level to make code more readable.
tcp_sync_mss() can be factorized.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/tcp_timer.c

@@ -107,26 +107,23 @@ static int tcp_orphan_retries(struct sock *sk, bool alive)
 
 static void tcp_mtu_probing(struct inet_connection_sock *icsk, struct sock *sk)
 {
-	struct net *net = sock_net(sk);
+	const struct net *net = sock_net(sk);
+	int mss;
 
 	/* Black hole detection */
-	if (net->ipv4.sysctl_tcp_mtu_probing) {
-		if (!icsk->icsk_mtup.enabled) {
-			icsk->icsk_mtup.enabled = 1;
-			icsk->icsk_mtup.probe_timestamp = tcp_jiffies32;
-			tcp_sync_mss(sk, icsk->icsk_pmtu_cookie);
-		} else {
-			struct net *net = sock_net(sk);
-			struct tcp_sock *tp = tcp_sk(sk);
-			int mss;
-
-			mss = tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low) >> 1;
-			mss = min(net->ipv4.sysctl_tcp_base_mss, mss);
-			mss = max(mss, 68 - tp->tcp_header_len);
-			icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss);
-			tcp_sync_mss(sk, icsk->icsk_pmtu_cookie);
-		}
+	if (!net->ipv4.sysctl_tcp_mtu_probing)
+		return;
+
+	if (!icsk->icsk_mtup.enabled) {
+		icsk->icsk_mtup.enabled = 1;
+		icsk->icsk_mtup.probe_timestamp = tcp_jiffies32;
+	} else {
+		mss = tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low) >> 1;
+		mss = min(net->ipv4.sysctl_tcp_base_mss, mss);
+		mss = max(mss, 68 - tcp_sk(sk)->tcp_header_len);
+		icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss);
 	}
+	tcp_sync_mss(sk, icsk->icsk_pmtu_cookie);
 }