tcp: don't check mtu probe completion in the loop

It seems that no variables clash such that we couldn't do
the check just once later on. Therefore move it.

Also kill dead obvious comment, dead argument and add
unlikely since this mtu probe does not happen too often.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index b7d02c5..311c30f 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2836,7 +2836,7 @@
 	icsk->icsk_mtup.probe_size = 0;
 }
 
-static void tcp_mtup_probe_success(struct sock *sk, struct sk_buff *skb)
+static void tcp_mtup_probe_success(struct sock *sk)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	struct inet_connection_sock *icsk = inet_csk(sk);
@@ -3219,12 +3219,6 @@
 			acked_pcount = tcp_skb_pcount(skb);
 		}
 
-		/* MTU probing checks */
-		if (fully_acked && icsk->icsk_mtup.probe_size &&
-		    !after(tp->mtu_probe.probe_seq_end, scb->end_seq)) {
-			tcp_mtup_probe_success(sk, skb);
-		}
-
 		if (sacked & TCPCB_RETRANS) {
 			if (sacked & TCPCB_SACKED_RETRANS)
 				tp->retrans_out -= acked_pcount;
@@ -3287,6 +3281,11 @@
 		const struct tcp_congestion_ops *ca_ops
 			= inet_csk(sk)->icsk_ca_ops;
 
+		if (unlikely(icsk->icsk_mtup.probe_size &&
+			     !after(tp->mtu_probe.probe_seq_end, tp->snd_una))) {
+			tcp_mtup_probe_success(sk);
+		}
+
 		tcp_ack_update_rtt(sk, flag, seq_rtt);
 		tcp_rearm_rto(sk);