tcp: remove tp->lost_out guard to make joining diff nicer

The validity of the retransmit_high must then be ensured
if no L'ed skb exits!

This makes a minor change to behavior, we now have to
iterate the head to find out that the loop terminates.
Signed-off-by: NIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/tcp_output.c

@@ -2034,13 +2034,15 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
 	struct sk_buff *skb;
 	int mib_idx;
 
+	if (!tp->lost_out)
+		tp->retransmit_high = tp->snd_una;
+
 	if (tp->retransmit_skb_hint)
 		skb = tp->retransmit_skb_hint;
 	else
 		skb = tcp_write_queue_head(sk);
 
 	/* First pass: retransmit lost packets. */
-	if (tp->lost_out) {
 	tcp_for_write_queue_from(skb, sk) {
 		__u8 sacked = TCP_SKB_CB(skb)->sacked;
 
@@ -2081,7 +2083,6 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
 						  inet_csk(sk)->icsk_rto,
 						  TCP_RTO_MAX);
 	}
-	}
 
 	/* OK, demanded retransmission is finished. */
 	if (!tcp_can_forward_retransmit(sk))