tcp: No need to clear retransmit_skb_hint when SACKing

Because lost counter no longer requires tuning, this is
trivial to remove (the tuning wouldn't have been too
hard either) because no "new" retransmittable skb appeared
below retransmit_skb_hint when SACKing for sure.
Signed-off-by: NIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/tcp_input.c

@@ -1298,9 +1298,6 @@ static int tcp_sacktag_one(struct sk_buff *skb, struct sock *sk,
 					~(TCPCB_LOST|TCPCB_SACKED_RETRANS);
 				tp->lost_out -= tcp_skb_pcount(skb);
 				tp->retrans_out -= tcp_skb_pcount(skb);
-
-				/* clear lost hint */
-				tp->retransmit_skb_hint = NULL;
 			}
 		} else {
 			if (!(sacked & TCPCB_RETRANS)) {
@@ -1319,9 +1316,6 @@ static int tcp_sacktag_one(struct sk_buff *skb, struct sock *sk,
 			if (sacked & TCPCB_LOST) {
 				TCP_SKB_CB(skb)->sacked &= ~TCPCB_LOST;
 				tp->lost_out -= tcp_skb_pcount(skb);
-
-				/* clear lost hint */
-				tp->retransmit_skb_hint = NULL;
 			}
 		}
 
@@ -1351,7 +1345,6 @@ static int tcp_sacktag_one(struct sk_buff *skb, struct sock *sk,
 	if (dup_sack && (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS)) {
 		TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS;
 		tp->retrans_out -= tcp_skb_pcount(skb);
-		tp->retransmit_skb_hint = NULL;
 	}
 
 	return flag;