[TCP] FRTO: remove unnecessary fackets/sacked_out recounting

F-RTO does not touch SACKED_ACKED bits at all, so there is no
need to recount them in tcp_enter_frto_loss. After removal of
the else branch, nested ifs can be combined.

This must also reset sacked_out when SACK is not in use as TCP
could have received some duplicate ACKs prior RTO. To achieve
that in a sane manner, tcp_reset_reno_sack was re-placed by the
previous patch.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 16 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 2711ef7df7b5..29999ef73b43 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1474,17 +1474,15 @@ static void tcp_enter_frto_loss(struct sock *sk, int allowed_segments, int flag)
 {
         struct tcp_sock *tp = tcp_sk(sk);
         struct sk_buff *skb;
-        int cnt = 0;
 
-        tp->sacked_out = 0;
         tp->lost_out = 0;
-        tp->fackets_out = 0;
         tp->retrans_out = 0;
+        if (IsReno(tp))
+                tcp_reset_reno_sack(tp);
 
         tcp_for_write_queue(skb, sk) {
                 if (skb == tcp_send_head(sk))
                         break;
-                cnt += tcp_skb_pcount(skb);
                 /*
                  * Count the retransmission made on RTO correctly (only when
                  * waiting for the first ACK and did not get it)...
@@ -1498,19 +1496,12 @@ static void tcp_enter_frto_loss(struct sock *sk, int allowed_segments, int flag)
                 } else {
                         TCP_SKB_CB(skb)->sacked &= ~(TCPCB_LOST|TCPCB_SACKED_RETRANS);
                 }
-                if (!(TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_ACKED)) {
 
-                        /* Do not mark those segments lost that were
-                         * forward transmitted after RTO
-                         */
-                        if (!after(TCP_SKB_CB(skb)->end_seq,
-                                   tp->frto_highmark)) {
-                                TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
-                                tp->lost_out += tcp_skb_pcount(skb);
-                        }
-                } else {
-                        tp->sacked_out += tcp_skb_pcount(skb);
-                        tp->fackets_out = cnt;
+                /* Don't lost mark skbs that were fwd transmitted after RTO */
+                if (!(TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_ACKED) &&
+                    !after(TCP_SKB_CB(skb)->end_seq, tp->frto_highmark)) {
+                        TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
+                        tp->lost_out += tcp_skb_pcount(skb);
                 }
         }
         tcp_sync_left_out(tp);