tcp FRTO: work-around inorder receivers

[linux-2.6-omap-h63xx.git] / net / ipv4 / tcp_input.c

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index d6edb98fd526b6471c34dd197d8c429a5c9ffb9f..b54d9d37b636a79b26de0f0ee36e9f6024ba453e 100644 (file)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1842,9 +1842,16 @@ static void tcp_enter_frto_loss(struct sock *sk, int allowed_segments, int flag)
                        TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS;
                }
 
-               /* 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)) {
+               /* Marking forward transmissions that were made after RTO lost
+                * can cause unnecessary retransmissions in some scenarios,
+                * SACK blocks will mitigate that in some but not in all cases.
+                * We used to not mark them but it was causing break-ups with
+                * receivers that do only in-order receival.
+                *
+                * TODO: we could detect presence of such receiver and select
+                * different behavior per flow.
+                */
+               if (!(TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED)) {
                        TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
                        tp->lost_out += tcp_skb_pcount(skb);
                }
@@ -1860,7 +1867,7 @@ static void tcp_enter_frto_loss(struct sock *sk, int allowed_segments, int flag)
        tp->reordering = min_t(unsigned int, tp->reordering,
                               sysctl_tcp_reordering);
        tcp_set_ca_state(sk, TCP_CA_Loss);
-       tp->high_seq = tp->frto_highmark;
+       tp->high_seq = tp->snd_nxt;
        TCP_ECN_queue_cwr(tp);
 
        tcp_clear_retrans_hints_partial(tp);