#define FLAG_FORWARD_PROGRESS (FLAG_ACKED|FLAG_DATA_SACKED)
#define FLAG_ANY_PROGRESS (FLAG_FORWARD_PROGRESS|FLAG_SND_UNA_ADVANCED)
-#define IsSackFrto() (sysctl_tcp_frto == 0x2)
-
#define TCP_REMNANT (TCP_FLAG_FIN|TCP_FLAG_URG|TCP_FLAG_SYN|TCP_FLAG_PSH)
#define TCP_HP_BITS (~(TCP_RESERVED_BITS|TCP_FLAG_PSH))
tp->sacked_out = 0;
}
+static int tcp_is_sackfrto(const struct tcp_sock *tp)
+{
+ return (sysctl_tcp_frto == 0x2) && !tcp_is_reno(tp);
+}
+
/* F-RTO can only be used if TCP has never retransmitted anything other than
* head (SACK enhanced variant from Appendix B of RFC4138 is more robust here)
*/
if (icsk->icsk_mtup.probe_size)
return 0;
- if (IsSackFrto())
+ if (tcp_is_sackfrto(tp))
return 1;
/* Avoid expensive walking of rexmit queue if possible */
/* Earlier loss recovery underway (see RFC4138; Appendix B).
* The last condition is necessary at least in tp->frto_counter case.
*/
- if (IsSackFrto() && (tp->frto_counter ||
+ if (tcp_is_sackfrto(tp) && (tp->frto_counter ||
((1 << icsk->icsk_ca_state) & (TCPF_CA_Recovery|TCPF_CA_Loss))) &&
after(tp->high_seq, tp->snd_una)) {
tp->frto_highmark = tp->high_seq;
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);
}
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);
tcp_verify_left_out(tp);
- if (tp->retrans_out == 0)
+ if (!tp->frto_counter && tp->retrans_out == 0)
tp->retrans_stamp = 0;
if (flag & FLAG_ECE)
return 1;
}
- if (!IsSackFrto() || tcp_is_reno(tp)) {
+ if (!tcp_is_sackfrto(tp)) {
/* RFC4138 shortcoming in step 2; should also have case c):
* ACK isn't duplicate nor advances window, e.g., opposite dir
* data, winupdate