* algorithm is not part of the F-RTO detection algorithm
* given in RFC4138 but can be selected separately).
* Otherwise (basically on duplicate ACK), RTO was (likely) caused by a loss
- * and TCP falls back to conventional RTO recovery.
+ * and TCP falls back to conventional RTO recovery. F-RTO allows overriding
+ * of Nagle, this is done using frto_counter states 2 and 3, when a new data
+ * segment of any size sent during F-RTO, state 2 is upgraded to 3.
*
* Rationale: if the RTO was spurious, new ACKs should arrive from the
* original window even after we transmit two new data segments.
inet_csk(sk)->icsk_retransmits = 0;
if (!before(tp->snd_una, tp->frto_highmark)) {
- tcp_enter_frto_loss(sk, tp->frto_counter + 1, flag);
+ tcp_enter_frto_loss(sk, (tp->frto_counter == 1 ? 2 : 3), flag);
return 1;
}
return 1;
}
- if ((tp->frto_counter == 2) &&
+ if ((tp->frto_counter >= 2) &&
(!(flag&FLAG_FORWARD_PROGRESS) ||
((flag&FLAG_DATA_SACKED) && !(flag&FLAG_ONLY_ORIG_SACKED)))) {
/* RFC4138 shortcoming (see comment above) */
if (!tcp_send_head(sk) ||
after(TCP_SKB_CB(tcp_send_head(sk))->end_seq,
tp->snd_una + tp->snd_wnd)) {
- tcp_enter_frto_loss(sk, tp->frto_counter + 1, flag);
+ tcp_enter_frto_loss(sk, (tp->frto_counter == 1 ? 2 : 3),
+ flag);
return 1;
}
tp->snd_cwnd = tcp_packets_in_flight(tp) + 2;
tp->frto_counter = 2;
return 1;
- } else /* frto_counter == 2 */ {
+ } else {
switch (sysctl_tcp_frto_response) {
case 2:
tcp_undo_spur_to_response(sk, flag);