[TCP]: Fix ratehalving with bidirectional flows

[pandora-kernel.git] / net / ipv4 / tcp_input.c

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index fec8a7a..41163dd 100644 (file)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1851,19 +1851,22 @@ static inline u32 tcp_cwnd_min(const struct sock *sk)
 }
 
 /* Decrease cwnd each second ack. */
-static void tcp_cwnd_down(struct sock *sk)
+static void tcp_cwnd_down(struct sock *sk, int flag)
 {
        struct tcp_sock *tp = tcp_sk(sk);
        int decr = tp->snd_cwnd_cnt + 1;
 
-       tp->snd_cwnd_cnt = decr&1;
-       decr >>= 1;
+       if ((flag&FLAG_FORWARD_PROGRESS) ||
+           (IsReno(tp) && !(flag&FLAG_NOT_DUP))) {
+               tp->snd_cwnd_cnt = decr&1;
+               decr >>= 1;
 
-       if (decr && tp->snd_cwnd > tcp_cwnd_min(sk))
-               tp->snd_cwnd -= decr;
+               if (decr && tp->snd_cwnd > tcp_cwnd_min(sk))
+                       tp->snd_cwnd -= decr;
 
-       tp->snd_cwnd = min(tp->snd_cwnd, tcp_packets_in_flight(tp)+1);
-       tp->snd_cwnd_stamp = tcp_time_stamp;
+               tp->snd_cwnd = min(tp->snd_cwnd, tcp_packets_in_flight(tp)+1);
+               tp->snd_cwnd_stamp = tcp_time_stamp;
+       }
 }
 
 /* Nothing was retransmitted or returned timestamp is less
@@ -2060,7 +2063,7 @@ static void tcp_try_to_open(struct sock *sk, int flag)
                }
                tcp_moderate_cwnd(tp);
        } else {
-               tcp_cwnd_down(sk);
+               tcp_cwnd_down(sk, flag);
        }
 }
 
@@ -2260,7 +2263,7 @@ tcp_fastretrans_alert(struct sock *sk, u32 prior_snd_una,
 
        if (is_dupack || tcp_head_timedout(sk))
                tcp_update_scoreboard(sk);
-       tcp_cwnd_down(sk);
+       tcp_cwnd_down(sk, flag);
        tcp_xmit_retransmit_queue(sk);
 }
 
@@ -2490,12 +2493,23 @@ static int tcp_clean_rtx_queue(struct sock *sk, __s32 *seq_rtt_p)
                tcp_ack_update_rtt(sk, acked, seq_rtt);
                tcp_ack_packets_out(sk);
 
-               /* Is the ACK triggering packet unambiguous? */
-               if (acked & FLAG_RETRANS_DATA_ACKED)
-                       last_ackt = net_invalid_timestamp();
+               if (ca_ops->pkts_acked) {
+                       s32 rtt_us = -1;
+
+                       /* Is the ACK triggering packet unambiguous? */
+                       if (!(acked & FLAG_RETRANS_DATA_ACKED)) {
+                               /* High resolution needed and available? */
+                               if (ca_ops->flags & TCP_CONG_RTT_STAMP &&
+                                   !ktime_equal(last_ackt,
+                                                net_invalid_timestamp()))
+                                       rtt_us = ktime_us_delta(ktime_get_real(),
+                                                               last_ackt);
+                               else if (seq_rtt > 0)
+                                       rtt_us = jiffies_to_usecs(seq_rtt);
+                       }
 
-               if (ca_ops->pkts_acked)
-                       ca_ops->pkts_acked(sk, pkts_acked, last_ackt);
+                       ca_ops->pkts_acked(sk, pkts_acked, rtt_us);
+               }
        }
 
 #if FASTRETRANS_DEBUG > 0