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tcp: fix cwnd reduction for non-sack recovery
The cwnd reduction in fast recovery is based on the number of packets newly delivered per ACK. For non-sack connections every DUPACK signifies a packet has been delivered, but the sender mistakenly skips counting them for cwnd reduction. The fix is to compute newly_acked_sacked after DUPACKs are accounted in sacked_out for non-sack connections. Signed-off-by: Yuchung Cheng <ycheng@google.com> Acked-by: Nandita Dukkipati <nanditad@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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parent
20e1db19db
commit
7c4a56fec3
1 changed files with 7 additions and 8 deletions
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@ -2926,13 +2926,14 @@ static void tcp_enter_recovery(struct sock *sk, bool ece_ack)
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* tcp_xmit_retransmit_queue().
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*/
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static void tcp_fastretrans_alert(struct sock *sk, int pkts_acked,
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int newly_acked_sacked, bool is_dupack,
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int prior_sacked, bool is_dupack,
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int flag)
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{
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struct inet_connection_sock *icsk = inet_csk(sk);
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struct tcp_sock *tp = tcp_sk(sk);
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int do_lost = is_dupack || ((flag & FLAG_DATA_SACKED) &&
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(tcp_fackets_out(tp) > tp->reordering));
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int newly_acked_sacked = 0;
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int fast_rexmit = 0;
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if (WARN_ON(!tp->packets_out && tp->sacked_out))
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@ -2992,6 +2993,7 @@ static void tcp_fastretrans_alert(struct sock *sk, int pkts_acked,
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tcp_add_reno_sack(sk);
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} else
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do_lost = tcp_try_undo_partial(sk, pkts_acked);
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newly_acked_sacked = pkts_acked + tp->sacked_out - prior_sacked;
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break;
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case TCP_CA_Loss:
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if (flag & FLAG_DATA_ACKED)
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@ -3013,6 +3015,7 @@ static void tcp_fastretrans_alert(struct sock *sk, int pkts_acked,
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if (is_dupack)
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tcp_add_reno_sack(sk);
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}
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newly_acked_sacked = pkts_acked + tp->sacked_out - prior_sacked;
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if (icsk->icsk_ca_state <= TCP_CA_Disorder)
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tcp_try_undo_dsack(sk);
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@ -3590,7 +3593,6 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
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int prior_packets;
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int prior_sacked = tp->sacked_out;
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int pkts_acked = 0;
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int newly_acked_sacked = 0;
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bool frto_cwnd = false;
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/* If the ack is older than previous acks
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@ -3666,8 +3668,6 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
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flag |= tcp_clean_rtx_queue(sk, prior_fackets, prior_snd_una);
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pkts_acked = prior_packets - tp->packets_out;
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newly_acked_sacked = (prior_packets - prior_sacked) -
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(tp->packets_out - tp->sacked_out);
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if (tp->frto_counter)
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frto_cwnd = tcp_process_frto(sk, flag);
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@ -3681,7 +3681,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
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tcp_may_raise_cwnd(sk, flag))
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tcp_cong_avoid(sk, ack, prior_in_flight);
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is_dupack = !(flag & (FLAG_SND_UNA_ADVANCED | FLAG_NOT_DUP));
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tcp_fastretrans_alert(sk, pkts_acked, newly_acked_sacked,
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tcp_fastretrans_alert(sk, pkts_acked, prior_sacked,
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is_dupack, flag);
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} else {
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if ((flag & FLAG_DATA_ACKED) && !frto_cwnd)
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@ -3698,7 +3698,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
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no_queue:
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/* If data was DSACKed, see if we can undo a cwnd reduction. */
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if (flag & FLAG_DSACKING_ACK)
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tcp_fastretrans_alert(sk, pkts_acked, newly_acked_sacked,
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tcp_fastretrans_alert(sk, pkts_acked, prior_sacked,
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is_dupack, flag);
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/* If this ack opens up a zero window, clear backoff. It was
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* being used to time the probes, and is probably far higher than
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@ -3718,8 +3718,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
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*/
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if (TCP_SKB_CB(skb)->sacked) {
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flag |= tcp_sacktag_write_queue(sk, skb, prior_snd_una);
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newly_acked_sacked = tp->sacked_out - prior_sacked;
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tcp_fastretrans_alert(sk, pkts_acked, newly_acked_sacked,
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tcp_fastretrans_alert(sk, pkts_acked, prior_sacked,
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is_dupack, flag);
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}
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