Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [ 025/218] tcp: fix cwnd reduction for non-sack recovery | Date | Fri, 28 Sep 2012 13:14:02 -0700 |
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3.4-stable review patch. If anyone has any objections, please let me know.
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From: Yuchung Cheng <ycheng@google.com>
[ Upstream commit 7c4a56fec379ac0d7754e0d4da6a7361f1a4fe64 ]
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> --- net/ipv4/tcp_input.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-)
--- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3037,13 +3037,14 @@ static void tcp_update_cwnd_in_recovery( * tcp_xmit_retransmit_queue(). */ static void tcp_fastretrans_alert(struct sock *sk, int pkts_acked, - int newly_acked_sacked, bool is_dupack, + int prior_sacked, bool is_dupack, int flag) { struct inet_connection_sock *icsk = inet_csk(sk); struct tcp_sock *tp = tcp_sk(sk); int do_lost = is_dupack || ((flag & FLAG_DATA_SACKED) && (tcp_fackets_out(tp) > tp->reordering)); + int newly_acked_sacked = 0; int fast_rexmit = 0, mib_idx; if (WARN_ON(!tp->packets_out && tp->sacked_out)) @@ -3103,6 +3104,7 @@ static void tcp_fastretrans_alert(struct tcp_add_reno_sack(sk); } else do_lost = tcp_try_undo_partial(sk, pkts_acked); + newly_acked_sacked = pkts_acked + tp->sacked_out - prior_sacked; break; case TCP_CA_Loss: if (flag & FLAG_DATA_ACKED) @@ -3124,6 +3126,7 @@ static void tcp_fastretrans_alert(struct if (is_dupack) tcp_add_reno_sack(sk); } + newly_acked_sacked = pkts_acked + tp->sacked_out - prior_sacked; if (icsk->icsk_ca_state <= TCP_CA_Disorder) tcp_try_undo_dsack(sk); @@ -3695,7 +3698,6 @@ static int tcp_ack(struct sock *sk, cons int prior_packets; int prior_sacked = tp->sacked_out; int pkts_acked = 0; - int newly_acked_sacked = 0; int frto_cwnd = 0; /* If the ack is older than previous acks @@ -3768,8 +3770,6 @@ static int tcp_ack(struct sock *sk, cons flag |= tcp_clean_rtx_queue(sk, prior_fackets, prior_snd_una); pkts_acked = prior_packets - tp->packets_out; - newly_acked_sacked = (prior_packets - prior_sacked) - - (tp->packets_out - tp->sacked_out); if (tp->frto_counter) frto_cwnd = tcp_process_frto(sk, flag); @@ -3783,7 +3783,7 @@ static int tcp_ack(struct sock *sk, cons tcp_may_raise_cwnd(sk, flag)) tcp_cong_avoid(sk, ack, prior_in_flight); is_dupack = !(flag & (FLAG_SND_UNA_ADVANCED | FLAG_NOT_DUP)); - tcp_fastretrans_alert(sk, pkts_acked, newly_acked_sacked, + tcp_fastretrans_alert(sk, pkts_acked, prior_sacked, is_dupack, flag); } else { if ((flag & FLAG_DATA_ACKED) && !frto_cwnd) @@ -3798,7 +3798,7 @@ static int tcp_ack(struct sock *sk, cons no_queue: /* If data was DSACKed, see if we can undo a cwnd reduction. */ if (flag & FLAG_DSACKING_ACK) - tcp_fastretrans_alert(sk, pkts_acked, newly_acked_sacked, + tcp_fastretrans_alert(sk, pkts_acked, prior_sacked, is_dupack, flag); /* If this ack opens up a zero window, clear backoff. It was * being used to time the probes, and is probably far higher than @@ -3818,8 +3818,7 @@ old_ack: */ if (TCP_SKB_CB(skb)->sacked) { flag |= tcp_sacktag_write_queue(sk, skb, prior_snd_una); - newly_acked_sacked = tp->sacked_out - prior_sacked; - tcp_fastretrans_alert(sk, pkts_acked, newly_acked_sacked, + tcp_fastretrans_alert(sk, pkts_acked, prior_sacked, is_dupack, flag); }
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