diff options
| author | Neal Cardwell <ncardwell@google.com> | 2011-11-16 08:58:03 (GMT) |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2011-11-27 23:54:09 (GMT) |
| commit | e95ae2f2cf10f7bf27b492aa6188f3cd745de162 (patch) | |
| tree | 2808047891b1c8e3eae559c55d09a5cfeef79fdb /net | |
| parent | 5628adf1a0ff39b9e76e1a8e1c94dadabfd46914 (diff) | |
| download | linux-e95ae2f2cf10f7bf27b492aa6188f3cd745de162.tar.xz | |
tcp: use SACKs and DSACKs that arrive on ACKs below snd_una
The bug: When the ACK field is below snd_una (which can happen when
ACKs are reordered), senders ignored DSACKs (preventing undo) and did
not call tcp_fastretrans_alert, so they did not increment
prr_delivered to reflect newly-SACKed sequence ranges, and did not
call tcp_xmit_retransmit_queue, thus passing up chances to send out
more retransmitted and new packets based on any newly-SACKed packets.
The change: When the ACK field is below snd_una (the "old_ack" goto
label), call tcp_fastretrans_alert to allow undo based on any
newly-arrived DSACKs and try to send out more packets based on
newly-SACKed packets.
Other patches in this series will provide other changes that are
necessary to fully fix this problem.
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/tcp_input.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index b49e418..751d390 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3805,10 +3805,14 @@ invalid_ack: return -1; old_ack: + /* If data was SACKed, tag it and see if we should send more data. + * If data was DSACKed, see if we can undo a cwnd reduction. + */ if (TCP_SKB_CB(skb)->sacked) { - tcp_sacktag_write_queue(sk, skb, prior_snd_una); - if (icsk->icsk_ca_state == TCP_CA_Open) - tcp_try_keep_open(sk); + 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, + is_dupack, flag); } SOCK_DEBUG(sk, "Ack %u before %u:%u\n", ack, tp->snd_una, tp->snd_nxt); |