diff options
| author | Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> | 2007-02-21 23:04:11 -0800 |
|---|---|---|
| committer | David S. Miller <davem@sunset.davemloft.net> | 2007-04-25 22:23:06 -0700 |
| commit | 6408d206c7484615ecae54bf6474a02c94e9e862 (patch) | |
| tree | 43dfb94f6da8445484d987aced10dd8d304bdc4e /net/ipv4/tcp_input.c | |
| parent | 7b0eb22b1d3b049306813a4aaa52966650f7491c (diff) | |
| download | lwn-6408d206c7484615ecae54bf6474a02c94e9e862.tar.gz lwn-6408d206c7484615ecae54bf6474a02c94e9e862.zip | |
[TCP] FRTO: Ignore some uninteresting ACKs
Handles RFC4138 shortcoming (in step 2); it should also have case
c) which ignores ACKs that are not duplicates nor advance window
(opposite dir data, winupdate).
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_input.c')
| -rw-r--r-- | net/ipv4/tcp_input.c | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index e806839acdd9..e990d562f5e3 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -2495,9 +2495,9 @@ static void tcp_conservative_spur_to_response(struct tcp_sock *tp) /* F-RTO spurious RTO detection algorithm (RFC4138) * - * F-RTO affects during two new ACKs following RTO. State (ACK number) is kept - * in frto_counter. When ACK advances window (but not to or beyond highest - * sequence sent before RTO): + * F-RTO affects during two new ACKs following RTO (well, almost, see inline + * comments). State (ACK number) is kept in frto_counter. When ACK advances + * window (but not to or beyond highest sequence sent before RTO): * On First ACK, send two new segments out. * On Second ACK, RTO was likely spurious. Do spurious response (response * algorithm is not part of the F-RTO detection algorithm @@ -2527,6 +2527,13 @@ static void tcp_process_frto(struct sock *sk, u32 prior_snd_una, int flag) if (flag&FLAG_DATA_ACKED) inet_csk(sk)->icsk_retransmits = 0; + /* RFC4138 shortcoming in step 2; should also have case c): ACK isn't + * duplicate nor advances window, e.g., opposite dir data, winupdate + */ + if ((tp->snd_una == prior_snd_una) && (flag&FLAG_NOT_DUP) && + !(flag&FLAG_FORWARD_PROGRESS)) + return; + if (tp->snd_una == prior_snd_una || !before(tp->snd_una, tp->frto_highmark)) { tcp_enter_frto_loss(sk); |