diff options
| author | Eric Dumazet <edumazet@google.com> | 2012-07-20 05:02:33 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2012-07-20 10:59:41 -0700 |
| commit | 9dc274151a548ffd215caecec5a8872db8799447 (patch) | |
| tree | 13b7199958243d28c43ea3ecdeca254edc2d7245 /net/ipv4/tcp_cong.c | |
| parent | 5815d5e7aae3cc9c5e85af83094d4d6498c3f4fc (diff) | |
tcp: fix ABC in tcp_slow_start()
When/if sysctl_tcp_abc > 1, we expect to increase cwnd by 2 if the
received ACK acknowledges more than 2*MSS bytes, in tcp_slow_start()
Problem is this RFC 3465 statement is not correctly coded, as
the while () loop increases snd_cwnd one by one.
Add a new variable to avoid this off-by one error.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Nandita Dukkipati <nanditad@google.com>
Cc: John Heffner <johnwheffner@gmail.com>
Cc: Stephen Hemminger <shemminger@vyatta.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_cong.c')
| -rw-r--r-- | net/ipv4/tcp_cong.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c index 04dbd7ae7c62..4d4db16e336e 100644 --- a/net/ipv4/tcp_cong.c +++ b/net/ipv4/tcp_cong.c @@ -307,6 +307,7 @@ EXPORT_SYMBOL_GPL(tcp_is_cwnd_limited); void tcp_slow_start(struct tcp_sock *tp) { int cnt; /* increase in packets */ + unsigned int delta = 0; /* RFC3465: ABC Slow start * Increase only after a full MSS of bytes is acked @@ -333,9 +334,9 @@ void tcp_slow_start(struct tcp_sock *tp) tp->snd_cwnd_cnt += cnt; while (tp->snd_cwnd_cnt >= tp->snd_cwnd) { tp->snd_cwnd_cnt -= tp->snd_cwnd; - if (tp->snd_cwnd < tp->snd_cwnd_clamp) - tp->snd_cwnd++; + delta++; } + tp->snd_cwnd = min(tp->snd_cwnd + delta, tp->snd_cwnd_clamp); } EXPORT_SYMBOL_GPL(tcp_slow_start); |