tcp: make congestion control optionally skip slow start after idle
Congestion control modules that want full control over congestion
control behavior do not want the cwnd modifications controlled by
the sysctl_tcp_slow_start_after_idle code path.
So skip those code paths for CC modules that use the cong_control()
API.
As an example, those cwnd effects are not desired for the BBR congestion
control algorithm.
Fixes: c0402760f565 ("tcp: new CC hook to set sending rate with rate_sample in any CA state")
Signed-off-by: Wei Wang <weiwan@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 8c0e5a9..38a7427 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1234,10 +1234,12 @@ void tcp_cwnd_restart(struct sock *sk, s32 delta);
static inline void tcp_slow_start_after_idle_check(struct sock *sk)
{
+ const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops;
struct tcp_sock *tp = tcp_sk(sk);
s32 delta;
- if (!sysctl_tcp_slow_start_after_idle || tp->packets_out)
+ if (!sysctl_tcp_slow_start_after_idle || tp->packets_out ||
+ ca_ops->cong_control)
return;
delta = tcp_time_stamp - tp->lsndtime;
if (delta > inet_csk(sk)->icsk_rto)