Commit 1f245e03 authored by Yuchung Cheng's avatar Yuchung Cheng Committed by Greg Kroah-Hartman

bpf: correctly set initial window on active Fast Open sender

[ Upstream commit 31aa6503 ]

The existing BPF TCP initial congestion window (TCP_BPF_IW) does not
to work on (active) Fast Open sender. This is because it changes the
(initial) window only if data_segs_out is zero -- but data_segs_out
is also incremented on SYN-data.  This patch fixes the issue by
proerly accounting for SYN-data additionally.

Fixes: fc747810 ("bpf: Adds support for setting initial cwnd")
Signed-off-by: 's avatarYuchung Cheng <>
Reviewed-by: 's avatarNeal Cardwell <>
Acked-by: 's avatarLawrence Brakmo <>
Signed-off-by: 's avatarAlexei Starovoitov <>
Signed-off-by: 's avatarSasha Levin <>
parent 980a9e53
......@@ -4019,7 +4019,7 @@ BPF_CALL_5(bpf_setsockopt, struct bpf_sock_ops_kern *, bpf_sock,
/* Only some options are supported */
switch (optname) {
case TCP_BPF_IW:
if (val <= 0 || tp->data_segs_out > 0)
if (val <= 0 || tp->data_segs_out > tp->syn_data)
ret = -EINVAL;
tp->snd_cwnd = val;
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