Adds a new bpf_setsockopt for TCP sockets, TCP_BPF_SNDCWND_CLAMP, which
sets the initial congestion window. It is useful to limit the sndcwnd
when the host are close to each other (small RTT).
Signed-off-by: Lawrence Brakmo <redacted>
---
include/uapi/linux/bpf.h | 1 +
net/core/filter.c | 7 +++++++
2 files changed, 8 insertions(+)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 32755b5..a6a91e5 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -784,5 +784,6 @@ enum {
};
#define TCP_BPF_IW 1001 /* Set TCP initial congestion window */
+#define TCP_BPF_SNDCWND_CLAMP 1002 /* Set sndcwnd_clamp */
#endif /* _UAPI__LINUX_BPF_H__ */diff --git a/net/core/filter.c b/net/core/filter.c
index a4695cf..7a43271 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2735,6 +2735,13 @@ BPF_CALL_5(bpf_setsockopt, struct bpf_sock_ops_kern *, bpf_sock,
else
tp->snd_cwnd = val;
break;
+ case TCP_BPF_SNDCWND_CLAMP:
+ if (val <= 0) {
+ ret = -EINVAL;
+ } else {
+ tp->snd_cwnd_clamp = val;
+ tp->snd_ssthresh = val;
+ }
default:
ret = -EINVAL;
}--
2.9.3