bpf: add BPF_CGROUP_SOCK_OPS callback that is executed on every RTT

Performance impact should be minimal because it's under a new
BPF_SOCK_OPS_RTT_CB_FLAG flag that has to be explicitly enabled.

Suggested-by: Eric Dumazet <edumazet@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Priyaranjan Jha <priyarjha@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 4 insertions, 0 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index b71efeb0ae5b..c21e8a22fb3b 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -778,6 +778,8 @@ static void tcp_rtt_estimator(struct sock *sk, long mrtt_us)
                                 tp->rttvar_us -= (tp->rttvar_us - tp->mdev_max_us) >> 2;
                         tp->rtt_seq = tp->snd_nxt;
                         tp->mdev_max_us = tcp_rto_min_us(sk);
+
+                        tcp_bpf_rtt(sk);
                 }
         } else {
                 /* no previous measure. */
@@ -786,6 +788,8 @@ static void tcp_rtt_estimator(struct sock *sk, long mrtt_us)
                 tp->rttvar_us = max(tp->mdev_us, tcp_rto_min_us(sk));
                 tp->mdev_max_us = tp->rttvar_us;
                 tp->rtt_seq = tp->snd_nxt;
+
+                tcp_bpf_rtt(sk);
         }
         tp->srtt_us = max(1U, srtt);
 }