From 23729ff23186424e54b4d6678fcd526cdacef4d3 Mon Sep 17 00:00:00 2001 From: Stanislav Fomichev Date: Tue, 2 Jul 2019 09:13:56 -0700 Subject: [PATCH] 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 Cc: Eric Dumazet Cc: Priyaranjan Jha Cc: Yuchung Cheng Cc: Soheil Hassas Yeganeh Acked-by: Soheil Hassas Yeganeh Acked-by: Yuchung Cheng Signed-off-by: Stanislav Fomichev Signed-off-by: Daniel Borkmann --- include/net/tcp.h | 8 ++++++++ include/uapi/linux/bpf.h | 6 +++++- net/ipv4/tcp_input.c | 4 ++++ 3 files changed, 17 insertions(+), 1 deletion(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index 9d36cc88d043..e16d8a3fd3b4 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -2221,6 +2221,14 @@ static inline bool tcp_bpf_ca_needs_ecn(struct sock *sk) return (tcp_call_bpf(sk, BPF_SOCK_OPS_NEEDS_ECN, 0, NULL) == 1); } +static inline void tcp_bpf_rtt(struct sock *sk) +{ + struct tcp_sock *tp = tcp_sk(sk); + + if (BPF_SOCK_OPS_TEST_FLAG(tp, BPF_SOCK_OPS_RTT_CB_FLAG)) + tcp_call_bpf(sk, BPF_SOCK_OPS_RTT_CB, 0, NULL); +} + #if IS_ENABLED(CONFIG_SMC) extern struct static_key_false tcp_have_smc; #endif diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index cffea1826a1f..9cdd0aaeba06 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -1770,6 +1770,7 @@ union bpf_attr { * * **BPF_SOCK_OPS_RTO_CB_FLAG** (retransmission time out) * * **BPF_SOCK_OPS_RETRANS_CB_FLAG** (retransmission) * * **BPF_SOCK_OPS_STATE_CB_FLAG** (TCP state change) + * * **BPF_SOCK_OPS_RTT_CB_FLAG** (every RTT) * * Therefore, this function can be used to clear a callback flag by * setting the appropriate bit to zero. e.g. to disable the RTO @@ -3314,7 +3315,8 @@ struct bpf_sock_ops { #define BPF_SOCK_OPS_RTO_CB_FLAG (1<<0) #define BPF_SOCK_OPS_RETRANS_CB_FLAG (1<<1) #define BPF_SOCK_OPS_STATE_CB_FLAG (1<<2) -#define BPF_SOCK_OPS_ALL_CB_FLAGS 0x7 /* Mask of all currently +#define BPF_SOCK_OPS_RTT_CB_FLAG (1<<3) +#define BPF_SOCK_OPS_ALL_CB_FLAGS 0xF /* Mask of all currently * supported cb flags */ @@ -3369,6 +3371,8 @@ enum { BPF_SOCK_OPS_TCP_LISTEN_CB, /* Called on listen(2), right after * socket transition to LISTEN state. */ + BPF_SOCK_OPS_RTT_CB, /* Called on every RTT. + */ }; /* List of TCP states. There is a build check in net/ipv4/tcp.c to detect 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); } -- 2.39.5