1 // SPDX-License-Identifier: GPL-2.0
2
3 #include "bpf_tracing_net.h"
4 #include <bpf/bpf_helpers.h>
5 #include <bpf/bpf_tracing.h>
6
7 char _license[] SEC("license") = "GPL";
8
9 #define USEC_PER_SEC 1000000UL
10
11 #define min(a, b) ((a) < (b) ? (a) : (b))
12
tcp_left_out(const struct tcp_sock * tp)13 static unsigned int tcp_left_out(const struct tcp_sock *tp)
14 {
15 return tp->sacked_out + tp->lost_out;
16 }
17
tcp_packets_in_flight(const struct tcp_sock * tp)18 static unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
19 {
20 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
21 }
22
23 SEC("struct_ops")
BPF_PROG(write_sk_pacing_init,struct sock * sk)24 void BPF_PROG(write_sk_pacing_init, struct sock *sk)
25 {
26 #ifdef ENABLE_ATOMICS_TESTS
27 __sync_bool_compare_and_swap(&sk->sk_pacing_status, SK_PACING_NONE,
28 SK_PACING_NEEDED);
29 #else
30 sk->sk_pacing_status = SK_PACING_NEEDED;
31 #endif
32 }
33
34 SEC("struct_ops")
BPF_PROG(write_sk_pacing_cong_control,struct sock * sk,const struct rate_sample * rs)35 void BPF_PROG(write_sk_pacing_cong_control, struct sock *sk,
36 const struct rate_sample *rs)
37 {
38 struct tcp_sock *tp = tcp_sk(sk);
39 unsigned long rate =
40 ((tp->snd_cwnd * tp->mss_cache * USEC_PER_SEC) << 3) /
41 (tp->srtt_us ?: 1U << 3);
42 sk->sk_pacing_rate = min(rate, sk->sk_max_pacing_rate);
43 tp->app_limited = (tp->delivered + tcp_packets_in_flight(tp)) ?: 1;
44 }
45
46 SEC("struct_ops")
BPF_PROG(write_sk_pacing_ssthresh,struct sock * sk)47 __u32 BPF_PROG(write_sk_pacing_ssthresh, struct sock *sk)
48 {
49 return tcp_sk(sk)->snd_ssthresh;
50 }
51
52 SEC("struct_ops")
BPF_PROG(write_sk_pacing_undo_cwnd,struct sock * sk)53 __u32 BPF_PROG(write_sk_pacing_undo_cwnd, struct sock *sk)
54 {
55 return tcp_sk(sk)->snd_cwnd;
56 }
57
58 SEC(".struct_ops")
59 struct tcp_congestion_ops write_sk_pacing = {
60 .init = (void *)write_sk_pacing_init,
61 .cong_control = (void *)write_sk_pacing_cong_control,
62 .ssthresh = (void *)write_sk_pacing_ssthresh,
63 .undo_cwnd = (void *)write_sk_pacing_undo_cwnd,
64 .name = "bpf_w_sk_pacing",
65 };
66