tcp_ca_write_sk_pacing.c

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