From 57bfc7605ca5b102ba336779ae9adbc5bbba1d96 Mon Sep 17 00:00:00 2001 From: Miao Xu Date: Wed, 1 May 2024 21:23:16 -0700 Subject: tcp: Add new args for cong_control in tcp_congestion_ops This patch adds two new arguments for cong_control of struct tcp_congestion_ops: - ack - flag These two arguments are inherited from the caller tcp_cong_control in tcp_intput.c. One use case of them is to update cwnd and pacing rate inside cong_control based on the info they provide. For example, the flag can be used to decide if it is the right time to raise or reduce a sender's cwnd. Reviewed-by: Eric Dumazet Signed-off-by: Miao Xu Link: https://lore.kernel.org/r/20240502042318.801932-2-miaxu@meta.com Signed-off-by: Martin KaFai Lau --- include/net/tcp.h | 2 +- net/ipv4/bpf_tcp_ca.c | 3 ++- net/ipv4/tcp_bbr.c | 2 +- net/ipv4/tcp_input.c | 2 +- tools/testing/selftests/bpf/progs/tcp_ca_kfunc.c | 6 +++--- 5 files changed, 8 insertions(+), 7 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index fe98fb01879b..7294da8fb780 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1172,7 +1172,7 @@ struct tcp_congestion_ops { /* call when packets are delivered to update cwnd and pacing rate, * after all the ca_state processing. (optional) */ - void (*cong_control)(struct sock *sk, const struct rate_sample *rs); + void (*cong_control)(struct sock *sk, u32 ack, int flag, const struct rate_sample *rs); /* new value of cwnd after loss (required) */ diff --git a/net/ipv4/bpf_tcp_ca.c b/net/ipv4/bpf_tcp_ca.c index 7f518ea5f4ac..6bd7f8db189a 100644 --- a/net/ipv4/bpf_tcp_ca.c +++ b/net/ipv4/bpf_tcp_ca.c @@ -307,7 +307,8 @@ static u32 bpf_tcp_ca_min_tso_segs(struct sock *sk) return 0; } -static void bpf_tcp_ca_cong_control(struct sock *sk, const struct rate_sample *rs) +static void bpf_tcp_ca_cong_control(struct sock *sk, u32 ack, int flag, + const struct rate_sample *rs) { } diff --git a/net/ipv4/tcp_bbr.c b/net/ipv4/tcp_bbr.c index 7e52ab24e40a..760941e55153 100644 --- a/net/ipv4/tcp_bbr.c +++ b/net/ipv4/tcp_bbr.c @@ -1024,7 +1024,7 @@ static void bbr_update_model(struct sock *sk, const struct rate_sample *rs) bbr_update_gains(sk); } -__bpf_kfunc static void bbr_main(struct sock *sk, const struct rate_sample *rs) +__bpf_kfunc static void bbr_main(struct sock *sk, u32 ack, int flag, const struct rate_sample *rs) { struct bbr *bbr = inet_csk_ca(sk); u32 bw; diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 53e1150f706f..23ccfc7b1d3c 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3541,7 +3541,7 @@ static void tcp_cong_control(struct sock *sk, u32 ack, u32 acked_sacked, const struct inet_connection_sock *icsk = inet_csk(sk); if (icsk->icsk_ca_ops->cong_control) { - icsk->icsk_ca_ops->cong_control(sk, rs); + icsk->icsk_ca_ops->cong_control(sk, ack, flag, rs); return; } diff --git a/tools/testing/selftests/bpf/progs/tcp_ca_kfunc.c b/tools/testing/selftests/bpf/progs/tcp_ca_kfunc.c index fcfbfe0336b4..52b610357309 100644 --- a/tools/testing/selftests/bpf/progs/tcp_ca_kfunc.c +++ b/tools/testing/selftests/bpf/progs/tcp_ca_kfunc.c @@ -5,7 +5,7 @@ #include extern void bbr_init(struct sock *sk) __ksym; -extern void bbr_main(struct sock *sk, const struct rate_sample *rs) __ksym; +extern void bbr_main(struct sock *sk, u32 ack, int flag, const struct rate_sample *rs) __ksym; extern u32 bbr_sndbuf_expand(struct sock *sk) __ksym; extern u32 bbr_undo_cwnd(struct sock *sk) __ksym; extern void bbr_cwnd_event(struct sock *sk, enum tcp_ca_event event) __ksym; @@ -42,9 +42,9 @@ void BPF_PROG(in_ack_event, struct sock *sk, u32 flags) } SEC("struct_ops/cong_control") -void BPF_PROG(cong_control, struct sock *sk, const struct rate_sample *rs) +void BPF_PROG(cong_control, struct sock *sk, u32 ack, int flag, const struct rate_sample *rs) { - bbr_main(sk, rs); + bbr_main(sk, ack, flag, rs); } SEC("struct_ops/cong_avoid") -- cgit From 0325cbd21e3c26eff88bc7da303ffb46b4f5d294 Mon Sep 17 00:00:00 2001 From: Miao Xu Date: Wed, 1 May 2024 21:23:17 -0700 Subject: bpf: tcp: Allow to write tp->snd_cwnd_stamp in bpf_tcp_ca This patch allows the write of tp->snd_cwnd_stamp in a bpf tcp ca program. An use case of writing this field is to keep track of the time whenever tp->snd_cwnd is raised or reduced inside the `cong_control` callback. Reviewed-by: Eric Dumazet Signed-off-by: Miao Xu Link: https://lore.kernel.org/r/20240502042318.801932-3-miaxu@meta.com Signed-off-by: Martin KaFai Lau --- net/ipv4/bpf_tcp_ca.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/ipv4/bpf_tcp_ca.c b/net/ipv4/bpf_tcp_ca.c index 6bd7f8db189a..18227757ec0c 100644 --- a/net/ipv4/bpf_tcp_ca.c +++ b/net/ipv4/bpf_tcp_ca.c @@ -107,6 +107,9 @@ static int bpf_tcp_ca_btf_struct_access(struct bpf_verifier_log *log, case offsetof(struct tcp_sock, snd_cwnd_cnt): end = offsetofend(struct tcp_sock, snd_cwnd_cnt); break; + case offsetof(struct tcp_sock, snd_cwnd_stamp): + end = offsetofend(struct tcp_sock, snd_cwnd_stamp); + break; case offsetof(struct tcp_sock, snd_ssthresh): end = offsetofend(struct tcp_sock, snd_ssthresh); break; -- cgit From 96c3490d6423b7f24d356e24a61c24de69f3de77 Mon Sep 17 00:00:00 2001 From: Miao Xu Date: Wed, 1 May 2024 21:23:18 -0700 Subject: selftests/bpf: Add test for the use of new args in cong_control This patch adds a selftest to show the usage of the new arguments in cong_control. For simplicity's sake, the testing example reuses cubic's kernel functions. Signed-off-by: Miao Xu Link: https://lore.kernel.org/r/20240502042318.801932-4-miaxu@meta.com Signed-off-by: Martin KaFai Lau --- .../testing/selftests/bpf/prog_tests/bpf_tcp_ca.c | 24 +++ tools/testing/selftests/bpf/progs/bpf_cc_cubic.c | 199 +++++++++++++++++++++ .../testing/selftests/bpf/progs/bpf_tracing_net.h | 10 ++ 3 files changed, 233 insertions(+) create mode 100644 tools/testing/selftests/bpf/progs/bpf_cc_cubic.c diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c b/tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c index 907bac46c774..0aca02532794 100644 --- a/tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c +++ b/tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c @@ -14,6 +14,7 @@ #include "tcp_ca_incompl_cong_ops.skel.h" #include "tcp_ca_unsupp_cong_op.skel.h" #include "tcp_ca_kfunc.skel.h" +#include "bpf_cc_cubic.skel.h" #ifndef ENOTSUPP #define ENOTSUPP 524 @@ -452,6 +453,27 @@ static void test_tcp_ca_kfunc(void) tcp_ca_kfunc__destroy(skel); } +static void test_cc_cubic(void) +{ + struct bpf_cc_cubic *cc_cubic_skel; + struct bpf_link *link; + + cc_cubic_skel = bpf_cc_cubic__open_and_load(); + if (!ASSERT_OK_PTR(cc_cubic_skel, "bpf_cc_cubic__open_and_load")) + return; + + link = bpf_map__attach_struct_ops(cc_cubic_skel->maps.cc_cubic); + if (!ASSERT_OK_PTR(link, "bpf_map__attach_struct_ops")) { + bpf_cc_cubic__destroy(cc_cubic_skel); + return; + } + + do_test("bpf_cc_cubic", NULL); + + bpf_link__destroy(link); + bpf_cc_cubic__destroy(cc_cubic_skel); +} + void test_bpf_tcp_ca(void) { if (test__start_subtest("dctcp")) @@ -482,4 +504,6 @@ void test_bpf_tcp_ca(void) test_link_replace(); if (test__start_subtest("tcp_ca_kfunc")) test_tcp_ca_kfunc(); + if (test__start_subtest("cc_cubic")) + test_cc_cubic(); } diff --git a/tools/testing/selftests/bpf/progs/bpf_cc_cubic.c b/tools/testing/selftests/bpf/progs/bpf_cc_cubic.c new file mode 100644 index 000000000000..5c7697c70e2a --- /dev/null +++ b/tools/testing/selftests/bpf/progs/bpf_cc_cubic.c @@ -0,0 +1,199 @@ +// SPDX-License-Identifier: GPL-2.0-only + +/* Highlights: + * 1. The major difference between this bpf program and tcp_cubic.c + * is that this bpf program relies on `cong_control` rather than + * `cong_avoid` in the struct tcp_congestion_ops. + * 2. Logic such as tcp_cwnd_reduction, tcp_cong_avoid, and + * tcp_update_pacing_rate is bypassed when `cong_control` is + * defined, so moving these logic to `cong_control`. + * 3. WARNING: This bpf program is NOT the same as tcp_cubic.c. + * The main purpose is to show use cases of the arguments in + * `cong_control`. For simplicity's sake, it reuses tcp cubic's + * kernel functions. + */ + +#include "vmlinux.h" + +#include +#include +#include "bpf_tracing_net.h" + +#define BPF_STRUCT_OPS(name, args...) \ +SEC("struct_ops/"#name) \ +BPF_PROG(name, args) + +#define USEC_PER_SEC 1000000UL +#define TCP_PACING_SS_RATIO (200) +#define TCP_PACING_CA_RATIO (120) +#define TCP_REORDERING (12) + +#define min(a, b) ((a) < (b) ? (a) : (b)) +#define max(a, b) ((a) > (b) ? (a) : (b)) +#define after(seq2, seq1) before(seq1, seq2) + +extern void cubictcp_init(struct sock *sk) __ksym; +extern void cubictcp_cwnd_event(struct sock *sk, enum tcp_ca_event event) __ksym; +extern __u32 cubictcp_recalc_ssthresh(struct sock *sk) __ksym; +extern void cubictcp_state(struct sock *sk, __u8 new_state) __ksym; +extern __u32 tcp_reno_undo_cwnd(struct sock *sk) __ksym; +extern void cubictcp_acked(struct sock *sk, const struct ack_sample *sample) __ksym; +extern void cubictcp_cong_avoid(struct sock *sk, __u32 ack, __u32 acked) __ksym; + +static struct inet_connection_sock *inet_csk(const struct sock *sk) +{ + return (struct inet_connection_sock *)sk; +} + +static struct tcp_sock *tcp_sk(const struct sock *sk) +{ + return (struct tcp_sock *)sk; +} + +static bool before(__u32 seq1, __u32 seq2) +{ + return (__s32)(seq1-seq2) < 0; +} + +static __u64 div64_u64(__u64 dividend, __u64 divisor) +{ + return dividend / divisor; +} + +static void tcp_update_pacing_rate(struct sock *sk) +{ + const struct tcp_sock *tp = tcp_sk(sk); + __u64 rate; + + /* set sk_pacing_rate to 200 % of current rate (mss * cwnd / srtt) */ + rate = (__u64)tp->mss_cache * ((USEC_PER_SEC / 100) << 3); + + /* current rate is (cwnd * mss) / srtt + * In Slow Start [1], set sk_pacing_rate to 200 % the current rate. + * In Congestion Avoidance phase, set it to 120 % the current rate. + * + * [1] : Normal Slow Start condition is (tp->snd_cwnd < tp->snd_ssthresh) + * If snd_cwnd >= (tp->snd_ssthresh / 2), we are approaching + * end of slow start and should slow down. + */ + if (tp->snd_cwnd < tp->snd_ssthresh / 2) + rate *= TCP_PACING_SS_RATIO; + else + rate *= TCP_PACING_CA_RATIO; + + rate *= max(tp->snd_cwnd, tp->packets_out); + + if (tp->srtt_us) + rate = div64_u64(rate, (__u64)tp->srtt_us); + + sk->sk_pacing_rate = min(rate, sk->sk_max_pacing_rate); +} + +static void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked, + int newly_lost, int flag) +{ + struct tcp_sock *tp = tcp_sk(sk); + int sndcnt = 0; + __u32 pkts_in_flight = tp->packets_out - (tp->sacked_out + tp->lost_out) + tp->retrans_out; + int delta = tp->snd_ssthresh - pkts_in_flight; + + if (newly_acked_sacked <= 0 || !tp->prior_cwnd) + return; + + __u32 prr_delivered = tp->prr_delivered + newly_acked_sacked; + + if (delta < 0) { + __u64 dividend = + (__u64)tp->snd_ssthresh * prr_delivered + tp->prior_cwnd - 1; + sndcnt = (__u32)div64_u64(dividend, (__u64)tp->prior_cwnd) - tp->prr_out; + } else { + sndcnt = max(prr_delivered - tp->prr_out, newly_acked_sacked); + if (flag & FLAG_SND_UNA_ADVANCED && !newly_lost) + sndcnt++; + sndcnt = min(delta, sndcnt); + } + /* Force a fast retransmit upon entering fast recovery */ + sndcnt = max(sndcnt, (tp->prr_out ? 0 : 1)); + tp->snd_cwnd = pkts_in_flight + sndcnt; +} + +/* Decide wheather to run the increase function of congestion control. */ +static bool tcp_may_raise_cwnd(const struct sock *sk, const int flag) +{ + if (tcp_sk(sk)->reordering > TCP_REORDERING) + return flag & FLAG_FORWARD_PROGRESS; + + return flag & FLAG_DATA_ACKED; +} + +void BPF_STRUCT_OPS(bpf_cubic_init, struct sock *sk) +{ + cubictcp_init(sk); +} + +void BPF_STRUCT_OPS(bpf_cubic_cwnd_event, struct sock *sk, enum tcp_ca_event event) +{ + cubictcp_cwnd_event(sk, event); +} + +void BPF_STRUCT_OPS(bpf_cubic_cong_control, struct sock *sk, __u32 ack, int flag, + const struct rate_sample *rs) +{ + struct tcp_sock *tp = tcp_sk(sk); + + if (((1<icsk_ca_state)) { + /* Reduce cwnd if state mandates */ + tcp_cwnd_reduction(sk, rs->acked_sacked, rs->losses, flag); + + if (!before(tp->snd_una, tp->high_seq)) { + /* Reset cwnd to ssthresh in CWR or Recovery (unless it's undone) */ + if (tp->snd_ssthresh < TCP_INFINITE_SSTHRESH && + inet_csk(sk)->icsk_ca_state == TCP_CA_CWR) { + tp->snd_cwnd = tp->snd_ssthresh; + tp->snd_cwnd_stamp = tcp_jiffies32; + } + } + } else if (tcp_may_raise_cwnd(sk, flag)) { + /* Advance cwnd if state allows */ + cubictcp_cong_avoid(sk, ack, rs->acked_sacked); + tp->snd_cwnd_stamp = tcp_jiffies32; + } + + tcp_update_pacing_rate(sk); +} + +__u32 BPF_STRUCT_OPS(bpf_cubic_recalc_ssthresh, struct sock *sk) +{ + return cubictcp_recalc_ssthresh(sk); +} + +void BPF_STRUCT_OPS(bpf_cubic_state, struct sock *sk, __u8 new_state) +{ + cubictcp_state(sk, new_state); +} + +void BPF_STRUCT_OPS(bpf_cubic_acked, struct sock *sk, + const struct ack_sample *sample) +{ + cubictcp_acked(sk, sample); +} + +__u32 BPF_STRUCT_OPS(bpf_cubic_undo_cwnd, struct sock *sk) +{ + return tcp_reno_undo_cwnd(sk); +} + +SEC(".struct_ops") +struct tcp_congestion_ops cc_cubic = { + .init = (void *)bpf_cubic_init, + .ssthresh = (void *)bpf_cubic_recalc_ssthresh, + .cong_control = (void *)bpf_cubic_cong_control, + .set_state = (void *)bpf_cubic_state, + .undo_cwnd = (void *)bpf_cubic_undo_cwnd, + .cwnd_event = (void *)bpf_cubic_cwnd_event, + .pkts_acked = (void *)bpf_cubic_acked, + .name = "bpf_cc_cubic", +}; + +char _license[] SEC("license") = "GPL"; diff --git a/tools/testing/selftests/bpf/progs/bpf_tracing_net.h b/tools/testing/selftests/bpf/progs/bpf_tracing_net.h index 7001965d1cc3..f9ec630dfcd5 100644 --- a/tools/testing/selftests/bpf/progs/bpf_tracing_net.h +++ b/tools/testing/selftests/bpf/progs/bpf_tracing_net.h @@ -80,6 +80,14 @@ #define TCP_INFINITE_SSTHRESH 0x7fffffff #define TCP_PINGPONG_THRESH 3 +#define FLAG_DATA_ACKED 0x04 /* This ACK acknowledged new data. */ +#define FLAG_SYN_ACKED 0x10 /* This ACK acknowledged SYN. */ +#define FLAG_DATA_SACKED 0x20 /* New SACK. */ +#define FLAG_SND_UNA_ADVANCED \ + 0x400 /* Snd_una was changed (!= FLAG_DATA_ACKED) */ +#define FLAG_ACKED (FLAG_DATA_ACKED | FLAG_SYN_ACKED) +#define FLAG_FORWARD_PROGRESS (FLAG_ACKED | FLAG_DATA_SACKED) + #define fib_nh_dev nh_common.nhc_dev #define fib_nh_gw_family nh_common.nhc_gw_family #define fib_nh_gw6 nh_common.nhc_gw.ipv6 @@ -119,4 +127,6 @@ #define tw_v6_daddr __tw_common.skc_v6_daddr #define tw_v6_rcv_saddr __tw_common.skc_v6_rcv_saddr +#define tcp_jiffies32 ((__u32)bpf_jiffies64()) + #endif -- cgit