Commit 78e60bbb authored by Martin KaFai Lau's avatar Martin KaFai Lau Committed by Alexei Starovoitov
Browse files

bpf: selftests: Bpf_cubic and bpf_dctcp calling kernel functions 



This patch removes the bpf implementation of tcp_slow_start()
and tcp_cong_avoid_ai().  Instead, it directly uses the kernel
implementation.

It also replaces the bpf_cubic_undo_cwnd implementation by directly
calling tcp_reno_undo_cwnd().  bpf_dctcp also directly calls
tcp_reno_cong_avoid() instead.

Signed-off-by: default avatarMartin KaFai Lau <kafai@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210325015246.1551062-1-kafai@fb.com
parent 39cd9e0f

tools/testing/selftests/bpf/bpf_tcp_helpers.h

+2 −27
Original line number Diff line number Diff line
@@ -187,16 +187,6 @@ struct tcp_congestion_ops { 
	typeof(y) __y = (y);			\

	__x == 0 ? __y : ((__y == 0) ? __x : min(__x, __y)); })



static __always_inline __u32 tcp_slow_start(struct tcp_sock *tp, __u32 acked)

{

	__u32 cwnd = min(tp->snd_cwnd + acked, tp->snd_ssthresh);



	acked -= cwnd - tp->snd_cwnd;

	tp->snd_cwnd = min(cwnd, tp->snd_cwnd_clamp);



	return acked;

}



static __always_inline bool tcp_in_slow_start(const struct tcp_sock *tp)

{

	return tp->snd_cwnd < tp->snd_ssthresh;
@@ -213,22 +203,7 @@ static __always_inline bool tcp_is_cwnd_limited(const struct sock *sk) 
	return !!BPF_CORE_READ_BITFIELD(tp, is_cwnd_limited);

}



static __always_inline void tcp_cong_avoid_ai(struct tcp_sock *tp, __u32 w, __u32 acked)

{

	/* If credits accumulated at a higher w, apply them gently now. */

	if (tp->snd_cwnd_cnt >= w) {

		tp->snd_cwnd_cnt = 0;

		tp->snd_cwnd++;

	}



	tp->snd_cwnd_cnt += acked;

	if (tp->snd_cwnd_cnt >= w) {

		__u32 delta = tp->snd_cwnd_cnt / w;



		tp->snd_cwnd_cnt -= delta * w;

		tp->snd_cwnd += delta;

	}

	tp->snd_cwnd = min(tp->snd_cwnd, tp->snd_cwnd_clamp);

}

extern __u32 tcp_slow_start(struct tcp_sock *tp, __u32 acked) __ksym;

extern void tcp_cong_avoid_ai(struct tcp_sock *tp, __u32 w, __u32 acked) __ksym;



#endif

tools/testing/selftests/bpf/progs/bpf_cubic.c

+3 −3
Original line number Diff line number Diff line
@@ -525,11 +525,11 @@ void BPF_STRUCT_OPS(bpf_cubic_acked, struct sock *sk, 
		hystart_update(sk, delay);

}



extern __u32 tcp_reno_undo_cwnd(struct sock *sk) __ksym;



__u32 BPF_STRUCT_OPS(bpf_cubic_undo_cwnd, struct sock *sk)

{

	const struct tcp_sock *tp = tcp_sk(sk);



	return max(tp->snd_cwnd, tp->prior_cwnd);

	return tcp_reno_undo_cwnd(sk);

}



SEC(".struct_ops")

tools/testing/selftests/bpf/progs/bpf_dctcp.c

+6 −16
Original line number Diff line number Diff line
@@ -194,22 +194,12 @@ __u32 BPF_PROG(dctcp_cwnd_undo, struct sock *sk) 
	return max(tcp_sk(sk)->snd_cwnd, ca->loss_cwnd);

}



SEC("struct_ops/tcp_reno_cong_avoid")

void BPF_PROG(tcp_reno_cong_avoid, struct sock *sk, __u32 ack, __u32 acked)

{

	struct tcp_sock *tp = tcp_sk(sk);



	if (!tcp_is_cwnd_limited(sk))

		return;

extern void tcp_reno_cong_avoid(struct sock *sk, __u32 ack, __u32 acked) __ksym;



	/* In "safe" area, increase. */

	if (tcp_in_slow_start(tp)) {

		acked = tcp_slow_start(tp, acked);

		if (!acked)

			return;

	}

	/* In dangerous area, increase slowly. */

	tcp_cong_avoid_ai(tp, tp->snd_cwnd, acked);

SEC("struct_ops/dctcp_reno_cong_avoid")

void BPF_PROG(dctcp_cong_avoid, struct sock *sk, __u32 ack, __u32 acked)

{

	tcp_reno_cong_avoid(sk, ack, acked);

}



SEC(".struct_ops")
@@ -226,7 +216,7 @@ struct tcp_congestion_ops dctcp = { 
	.in_ack_event   = (void *)dctcp_update_alpha,

	.cwnd_event	= (void *)dctcp_cwnd_event,

	.ssthresh	= (void *)dctcp_ssthresh,

	.cong_avoid	= (void *)tcp_reno_cong_avoid,

	.cong_avoid	= (void *)dctcp_cong_avoid,

	.undo_cwnd	= (void *)dctcp_cwnd_undo,

	.set_state	= (void *)dctcp_state,

	.flags		= TCP_CONG_NEEDS_ECN,