Re: [PATCH mptcp-next v4 07/10] selftests/bpf: add bpf_bkup scheduler

[Mat Martineau <mathew.j.martineau@linux.intel.com>]

On Tue, 31 May 2022, Geliang Tang wrote:

> This patch implements the backup flag test scheduler, named bpf_bkup,
> which picks the first non-backup subflow to send data.
>
> Signed-off-by: Geliang Tang <geliang.tang@suse.com>
> ---
> tools/testing/selftests/bpf/bpf_tcp_helpers.h |  2 +
> .../selftests/bpf/progs/mptcp_bpf_bkup.c      | 43 +++++++++++++++++++
> 2 files changed, 45 insertions(+)
> create mode 100644 tools/testing/selftests/bpf/progs/mptcp_bpf_bkup.c
>
> diff --git a/tools/testing/selftests/bpf/bpf_tcp_helpers.h b/tools/testing/selftests/bpf/bpf_tcp_helpers.h
> index 870deb5cf5ed..6fa496a65bef 100644
> --- a/tools/testing/selftests/bpf/bpf_tcp_helpers.h
> +++ b/tools/testing/selftests/bpf/bpf_tcp_helpers.h
> @@ -234,6 +234,8 @@ extern void tcp_cong_avoid_ai(struct tcp_sock *tp, __u32 w, __u32 acked) __ksym;
> #define MPTCP_SUBFLOWS_MAX	8
>
> struct mptcp_subflow_context {
> +	__u32	padding : 12,
> +		backup : 1;

Is the padding required? It looks like the BTF code might know how to 
handle bitfield members.

- Mat

> 	bool	scheduled;
> } __attribute__((preserve_access_index));
>
> diff --git a/tools/testing/selftests/bpf/progs/mptcp_bpf_bkup.c b/tools/testing/selftests/bpf/progs/mptcp_bpf_bkup.c
> new file mode 100644
> index 000000000000..ad2b2b4de8a5
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/mptcp_bpf_bkup.c
> @@ -0,0 +1,43 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2022, SUSE. */
> +
> +#include <linux/bpf.h>
> +#include "bpf_tcp_helpers.h"
> +
> +char _license[] SEC("license") = "GPL";
> +
> +SEC("struct_ops/mptcp_sched_bkup_init")
> +void BPF_PROG(mptcp_sched_bkup_init, const struct mptcp_sock *msk)
> +{
> +}
> +
> +SEC("struct_ops/mptcp_sched_bkup_release")
> +void BPF_PROG(mptcp_sched_bkup_release, const struct mptcp_sock *msk)
> +{
> +}
> +
> +void BPF_STRUCT_OPS(bpf_bkup_get_subflow, const struct mptcp_sock *msk,
> +		    struct mptcp_sched_data *data)
> +{
> +	int nr = 0;
> +
> +	for (int i = 0; i < MPTCP_SUBFLOWS_MAX; i++) {
> +		if (!data->contexts[i])
> +			break;
> +
> +		if (!data->contexts[i]->backup) {
> +			nr = i;
> +			break;
> +		}
> +	}
> +
> +	data->contexts[nr]->scheduled = 1;
> +}
> +
> +SEC(".struct_ops")
> +struct mptcp_sched_ops bkup = {
> +	.init		= (void *)mptcp_sched_bkup_init,
> +	.release	= (void *)mptcp_sched_bkup_release,
> +	.get_subflow	= (void *)bpf_bkup_get_subflow,
> +	.name		= "bpf_bkup",
> +};
> -- 
> 2.34.1
>
>
>

--
Mat Martineau
Intel