Subject: Re: [PATCH bpf-next/net v6 3/3] selftests/bpf: Add mptcp subflow subtest

From: Martin KaFai Lau <[email-masked]>
Date: Fri, 13 Sep 2024 17:29:25 -0700

On 9/11/24 8:16 AM, Matthieu Baerts (NGI0) wrote:
> +static void test_subflow(void)
> +{
> +	int cgroup_fd, prog_fd, err;
> +	struct mptcp_subflow *skel;
> +	struct nstoken *nstoken;
> +	struct bpf_link *link;
> +
> +	cgroup_fd = test__join_cgroup("/mptcp_subflow");
> +	if (!ASSERT_OK_FD(cgroup_fd, "join_cgroup: mptcp_subflow"))
> +		return;
> +
> +	skel = mptcp_subflow__open_and_load();
> +	if (!ASSERT_OK_PTR(skel, "skel_open_load: mptcp_subflow"))
> +		goto close_cgroup;
> +
> +	skel->bss->pid = getpid();
> +
> +	err = mptcp_subflow__attach(skel);

This is not needed.

> +	if (!ASSERT_OK(err, "skel_attach: mptcp_subflow"))
> +		goto skel_destroy;
> +
> +	prog_fd = bpf_program__fd(skel->progs.mptcp_subflow);
> +	err = bpf_prog_attach(prog_fd, cgroup_fd, BPF_CGROUP_SOCK_OPS, 0);

Use bpf_program__attach_cgroup here instead since ...

> +	if (!ASSERT_OK(err, "prog_attach"))
> +		goto skel_destroy;
> +
> +	nstoken = create_netns();
> +	if (!ASSERT_OK_PTR(nstoken, "create_netns: mptcp_subflow"))
> +		goto skel_destroy;
> +
> +	if (endpoint_init("subflow") < 0)
> +		goto close_netns;
> +
> +	link = bpf_program__attach_cgroup(skel->progs._getsockopt_subflow,
> +					  cgroup_fd);

... bpf_program__attach_cgroup is used here also.

Instead of declaring a local "link", use the skel->links.{mptcp_subflow, 
_getsockopt_subflow}. Then mptcp_subflow__destroy(skel) will take care of them 
also. e.g. "skel->links._getsockopt_subflow = bpf_program__attach_cgroup(...)"

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