Re: [PATCH bpf-next v7 2/2] selftests/bpf: add tests for selective module BTF loading

[Jiri Olsa <olsajiri@gmail.com>]

On Mon, Sep 07, 2026 at 01:38:47PM +0800, Fuyu Zhao wrote:

SNIP

> +static void btf_module_allowlist_default(void)
> +{
> +	struct btf_module_allowlist *skel;
> +	int ret;
> +	LIBBPF_OPTS(bpf_object_open_opts, opts);
> +
> +	skel = btf_module_allowlist__open();
> +	if (!ASSERT_OK_PTR(skel, "btf_module_allowlist__open"))
> +		return;
> +
> +	ret = btf_module_allowlist__load(skel);
> +	ASSERT_OK(ret, "btf_module_allowlist__load");
> +
> +	btf_module_allowlist__destroy(skel);
> +	skel = NULL;
> +
> +	skel = btf_module_allowlist__open_opts(&opts);
> +	if (!ASSERT_OK_PTR(skel, "btf_module_allowlist__open_opts"))
> +		return;
> +
> +	ret = btf_module_allowlist__load(skel);
> +	ASSERT_OK(ret, "btf_module_allowlist__load opts");
> +
> +	btf_module_allowlist__destroy(skel);

^^^ seems redundant, I don't think we need to test that

SNIP

> +void test_btf_module_allowlist(void)
> +{
> +	struct btf *vmlinux_btf = NULL;
> +	struct btf *module_btf = NULL;
> +
> +	if (!env.has_testmod) {
> +		printf("%s:SKIP: bpf_testmod is not available\n", __func__);
> +		test__skip();
> +		return;
> +	}
> +
> +	vmlinux_btf = btf__load_vmlinux_btf();
> +	if (libbpf_get_error(vmlinux_btf)) {
> +		printf("%s:SKIP: vmlinux_btf is not available\n", __func__);
> +		test__skip();
> +		return;
> +	}
> +
> +	/* Ensure bpf_testmod BTF is available. */
> +	module_btf = btf__load_module_btf("bpf_testmod", vmlinux_btf);
> +	if (libbpf_get_error(module_btf)) {
> +		printf("%s:SKIP: bpf_testmod's BTF is not available\n", __func__);
> +		btf__free(vmlinux_btf);
> +		test__skip();
> +		return;
> +	}
> +
> +	btf__free(module_btf);
> +	btf__free(vmlinux_btf);
> +
> +	if (test__start_subtest("default"))
> +		btf_module_allowlist_default();
> +
> +	if (test__start_subtest("allowlist"))
> +		btf_module_allowlist_allow();
> +
> +	if (test__start_subtest("skip_unlisted"))
> +		btf_module_allowlist_skip();
> +
> +	if (test__start_subtest("emptylist"))
> +		btf_module_allowlist_empty();
> +
> +	if (test__start_subtest("invalid_input"))
> +		btf_module_allowlist_invalid();

could you add test that verifies the module's BTF did not get
load because of the allow list setup, something like:

  bpf_program__set_attach_target(prog, 0, "bpf_testmod:bpf_fentry_test1")

would fail, or some other way that uses obj->btf_modules

thanks,
jirka