Re: [PATCH bpf-next v3 5/5] selftests/bpf: Add some tests with new bpf_program__attach_sockmap() APIs

[Eduard Zingerman <eddyz87@gmail.com>]

On Mon, 2024-03-25 at 19:22 -0700, Yonghong Song wrote:
> Add a few more tests in sockmap_basic.c and sockmap_listen.c to
> test bpf_link based APIs for SK_MSG and SK_SKB programs.
> Link attach/detach/update are all tested.
> 
> All tests are passed.
> 
> Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
> ---

Acked-by: Eduard Zingerman <eddyz87@gmail.com>

As far as I understand patch #1 there are several error conditions
that are not covered by these tests:
- update link using program with wrong expected attach type;
- bpf_program__attach_sockmap() _after_ bpf_prog_attach();
- creation of a second link between same prog and map
  (if I understand 'link && link != progs->msg_parser_link' checks in
   sock_map_link_lookup() correctly).

Are these important enough to have a dedicated test?

[...]

> diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
> index 63fb2da7930a..b4b38f92b864 100644
> --- a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
> +++ b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
> @@ -131,6 +131,40 @@ static void test_skmsg_helpers(enum bpf_map_type map_type)
>  	test_skmsg_load_helpers__destroy(skel);
>  }
>  
> +static void test_skmsg_helpers_with_link(enum bpf_map_type map_type)
> +{
> +	struct test_skmsg_load_helpers *skel;
> +	struct bpf_link *link, *link2;
> +	struct bpf_program *prog;
> +	int err, map;
> +
> +	skel = test_skmsg_load_helpers__open_and_load();
> +	if (!ASSERT_OK_PTR(skel, "test_skmsg_load_helpers__open_and_load"))
> +		return;
> +
> +	prog = skel->progs.prog_msg_verdict;
> +	map = bpf_map__fd(skel->maps.sock_map);
> +
> +	link = bpf_program__attach_sockmap(prog, map);
> +	if (!ASSERT_OK_PTR(link, "bpf_program__attach_sockmap"))
> +		goto out;
> +
> +	err = bpf_prog_attach(bpf_program__fd(prog), map, BPF_SK_MSG_VERDICT, 0);
> +	if (!ASSERT_ERR(err, "bpf_prog_attach"))
> +		goto out;
> +
> +	link2 = bpf_program__attach_sockmap(skel->progs.prog_msg_verdict_clone, map);
> +	if (!ASSERT_ERR_PTR(link2, "bpf_program__attach_sockmap"))
> +		goto out;

Nit: should bpf_link__detach(link2) be called before 'goto out' ? 

> +
> +	err = bpf_link__update_program(link, skel->progs.prog_msg_verdict_clone);
> +	ASSERT_OK(err, "bpf_link__update_program");
> +
> +out:
> +	bpf_link__detach(link);
> +	test_skmsg_load_helpers__destroy(skel);
> +}
> +
>  static void test_sockmap_update(enum bpf_map_type map_type)
>  {
>  	int err, prog, src;