Re: [PATCH bpf-next 2/3] selftests: bpf: Add helper to compare socket cookies

[Jakub Sitnicki <jakub@cloudflare.com>]

On Fri, Aug 28, 2020 at 11:48 AM CEST, Lorenz Bauer wrote:
> We compare socket cookies to ensure that insertion into a sockmap worked.
> Pull this out into a helper function for use in other tests.
>
> Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
> ---
>  .../selftests/bpf/prog_tests/sockmap_basic.c  | 51 ++++++++++++++-----
>  1 file changed, 37 insertions(+), 14 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
> index 0b79d78b98db..b989f8760f1a 100644
> --- a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
> +++ b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
> @@ -47,6 +47,38 @@ static int connected_socket_v4(void)
>  	return -1;
>  }
>  
> +static void compare_cookies(struct bpf_map *src, struct bpf_map *dst)
> +{
> +	__u32 i, max_entries = bpf_map__max_entries(src);
> +	int err, duration, src_fd, dst_fd;
> +
> +	src_fd = bpf_map__fd(src);
> +	dst_fd = bpf_map__fd(src);
                             ^^^
That looks like a typo. We're comparing src map to src map.

> +
> +	for (i = 0; i < max_entries; i++) {
> +		__u64 src_cookie, dst_cookie;
> +
> +		err = bpf_map_lookup_elem(src_fd, &i, &src_cookie);
> +		if (err && errno == ENOENT) {
> +			err = bpf_map_lookup_elem(dst_fd, &i, &dst_cookie);
> +			if (err && errno == ENOENT)
> +				continue;
> +
> +			CHECK(err, "map_lookup_elem(dst)", "element not deleted\n");
> +			continue;
> +		}
> +		if (CHECK(err, "lookup_elem(src, cookie)", "%s\n", strerror(errno)))
> +			continue;
> +
> +		err = bpf_map_lookup_elem(dst_fd, &i, &dst_cookie);
> +		if (CHECK(err, "lookup_elem(dst, cookie)", "%s\n", strerror(errno)))
> +			continue;
> +
> +		CHECK(dst_cookie != src_cookie, "cookie mismatch",
> +		      "%llu != %llu (pos %u)\n", dst_cookie, src_cookie, i);
> +	}
> +}
> +
>  /* Create a map, populate it with one socket, and free the map. */
>  static void test_sockmap_create_update_free(enum bpf_map_type map_type)
>  {
> @@ -106,9 +138,9 @@ static void test_skmsg_helpers(enum bpf_map_type map_type)
>  static void test_sockmap_update(enum bpf_map_type map_type)
>  {
>  	struct bpf_prog_test_run_attr tattr;
> -	int err, prog, src, dst, duration = 0;
> +	int err, prog, src, duration = 0;
>  	struct test_sockmap_update *skel;
> -	__u64 src_cookie, dst_cookie;
> +	struct bpf_map *dst_map;
>  	const __u32 zero = 0;
>  	char dummy[14] = {0};
>  	__s64 sk;
> @@ -124,18 +156,14 @@ static void test_sockmap_update(enum bpf_map_type map_type)
>  	prog = bpf_program__fd(skel->progs.copy_sock_map);
>  	src = bpf_map__fd(skel->maps.src);
>  	if (map_type == BPF_MAP_TYPE_SOCKMAP)
> -		dst = bpf_map__fd(skel->maps.dst_sock_map);
> +		dst_map = skel->maps.dst_sock_map;
>  	else
> -		dst = bpf_map__fd(skel->maps.dst_sock_hash);
> +		dst_map = skel->maps.dst_sock_hash;
>  
>  	err = bpf_map_update_elem(src, &zero, &sk, BPF_NOEXIST);
>  	if (CHECK(err, "update_elem(src)", "errno=%u\n", errno))
>  		goto out;
>  
> -	err = bpf_map_lookup_elem(src, &zero, &src_cookie);
> -	if (CHECK(err, "lookup_elem(src, cookie)", "errno=%u\n", errno))
> -		goto out;
> -
>  	tattr = (struct bpf_prog_test_run_attr){
>  		.prog_fd = prog,
>  		.repeat = 1,
> @@ -148,12 +176,7 @@ static void test_sockmap_update(enum bpf_map_type map_type)
>  		       "errno=%u retval=%u\n", errno, tattr.retval))
>  		goto out;
>  
> -	err = bpf_map_lookup_elem(dst, &zero, &dst_cookie);
> -	if (CHECK(err, "lookup_elem(dst, cookie)", "errno=%u\n", errno))
> -		goto out;
> -
> -	CHECK(dst_cookie != src_cookie, "cookie mismatch", "%llu != %llu\n",
> -	      dst_cookie, src_cookie);
> +	compare_cookies(skel->maps.src, dst_map);
>  
>  out:
>  	test_sockmap_update__destroy(skel);