Re: [PATCH bpf v4 2/2] selftest/bpf: Add map_in_maps with BPF_MAP_TYPE_PERF_EVENT_ARRAY values

[Yonghong Song <yonghong.song@linux.dev>]

On 1/16/24 6:01 AM, Andrey Grafin wrote:
> Check that bpf_object__load() successfully creates map_in_maps
> with BPF_MAP_TYPE_PERF_EVENT_ARRAY values.
> These changes cover fix in the previous patch
> "libbpf: Apply map_set_def_max_entries() for inner_maps on creation".
>
> A command line output is:
> - w/o fix
> $ sudo ./test_maps
> libbpf: map 'mim_array_pe': failed to create inner map: -22
> libbpf: map 'mim_array_pe': failed to create: Invalid argument(-22)
> libbpf: failed to load object './test_map_in_map.bpf.o'
> Failed to load test prog
>
> - with fix
> $ sudo ./test_maps
> ...
> test_maps: OK, 0 SKIPPED
>
> Signed-off-by: Andrey Grafin <conquistador@yandex-team.ru>

Ack with a nit below.

Acked-by: Yonghong Song <yonghong.song@linux.dev>

> ---
>   .../selftests/bpf/progs/test_map_in_map.c     | 23 +++++++++++++++++++
>   tools/testing/selftests/bpf/test_maps.c       |  6 ++++-
>   2 files changed, 28 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/bpf/progs/test_map_in_map.c b/tools/testing/selftests/bpf/progs/test_map_in_map.c
> index f416032ba858..54ce1f4bdc7b 100644
> --- a/tools/testing/selftests/bpf/progs/test_map_in_map.c
> +++ b/tools/testing/selftests/bpf/progs/test_map_in_map.c
> @@ -21,6 +21,29 @@ struct {
>   	__type(value, __u32);
>   } mim_hash SEC(".maps");
>   

To avoid confusion for users looking at code why
the following three maps are not used. Maybe add
a comment below like:

/* The following three maps are used to test
  * perf_event_array map can be an inner
  * map of hash/array_of_maps.
  */

> +struct perf_event_array {
> +	__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
> +	__type(key, __u32);
> +	__type(value, __u32);
> +} inner_map0 SEC(".maps"), inner_map1 SEC(".maps");
> +
> +struct {
> +	__uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS);
> +	__uint(max_entries, 2);
> +	__type(key, __u32);
> +	__array(values, struct perf_event_array);
> +} mim_array_pe SEC(".maps") = {
> +	.values = {&inner_map0, &inner_map1}};
> +
> +struct {
> +	__uint(type, BPF_MAP_TYPE_HASH_OF_MAPS);
> +	__uint(max_entries, 1);
> +	__type(key, __u32);
> +	__array(values, struct perf_event_array);
> +} mim_hash_pe SEC(".maps") = {
> +	.values = {&inner_map0}};
> +
> +
>   SEC("xdp")
>   int xdp_mimtest0(struct xdp_md *ctx)
>   {
> diff --git a/tools/testing/selftests/bpf/test_maps.c b/tools/testing/selftests/bpf/test_maps.c
> index 7fc00e423e4d..e0dd101c9f2b 100644
> --- a/tools/testing/selftests/bpf/test_maps.c
> +++ b/tools/testing/selftests/bpf/test_maps.c
> @@ -1190,7 +1190,11 @@ static void test_map_in_map(void)
>   		goto out_map_in_map;
>   	}
>   
> -	bpf_object__load(obj);
> +	err = bpf_object__load(obj);
> +	if (err) {
> +		printf("Failed to load test prog\n");
> +		goto out_map_in_map;
> +	}
>   
>   	map = bpf_object__find_map_by_name(obj, "mim_array");
>   	if (!map) {