Hi,
On 1/15/2024 8:59 PM, Andrey Grafin wrote:
> This patch allows to create BPF_MAP_TYPE_ARRAY_OF_MAPS and
> BPF_MAP_TYPE_HASH_OF_MAPS with values of BPF_MAP_TYPE_PERF_EVENT_ARRAY.
>
> Previous behaviour created a zero filled btf_map_def for inner maps and
> tried to use it for a map creation but the linux kernel forbids to create
> a BPF_MAP_TYPE_PERF_EVENT_ARRAY map with max_entries=0.
>
> Signed-off-by: Andrey Grafin <conquistador@xxxxxxxxxxxxxx>
> ---
> tools/lib/bpf/libbpf.c | 4 +++
> .../selftests/bpf/progs/test_map_in_map.c | 23 +++++++++++++++
> tools/testing/selftests/bpf/test_maps.c | 29 ++++++++++++++++++-
It would be better to move the selftest into a separated patch, so the
fix patch for libbpf could be backported alone.
> 3 files changed, 55 insertions(+), 1 deletion(-)
>
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index e067be95da3c..8f4d580187aa 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -70,6 +70,7 @@
>
> static struct bpf_map *bpf_object__add_map(struct bpf_object *obj);
> static bool prog_is_subprog(const struct bpf_object *obj, const struct bpf_program *prog);
> +static int map_set_def_max_entries(struct bpf_map *map);
>
> static const char * const attach_type_name[] = {
> [BPF_CGROUP_INET_INGRESS] = "cgroup_inet_ingress",
> @@ -5212,6 +5213,9 @@ static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map, b
>
> if (bpf_map_type__is_map_in_map(def->type)) {
> if (map->inner_map) {
> + err = map_set_def_max_entries(map->inner_map);
> + if (err)
> + return err;
> err = bpf_object__create_map(obj, map->inner_map, true);
> if (err) {
> pr_warn("map '%s': failed to create inner map: %d\n",
> 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..b393d2b8bd6f 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");
>
> +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, 2);
> + __type(key, __u32);
> + __array(values, struct perf_event_array);
> +} mim_hash_pe SEC(".maps") = {
> + .values = {&inner_map0, &inner_map1}};
> +
> +
> 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..03f4d448fd3b 100644
> --- a/tools/testing/selftests/bpf/test_maps.c
> +++ b/tools/testing/selftests/bpf/test_maps.c
> @@ -1159,6 +1159,7 @@ static void test_map_in_map(void)
> __u32 len = sizeof(info);
> __u32 id = 0;
> libbpf_print_fn_t old_print_fn;
> + int ret;
Why not use err instead ?
>
> obj = bpf_object__open(MAPINMAP_PROG);
>
> @@ -1190,7 +1191,11 @@ static void test_map_in_map(void)
> goto out_map_in_map;
> }
>
> - bpf_object__load(obj);
> + ret = bpf_object__load(obj);
> + if (ret) {
> + printf("Failed to load test prog\n");
> + goto out_map_in_map;
> + }
>
> map = bpf_object__find_map_by_name(obj, "mim_array");
> if (!map) {
> @@ -1226,6 +1231,28 @@ static void test_map_in_map(void)
> goto out_map_in_map;
> }
>
> + map = bpf_object__find_map_by_name(obj, "mim_array_pe");
> + if (!map) {
> + printf("Failed to load array of perf event array maps\n");
> + goto out_map_in_map;
> + }
> + mim_fd = bpf_map__fd(map);
> + if (mim_fd < 0) {
> + printf("Failed to get descriptor for array of perf event array maps\n");
> + goto out_map_in_map;
> + }
> +
> + map = bpf_object__find_map_by_name(obj, "mim_hash_pe");
> + if (!map) {
> + printf("Failed to load hash of perf event array maps\n");
> + goto out_map_in_map;
> + }
> + mim_fd = bpf_map__fd(map);
> + if (mim_fd < 0) {
> + printf("Failed to get descriptor for array of perf event array maps\n");
array -> hash ?
> + goto out_map_in_map;
> + }
> +
> close(fd);
> fd = -1;
> bpf_object__close(obj);
