libbpf: Add bpf_map__inner_map API

The API gives access to inner map for map in map types (array or
hash of map). It will be used to dynamically set max_entries in it.

Signed-off-by: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210408061310.95877-7-yauheni.kaliuta@redhat.com

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 7aad78d..ed5586c 100644 (file)
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -2194,6 +2194,7 @@ static int parse_btf_map_def(struct bpf_object *obj,
                        map->inner_map = calloc(1, sizeof(*map->inner_map));
                        if (!map->inner_map)
                                return -ENOMEM;
+                       map->inner_map->fd = -1;
                        map->inner_map->sec_idx = obj->efile.btf_maps_shndx;
                        map->inner_map->name = malloc(strlen(map->name) +
                                                      sizeof(".inner") + 1);
@@ -3845,6 +3846,14 @@ __u32 bpf_map__max_entries(const struct bpf_map *map)
        return map->def.max_entries;
 }
 
+struct bpf_map *bpf_map__inner_map(struct bpf_map *map)
+{
+       if (!bpf_map_type__is_map_in_map(map->def.type))
+               return NULL;
+
+       return map->inner_map;
+}
+
 int bpf_map__set_max_entries(struct bpf_map *map, __u32 max_entries)
 {
        if (map->fd >= 0)
@@ -9476,6 +9485,7 @@ int bpf_map__set_inner_map_fd(struct bpf_map *map, int fd)
                pr_warn("error: inner_map_fd already specified\n");
                return -EINVAL;
        }
+       zfree(&map->inner_map);
        map->inner_map_fd = fd;
        return 0;
 }

diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index f500621..bec4e6a 100644 (file)
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -480,6 +480,7 @@ LIBBPF_API int bpf_map__pin(struct bpf_map *map, const char *path);
 LIBBPF_API int bpf_map__unpin(struct bpf_map *map, const char *path);
 
 LIBBPF_API int bpf_map__set_inner_map_fd(struct bpf_map *map, int fd);
+LIBBPF_API struct bpf_map *bpf_map__inner_map(struct bpf_map *map);
 
 LIBBPF_API long libbpf_get_error(const void *ptr);
 

diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index f5990f7..b9b29ba 100644 (file)
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -359,5 +359,6 @@ LIBBPF_0.4.0 {
                bpf_linker__finalize;
                bpf_linker__free;
                bpf_linker__new;
+               bpf_map__inner_map;
                bpf_object__set_kversion;
 } LIBBPF_0.3.0;