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author | Andrey Ignatov <rdna@fb.com> | 2019-02-14 15:01:42 -0800 |
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committer | Daniel Borkmann <daniel@iogearbox.net> | 2019-02-15 15:20:42 +0100 |
commit | 1a11a4c74f73adb840d61371c3bb560ed4d7a87f (patch) | |
tree | c550a378980ca3070ac1398ebe7eea853f2149f2 | |
parent | f8ebfaf6684b03084858d8c55f81867e5171af08 (diff) | |
download | linux-stable-1a11a4c74f73adb840d61371c3bb560ed4d7a87f.tar.gz linux-stable-1a11a4c74f73adb840d61371c3bb560ed4d7a87f.tar.bz2 linux-stable-1a11a4c74f73adb840d61371c3bb560ed4d7a87f.zip |
libbpf: Introduce bpf_map__resize
Add bpf_map__resize() to change max_entries for a map.
Quite often necessary map size is unknown at compile time and can be
calculated only at run time.
Currently the following approach is used to do so:
* bpf_object__open_buffer() to open Elf file from a buffer;
* bpf_object__find_map_by_name() to find relevant map;
* bpf_map__def() to get map attributes and create struct
bpf_create_map_attr from them;
* update max_entries in bpf_create_map_attr;
* bpf_create_map_xattr() to create new map with updated max_entries;
* bpf_map__reuse_fd() to replace the map in bpf_object with newly
created one.
And after all this bpf_object can finally be loaded. The map will have
new size.
It 1) is quite a lot of steps; 2) doesn't take BTF into account.
For "2)" even more steps should be made and some of them require changes
to libbpf (e.g. to get struct btf * from bpf_object).
Instead the whole problem can be solved by introducing simple
bpf_map__resize() API that checks the map and sets new max_entries if
the map is not loaded yet.
So the new steps are:
* bpf_object__open_buffer() to open Elf file from a buffer;
* bpf_object__find_map_by_name() to find relevant map;
* bpf_map__resize() to update max_entries.
That's much simpler and works with BTF.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
-rw-r--r-- | tools/lib/bpf/libbpf.c | 14 | ||||
-rw-r--r-- | tools/lib/bpf/libbpf.h | 1 | ||||
-rw-r--r-- | tools/lib/bpf/libbpf.map | 1 |
3 files changed, 16 insertions, 0 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 6ef7e6e4cbd3..9597d4dace34 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -1113,6 +1113,20 @@ err_free_new_name: return -errno; } +int bpf_map__resize(struct bpf_map *map, __u32 max_entries) +{ + if (!map || !max_entries) + return -EINVAL; + + /* If map already created, its attributes can't be changed. */ + if (map->fd >= 0) + return -EBUSY; + + map->def.max_entries = max_entries; + + return 0; +} + static int bpf_object__probe_name(struct bpf_object *obj) { diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index 69a7c25eaccc..987fd92661d6 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -294,6 +294,7 @@ LIBBPF_API int bpf_map__set_priv(struct bpf_map *map, void *priv, bpf_map_clear_priv_t clear_priv); LIBBPF_API void *bpf_map__priv(struct bpf_map *map); LIBBPF_API int bpf_map__reuse_fd(struct bpf_map *map, int fd); +LIBBPF_API int bpf_map__resize(struct bpf_map *map, __u32 max_entries); LIBBPF_API bool bpf_map__is_offload_neutral(struct bpf_map *map); LIBBPF_API void bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex); LIBBPF_API int bpf_map__pin(struct bpf_map *map, const char *path); diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index 5fc8222209f8..16f342c3d4bc 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -130,6 +130,7 @@ LIBBPF_0.0.2 { bpf_probe_helper; bpf_probe_map_type; bpf_probe_prog_type; + bpf_map__resize; bpf_map_lookup_elem_flags; bpf_object__find_map_fd_by_name; bpf_get_link_xdp_id; |