It is useful to print map ID on successful creation.
JSON case: $ ./bpftool -j map create /sys/fs/bpf/test_map4 type hash key 4 value 8 entries 128 name map4 {"id":12}
Generic case: $ ./bpftool map create /sys/fs/bpf/test_map5 type hash key 4 value 8 entries 128 name map5 Map successfully created with ID: 15
Bpftool Issue: https://github.com/libbpf/bpftool/issues/121 Acked-by: Yonghong Song yonghong.song@linux.dev Reviewed-by: Quentin Monnet qmo@kernel.org Signed-off-by: Harshit Mogalapalli harshit.m.mogalapalli@oracle.com --- v2->v3: remove a line break("\n" ) in p_err statement. [Thanks Quentin] --- tools/bpf/bpftool/map.c | 21 +++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-)
diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c index c9de44a45778..f32ae5476d76 100644 --- a/tools/bpf/bpftool/map.c +++ b/tools/bpf/bpftool/map.c @@ -1251,6 +1251,8 @@ static int do_create(int argc, char **argv) LIBBPF_OPTS(bpf_map_create_opts, attr); enum bpf_map_type map_type = BPF_MAP_TYPE_UNSPEC; __u32 key_size = 0, value_size = 0, max_entries = 0; + struct bpf_map_info map_info = {}; + __u32 map_info_len = sizeof(map_info); const char *map_name = NULL; const char *pinfile; int err = -1, fd; @@ -1353,13 +1355,24 @@ static int do_create(int argc, char **argv) }
err = do_pin_fd(fd, pinfile); - close(fd); if (err) - goto exit; + goto close_fd;
- if (json_output) - jsonw_null(json_wtr); + err = bpf_obj_get_info_by_fd(fd, &map_info, &map_info_len); + if (err) { + p_err("Failed to fetch map info: %s", strerror(errno)); + goto close_fd; + }
+ if (json_output) { + jsonw_start_object(json_wtr); + jsonw_int_field(json_wtr, "id", map_info.id); + jsonw_end_object(json_wtr); + } else { + printf("Map successfully created with ID: %u\n", map_info.id); + } +close_fd: + close(fd); exit: if (attr.inner_map_fd > 0) close(attr.inner_map_fd);