On Fri, Oct 02, 2020 at 03:57:50PM +0800, Hangbin Liu wrote:
> Say a user reuse map fd after creating a map manually and set the
> pin_path, then load the object via libbpf.
>
> In libbpf bpf_object__create_maps(), bpf_object__reuse_map() will
> return 0 if there is no pinned map in map->pin_path. Then after
> checking if map fd exist, we should also check if pin_path was set
> and do bpf_map__pin() instead of continue the loop.
>
> Fix it by creating map if fd not exist and continue checking pin_path
> after that.
>
> Suggested-by: Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx>
> Signed-off-by: Hangbin Liu <liuhangbin@xxxxxxxxx>
> ---
> tools/lib/bpf/libbpf.c | 75 +++++++++++++++++++++---------------------
> 1 file changed, 37 insertions(+), 38 deletions(-)
>
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index e493d6048143..d4149585a76c 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -3861,50 +3861,49 @@ bpf_object__create_maps(struct bpf_object *obj)
> }
> }
>
> - if (map->fd >= 0) {
> - pr_debug("map '%s': skipping creation (preset fd=%d)\n",
> - map->name, map->fd);
> - continue;
> - }
> -
> - err = bpf_object__create_map(obj, map);
> - if (err)
> - goto err_out;
> -
> - pr_debug("map '%s': created successfully, fd=%d\n", map->name,
> - map->fd);
> -
> - if (bpf_map__is_internal(map)) {
> - err = bpf_object__populate_internal_map(obj, map);
> - if (err < 0) {
> - zclose(map->fd);
> + if (map->fd < 0) {
> + err = bpf_object__create_map(obj, map);
> + if (err)
> goto err_out;
> - }
> - }
> -
> - if (map->init_slots_sz) {
> - for (j = 0; j < map->init_slots_sz; j++) {
> - const struct bpf_map *targ_map;
> - int fd;
>
> - if (!map->init_slots[j])
> - continue;
> + pr_debug("map '%s': created successfully, fd=%d\n", map->name,
> + map->fd);
>
> - targ_map = map->init_slots[j];
> - fd = bpf_map__fd(targ_map);
> - err = bpf_map_update_elem(map->fd, &j, &fd, 0);
> - if (err) {
> - err = -errno;
> - pr_warn("map '%s': failed to initialize slot [%d] to map '%s' fd=%d: %d\n",
> - map->name, j, targ_map->name,
> - fd, err);
> + if (bpf_map__is_internal(map)) {
> + err = bpf_object__populate_internal_map(obj, map);
> + if (err < 0) {
> + zclose(map->fd);
> goto err_out;
> }
> - pr_debug("map '%s': slot [%d] set to map '%s' fd=%d\n",
> - map->name, j, targ_map->name, fd);
> }
> - zfree(&map->init_slots);
> - map->init_slots_sz = 0;
> +
> + if (map->init_slots_sz) {
Couldn't we flatten the code by inverting the logic here and using goto?
if (!map->init_slot_sz) {
pr_debug("map '%s': skipping creation (preset fd=%d)\n",
map->name, map->fd);
goto map_pin;
}
(...)
map_pin:
if (map->pin_path && !map->pinned) {
If I'm reading this right.
> + for (j = 0; j < map->init_slots_sz; j++) {
> + const struct bpf_map *targ_map;
> + int fd;
> +
> + if (!map->init_slots[j])
> + continue;
> +
> + targ_map = map->init_slots[j];
> + fd = bpf_map__fd(targ_map);
> + err = bpf_map_update_elem(map->fd, &j, &fd, 0);
> + if (err) {
> + err = -errno;
> + pr_warn("map '%s': failed to initialize slot [%d] to map '%s' fd=%d: %d\n",
> + map->name, j, targ_map->name,
> + fd, err);
> + goto err_out;
> + }
> + pr_debug("map '%s': slot [%d] set to map '%s' fd=%d\n",
> + map->name, j, targ_map->name, fd);
> + }
> + zfree(&map->init_slots);
> + map->init_slots_sz = 0;
> + }
> + } else {
> + pr_debug("map '%s': skipping creation (preset fd=%d)\n",
> + map->name, map->fd);
> }
>
> if (map->pin_path && !map->pinned) {
> --
> 2.25.4
>
