On Fri, Nov 8, 2019 at 1:33 PM Toke Høiland-Jørgensen <toke@xxxxxxxxxx> wrote:
>
> From: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
>
> Since the automatic map-pinning happens during load, it will leave pinned
> maps around if the load fails at a later stage. Fix this by unpinning any
> pinned maps on cleanup. To avoid unpinning pinned maps that were reused
> rather than newly pinned, add a new boolean property on struct bpf_map to
> keep track of whether that map was reused or not; and only unpin those maps
> that were not reused.
>
> Fixes: 57a00f41644f ("libbpf: Add auto-pinning of maps when loading BPF objects")
> Acked-by: Song Liu <songliubraving@xxxxxx>
> Signed-off-by: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
> ---
> tools/lib/bpf/libbpf.c | 16 +++++++++++++---
> 1 file changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index be4af95d5a2c..cea61b2ec9d3 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -229,6 +229,7 @@ struct bpf_map {
> enum libbpf_map_type libbpf_type;
> char *pin_path;
> bool pinned;
> + bool was_reused;
nit: just reused, similar to pinned?
> };
>
> struct bpf_secdata {
> @@ -1995,6 +1996,7 @@ int bpf_map__reuse_fd(struct bpf_map *map, int fd)
> map->def.map_flags = info.map_flags;
> map->btf_key_type_id = info.btf_key_type_id;
> map->btf_value_type_id = info.btf_value_type_id;
> + map->was_reused = true;
>
> return 0;
>
> @@ -4007,15 +4009,18 @@ bpf_object__open_buffer(const void *obj_buf, size_t obj_buf_sz,
> return bpf_object__open_mem(obj_buf, obj_buf_sz, &opts);
> }
>
> -int bpf_object__unload(struct bpf_object *obj)
> +static int __bpf_object__unload(struct bpf_object *obj, bool unpin)
> {
> size_t i;
>
> if (!obj)
> return -EINVAL;
>
> - for (i = 0; i < obj->nr_maps; i++)
> + for (i = 0; i < obj->nr_maps; i++) {
> zclose(obj->maps[i].fd);
> + if (unpin && obj->maps[i].pinned && !obj->maps[i].was_reused)
> + bpf_map__unpin(&obj->maps[i], NULL);
> + }
>
> for (i = 0; i < obj->nr_programs; i++)
> bpf_program__unload(&obj->programs[i]);
> @@ -4023,6 +4028,11 @@ int bpf_object__unload(struct bpf_object *obj)
> return 0;
> }
>
> +int bpf_object__unload(struct bpf_object *obj)
> +{
> + return __bpf_object__unload(obj, false);
> +}
> +
> int bpf_object__load_xattr(struct bpf_object_load_attr *attr)
> {
> struct bpf_object *obj;
> @@ -4047,7 +4057,7 @@ int bpf_object__load_xattr(struct bpf_object_load_attr *attr)
>
> return 0;
> out:
> - bpf_object__unload(obj);
> + __bpf_object__unload(obj, true);
giving this is the only (special) case of auto-unpinning auto-pinned
maps, why not do a trivial loop here, instead of having this extra
unpin flag and extra __bpf_object__unload function?
> pr_warn("failed to load object '%s'\n", obj->path);
> return err;
> }
>
