Hi,
On 2/17/2025 9:41 AM, Xiaomeng Zhang wrote:
> Remove redundant map_peek_elem callbacks with return -EOPNOTSUPP. We can
> directly return -EOPNOTSUPP when calling the unimplemented callbacks.
>
> Signed-off-by: Xiaomeng Zhang <zhangxiaomeng13@xxxxxxxxxx>
> ---
> kernel/bpf/arena.c | 6 ------
> kernel/bpf/helpers.c | 5 ++++-
> kernel/bpf/syscall.c | 5 ++++-
> 3 files changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/kernel/bpf/arena.c b/kernel/bpf/arena.c
> index 095a9554e1de..0aaefa5d6b09 100644
> --- a/kernel/bpf/arena.c
> +++ b/kernel/bpf/arena.c
> @@ -62,11 +62,6 @@ u64 bpf_arena_get_user_vm_start(struct bpf_arena *arena)
> return arena ? arena->user_vm_start : 0;
> }
>
> -static long arena_map_peek_elem(struct bpf_map *map, void *value)
> -{
> - return -EOPNOTSUPP;
> -}
> -
> static long arena_map_push_elem(struct bpf_map *map, void *value, u64 flags)
> {
> return -EOPNOTSUPP;
> @@ -404,7 +399,6 @@ const struct bpf_map_ops arena_map_ops = {
> .map_get_unmapped_area = arena_get_unmapped_area,
> .map_get_next_key = arena_map_get_next_key,
> .map_push_elem = arena_map_push_elem,
> - .map_peek_elem = arena_map_peek_elem,
> .map_pop_elem = arena_map_pop_elem,
> .map_lookup_elem = arena_map_lookup_elem,
> .map_update_elem = arena_map_update_elem,
> diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
> index f27ce162427a..0f429171de6d 100644
> --- a/kernel/bpf/helpers.c
> +++ b/kernel/bpf/helpers.c
> @@ -116,7 +116,10 @@ const struct bpf_func_proto bpf_map_pop_elem_proto = {
>
> BPF_CALL_2(bpf_map_peek_elem, struct bpf_map *, map, void *, value)
> {
> - return map->ops->map_peek_elem(map, value);
> + if (map->ops->map_peek_elem)
> + return map->ops->map_peek_elem(map, value);
> + else
> + return -EOPNOTSUPP;
> }
It is unnecessary. Because the verifier has ensured the
bpf_map_peek_elem helper is only available for specific maps in
check_map_func_compatibility().
>
> const struct bpf_func_proto bpf_map_peek_elem_proto = {
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index ff1f980bd59a..e6e859f71c5d 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -325,7 +325,10 @@ static int bpf_map_copy_value(struct bpf_map *map, void *key, void *value,
> } else if (map->map_type == BPF_MAP_TYPE_QUEUE ||
> map->map_type == BPF_MAP_TYPE_STACK ||
> map->map_type == BPF_MAP_TYPE_BLOOM_FILTER) {
> - err = map->ops->map_peek_elem(map, value);
> + if (map->ops->map_peek_elem)
> + err = map->ops->map_peek_elem(map, value);
> + else
> + err = -EOPNOTSUPP;
It is also unnecessary due to the similar reason.
> } else if (map->map_type == BPF_MAP_TYPE_STRUCT_OPS) {
> /* struct_ops map requires directly updating "value" */
> err = bpf_struct_ops_map_sys_lookup_elem(map, key, value);
