Re: [PATCH bpf-next] bpf: Return EINVAL instead of NULL for map_lookup_elem of queue

[Yonghong Song <yonghong.song@linux.dev>]

On 6/8/24 2:29 AM, Florian Lehner wrote:
> Programs should use map_peek_elem over map_lookup_elem for queues. NULL is
> also not a valid queue return nor a proper error, that could be handled.
>
> Signed-off-by: Florian Lehner <dev@der-flo.net>

Acked-by: Yonghong Song <yonghong.song@linux.dev>

> ---
>   kernel/bpf/queue_stack_maps.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/bpf/queue_stack_maps.c b/kernel/bpf/queue_stack_maps.c
> index d869f51ea93a..85bead55024d 100644
> --- a/kernel/bpf/queue_stack_maps.c
> +++ b/kernel/bpf/queue_stack_maps.c
> @@ -234,7 +234,8 @@ static long queue_stack_map_push_elem(struct bpf_map *map, void *value,
>   /* Called from syscall or from eBPF program */
>   static void *queue_stack_map_lookup_elem(struct bpf_map *map, void *key)
>   {
> -	return NULL;
> +	/* The eBPF program should use map_peek_elem instead */
> +	return ERR_PTR(-EINVAL);
>   }
>   
>   /* Called from syscall or from eBPF program */