On Mon, Oct 8, 2018 at 6:06 PM Prashant Bhole
<bhole_prashant...@lab.ntt.co.jp> wrote:
>
> The error value returned by map_lookup_elem doesn't differentiate
> whether lookup was failed because of invalid key or lookup is not
> supported.
>
> Lets add handling for -EOPNOTSUPP return value of map_lookup_elem()
> method of map, with expectation from map's implementation that it
> should return -EOPNOTSUPP if lookup is not supported.
>
> The errno for bpf syscall for BPF_MAP_LOOKUP_ELEM command will be set
> to EOPNOTSUPP if map lookup is not supported.
>
> Signed-off-by: Prashant Bhole <bhole_prashant...@lab.ntt.co.jp>
> Acked-by: Alexei Starovoitov <a...@kernel.org>
Acked-by: Song Liu <songliubrav...@fb.com>
> ---
> kernel/bpf/syscall.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index 5742df21598c..4f416234251f 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -719,10 +719,15 @@ static int map_lookup_elem(union bpf_attr *attr)
> } else {
> rcu_read_lock();
> ptr = map->ops->map_lookup_elem(map, key);
> - if (ptr)
> + if (IS_ERR(ptr)) {
> + err = PTR_ERR(ptr);
> + } else if (!ptr) {
> + err = -ENOENT;
> + } else {
> + err = 0;
> memcpy(value, ptr, value_size);
> + }
> rcu_read_unlock();
> - err = ptr ? 0 : -ENOENT;
> }
>
> if (err)
> --
> 2.17.1
>
>
