Re: [PATCH RFC bpf-next v2 03/18] bpf: Implement lookup, delete, update for resizable hashtab

[Leon Hwang <leon.hwang@linux.dev>]

On Wed, Apr 08, 2026 at 08:10:08AM -0700, Mykyta Yatsenko wrote:
[...]
>
> static int rhtab_map_lookup_and_delete_elem(struct bpf_map *map, void *key, void *value, u64 flags)
> {
>-	return -EOPNOTSUPP;
>+	struct bpf_rhtab *rhtab = container_of(map, struct bpf_rhtab, map);
>+	struct rhtab_elem *l;
>+	int err;
>+
>+	if ((flags & ~BPF_F_LOCK) ||
>+	    ((flags & BPF_F_LOCK) && !btf_record_has_field(map->record, BPF_SPIN_LOCK)))
>+		return -EINVAL;

At the moment, we can check the flags using bpf_map_check_op_flags() helper.

This helper can be applied to flags check in this series.

>+
>+	/* Make sure element is not deleted between lookup and copy */
>+	guard(rcu)();
>+
>+	l = rhtab_lookup_elem(map, key);
>+	if (!l)
>+		return -ENOENT;
>+
>+	rhtab_read_elem_value(map, value, l, flags);
>+	err = rhtab_delete_elem(rhtab, l);
>+	if (err)
>+		return err;
>+
>+	check_and_init_map_value(map, value);
>+	return 0;
> }
[...]
>
>-static void rhtab_map_free_internal_structs(struct bpf_map *map)
>+static long rhtab_map_update_elem(struct bpf_map *map, void *key, void *value, u64 map_flags)
> {
>+	struct bpf_rhtab *rhtab = container_of(map, struct bpf_rhtab, map);
>+	struct rhtab_elem *elem, *tmp;
>+
>+	if (unlikely((map_flags & ~BPF_F_LOCK) > BPF_EXIST))
>+		return -EINVAL;
>+
>+	if ((map_flags & BPF_F_LOCK) && !btf_record_has_field(map->record, BPF_SPIN_LOCK))
>+		return -EINVAL;

ditto

Thanks,
Leon

>+ [...]