Allow user space programs to detach a struct_ops map from the attached
link.
Signed-off-by: Kui-Feng Lee <thinker.li@xxxxxxxxx>
---
kernel/bpf/bpf_struct_ops.c | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)
diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c
index 8e79b02a1ccb..4a8a7e5ffc56 100644
--- a/kernel/bpf/bpf_struct_ops.c
+++ b/kernel/bpf/bpf_struct_ops.c
@@ -1252,8 +1252,36 @@ static int bpf_struct_ops_map_link_update(struct bpf_link *link, struct bpf_map
return err;
}
+static int bpf_struct_ops_map_link_detach(struct bpf_link *link)
+{
+ struct bpf_struct_ops_link *st_link;
+ struct bpf_struct_ops_map *st_map;
+ struct bpf_map *map;
+
+ mutex_lock(&update_mutex);
+
+ st_link = container_of(link, struct bpf_struct_ops_link, link);
+ map = rcu_dereference_protected(st_link->map, lockdep_is_held(&update_mutex));
+ if (!map) {
+ mutex_unlock(&update_mutex);
+ return -ENOENT;
+ }
+ st_map = container_of(map, struct bpf_struct_ops_map, map);
+
+ st_map->st_ops_desc->st_ops->unreg(&st_map->kvalue.data);
+
+ map_attached_null(st_map);
+ rcu_assign_pointer(st_link->map, NULL);
+ bpf_map_put(map);
+
+ mutex_unlock(&update_mutex);
+
+ return 0;
+}
+
static const struct bpf_link_ops bpf_struct_ops_map_lops = {
.dealloc = bpf_struct_ops_map_link_dealloc,
+ .detach = bpf_struct_ops_map_link_detach,
.show_fdinfo = bpf_struct_ops_map_link_show_fdinfo,
.fill_link_info = bpf_struct_ops_map_link_fill_link_info,
.update_map = bpf_struct_ops_map_link_update,
--
2.34.1
