spin_lock(&device_klist->k_lock);
list_for_each_safe(pos, tmp, &device_klist->k_list) {
n = container_of(pos, struct klist_node, n_node);
spin_lock(&device_klist->k_lock);
list_for_each_safe(pos, tmp, &device_klist->k_list) {
n = container_of(pos, struct klist_node, n_node);