#define border_next(b) (list_entry((b)->list.next, border_t, list))
#define border_prev(b) (list_entry((b)->list.prev, border_t, list))
#define border_next(b) (list_entry((b)->list.next, border_t, list))
#define border_prev(b) (list_entry((b)->list.prev, border_t, list))