plist_first
container_of(plist_first(head), type, member); \
container_of(plist_first(head), type, member)
return plist_first(&c->list)->prio;
prio_pos = first = plist_first(&test_head);
plist_check_list(&plist_first(head)->prio_list);
first = iter = plist_first(head);