ipc_obtain_object_check
struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&msg_ids(ns), id);
struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&sem_ids(ns), id);
struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&shm_ids(ns), id);
ipcp = ipc_obtain_object_check(ids, id);
struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);