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