donice
error = donice(td, curp, prio);
error = donice(td, p, prio);
error = donice(td, p, prio);
error = donice(td, p, prio);
static int donice(struct thread *td, struct proc *chgp, int n);
errs += donice(which, who, prio, incr);
static int donice(int, int, int, bool);