C ullk-ww

(*
 * Result: Never
 *
 * If two locked critical sections execute on the same CPU, stores in the
 * first must propagate to each CPU before stores in the second do, even if
 * the critical sections are protected by different locks.
 *)

{}

P0(spinlock_t *s, spinlock_t *t, int *x, int *y)
{
	spin_lock(s);
	WRITE_ONCE(*x, 1);
	spin_unlock(s);
	spin_lock(t);
	WRITE_ONCE(*y, 1);
	spin_unlock(t);
}

P1(int *x, int *y)
{
	int r1;
	int r2;

	r1 = READ_ONCE(*y);
	smp_rmb();
	r2 = READ_ONCE(*x);
}

exists (1:r1=1 /\ 1:r2=0)