C C-MP+o-mb-o+o-mb-o

{
}

P0(int *x, int *y)
{
	WRITE_ONCE(*y, 1);
	smp_mb();
	WRITE_ONCE(*x, 1);
}

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

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

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