C MP+polocks

{}

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

P1(int *x, int *y, spinlock_t *mylock)
{
	int r0;
	int r1;

	spin_lock(mylock);
	r0 = READ_ONCE(*y);
	spin_unlock(mylock);
	r1 = READ_ONCE(*x);
}

exists (1:r0=1 /\ 1:r1=0)