1C Z6.0+pooncelock+pooncelock+pombonce
2
3(*
4 * Result: Sometimes
5 *
6 * This example demonstrates that a pair of accesses made by different
7 * processes each while holding a given lock will not necessarily be
8 * seen as ordered by a third process not holding that lock.
9 *)
10
11{
12	spinlock_t mylock;
13	int x;
14	int y;
15	int z;
16}
17
18P0(int *x, int *y, spinlock_t *mylock)
19{
20	spin_lock(mylock);
21	WRITE_ONCE(*x, 1);
22	WRITE_ONCE(*y, 1);
23	spin_unlock(mylock);
24}
25
26P1(int *y, int *z, spinlock_t *mylock)
27{
28	int r0;
29
30	spin_lock(mylock);
31	r0 = READ_ONCE(*y);
32	WRITE_ONCE(*z, 1);
33	spin_unlock(mylock);
34}
35
36P2(int *x, int *z)
37{
38	int r1;
39
40	WRITE_ONCE(*z, 2);
41	smp_mb();
42	r1 = READ_ONCE(*x);
43}
44
45exists (1:r0=1 /\ z=2 /\ 2:r1=0)
46