1C MP+fencewmbonceonce+fencermbonceonce
2
3(*
4 * Result: Never
5 *
6 * This litmus test demonstrates that smp_wmb() and smp_rmb() provide
7 * sufficient ordering for the message-passing pattern.  However, it
8 * is usually better to use smp_store_release() and smp_load_acquire().
9 *)
10
11{
12	int buf;
13	int flag;
14}
15
16P0(int *buf, int *flag) // Producer
17{
18	WRITE_ONCE(*buf, 1);
19	smp_wmb();
20	WRITE_ONCE(*flag, 1);
21}
22
23P1(int *buf, int *flag) // Consumer
24{
25	int r0;
26	int r1;
27
28	r0 = READ_ONCE(*flag);
29	smp_rmb();
30	r1 = READ_ONCE(*buf);
31}
32
33exists (1:r0=1 /\ 1:r1=0) (* Bad outcome. *)
34