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
13P0(int *x, int *y)
14{
15	WRITE_ONCE(*x, 1);
16	smp_wmb();
17	WRITE_ONCE(*y, 1);
18}
19
20P1(int *x, int *y)
21{
22	int r0;
23	int r1;
24
25	r0 = READ_ONCE(*y);
26	smp_rmb();
27	r1 = READ_ONCE(*x);
28}
29
30exists (1:r0=1 /\ 1:r1=0)
31