1C MP+onceassign+derefonce
2
3(*
4 * Result: Never
5 *
6 * This litmus test demonstrates that rcu_assign_pointer() and
7 * rcu_dereference() suffice to ensure that an RCU reader will not see
8 * pre-initialization garbage when it traverses an RCU-protected data
9 * structure containing a newly inserted element.
10 *)
11
12{
13	int *p=y;
14	int x;
15	int y=0;
16}
17
18P0(int *x, int **p) // Producer
19{
20	WRITE_ONCE(*x, 1);
21	rcu_assign_pointer(*p, x);
22}
23
24P1(int *x, int **p) // Consumer
25{
26	int *r0;
27	int r1;
28
29	rcu_read_lock();
30	r0 = rcu_dereference(*p);
31	r1 = READ_ONCE(*r0);
32	rcu_read_unlock();
33}
34
35exists (1:r0=x /\ 1:r1=0) (* Bad outcome. *)
36