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{
13p=y;
 
14}
15
16P0(int *x, int **p) // Producer
17{
18	WRITE_ONCE(*x, 1);
19	rcu_assign_pointer(*p, x);
20}
21
22P1(int *x, int **p) // Consumer
23{
24	int *r0;
25	int r1;
26
27	rcu_read_lock();
28	r0 = rcu_dereference(*p);
29	r1 = READ_ONCE(*r0);
30	rcu_read_unlock();
31}
32
33exists (1:r0=x /\ 1:r1=0) (* Bad outcome. *)

 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{
13y=z;
14z=0;
15}
16
17P0(int *x, int **y)
18{
19	WRITE_ONCE(*x, 1);
20	rcu_assign_pointer(*y, x);
21}
22
23P1(int *x, int **y)
24{
25	int *r0;
26	int r1;
27
28	rcu_read_lock();
29	r0 = rcu_dereference(*y);
30	r1 = READ_ONCE(*r0);
31	rcu_read_unlock();
32}
33
34exists (1:r0=x /\ 1:r1=0)