0001 C MP+onceassign+derefonce
0002
0003 (*
0004 * Result: Never
0005 *
0006 * This litmus test demonstrates that rcu_assign_pointer() and
0007 * rcu_dereference() suffice to ensure that an RCU reader will not see
0008 * pre-initialization garbage when it traverses an RCU-protected data
0009 * structure containing a newly inserted element.
0010 *)
0011
0012 {
0013 p=y;
0014 }
0015
0016 P0(int *x, int **p) // Producer
0017 {
0018 WRITE_ONCE(*x, 1);
0019 rcu_assign_pointer(*p, x);
0020 }
0021
0022 P1(int *x, int **p) // Consumer
0023 {
0024 int *r0;
0025 int r1;
0026
0027 rcu_read_lock();
0028 r0 = rcu_dereference(*p);
0029 r1 = READ_ONCE(*r0);
0030 rcu_read_unlock();
0031 }
0032
0033 exists (1:r0=x /\ 1:r1=0) (* Bad outcome. *)
