162306a36Sopenharmony_ciC MP+onceassign+derefonce 262306a36Sopenharmony_ci 362306a36Sopenharmony_ci(* 462306a36Sopenharmony_ci * Result: Never 562306a36Sopenharmony_ci * 662306a36Sopenharmony_ci * This litmus test demonstrates that rcu_assign_pointer() and 762306a36Sopenharmony_ci * rcu_dereference() suffice to ensure that an RCU reader will not see 862306a36Sopenharmony_ci * pre-initialization garbage when it traverses an RCU-protected data 962306a36Sopenharmony_ci * structure containing a newly inserted element. 1062306a36Sopenharmony_ci *) 1162306a36Sopenharmony_ci 1262306a36Sopenharmony_ci{ 1362306a36Sopenharmony_cip=y; 1462306a36Sopenharmony_ci} 1562306a36Sopenharmony_ci 1662306a36Sopenharmony_ciP0(int *x, int **p) // Producer 1762306a36Sopenharmony_ci{ 1862306a36Sopenharmony_ci WRITE_ONCE(*x, 1); 1962306a36Sopenharmony_ci rcu_assign_pointer(*p, x); 2062306a36Sopenharmony_ci} 2162306a36Sopenharmony_ci 2262306a36Sopenharmony_ciP1(int *x, int **p) // Consumer 2362306a36Sopenharmony_ci{ 2462306a36Sopenharmony_ci int *r0; 2562306a36Sopenharmony_ci int r1; 2662306a36Sopenharmony_ci 2762306a36Sopenharmony_ci rcu_read_lock(); 2862306a36Sopenharmony_ci r0 = rcu_dereference(*p); 2962306a36Sopenharmony_ci r1 = READ_ONCE(*r0); 3062306a36Sopenharmony_ci rcu_read_unlock(); 3162306a36Sopenharmony_ci} 3262306a36Sopenharmony_ci 3362306a36Sopenharmony_ciexists (1:r0=x /\ 1:r1=0) (* Bad outcome. *) 34