162306a36Sopenharmony_ciC SB+fencembonceonces 262306a36Sopenharmony_ci 362306a36Sopenharmony_ci(* 462306a36Sopenharmony_ci * Result: Never 562306a36Sopenharmony_ci * 662306a36Sopenharmony_ci * This litmus test demonstrates that full memory barriers suffice to 762306a36Sopenharmony_ci * order the store-buffering pattern, where each process writes to the 862306a36Sopenharmony_ci * variable that the preceding process reads. (Locking and RCU can also 962306a36Sopenharmony_ci * suffice, but not much else.) 1062306a36Sopenharmony_ci *) 1162306a36Sopenharmony_ci 1262306a36Sopenharmony_ci{} 1362306a36Sopenharmony_ci 1462306a36Sopenharmony_ciP0(int *x, int *y) 1562306a36Sopenharmony_ci{ 1662306a36Sopenharmony_ci int r0; 1762306a36Sopenharmony_ci 1862306a36Sopenharmony_ci WRITE_ONCE(*x, 1); 1962306a36Sopenharmony_ci smp_mb(); 2062306a36Sopenharmony_ci r0 = READ_ONCE(*y); 2162306a36Sopenharmony_ci} 2262306a36Sopenharmony_ci 2362306a36Sopenharmony_ciP1(int *x, int *y) 2462306a36Sopenharmony_ci{ 2562306a36Sopenharmony_ci int r0; 2662306a36Sopenharmony_ci 2762306a36Sopenharmony_ci WRITE_ONCE(*y, 1); 2862306a36Sopenharmony_ci smp_mb(); 2962306a36Sopenharmony_ci r0 = READ_ONCE(*x); 3062306a36Sopenharmony_ci} 3162306a36Sopenharmony_ci 3262306a36Sopenharmony_ciexists (0:r0=0 /\ 1:r0=0) 33