18c2ecf20Sopenharmony_ciC Z6.0+pooncelock+poonceLock+pombonce 28c2ecf20Sopenharmony_ci 38c2ecf20Sopenharmony_ci(* 48c2ecf20Sopenharmony_ci * Result: Never 58c2ecf20Sopenharmony_ci * 68c2ecf20Sopenharmony_ci * This litmus test demonstrates how smp_mb__after_spinlock() may be 78c2ecf20Sopenharmony_ci * used to ensure that accesses in different critical sections for a 88c2ecf20Sopenharmony_ci * given lock running on different CPUs are nevertheless seen in order 98c2ecf20Sopenharmony_ci * by CPUs not holding that lock. 108c2ecf20Sopenharmony_ci *) 118c2ecf20Sopenharmony_ci 128c2ecf20Sopenharmony_ci{} 138c2ecf20Sopenharmony_ci 148c2ecf20Sopenharmony_ciP0(int *x, int *y, spinlock_t *mylock) 158c2ecf20Sopenharmony_ci{ 168c2ecf20Sopenharmony_ci spin_lock(mylock); 178c2ecf20Sopenharmony_ci WRITE_ONCE(*x, 1); 188c2ecf20Sopenharmony_ci WRITE_ONCE(*y, 1); 198c2ecf20Sopenharmony_ci spin_unlock(mylock); 208c2ecf20Sopenharmony_ci} 218c2ecf20Sopenharmony_ci 228c2ecf20Sopenharmony_ciP1(int *y, int *z, spinlock_t *mylock) 238c2ecf20Sopenharmony_ci{ 248c2ecf20Sopenharmony_ci int r0; 258c2ecf20Sopenharmony_ci 268c2ecf20Sopenharmony_ci spin_lock(mylock); 278c2ecf20Sopenharmony_ci smp_mb__after_spinlock(); 288c2ecf20Sopenharmony_ci r0 = READ_ONCE(*y); 298c2ecf20Sopenharmony_ci WRITE_ONCE(*z, 1); 308c2ecf20Sopenharmony_ci spin_unlock(mylock); 318c2ecf20Sopenharmony_ci} 328c2ecf20Sopenharmony_ci 338c2ecf20Sopenharmony_ciP2(int *x, int *z) 348c2ecf20Sopenharmony_ci{ 358c2ecf20Sopenharmony_ci int r1; 368c2ecf20Sopenharmony_ci 378c2ecf20Sopenharmony_ci WRITE_ONCE(*z, 2); 388c2ecf20Sopenharmony_ci smp_mb(); 398c2ecf20Sopenharmony_ci r1 = READ_ONCE(*x); 408c2ecf20Sopenharmony_ci} 418c2ecf20Sopenharmony_ci 428c2ecf20Sopenharmony_ciexists (1:r0=1 /\ z=2 /\ 2:r1=0) 43