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1C Z6.0+pooncelock+poonceLock+pombonce2 3(*4 * Result: Never5 *6 * This litmus test demonstrates how smp_mb__after_spinlock() may be7 * used to ensure that accesses in different critical sections for a8 * given lock running on different CPUs are nevertheless seen in order9 * by CPUs not holding that lock.10 *)11 12{}13 14P0(int *x, int *y, spinlock_t *mylock)15{16 spin_lock(mylock);17 WRITE_ONCE(*x, 1);18 WRITE_ONCE(*y, 1);19 spin_unlock(mylock);20}21 22P1(int *y, int *z, spinlock_t *mylock)23{24 int r0;25 26 spin_lock(mylock);27 smp_mb__after_spinlock();28 r0 = READ_ONCE(*y);29 WRITE_ONCE(*z, 1);30 spin_unlock(mylock);31}32 33P2(int *x, int *z)34{35 int r1;36 37 WRITE_ONCE(*z, 2);38 smp_mb();39 r1 = READ_ONCE(*x);40}41 42exists (1:r0=1 /\ z=2 /\ 2:r1=0)43