C Z6.0+pooncelock+poonceLock+pombonce (* * Result: Never * * This litmus test demonstrates how smp_mb__after_spinlock() may be * used to ensure that accesses in different critical sections for a * given lock running on different CPUs are nevertheless seen in order * by CPUs not holding that lock. *) {} P0(int *x, int *y, spinlock_t *mylock) { spin_lock(mylock); WRITE_ONCE(*x, 1); WRITE_ONCE(*y, 1); spin_unlock(mylock); } P1(int *y, int *z, spinlock_t *mylock) { int r0; spin_lock(mylock); smp_mb__after_spinlock(); r0 = READ_ONCE(*y); WRITE_ONCE(*z, 1); spin_unlock(mylock); } P2(int *x, int *z) { int r1; WRITE_ONCE(*z, 2); smp_mb(); r1 = READ_ONCE(*x); } exists (1:r0=1 /\ z=2 /\ 2:r1=0) |