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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)
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