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C Z6.0+pooncelock+pooncelock+pombonce
(*
* Result: Sometimes
*
* This example demonstrates that a pair of accesses made by different
* processes each while holding a given lock will not necessarily be
* seen as ordered by a third process 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);
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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