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C MP+unlocklockonceonce+fencermbonceonce
(*
* Result: Never
*
* If two locked critical sections execute on the same CPU, stores in the
* first must propagate to each CPU before stores in the second do, even if
* the critical sections are protected by different locks.
*)
{}
P0(spinlock_t *s, spinlock_t *t, int *x, int *y)
{
spin_lock(s);
WRITE_ONCE(*x, 1);
spin_unlock(s);
spin_lock(t);
WRITE_ONCE(*y, 1);
spin_unlock(t);
}
P1(int *x, int *y)
{
int r1;
int r2;
r1 = READ_ONCE(*y);
smp_rmb();
r2 = READ_ONCE(*x);
}
exists (1:r1=1 /\ 1:r2=0)
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