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C LB+unlocklockonceonce+poacquireonce
(*
* Result: Never
*
* If two locked critical sections execute on the same CPU, all accesses
* in the first must execute before any accesses in the second, even if the
* critical sections are protected by different locks. Note: Even when a
* write executes before a read, their memory effects can be reordered from
* the viewpoint of another CPU (the kind of reordering allowed by TSO).
*)
{}
P0(spinlock_t *s, spinlock_t *t, int *x, int *y)
{
int r1;
spin_lock(s);
r1 = READ_ONCE(*x);
spin_unlock(s);
spin_lock(t);
WRITE_ONCE(*y, 1);
spin_unlock(t);
}
P1(int *x, int *y)
{
int r2;
r2 = smp_load_acquire(y);
WRITE_ONCE(*x, 1);
}
exists (0:r1=1 /\ 1:r2=1)
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