1C MP+polockonce+poacquiresilsil
 2
 3(*
 4 * Result: Sometimes
 5 *
 6 * Do spinlocks provide order to outside observers using spin_is_locked()
 7 * to sense the lock-held state, ordered by acquire?  Note that when the
 8 * first spin_is_locked() returns false and the second true, we know that
 9 * the smp_load_acquire() executed before the lock was acquired (loosely
10 * speaking).
11 *)
12
13{}
14
15P0(spinlock_t *lo, int *x) // Producer
16{
17	spin_lock(lo);
18	WRITE_ONCE(*x, 1);
19	spin_unlock(lo);
20}
21
22P1(spinlock_t *lo, int *x) // Consumer
23{
24	int r1;
25	int r2;
26	int r3;
27
28	r1 = smp_load_acquire(x);
29	r2 = spin_is_locked(lo);
30	r3 = spin_is_locked(lo);
31}
32
33exists (1:r1=1 /\ 1:r2=0 /\ 1:r3=1) (* Bad outcome. *)