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	spinlock_t lo;
15	int x;
16}
17
18P0(spinlock_t *lo, int *x) // Producer
19{
20	spin_lock(lo);
21	WRITE_ONCE(*x, 1);
22	spin_unlock(lo);
23}
24
25P1(spinlock_t *lo, int *x) // Consumer
26{
27	int r1;
28	int r2;
29	int r3;
30
31	r1 = smp_load_acquire(x);
32	r2 = spin_is_locked(lo);
33	r3 = spin_is_locked(lo);
34}
35
36exists (1:r1=1 /\ 1:r2=0 /\ 1:r3=1) (* Bad outcome. *)
37