[linux-block.git] / tools / memory-model / litmus-tests / MP+polockmbonce+poacquiresilsil.litmus

C MP+polockmbonce+poacquiresilsil

(*
 * Result: Never
 *
 * Do spinlocks combined with smp_mb__after_spinlock() provide order
 * to outside observers using spin_is_locked() to sense the lock-held
 * state, ordered by acquire?  Note that when the first spin_is_locked()
 * returns false and the second true, we know that the smp_load_acquire()
 * executed before the lock was acquired (loosely speaking).
 *)

{
	spinlock_t lo;
	int x;
}

P0(spinlock_t *lo, int *x) // Producer
{
	spin_lock(lo);
	smp_mb__after_spinlock();
	WRITE_ONCE(*x, 1);
	spin_unlock(lo);
}

P1(spinlock_t *lo, int *x) // Consumer
{
	int r1;
	int r2;
	int r3;

	r1 = smp_load_acquire(x);
	r2 = spin_is_locked(lo);
	r3 = spin_is_locked(lo);
}

exists (1:r1=1 /\ 1:r2=0 /\ 1:r3=1) (* Bad outcome. *)
Commit	Line	Data
15553dcb LM	1	C MP+polockmbonce+poacquiresilsil
	2
	3	(*
	4	* Result: Never
	5	*
	6	* Do spinlocks combined with smp_mb__after_spinlock() provide order
	7	* to outside observers using spin_is_locked() to sense the lock-held
	8	* state, ordered by acquire? Note that when the first spin_is_locked()
	9	* returns false and the second true, we know that the smp_load_acquire()
	10	* executed before the lock was acquired (loosely speaking).
	11	*)
	12
	13	{
1947bfcf PM	14	spinlock_t lo;
1947bfcf PM	15	int x;
15553dcb LM	16	}
15553dcb LM	17
b6ff3084	18	P0(spinlock_t lo, int x) // Producer
15553dcb LM	19	{
	20	spin_lock(lo);
	21	smp_mb__after_spinlock();
	22	WRITE_ONCE(*x, 1);
	23	spin_unlock(lo);
	24	}
	25
b6ff3084	26	P1(spinlock_t lo, int x) // Consumer
15553dcb LM	27	{
	28	int r1;
	29	int r2;
	30	int r3;
	31
	32	r1 = smp_load_acquire(x);
	33	r2 = spin_is_locked(lo);
	34	r3 = spin_is_locked(lo);
	35	}
	36
b6ff3084	37	exists (1:r1=1 /\ 1:r2=0 /\ 1:r3=1) (* Bad outcome. *)