tools/memory-model/litmus-tests/Z6.0+pooncelock+poonceLock+pombonce.litmus

C Z6.0+pooncelock+poonceLock+pombonce

(*
 * Result: Never
 *
 * This litmus test demonstrates how smp_mb__after_spinlock() may be
 * used to ensure that accesses in different critical sections for a
 * given lock running on different CPUs are nevertheless seen in order
 * by CPUs not holding that lock.
 *)

{
	spinlock_t mylock;
	int x;
	int y;
	int z;
}

P0(int *x, int *y, spinlock_t *mylock)
{
	spin_lock(mylock);
	WRITE_ONCE(*x, 1);
	WRITE_ONCE(*y, 1);
	spin_unlock(mylock);
}

P1(int *y, int *z, spinlock_t *mylock)
{
	int r0;

	spin_lock(mylock);
	smp_mb__after_spinlock();
	r0 = READ_ONCE(*y);
	WRITE_ONCE(*z, 1);
	spin_unlock(mylock);
}

P2(int *x, int *z)
{
	int r1;

	WRITE_ONCE(*z, 2);
	smp_mb();
	r1 = READ_ONCE(*x);
}

exists (1:r0=1 /\ z=2 /\ 2:r1=0)