KVM: i8254: simplify atomics in kvm_pit_ack_irq

{

	struct kvm_kpit_state *ps = container_of(kian, struct kvm_kpit_state,

						 irq_ack_notifier);

	int value;

	spin_lock(&ps->inject_lock);

	value = atomic_dec_return(&ps->pending);

	if (value < 0)

		/* spurious acks can be generated if, for example, the

		 * PIC is being reset.  Handle it gracefully here

		 */

		atomic_inc(&ps->pending);

	else if (value > 0 && ps->reinject)

		/* in this case, we had multiple outstanding pit interrupts

		 * that we needed to inject.  Reinject

		 */

	if (atomic_dec_if_positive(&ps->pending) > 0 && ps->reinject)

		queue_kthread_work(&ps->pit->worker, &ps->pit->expired);

	ps->irq_ack = 1;

	spin_unlock(&ps->inject_lock);