kernel: implement a generic object signalling system

kernel/object.c

@@ -226,3 +226,35 @@ struct object *object_header(void *p)
 
 	return obj;
 }
+
+void object_assert_signal(struct object *obj, uint32_t signals)
+{
+	obj->ob_signals |= signals;
+	wakeup_queue(&obj->ob_wq);
+}
+
+void object_clear_signal(struct object *obj, uint32_t signals)
+{
+	obj->ob_signals &= ~signals;
+}
+
+void object_wait_signal(
+	struct object *obj,
+	uint32_t signals,
+	unsigned long *irq_flags)
+{
+	struct thread *self = current_thread();
+	struct wait_item waiter;
+	wait_item_init(&waiter, self);
+	for (;;) {
+		thread_wait_begin(&waiter, &obj->ob_wq);
+		if (obj->ob_signals & signals) {
+			break;
+		}
+
+		object_unlock_irqrestore(obj, *irq_flags);
+		schedule(SCHED_NORMAL);
+		object_lock_irqsave(obj, irq_flags);
+	}
+	thread_wait_end(&waiter, &obj->ob_wq);
+}