sched: enforce ref-counting on current task/thread pointers

sched/task.c

@@ -282,7 +282,7 @@ struct task *task_from_tid(tid_t id)
 
 void task_exit(int status)
 {
-	struct task *self = current_task();
+	struct task *self = get_current_task();
 	unsigned long flags;
 	task_lock_irqsave(self, &flags);
 	struct task *parent = self->t_parent;
@@ -295,7 +295,7 @@ void task_exit(int status)
 		task_unlock(parent);
 	}
 
-	struct thread *cur_thread = current_thread();
+	struct thread *cur_thread = get_current_thread();
 
 	self->t_state = TASK_STOPPED;
 	cur_thread->tr_state = THREAD_STOPPED;
@@ -340,6 +340,9 @@ void task_exit(int status)
 	       self->t_base.ob_refcount);
 	spin_unlock_irqrestore(handles_lock, flags);
 
+	put_current_thread(cur_thread);
+	put_current_task(self);
+
 	while (1) {
 		schedule(SCHED_NORMAL);
 	}
@@ -410,8 +413,19 @@ struct thread *task_create_thread(struct task *parent)
 	return thread;
 }
 
-struct task *current_task(void)
+struct task *get_current_task(void)
 {
-	struct thread *thr = current_thread();
-	return thr ? thr->tr_parent : NULL;
+	struct thread *thr = get_current_thread();
+	if (!thr) {
+		return NULL;
+	}
+
+	struct task *out = task_ref(thr->tr_parent);
+	put_current_thread(thr);
+	return out;
+}
+
+void put_current_task(struct task *task)
+{
+	task_unref(task);
 }