+/**
+ * Obtain the error status of a task and deallocate its resources.
+ *
+ * \param tptr Identifies the task to reap.
+ *
+ * This function is similar to wait(2) in that it returns information about a
+ * terminated task which allows releasing the resources associated with the
+ * task. Until this function is called, the terminated task remains in a zombie
+ * state.
+ *
+ * \return If \a tptr is \p NULL, or \a *tptr is \p NULL, the function does
+ * nothing and returns zero. Otherwise, it is checked whether the task
+ * identified by \a tptr is still running. If it is, the function returns zero
+ * and again, no action is taken. Otherwise the (negative) error code of the
+ * terminated task is returned and \a *tptr is set to \p NULL. The task will
+ * then be removed removed from the scheduler task list.
+ *
+ * \sa \ref sched_shutdown(), wait(2).
+ */
+int task_reap(struct task **tptr)
+{
+ struct task *t;
+ int ret;
+
+ if (!tptr)
+ return 0;
+ t = *tptr;
+ if (!t)
+ return 0;
+ if (t->status >= 0)
+ return 0;
+ ret = t->status;
+ /*
+ * With list_for_each_entry_safe() it is only safe to remove the
+ * _current_ list item. Since we are being called from the loop in
+ * schedule() via some task's ->post_select() function, freeing the
+ * given task here would result in use-after-free bugs in schedule().
+ * So we only set the task status to TS_DEAD which tells schedule() to
+ * free the task in the next iteration of its loop.
+ */
+ t->status = TS_DEAD;
+
+ *tptr = NULL;
+ return ret;
+}
+