On Thu, Sep 23, 2021 at 02:05:00PM +0200, Petr Mladek wrote:

On Wed 2021-09-22 13:05:09, Peter Zijlstra wrote:

quoted

+static int klp_check_task(struct task_struct *task, void *arg)

Please, call this klp_check_and_switch_task() to make it clear
that it actually does the switch.

Sure.

quoted

+	ret = task_try_func(task, klp_check_task, &old_name);
+	switch (ret) {
+	case -EBUSY:
+		pr_debug("%s: %s:%d is running\n",
+			 __func__, task->comm, task->pid);
+		break;
+	case -EINVAL:
+		pr_debug("%s: %s:%d has an unreliable stack\n",
+			 __func__, task->comm, task->pid);
+		break;
+	case -EADDRINUSE:
+		pr_debug("%s: %s:%d is sleeping on function %s\n",
+			 __func__, task->comm, task->pid, old_name);
+		break;

I would prefer to be on the safe side and catch error codes that might
eventually appear in the future.

	case 0:
		/* success */
		break;

	case -EAGAIN:
		/* task_try_func() raced */
		break;

	default:
		pr_debug("%s: Unknown error code (%d) when trying to switch %s:%d\n",
			 __func__, ret, task->comm, task->pid);

quoted

 	}

Done.