1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * An API to allow a function, that may fail, to be executed, and recover in a
  4 * controlled manner.
  5 *
  6 * Copyright (C) 2019, Google LLC.
  7 * Author: Brendan Higgins <brendanhiggins@google.com>
  8 */
  9
 10#include <kunit/test.h>
 11#include <linux/completion.h>
 12#include <linux/kernel.h>
 13#include <linux/kthread.h>
 14#include <linux/sched/task.h>
 15
 16#include "try-catch-impl.h"
 17
 18void __noreturn kunit_try_catch_throw(struct kunit_try_catch *try_catch)
 19{
 20	try_catch->try_result = -EFAULT;
 21	kthread_complete_and_exit(try_catch->try_completion, -EFAULT);
 22}
 23EXPORT_SYMBOL_GPL(kunit_try_catch_throw);
 24
 25static int kunit_generic_run_threadfn_adapter(void *data)
 26{
 27	struct kunit_try_catch *try_catch = data;
 28
 29	try_catch->try(try_catch->context);
 30
 31	kthread_complete_and_exit(try_catch->try_completion, 0);
 32}
 33
 34static unsigned long kunit_test_timeout(void)
 35{
 36	/*
 37	 * TODO(brendanhiggins@google.com): We should probably have some type of
 38	 * variable timeout here. The only question is what that timeout value
 39	 * should be.
 40	 *
 41	 * The intention has always been, at some point, to be able to label
 42	 * tests with some type of size bucket (unit/small, integration/medium,
 43	 * large/system/end-to-end, etc), where each size bucket would get a
 44	 * default timeout value kind of like what Bazel does:
 45	 * https://docs.bazel.build/versions/master/be/common-definitions.html#test.size
 46	 * There is still some debate to be had on exactly how we do this. (For
 47	 * one, we probably want to have some sort of test runner level
 48	 * timeout.)
 49	 *
 50	 * For more background on this topic, see:
 51	 * https://mike-bland.com/2011/11/01/small-medium-large.html
 52	 *
 53	 * If tests timeout due to exceeding sysctl_hung_task_timeout_secs,
 54	 * the task will be killed and an oops generated.
 55	 */
 56	return 300 * msecs_to_jiffies(MSEC_PER_SEC); /* 5 min */
 57}
 58
 59void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context)
 60{
 61	DECLARE_COMPLETION_ONSTACK(try_completion);
 62	struct kunit *test = try_catch->test;
 63	struct task_struct *task_struct;
 64	int exit_code, time_remaining;
 65
 66	try_catch->context = context;
 67	try_catch->try_completion = &try_completion;
 68	try_catch->try_result = 0;
 69	task_struct = kthread_create(kunit_generic_run_threadfn_adapter,
 70				     try_catch, "kunit_try_catch_thread");
 71	if (IS_ERR(task_struct)) {
 72		try_catch->catch(try_catch->context);
 73		return;
 74	}
 75	get_task_struct(task_struct);
 76	wake_up_process(task_struct);
 77
 78	time_remaining = wait_for_completion_timeout(&try_completion,
 79						     kunit_test_timeout());
 80	if (time_remaining == 0) {
 81		kunit_err(test, "try timed out\n");
 82		try_catch->try_result = -ETIMEDOUT;
 83		kthread_stop(task_struct);
 84	}
 85
 86	put_task_struct(task_struct);
 87	exit_code = try_catch->try_result;
 88
 89	if (!exit_code)
 90		return;
 91
 92	if (exit_code == -EFAULT)
 93		try_catch->try_result = 0;
 94	else if (exit_code == -EINTR)
 95		kunit_err(test, "wake_up_process() was never called\n");
 96	else if (exit_code)
 97		kunit_err(test, "Unknown error: %d\n", exit_code);
 98
 99	try_catch->catch(try_catch->context);
100}
101EXPORT_SYMBOL_GPL(kunit_try_catch_run);