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