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 
kunit_try_catch_throw(struct kunit_try_catch * try_catch)17 void __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 }
22 EXPORT_SYMBOL_GPL(kunit_try_catch_throw);
23 
kunit_generic_run_threadfn_adapter(void * data)24 static 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 
kunit_test_timeout(void)33 static 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 
kunit_try_catch_run(struct kunit_try_catch * try_catch,void * context)58 void 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 }
98 EXPORT_SYMBOL_GPL(kunit_try_catch_run);
99