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 
kunit_try_catch_throw(struct kunit_try_catch * try_catch)18 void __noreturn kunit_try_catch_throw(struct kunit_try_catch *try_catch)
19 {
20 	try_catch->try_result = -EFAULT;
21 	kthread_exit(0);
22 }
23 EXPORT_SYMBOL_GPL(kunit_try_catch_throw);
24 
kunit_generic_run_threadfn_adapter(void * data)25 static int kunit_generic_run_threadfn_adapter(void *data)
26 {
27 	struct kunit_try_catch *try_catch = data;
28 
29 	try_catch->try_result = -EINTR;
30 	try_catch->try(try_catch->context);
31 	if (try_catch->try_result == -EINTR)
32 		try_catch->try_result = 0;
33 
34 	return 0;
35 }
36 
kunit_try_catch_run(struct kunit_try_catch * try_catch,void * context)37 void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context)
38 {
39 	struct kunit *test = try_catch->test;
40 	struct task_struct *task_struct;
41 	struct completion *task_done;
42 	int exit_code, time_remaining;
43 
44 	try_catch->context = context;
45 	try_catch->try_result = 0;
46 	task_struct = kthread_create(kunit_generic_run_threadfn_adapter,
47 				     try_catch, "kunit_try_catch_thread");
48 	if (IS_ERR(task_struct)) {
49 		try_catch->try_result = PTR_ERR(task_struct);
50 		try_catch->catch(try_catch->context);
51 		return;
52 	}
53 	get_task_struct(task_struct);
54 	/*
55 	 * As for a vfork(2), task_struct->vfork_done (pointing to the
56 	 * underlying kthread->exited) can be used to wait for the end of a
57 	 * kernel thread. It is set to NULL when the thread exits, so we
58 	 * keep a copy here.
59 	 */
60 	task_done = task_struct->vfork_done;
61 	wake_up_process(task_struct);
62 
63 	time_remaining = wait_for_completion_timeout(
64 		task_done, try_catch->timeout);
65 	if (time_remaining == 0) {
66 		try_catch->try_result = -ETIMEDOUT;
67 		kthread_stop(task_struct);
68 	}
69 
70 	put_task_struct(task_struct);
71 	exit_code = try_catch->try_result;
72 
73 	if (!exit_code)
74 		return;
75 
76 	if (exit_code == -EFAULT)
77 		try_catch->try_result = 0;
78 	else if (exit_code == -EINTR) {
79 		if (test->last_seen.file)
80 			kunit_err(test, "try faulted: last line seen %s:%d\n",
81 				  test->last_seen.file, test->last_seen.line);
82 		else
83 			kunit_err(test, "try faulted\n");
84 	} else if (exit_code == -ETIMEDOUT)
85 		kunit_err(test, "try timed out\n");
86 	else if (exit_code)
87 		kunit_err(test, "Unknown error: %d\n", exit_code);
88 
89 	try_catch->catch(try_catch->context);
90 }
91 EXPORT_SYMBOL_GPL(kunit_try_catch_run);
92