1// SPDX-License-Identifier: GPL-2.0-only
2#include <linux/module.h>
3#include <linux/kthread.h>
4
5/*
6 * Any file that uses trace points, must include the header.
7 * But only one file, must include the header by defining
8 * CREATE_TRACE_POINTS first.  This will make the C code that
9 * creates the handles for the trace points.
10 */
11#define CREATE_TRACE_POINTS
12#include "trace-events-sample.h"
13
14static const char *random_strings[] = {
15	"Mother Goose",
16	"Snoopy",
17	"Gandalf",
18	"Frodo",
19	"One ring to rule them all"
20};
21
22static void simple_thread_func(int cnt)
23{
24	int array[6];
25	int len = cnt % 5;
26	int i;
27
28	set_current_state(TASK_INTERRUPTIBLE);
29	schedule_timeout(HZ);
30
31	for (i = 0; i < len; i++)
32		array[i] = i + 1;
33	array[i] = 0;
34
35	/* Silly tracepoints */
36	trace_foo_bar("hello", cnt, array, random_strings[len],
37		      current->cpus_ptr);
38
39	trace_foo_with_template_simple("HELLO", cnt);
40
41	trace_foo_bar_with_cond("Some times print", cnt);
42
43	trace_foo_with_template_cond("prints other times", cnt);
44
45	trace_foo_with_template_print("I have to be different", cnt);
46}
47
48static int simple_thread(void *arg)
49{
50	int cnt = 0;
51
52	while (!kthread_should_stop())
53		simple_thread_func(cnt++);
54
55	return 0;
56}
57
58static struct task_struct *simple_tsk;
59static struct task_struct *simple_tsk_fn;
60
61static void simple_thread_func_fn(int cnt)
62{
63	set_current_state(TASK_INTERRUPTIBLE);
64	schedule_timeout(HZ);
65
66	/* More silly tracepoints */
67	trace_foo_bar_with_fn("Look at me", cnt);
68	trace_foo_with_template_fn("Look at me too", cnt);
69}
70
71static int simple_thread_fn(void *arg)
72{
73	int cnt = 0;
74
75	while (!kthread_should_stop())
76		simple_thread_func_fn(cnt++);
77
78	return 0;
79}
80
81static DEFINE_MUTEX(thread_mutex);
82static int simple_thread_cnt;
83
84int foo_bar_reg(void)
85{
86	mutex_lock(&thread_mutex);
87	if (simple_thread_cnt++)
88		goto out;
89
90	pr_info("Starting thread for foo_bar_fn\n");
91	/*
92	 * We shouldn't be able to start a trace when the module is
93	 * unloading (there's other locks to prevent that). But
94	 * for consistency sake, we still take the thread_mutex.
95	 */
96	simple_tsk_fn = kthread_run(simple_thread_fn, NULL, "event-sample-fn");
97 out:
98	mutex_unlock(&thread_mutex);
99	return 0;
100}
101
102void foo_bar_unreg(void)
103{
104	mutex_lock(&thread_mutex);
105	if (--simple_thread_cnt)
106		goto out;
107
108	pr_info("Killing thread for foo_bar_fn\n");
109	if (simple_tsk_fn)
110		kthread_stop(simple_tsk_fn);
111	simple_tsk_fn = NULL;
112 out:
113	mutex_unlock(&thread_mutex);
114}
115
116static int __init trace_event_init(void)
117{
118	simple_tsk = kthread_run(simple_thread, NULL, "event-sample");
119	if (IS_ERR(simple_tsk))
120		return -1;
121
122	return 0;
123}
124
125static void __exit trace_event_exit(void)
126{
127	kthread_stop(simple_tsk);
128	mutex_lock(&thread_mutex);
129	if (simple_tsk_fn)
130		kthread_stop(simple_tsk_fn);
131	simple_tsk_fn = NULL;
132	mutex_unlock(&thread_mutex);
133}
134
135module_init(trace_event_init);
136module_exit(trace_event_exit);
137
138MODULE_AUTHOR("Steven Rostedt");
139MODULE_DESCRIPTION("trace-events-sample");
140MODULE_LICENSE("GPL");
141