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 do_simple_thread_func(int cnt, const char *fmt, ...)
23{
24	unsigned long bitmask[1] = {0xdeadbeefUL};
25	va_list va;
26	int array[6];
27	int len = cnt % 5;
28	int i;
29
30	set_current_state(TASK_INTERRUPTIBLE);
31	schedule_timeout(HZ);
32
33	for (i = 0; i < len; i++)
34		array[i] = i + 1;
35	array[i] = 0;
36
37	va_start(va, fmt);
38
39	/* Silly tracepoints */
40	trace_foo_bar("hello", cnt, array, random_strings[len],
41		      current->cpus_ptr, fmt, &va);
42
43	va_end(va);
44
45	trace_foo_with_template_simple("HELLO", cnt);
46
47	trace_foo_bar_with_cond("Some times print", cnt);
48
49	trace_foo_with_template_cond("prints other times", cnt);
50
51	trace_foo_with_template_print("I have to be different", cnt);
52
53	trace_foo_rel_loc("Hello __rel_loc", cnt, bitmask, current->cpus_ptr);
54}
55
56static void simple_thread_func(int cnt)
57{
58	do_simple_thread_func(cnt, "iter=%d", cnt);
59}
60
61static int simple_thread(void *arg)
62{
63	int cnt = 0;
64
65	while (!kthread_should_stop())
66		simple_thread_func(cnt++);
67
68	return 0;
69}
70
71static struct task_struct *simple_tsk;
72static struct task_struct *simple_tsk_fn;
73
74static void simple_thread_func_fn(int cnt)
75{
76	set_current_state(TASK_INTERRUPTIBLE);
77	schedule_timeout(HZ);
78
79	/* More silly tracepoints */
80	trace_foo_bar_with_fn("Look at me", cnt);
81	trace_foo_with_template_fn("Look at me too", cnt);
82}
83
84static int simple_thread_fn(void *arg)
85{
86	int cnt = 0;
87
88	while (!kthread_should_stop())
89		simple_thread_func_fn(cnt++);
90
91	return 0;
92}
93
94static DEFINE_MUTEX(thread_mutex);
95static int simple_thread_cnt;
96
97int foo_bar_reg(void)
98{
99	mutex_lock(&thread_mutex);
100	if (simple_thread_cnt++)
101		goto out;
102
103	pr_info("Starting thread for foo_bar_fn\n");
104	/*
105	 * We shouldn't be able to start a trace when the module is
106	 * unloading (there's other locks to prevent that). But
107	 * for consistency sake, we still take the thread_mutex.
108	 */
109	simple_tsk_fn = kthread_run(simple_thread_fn, NULL, "event-sample-fn");
110 out:
111	mutex_unlock(&thread_mutex);
112	return 0;
113}
114
115void foo_bar_unreg(void)
116{
117	mutex_lock(&thread_mutex);
118	if (--simple_thread_cnt)
119		goto out;
120
121	pr_info("Killing thread for foo_bar_fn\n");
122	if (simple_tsk_fn)
123		kthread_stop(simple_tsk_fn);
124	simple_tsk_fn = NULL;
125 out:
126	mutex_unlock(&thread_mutex);
127}
128
129static int __init trace_event_init(void)
130{
131	simple_tsk = kthread_run(simple_thread, NULL, "event-sample");
132	if (IS_ERR(simple_tsk))
133		return -1;
134
135	return 0;
136}
137
138static void __exit trace_event_exit(void)
139{
140	kthread_stop(simple_tsk);
141	mutex_lock(&thread_mutex);
142	if (simple_tsk_fn)
143		kthread_stop(simple_tsk_fn);
144	simple_tsk_fn = NULL;
145	mutex_unlock(&thread_mutex);
146}
147
148module_init(trace_event_init);
149module_exit(trace_event_exit);
150
151MODULE_AUTHOR("Steven Rostedt");
152MODULE_DESCRIPTION("trace-events-sample");
153MODULE_LICENSE("GPL");
154