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