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(foo: "hello", bar: cnt, lst: array, string: random_strings[len],
41 current->cpus_ptr, fmt, va: &va);
42
43 va_end(va);
44
45 trace_foo_with_template_simple(foo: "HELLO", bar: cnt);
46
47 trace_foo_bar_with_cond(foo: "Some times print", bar: cnt);
48
49 trace_foo_with_template_cond(foo: "prints other times", bar: cnt);
50
51 trace_foo_with_template_print(foo: "I have to be different", bar: cnt);
52
53 trace_foo_rel_loc(foo: "Hello __rel_loc", bar: cnt, mask: bitmask, current->cpus_ptr);
54}
55
56static void simple_thread_func(int cnt)
57{
58 do_simple_thread_func(cnt, fmt: "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: 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(foo: "Look at me", bar: cnt);
81 trace_foo_with_template_fn(foo: "Look at me too", bar: 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: 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(lock: &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(k: simple_tsk_fn);
124 simple_tsk_fn = NULL;
125 out:
126 mutex_unlock(lock: &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(ptr: simple_tsk))
133 return -1;
134
135 return 0;
136}
137
138static void __exit trace_event_exit(void)
139{
140 kthread_stop(k: simple_tsk);
141 mutex_lock(&thread_mutex);
142 if (simple_tsk_fn)
143 kthread_stop(k: simple_tsk_fn);
144 simple_tsk_fn = NULL;
145 mutex_unlock(lock: &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

source code of linux/samples/trace_events/trace-events-sample.c