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