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
13 static const char *random_strings[] = {
14 "Mother Goose",
15 "Snoopy",
16 "Gandalf",
17 "Frodo",
18 "One ring to rule them all"
19 };
20
simple_thread_func(int cnt)21 static 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
simple_thread(void * arg)47 static 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
57 static struct task_struct *simple_tsk;
58 static struct task_struct *simple_tsk_fn;
59
simple_thread_func_fn(int cnt)60 static 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
simple_thread_fn(void * arg)70 static 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
80 static DEFINE_MUTEX(thread_mutex);
81 static int simple_thread_cnt;
82
foo_bar_reg(void)83 void foo_bar_reg(void)
84 {
85 mutex_lock(&thread_mutex);
86 if (simple_thread_cnt++)
87 goto out;
88
89 pr_info("Starting thread for foo_bar_fn\n");
90 /*
91 * We shouldn't be able to start a trace when the module is
92 * unloading (there's other locks to prevent that). But
93 * for consistency sake, we still take the thread_mutex.
94 */
95 simple_tsk_fn = kthread_run(simple_thread_fn, NULL, "event-sample-fn");
96 out:
97 mutex_unlock(&thread_mutex);
98 }
99
foo_bar_unreg(void)100 void foo_bar_unreg(void)
101 {
102 mutex_lock(&thread_mutex);
103 if (--simple_thread_cnt)
104 goto out;
105
106 pr_info("Killing thread for foo_bar_fn\n");
107 if (simple_tsk_fn)
108 kthread_stop(simple_tsk_fn);
109 simple_tsk_fn = NULL;
110 out:
111 mutex_unlock(&thread_mutex);
112 }
113
trace_event_init(void)114 static int __init trace_event_init(void)
115 {
116 simple_tsk = kthread_run(simple_thread, NULL, "event-sample");
117 if (IS_ERR(simple_tsk))
118 return -1;
119
120 return 0;
121 }
122
trace_event_exit(void)123 static void __exit trace_event_exit(void)
124 {
125 kthread_stop(simple_tsk);
126 mutex_lock(&thread_mutex);
127 if (simple_tsk_fn)
128 kthread_stop(simple_tsk_fn);
129 simple_tsk_fn = NULL;
130 mutex_unlock(&thread_mutex);
131 }
132
133 module_init(trace_event_init);
134 module_exit(trace_event_exit);
135
136 MODULE_AUTHOR("Steven Rostedt");
137 MODULE_DESCRIPTION("trace-events-sample");
138 MODULE_LICENSE("GPL");
139