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
14 static const char *random_strings[] = {
15 "Mother Goose",
16 "Snoopy",
17 "Gandalf",
18 "Frodo",
19 "One ring to rule them all"
20 };
21
22 static 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
56 static void simple_thread_func(int cnt)
57 {
58 do_simple_thread_func(cnt, "iter=%d", cnt);
59 }
60
61 static 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
71 static struct task_struct *simple_tsk;
72 static struct task_struct *simple_tsk_fn;
73
74 static 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
84 static 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
94 static DEFINE_MUTEX(thread_mutex);
95 static int simple_thread_cnt;
96
97 int 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
115 void 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
129 static 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
138 static 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
148 module_init(trace_event_init);
149 module_exit(trace_event_exit);
150
151 MODULE_AUTHOR("Steven Rostedt");
152 MODULE_DESCRIPTION("trace-events-sample");
153 MODULE_LICENSE("GPL");
154
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