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
do_simple_thread_func(int cnt,const char * fmt,...)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
simple_thread_func(int cnt)56 static void simple_thread_func(int cnt)
57 {
58 do_simple_thread_func(cnt, "iter=%d", cnt);
59 }
60
simple_thread(void * arg)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
simple_thread_func_fn(int cnt)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
simple_thread_fn(void * arg)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 static struct foo_timer_data *foo_timer_data;
98
sample_timer_cb(struct timer_list * t)99 static void sample_timer_cb(struct timer_list *t)
100 {
101 struct foo_timer_data *data = container_of(t, struct foo_timer_data, timer);
102
103 get_cpu();
104 trace_foo_timer_fn(data);
105 (*this_cpu_ptr(data->counter))++;
106 put_cpu();
107
108 mod_timer(t, jiffies + HZ);
109 }
110
foo_bar_reg(void)111 int foo_bar_reg(void)
112 {
113 mutex_lock(&thread_mutex);
114 if (simple_thread_cnt++)
115 goto out;
116
117 pr_info("Starting thread for foo_bar_fn\n");
118 /*
119 * We shouldn't be able to start a trace when the module is
120 * unloading (there's other locks to prevent that). But
121 * for consistency sake, we still take the thread_mutex.
122 */
123 simple_tsk_fn = kthread_run(simple_thread_fn, NULL, "event-sample-fn");
124 if (IS_ERR_OR_NULL(simple_tsk_fn)) {
125 pr_err("Failed to create simple_thread_fn\n");
126 simple_tsk_fn = NULL;
127 }
128 out:
129 mutex_unlock(&thread_mutex);
130 return 0;
131 }
132
foo_bar_unreg(void)133 void foo_bar_unreg(void)
134 {
135 mutex_lock(&thread_mutex);
136 if (--simple_thread_cnt)
137 goto out;
138
139 pr_info("Killing thread for foo_bar_fn\n");
140 if (simple_tsk_fn)
141 kthread_stop(simple_tsk_fn);
142 simple_tsk_fn = NULL;
143 out:
144 mutex_unlock(&thread_mutex);
145 }
146
trace_event_init(void)147 static int __init trace_event_init(void)
148 {
149 foo_timer_data = kzalloc_obj(*foo_timer_data, GFP_KERNEL);
150 if (!foo_timer_data)
151 return -ENOMEM;
152
153 foo_timer_data->name = "sample_timer_counter";
154 foo_timer_data->counter = alloc_percpu(int);
155 if (!foo_timer_data->counter) {
156 kfree(foo_timer_data);
157 return -ENOMEM;
158 }
159
160 timer_setup(&foo_timer_data->timer, sample_timer_cb, 0);
161 mod_timer(&foo_timer_data->timer, jiffies + HZ);
162
163 simple_tsk = kthread_run(simple_thread, NULL, "event-sample");
164 if (IS_ERR(simple_tsk)) {
165 timer_shutdown_sync(&foo_timer_data->timer);
166 free_percpu(foo_timer_data->counter);
167 kfree(foo_timer_data);
168 return PTR_ERR(simple_tsk);
169 }
170
171 return 0;
172 }
173
trace_event_exit(void)174 static void __exit trace_event_exit(void)
175 {
176 kthread_stop(simple_tsk);
177 mutex_lock(&thread_mutex);
178 if (simple_tsk_fn)
179 kthread_stop(simple_tsk_fn);
180 simple_tsk_fn = NULL;
181 mutex_unlock(&thread_mutex);
182
183 timer_shutdown_sync(&foo_timer_data->timer);
184 free_percpu(foo_timer_data->counter);
185 kfree(foo_timer_data);
186 }
187
188 module_init(trace_event_init);
189 module_exit(trace_event_exit);
190
191 MODULE_AUTHOR("Steven Rostedt");
192 MODULE_DESCRIPTION("trace-events-sample");
193 MODULE_LICENSE("GPL");
194