1 // SPDX-License-Identifier: GPL-2.0-only
2 #include <linux/module.h>
3 #include <linux/kthread.h>
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.
11 #define CREATE_TRACE_POINTS
12 #include "trace-events-sample.h"
14 static const char *random_strings[] = {
19 "One ring to rule them all"
22 static void simple_thread_func(int cnt)
24 unsigned long bitmask[1] = {0xdeadbeefUL};
29 set_current_state(TASK_INTERRUPTIBLE);
32 for (i = 0; i < len; i++)
36 /* Silly tracepoints */
37 trace_foo_bar("hello", cnt, array, random_strings[len],
40 trace_foo_with_template_simple("HELLO", cnt);
42 trace_foo_bar_with_cond("Some times print", cnt);
44 trace_foo_with_template_cond("prints other times", cnt);
46 trace_foo_with_template_print("I have to be different", cnt);
48 trace_foo_rel_loc("Hello __rel_loc", cnt, bitmask);
51 static int simple_thread(void *arg)
55 while (!kthread_should_stop())
56 simple_thread_func(cnt++);
61 static struct task_struct *simple_tsk;
62 static struct task_struct *simple_tsk_fn;
64 static void simple_thread_func_fn(int cnt)
66 set_current_state(TASK_INTERRUPTIBLE);
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);
74 static int simple_thread_fn(void *arg)
78 while (!kthread_should_stop())
79 simple_thread_func_fn(cnt++);
84 static DEFINE_MUTEX(thread_mutex);
85 static int simple_thread_cnt;
89 mutex_lock(&thread_mutex);
90 if (simple_thread_cnt++)
93 pr_info("Starting thread for foo_bar_fn\n");
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.
99 simple_tsk_fn = kthread_run(simple_thread_fn, NULL, "event-sample-fn");
101 mutex_unlock(&thread_mutex);
105 void foo_bar_unreg(void)
107 mutex_lock(&thread_mutex);
108 if (--simple_thread_cnt)
111 pr_info("Killing thread for foo_bar_fn\n");
113 kthread_stop(simple_tsk_fn);
114 simple_tsk_fn = NULL;
116 mutex_unlock(&thread_mutex);
119 static int __init trace_event_init(void)
121 simple_tsk = kthread_run(simple_thread, NULL, "event-sample");
122 if (IS_ERR(simple_tsk))
128 static void __exit trace_event_exit(void)
130 kthread_stop(simple_tsk);
131 mutex_lock(&thread_mutex);
133 kthread_stop(simple_tsk_fn);
134 simple_tsk_fn = NULL;
135 mutex_unlock(&thread_mutex);
138 module_init(trace_event_init);
139 module_exit(trace_event_exit);
141 MODULE_AUTHOR("Steven Rostedt");
142 MODULE_DESCRIPTION("trace-events-sample");
143 MODULE_LICENSE("GPL");