1 /* probe-example.c
2 *
3 * Connects two functions to marker call sites.
4 *
5 * (C) Copyright 2007 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
6 *
7 * This file is released under the GPLv2.
8 * See the file COPYING for more details.
9 */
10
11 #include <linux/sched.h>
12 #include <linux/kernel.h>
13 #include <linux/module.h>
14 #include <linux/marker.h>
15 #include <asm/atomic.h>
16
17 struct probe_data {
18 const char *name;
19 const char *format;
20 marker_probe_func *probe_func;
21 };
22
23 void probe_subsystem_event(void *probe_data, void *call_data,
24 const char *format, va_list *args)
25 {
26 /* Declare args */
27 unsigned int value;
28 const char *mystr;
29
30 /* Assign args */
31 value = va_arg(*args, typeof(value));
32 mystr = va_arg(*args, typeof(mystr));
33
34 /* Call printk */
35 printk(KERN_INFO "Value %u, string %s\n", value, mystr);
36
37 /* or count, check rights, serialize data in a buffer */
38 }
39
40 atomic_t eventb_count = ATOMIC_INIT(0);
41
42 void probe_subsystem_eventb(void *probe_data, void *call_data,
43 const char *format, va_list *args)
44 {
45 /* Increment counter */
46 atomic_inc(&eventb_count);
47 }
48
49 static struct probe_data probe_array[] =
50 {
51 { .name = "subsystem_event",
52 .format = "integer %d string %s",
53 .probe_func = probe_subsystem_event },
54 { .name = "subsystem_eventb",
55 .format = MARK_NOARGS,
56 .probe_func = probe_subsystem_eventb },
57 };
58
59 static int __init probe_init(void)
60 {
61 int result;
62 int i;
63
64 for (i = 0; i < ARRAY_SIZE(probe_array); i++) {
65 result = marker_probe_register(probe_array[i].name,
66 probe_array[i].format,
67 probe_array[i].probe_func, &probe_array[i]);
68 if (result)
69 printk(KERN_INFO "Unable to register probe %s\n",
70 probe_array[i].name);
71 }
72 return 0;
73 }
74
75 static void __exit probe_fini(void)
76 {
77 int i;
78
79 for (i = 0; i < ARRAY_SIZE(probe_array); i++)
80 marker_probe_unregister(probe_array[i].name,
81 probe_array[i].probe_func, &probe_array[i]);
82 printk(KERN_INFO "Number of event b : %u\n",
83 atomic_read(&eventb_count));
84 marker_synchronize_unregister();
85 }
86
87 module_init(probe_init);
88 module_exit(probe_fini);
89
90 MODULE_LICENSE("GPL");
91 MODULE_AUTHOR("Mathieu Desnoyers");
92 MODULE_DESCRIPTION("SUBSYSTEM Probe");
93
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