1 /*
2  * tracepoint-probe-sample.c
3  *
4  * sample tracepoint probes.
5  */
6 
7 #include <linux/module.h>
8 #include <linux/file.h>
9 #include <linux/dcache.h>
10 #include "tp-samples-trace.h"
11 
12 /*
13  * Here the caller only guarantees locking for struct file and struct inode.
14  * Locking must therefore be done in the probe to use the dentry.
15  */
probe_subsys_event(void * ignore,struct inode * inode,struct file * file)16 static void probe_subsys_event(void *ignore,
17 			       struct inode *inode, struct file *file)
18 {
19 	path_get(&file->f_path);
20 	dget(file->f_path.dentry);
21 	printk(KERN_INFO "Event is encountered with filename %s\n",
22 		file->f_path.dentry->d_name.name);
23 	dput(file->f_path.dentry);
24 	path_put(&file->f_path);
25 }
26 
probe_subsys_eventb(void * ignore)27 static void probe_subsys_eventb(void *ignore)
28 {
29 	printk(KERN_INFO "Event B is encountered\n");
30 }
31 
tp_sample_trace_init(void)32 static int __init tp_sample_trace_init(void)
33 {
34 	int ret;
35 
36 	ret = register_trace_subsys_event(probe_subsys_event, NULL);
37 	WARN_ON(ret);
38 	ret = register_trace_subsys_eventb(probe_subsys_eventb, NULL);
39 	WARN_ON(ret);
40 
41 	return 0;
42 }
43 
44 module_init(tp_sample_trace_init);
45 
tp_sample_trace_exit(void)46 static void __exit tp_sample_trace_exit(void)
47 {
48 	unregister_trace_subsys_eventb(probe_subsys_eventb, NULL);
49 	unregister_trace_subsys_event(probe_subsys_event, NULL);
50 	tracepoint_synchronize_unregister();
51 }
52 
53 module_exit(tp_sample_trace_exit);
54 
55 MODULE_LICENSE("GPL");
56 MODULE_AUTHOR("Mathieu Desnoyers");
57 MODULE_DESCRIPTION("Tracepoint Probes Samples");
58