samples/tracepoints/tracepoint-probe-sample.c

   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  */
  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
  27 static void probe_subsys_eventb(void *ignore)
  28 {
  29         printk(KERN_INFO "Event B is encountered\n");
  30 }
  31
  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
  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");