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(struct inode *inode, struct file *file)
  17 {
  18         path_get(&file->f_path);
  19         dget(file->f_path.dentry);
  20         printk(KERN_INFO "Event is encountered with filename %s\n",
  21                 file->f_path.dentry->d_name.name);
  22         dput(file->f_path.dentry);
  23         path_put(&file->f_path);
  24 }
  25
  26 static void probe_subsys_eventb(void)
  27 {
  28         printk(KERN_INFO "Event B is encountered\n");
  29 }
  30
  31 static int __init tp_sample_trace_init(void)
  32 {
  33         int ret;
  34
  35         ret = register_trace_subsys_event(probe_subsys_event);
  36         WARN_ON(ret);
  37         ret = register_trace_subsys_eventb(probe_subsys_eventb);
  38         WARN_ON(ret);
  39
  40         return 0;
  41 }
  42
  43 module_init(tp_sample_trace_init);
  44
  45 static void __exit tp_sample_trace_exit(void)
  46 {
  47         unregister_trace_subsys_eventb(probe_subsys_eventb);
  48         unregister_trace_subsys_event(probe_subsys_event);
  49         tracepoint_synchronize_unregister();
  50 }
  51
  52 module_exit(tp_sample_trace_exit);
  53
  54 MODULE_LICENSE("GPL");
  55 MODULE_AUTHOR("Mathieu Desnoyers");
  56 MODULE_DESCRIPTION("Tracepoint Probes Samples");