LXR linux/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 */
  16static 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
  26static void probe_subsys_eventb(void)
  27{
  28        printk(KERN_INFO "Event B is encountered\n");
  29}
  30
  31static 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
  43module_init(tp_sample_trace_init);
  44
  45static 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
  52module_exit(tp_sample_trace_exit);
  53
  54MODULE_LICENSE("GPL");
  55MODULE_AUTHOR("Mathieu Desnoyers");
  56MODULE_DESCRIPTION("Tracepoint Probes Samples");
  57