ltt-core.c

   1 /*
   2  * LTT core in-kernel infrastructure.
   3  *
   4  * Copyright 2006 - Mathieu Desnoyers mathieu.desnoyers@polymtl.ca
   5  *
   6  * Dual LGPL v2.1/GPL v2 license.
   7  */
   8
   9 #include <linux/percpu.h>
  10 #include <linux/module.h>
  11 #include <linux/debugfs.h>
  12 #include <linux/kref.h>
  13 #include <linux/cpu.h>
  14
  15 #include "ltt-tracer-core.h"
  16
  17 /* Traces structures */
  18 struct ltt_traces ltt_traces = {
  19         .setup_head = LIST_HEAD_INIT(ltt_traces.setup_head),
  20         .head = LIST_HEAD_INIT(ltt_traces.head),
  21 };
  22 EXPORT_SYMBOL(ltt_traces);
  23
  24 /* Traces list writer locking */
  25 static DEFINE_MUTEX(ltt_traces_mutex);
  26
  27 /* root dentry mutex */
  28 static DEFINE_MUTEX(ltt_root_mutex);
  29 /* dentry of ltt's root dir */
  30 static struct dentry *ltt_root_dentry;
  31 static struct kref ltt_root_kref = {
  32         .refcount = ATOMIC_INIT(0),
  33 };
  34
  35 static void ltt_root_release(struct kref *ref)
  36 {
  37         debugfs_remove(ltt_root_dentry);
  38         ltt_root_dentry = NULL;
  39 }
  40
  41 void put_ltt_root(void)
  42 {
  43         mutex_lock(&ltt_root_mutex);
  44         if (ltt_root_dentry)
  45                 kref_put(&ltt_root_kref, ltt_root_release);
  46         mutex_unlock(&ltt_root_mutex);
  47 }
  48 EXPORT_SYMBOL_GPL(put_ltt_root);
  49
  50 struct dentry *get_ltt_root(void)
  51 {
  52         mutex_lock(&ltt_root_mutex);
  53         if (!ltt_root_dentry) {
  54                 ltt_root_dentry = debugfs_create_dir(LTT_ROOT, NULL);
  55                 if (!ltt_root_dentry) {
  56                         printk(KERN_ERR "LTT : create ltt root dir failed\n");
  57                         goto out;
  58                 }
  59                 kref_init(&ltt_root_kref);
  60                 goto out;
  61         }
  62         kref_get(&ltt_root_kref);
  63 out:
  64         mutex_unlock(&ltt_root_mutex);
  65         return ltt_root_dentry;
  66 }
  67 EXPORT_SYMBOL_GPL(get_ltt_root);
  68
  69 /*
  70  * ltt_lock_traces/ltt_unlock_traces also disables cpu hotplug.
  71  */
  72 void ltt_lock_traces(void)
  73 {
  74         mutex_lock(&ltt_traces_mutex);
  75         get_online_cpus();
  76 }
  77 EXPORT_SYMBOL_GPL(ltt_lock_traces);
  78
  79 void ltt_unlock_traces(void)
  80 {
  81         put_online_cpus();
  82         mutex_unlock(&ltt_traces_mutex);
  83 }
  84 EXPORT_SYMBOL_GPL(ltt_unlock_traces);
  85
  86 DEFINE_PER_CPU(unsigned int, ltt_nesting);
  87 EXPORT_PER_CPU_SYMBOL(ltt_nesting);
  88
  89 int ltt_run_filter_default(void *trace, uint16_t eID)
  90 {
  91         return 1;
  92 }
  93
  94 /* This function pointer is protected by a trace activation check */
  95 ltt_run_filter_functor ltt_run_filter = ltt_run_filter_default;
  96 EXPORT_SYMBOL_GPL(ltt_run_filter);
  97
  98 void ltt_filter_register(ltt_run_filter_functor func)
  99 {
 100         ltt_run_filter = func;
 101 }
 102 EXPORT_SYMBOL_GPL(ltt_filter_register);
 103
 104 void ltt_filter_unregister(void)
 105 {
 106         ltt_run_filter = ltt_run_filter_default;
 107 }
 108 EXPORT_SYMBOL_GPL(ltt_filter_unregister);
 109
 110 MODULE_LICENSE("GPL and additional rights");
 111 MODULE_AUTHOR("Mathieu Desnoyers");
 112 MODULE_DESCRIPTION("Linux Trace Toolkit Next Generation Tracer Core");