LXR RHEL4/lib/kref.c

   1/*
   2 * kref.c - library routines for handling generic reference counted objects
   3 *
   4 * Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
   5 * Copyright (C) 2004 IBM Corp.
   6 *
   7 * based on lib/kobject.c which was:
   8 * Copyright (C) 2002-2003 Patrick Mochel <mochel@osdl.org>
   9 *
  10 * This file is released under the GPLv2.
  11 *
  12 */
  13
  14#include <linux/kref.h>
  15#include <linux/module.h>
  16
  17/**
  18 * kref_init - initialize object.
  19 * @kref: object in question.
  20 */
  21void kref_init(struct kref *kref)
  22{
  23        atomic_set(&kref->refcount,1);
  24}
  25
  26/**
  27 * kref_get - increment refcount for object.
  28 * @kref: object.
  29 */
  30void kref_get(struct kref *kref)
  31{
  32        WARN_ON(!atomic_read(&kref->refcount));
  33        atomic_inc(&kref->refcount);
  34}
  35
  36/**
  37 * kref_put - decrement refcount for object.
  38 * @kref: object.
  39 * @release: pointer to the function that will clean up the object when the
  40 *           last reference to the object is released.
  41 *           This pointer is required, and it is not acceptable to pass kfree
  42 *           in as this function.
  43 *
  44 * Decrement the refcount, and if 0, call release().
  45 */
  46void kref_put(struct kref *kref, void (*release) (struct kref *kref))
  47{
  48        WARN_ON(release == NULL);
  49        WARN_ON(release == (void (*)(struct kref *))kfree);
  50
  51        if (atomic_dec_and_test(&kref->refcount))
  52                release(kref);
  53}
  54
  55EXPORT_SYMBOL(kref_init);
  56EXPORT_SYMBOL(kref_get);
  57EXPORT_SYMBOL(kref_put);
  58