ia64/linux-2.6.18-xen.hg

view lib/kref.c @ 647:a5bb490065f6

Fix the build after public header sync.
Signed-off-by: Keir Fraser <keir.fraser@citrix.com>
author Keir Fraser <keir.fraser@citrix.com>
date Wed Aug 13 14:01:49 2008 +0100 (2008-08-13)
parents 831230e53067
children
line source
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 */
14 #include <linux/kref.h>
15 #include <linux/module.h>
17 /**
18 * kref_init - initialize object.
19 * @kref: object in question.
20 */
21 void kref_init(struct kref *kref)
22 {
23 atomic_set(&kref->refcount,1);
24 }
26 /**
27 * kref_get - increment refcount for object.
28 * @kref: object.
29 */
30 void kref_get(struct kref *kref)
31 {
32 WARN_ON(!atomic_read(&kref->refcount));
33 atomic_inc(&kref->refcount);
34 }
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 * Return 1 if the object was removed, otherwise return 0. Beware, if this
46 * function returns 0, you still can not count on the kref from remaining in
47 * memory. Only use the return value if you want to see if the kref is now
48 * gone, not present.
49 */
50 int kref_put(struct kref *kref, void (*release)(struct kref *kref))
51 {
52 WARN_ON(release == NULL);
53 WARN_ON(release == (void (*)(struct kref *))kfree);
55 /*
56 * if current count is one, we are the last user and can release object
57 * right now, avoiding an atomic operation on 'refcount'
58 */
59 if ((atomic_read(&kref->refcount) == 1) ||
60 (atomic_dec_and_test(&kref->refcount))) {
61 release(kref);
62 return 1;
63 }
64 return 0;
65 }
67 EXPORT_SYMBOL(kref_init);
68 EXPORT_SYMBOL(kref_get);
69 EXPORT_SYMBOL(kref_put);