Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/lib/kref.c
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
File MIME type: text/plain
File size: 1623 byte(s)
Tag kernel26-2.6.12-alx-r9
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 | */ |
21 | void 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 | */ |
30 | void 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 | * 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); |
54 | |
55 | if (atomic_dec_and_test(&kref->refcount)) { |
56 | release(kref); |
57 | return 1; |
58 | } |
59 | return 0; |
60 | } |
61 | |
62 | EXPORT_SYMBOL(kref_init); |
63 | EXPORT_SYMBOL(kref_get); |
64 | EXPORT_SYMBOL(kref_put); |