1 /*-
2 * Copyright (c) 2010 Isilon Systems, Inc.
3 * Copyright (c) 2010 iX Systems, Inc.
4 * Copyright (c) 2010 Panasas, Inc.
5 * Copyright (c) 2013-2015 Mellanox Technologies, Ltd.
6 * Copyright (c) 2013 François Tigeot
7 * All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice unmodified, this list of conditions, and the following
14 * disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 *
30 * $FreeBSD$
31 */
32 #ifndef _LINUX_KREF_H_
33 #define _LINUX_KREF_H_
34
35 #include <sys/types.h>
36 #include <sys/refcount.h>
37
38 #include <linux/compiler.h>
39 #include <asm/atomic.h>
40
41 struct kref {
42 atomic_t refcount;
43 };
44
45 static inline void
kref_init(struct kref * kref)46 kref_init(struct kref *kref)
47 {
48
49 refcount_init(&kref->refcount.counter, 1);
50 }
51
52 static inline void
kref_get(struct kref * kref)53 kref_get(struct kref *kref)
54 {
55
56 refcount_acquire(&kref->refcount.counter);
57 }
58
59 static inline int
kref_put(struct kref * kref,void (* rel)(struct kref * kref))60 kref_put(struct kref *kref, void (*rel)(struct kref *kref))
61 {
62
63 if (refcount_release(&kref->refcount.counter)) {
64 rel(kref);
65 return 1;
66 }
67 return 0;
68 }
69
70 static inline int
kref_sub(struct kref * kref,unsigned int count,void (* rel)(struct kref * kref))71 kref_sub(struct kref *kref, unsigned int count,
72 void (*rel)(struct kref *kref))
73 {
74
75 while (count--) {
76 if (refcount_release(&kref->refcount.counter)) {
77 rel(kref);
78 return 1;
79 }
80 }
81 return 0;
82 }
83
84 static inline int __must_check
kref_get_unless_zero(struct kref * kref)85 kref_get_unless_zero(struct kref *kref)
86 {
87
88 return atomic_add_unless(&kref->refcount, 1, 0);
89 }
90
91 #endif /* _LINUX_KREF_H_ */
92