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 <linux/kernel.h>
40 #include <linux/mutex.h>
41
42 #include <asm/atomic.h>
43
44 struct kref {
45 atomic_t refcount;
46 };
47
48 static inline void
kref_init(struct kref * kref)49 kref_init(struct kref *kref)
50 {
51
52 refcount_init(&kref->refcount.counter, 1);
53 }
54
55 static inline unsigned int
kref_read(const struct kref * kref)56 kref_read(const struct kref *kref)
57 {
58
59 return (atomic_read(&kref->refcount));
60 }
61
62 static inline void
kref_get(struct kref * kref)63 kref_get(struct kref *kref)
64 {
65
66 refcount_acquire(&kref->refcount.counter);
67 }
68
69 static inline int
kref_put(struct kref * kref,void (* rel)(struct kref * kref))70 kref_put(struct kref *kref, void (*rel)(struct kref *kref))
71 {
72
73 if (refcount_release(&kref->refcount.counter)) {
74 rel(kref);
75 return 1;
76 }
77 return 0;
78 }
79
80 static inline int
kref_sub(struct kref * kref,unsigned int count,void (* rel)(struct kref * kref))81 kref_sub(struct kref *kref, unsigned int count,
82 void (*rel)(struct kref *kref))
83 {
84
85 while (count--) {
86 if (refcount_release(&kref->refcount.counter)) {
87 rel(kref);
88 return 1;
89 }
90 }
91 return 0;
92 }
93
94 static inline int __must_check
kref_get_unless_zero(struct kref * kref)95 kref_get_unless_zero(struct kref *kref)
96 {
97
98 return atomic_add_unless(&kref->refcount, 1, 0);
99 }
100
kref_put_mutex(struct kref * kref,void (* release)(struct kref * kref),struct mutex * lock)101 static inline int kref_put_mutex(struct kref *kref,
102 void (*release)(struct kref *kref), struct mutex *lock)
103 {
104 WARN_ON(release == NULL);
105 if (unlikely(!atomic_add_unless(&kref->refcount, -1, 1))) {
106 mutex_lock(lock);
107 if (unlikely(!atomic_dec_and_test(&kref->refcount))) {
108 mutex_unlock(lock);
109 return 0;
110 }
111 release(kref);
112 return 1;
113 }
114 return 0;
115 }
116
117 #endif /* _LINUX_KREF_H_ */
118