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 Fran��ois 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#include <linux/refcount.h>
42
43#include <asm/atomic.h>
44
45struct kref {
46	atomic_t refcount;
47};
48
49static inline void
50kref_init(struct kref *kref)
51{
52
53	refcount_init(&kref->refcount.counter, 1);
54}
55
56static inline unsigned int
57kref_read(const struct kref *kref)
58{
59
60	return (atomic_read(&kref->refcount));
61}
62
63static inline void
64kref_get(struct kref *kref)
65{
66
67	refcount_acquire(&kref->refcount.counter);
68}
69
70static inline int
71kref_put(struct kref *kref, void (*rel)(struct kref *kref))
72{
73
74	if (refcount_release(&kref->refcount.counter)) {
75		rel(kref);
76		return 1;
77	}
78	return 0;
79}
80
81static inline int
82kref_put_lock(struct kref *kref, void (*rel)(struct kref *kref),
83    spinlock_t *lock)
84{
85
86	if (refcount_release(&kref->refcount.counter)) {
87		spin_lock(lock);
88		rel(kref);
89		return (1);
90	}
91	return (0);
92}
93
94static inline int
95kref_sub(struct kref *kref, unsigned int count,
96    void (*rel)(struct kref *kref))
97{
98
99	while (count--) {
100		if (refcount_release(&kref->refcount.counter)) {
101			rel(kref);
102			return 1;
103		}
104	}
105	return 0;
106}
107
108static inline int __must_check
109kref_get_unless_zero(struct kref *kref)
110{
111
112	return atomic_add_unless(&kref->refcount, 1, 0);
113}
114
115static inline int kref_put_mutex(struct kref *kref,
116    void (*release)(struct kref *kref), struct mutex *lock)
117{
118	WARN_ON(release == NULL);
119	if (unlikely(!atomic_add_unless(&kref->refcount, -1, 1))) {
120		mutex_lock(lock);
121		if (unlikely(!atomic_dec_and_test(&kref->refcount))) {
122			mutex_unlock(lock);
123			return 0;
124		}
125		release(kref);
126		return 1;
127	}
128	return 0;
129}
130
131#endif /* _LINUX_KREF_H_ */
132