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: stable/11/sys/compat/linuxkpi/common/include/linux/kref.h 329961 2018-02-25 10:25:47Z hselasky $
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
44struct kref {
45	atomic_t refcount;
46};
47
48static inline void
49kref_init(struct kref *kref)
50{
51
52	refcount_init(&kref->refcount.counter, 1);
53}
54
55static inline unsigned int
56kref_read(const struct kref *kref)
57{
58
59	return (atomic_read(&kref->refcount));
60}
61
62static inline void
63kref_get(struct kref *kref)
64{
65
66	refcount_acquire(&kref->refcount.counter);
67}
68
69static inline int
70kref_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
80static inline int
81kref_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
94static inline int __must_check
95kref_get_unless_zero(struct kref *kref)
96{
97
98	return atomic_add_unless(&kref->refcount, 1, 0);
99}
100
101static 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