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: releng/11.0/sys/compat/linuxkpi/common/include/linux/kref.h 300497 2016-05-23 12:06:34Z 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 void
56kref_get(struct kref *kref)
57{
58
59	refcount_acquire(&kref->refcount.counter);
60}
61
62static inline int
63kref_put(struct kref *kref, void (*rel)(struct kref *kref))
64{
65
66	if (refcount_release(&kref->refcount.counter)) {
67		rel(kref);
68		return 1;
69	}
70	return 0;
71}
72
73static inline int
74kref_sub(struct kref *kref, unsigned int count,
75    void (*rel)(struct kref *kref))
76{
77
78	while (count--) {
79		if (refcount_release(&kref->refcount.counter)) {
80			rel(kref);
81			return 1;
82		}
83	}
84	return 0;
85}
86
87static inline int __must_check
88kref_get_unless_zero(struct kref *kref)
89{
90
91	return atomic_add_unless(&kref->refcount, 1, 0);
92}
93
94static inline int kref_put_mutex(struct kref *kref,
95    void (*release)(struct kref *kref), struct mutex *lock)
96{
97	WARN_ON(release == NULL);
98	if (unlikely(!atomic_add_unless(&kref->refcount, -1, 1))) {
99		mutex_lock(lock);
100		if (unlikely(!atomic_dec_and_test(&kref->refcount))) {
101			mutex_unlock(lock);
102			return 0;
103		}
104		release(kref);
105		return 1;
106	}
107	return 0;
108}
109
110#endif /* _LINUX_KREF_H_ */
111