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 _LINUXKPI_LINUX_KREF_H_
33 #define _LINUXKPI_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 
45 struct kref {
46 	/* XXX In Linux this is a refcount_t */
47 	atomic_t refcount;
48 };
49 
50 static inline void
51 kref_init(struct kref *kref)
52 {
53 
54 	refcount_init((uint32_t *)&kref->refcount, 1);
55 }
56 
57 static inline unsigned int
58 kref_read(const struct kref *kref)
59 {
60 
61 	return (refcount_load(__DECONST(u_int32_t *, &kref->refcount)));
62 }
63 
64 static inline void
65 kref_get(struct kref *kref)
66 {
67 
68 	refcount_acquire((uint32_t *)&kref->refcount);
69 }
70 
71 static inline int
72 kref_put(struct kref *kref, void (*rel)(struct kref *kref))
73 {
74 
75 	if (refcount_release((uint32_t *)&kref->refcount)) {
76 		rel(kref);
77 		return 1;
78 	}
79 	return 0;
80 }
81 
82 static inline int
83 kref_put_lock(struct kref *kref, void (*rel)(struct kref *kref),
84     spinlock_t *lock)
85 {
86 
87 	if (refcount_release((uint32_t *)&kref->refcount)) {
88 		spin_lock(lock);
89 		rel(kref);
90 		return (1);
91 	}
92 	return (0);
93 }
94 
95 static inline int
96 kref_sub(struct kref *kref, unsigned int count,
97     void (*rel)(struct kref *kref))
98 {
99 
100 	while (count--) {
101 		if (refcount_release((uint32_t *)&kref->refcount)) {
102 			rel(kref);
103 			return 1;
104 		}
105 	}
106 	return 0;
107 }
108 
109 static inline int __must_check
110 kref_get_unless_zero(struct kref *kref)
111 {
112 
113 	return refcount_acquire_if_not_zero((uint32_t *)&kref->refcount);
114 }
115 
116 static inline int kref_put_mutex(struct kref *kref,
117     void (*release)(struct kref *kref), struct mutex *lock)
118 {
119 	WARN_ON(release == NULL);
120 	if (unlikely(!refcount_release_if_not_last((uint32_t *)&kref->refcount))) {
121 		mutex_lock(lock);
122 		if (unlikely(!refcount_release((uint32_t *)&kref->refcount))) {
123 			mutex_unlock(lock);
124 			return 0;
125 		}
126 		release(kref);
127 		return 1;
128 	}
129 	return 0;
130 }
131 
132 #endif /* _LINUXKPI_LINUX_KREF_H_ */
133