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 #ifndef _LINUXKPI_LINUX_KREF_H_
31 #define _LINUXKPI_LINUX_KREF_H_
32
33 #include <sys/types.h>
34 #include <sys/refcount.h>
35
36 #include <linux/compiler.h>
37 #include <linux/kernel.h>
38 #include <linux/mutex.h>
39 #include <linux/refcount.h>
40
41 #include <asm/atomic.h>
42
43 struct kref {
44 refcount_t refcount;
45 };
46
47 static inline void
kref_init(struct kref * kref)48 kref_init(struct kref *kref)
49 {
50
51 refcount_init((uint32_t *)&kref->refcount, 1);
52 }
53
54 static inline unsigned int
kref_read(const struct kref * kref)55 kref_read(const struct kref *kref)
56 {
57
58 return (refcount_load(__DECONST(u_int32_t *, &kref->refcount)));
59 }
60
61 static inline void
kref_get(struct kref * kref)62 kref_get(struct kref *kref)
63 {
64
65 refcount_acquire((uint32_t *)&kref->refcount);
66 }
67
68 static inline int
kref_put(struct kref * kref,void (* rel)(struct kref * kref))69 kref_put(struct kref *kref, void (*rel)(struct kref *kref))
70 {
71
72 if (refcount_release((uint32_t *)&kref->refcount)) {
73 rel(kref);
74 return 1;
75 }
76 return 0;
77 }
78
79 static inline int
kref_put_lock(struct kref * kref,void (* rel)(struct kref * kref),spinlock_t * lock)80 kref_put_lock(struct kref *kref, void (*rel)(struct kref *kref),
81 spinlock_t *lock)
82 {
83
84 if (refcount_release((uint32_t *)&kref->refcount)) {
85 spin_lock(lock);
86 rel(kref);
87 return (1);
88 }
89 return (0);
90 }
91
92 static inline int
kref_sub(struct kref * kref,unsigned int count,void (* rel)(struct kref * kref))93 kref_sub(struct kref *kref, unsigned int count,
94 void (*rel)(struct kref *kref))
95 {
96
97 while (count--) {
98 if (refcount_release((uint32_t *)&kref->refcount)) {
99 rel(kref);
100 return 1;
101 }
102 }
103 return 0;
104 }
105
106 static inline int __must_check
kref_get_unless_zero(struct kref * kref)107 kref_get_unless_zero(struct kref *kref)
108 {
109
110 return refcount_acquire_if_not_zero((uint32_t *)&kref->refcount);
111 }
112
kref_put_mutex(struct kref * kref,void (* release)(struct kref * kref),struct mutex * lock)113 static inline int kref_put_mutex(struct kref *kref,
114 void (*release)(struct kref *kref), struct mutex *lock)
115 {
116 WARN_ON(release == NULL);
117 if (unlikely(!refcount_release_if_not_last((uint32_t *)&kref->refcount))) {
118 mutex_lock(lock);
119 if (unlikely(!refcount_release((uint32_t *)&kref->refcount))) {
120 mutex_unlock(lock);
121 return 0;
122 }
123 release(kref);
124 return 1;
125 }
126 return 0;
127 }
128
129 #endif /* _LINUXKPI_LINUX_KREF_H_ */
130