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1 | /* |
2 | * net/tipc/ref.h: Include file for TIPC object registry code | |
3 | * | |
9da1c8b6 | 4 | * Copyright (c) 2003-2006, Ericsson AB |
b97bf3fd | 5 | * Copyright (c) 2005, Wind River Systems |
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6 | * All rights reserved. |
7 | * | |
9ea1fd3c | 8 | * Redistribution and use in source and binary forms, with or without |
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9 | * modification, are permitted provided that the following conditions are met: |
10 | * | |
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11 | * 1. Redistributions of source code must retain the above copyright |
12 | * notice, this list of conditions and the following disclaimer. | |
13 | * 2. Redistributions in binary form must reproduce the above copyright | |
14 | * notice, this list of conditions and the following disclaimer in the | |
15 | * documentation and/or other materials provided with the distribution. | |
16 | * 3. Neither the names of the copyright holders nor the names of its | |
17 | * contributors may be used to endorse or promote products derived from | |
18 | * this software without specific prior written permission. | |
b97bf3fd | 19 | * |
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20 | * Alternatively, this software may be distributed under the terms of the |
21 | * GNU General Public License ("GPL") version 2 as published by the Free | |
22 | * Software Foundation. | |
23 | * | |
24 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" | |
25 | * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
26 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
27 | * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE | |
28 | * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR | |
29 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF | |
30 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS | |
31 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN | |
32 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | |
33 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE | |
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34 | * POSSIBILITY OF SUCH DAMAGE. |
35 | */ | |
36 | ||
37 | #ifndef _TIPC_REF_H | |
38 | #define _TIPC_REF_H | |
39 | ||
40 | /** | |
41 | * struct reference - TIPC object reference entry | |
42 | * @object: pointer to object associated with reference entry | |
43 | * @lock: spinlock controlling access to object | |
44 | * @data: reference value associated with object (or link to next unused entry) | |
45 | */ | |
46 | ||
47 | struct reference { | |
48 | void *object; | |
49 | spinlock_t lock; | |
50 | union { | |
51 | u32 next_plus_upper; | |
52 | u32 reference; | |
53 | } data; | |
54 | }; | |
55 | ||
56 | /** | |
57 | * struct ref_table - table of TIPC object reference entries | |
58 | * @entries: pointer to array of reference entries | |
59 | * @index_mask: bitmask for array index portion of reference values | |
60 | * @first_free: array index of first unused object reference entry | |
61 | * @last_free: array index of last unused object reference entry | |
62 | */ | |
63 | ||
64 | struct ref_table { | |
65 | struct reference *entries; | |
66 | u32 index_mask; | |
67 | u32 first_free; | |
68 | u32 last_free; | |
69 | }; | |
70 | ||
71 | extern struct ref_table ref_table; | |
72 | ||
73 | int ref_table_init(u32 requested_size, u32 start); | |
74 | void ref_table_stop(void); | |
75 | ||
76 | u32 ref_acquire(void *object, spinlock_t **lock); | |
77 | void ref_discard(u32 ref); | |
78 | ||
79 | ||
80 | /** | |
81 | * ref_lock - lock referenced object and return pointer to it | |
82 | */ | |
83 | ||
84 | static inline void *ref_lock(u32 ref) | |
85 | { | |
86 | if (likely(ref_table.entries)) { | |
87 | struct reference *r = | |
88 | &ref_table.entries[ref & ref_table.index_mask]; | |
89 | ||
90 | spin_lock_bh(&r->lock); | |
91 | if (likely(r->data.reference == ref)) | |
92 | return r->object; | |
93 | spin_unlock_bh(&r->lock); | |
94 | } | |
95 | return 0; | |
96 | } | |
97 | ||
98 | /** | |
99 | * ref_unlock - unlock referenced object | |
100 | */ | |
101 | ||
102 | static inline void ref_unlock(u32 ref) | |
103 | { | |
104 | if (likely(ref_table.entries)) { | |
105 | struct reference *r = | |
106 | &ref_table.entries[ref & ref_table.index_mask]; | |
107 | ||
108 | if (likely(r->data.reference == ref)) | |
109 | spin_unlock_bh(&r->lock); | |
110 | else | |
111 | err("ref_unlock() invoked using obsolete reference\n"); | |
112 | } | |
113 | } | |
114 | ||
115 | /** | |
116 | * ref_deref - return pointer referenced object (without locking it) | |
117 | */ | |
118 | ||
119 | static inline void *ref_deref(u32 ref) | |
120 | { | |
121 | if (likely(ref_table.entries)) { | |
122 | struct reference *r = | |
123 | &ref_table.entries[ref & ref_table.index_mask]; | |
124 | ||
125 | if (likely(r->data.reference == ref)) | |
126 | return r->object; | |
127 | } | |
128 | return 0; | |
129 | } | |
130 | ||
131 | #endif |