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