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Per Lidenb97bf3f2006-01-02 19:04:38 +01001/*
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 *
Per Liden9ea1fd32006-01-11 13:30:43 +01009 * Redistribution and use in source and binary forms, with or without
Per Lidenb97bf3f2006-01-02 19:04:38 +010010 * modification, are permitted provided that the following conditions are met:
11 *
Per Liden9ea1fd32006-01-11 13:30:43 +010012 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. Neither the names of the copyright holders nor the names of its
18 * contributors may be used to endorse or promote products derived from
19 * this software without specific prior written permission.
Per Lidenb97bf3f2006-01-02 19:04:38 +010020 *
Per Liden9ea1fd32006-01-11 13:30:43 +010021 * Alternatively, this software may be distributed under the terms of the
22 * GNU General Public License ("GPL") version 2 as published by the Free
23 * Software Foundation.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
26 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
29 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
30 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
31 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
32 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
33 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
34 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
Per Lidenb97bf3f2006-01-02 19:04:38 +010035 * POSSIBILITY OF SUCH DAMAGE.
36 */
37
38#ifndef _TIPC_REF_H
39#define _TIPC_REF_H
40
41/**
42 * struct reference - TIPC object reference entry
43 * @object: pointer to object associated with reference entry
44 * @lock: spinlock controlling access to object
45 * @data: reference value associated with object (or link to next unused entry)
46 */
47
48struct reference {
49 void *object;
50 spinlock_t lock;
51 union {
52 u32 next_plus_upper;
53 u32 reference;
54 } data;
55};
56
57/**
58 * struct ref_table - table of TIPC object reference entries
59 * @entries: pointer to array of reference entries
60 * @index_mask: bitmask for array index portion of reference values
61 * @first_free: array index of first unused object reference entry
62 * @last_free: array index of last unused object reference entry
63 */
64
65struct ref_table {
66 struct reference *entries;
67 u32 index_mask;
68 u32 first_free;
69 u32 last_free;
70};
71
72extern struct ref_table ref_table;
73
74int ref_table_init(u32 requested_size, u32 start);
75void ref_table_stop(void);
76
77u32 ref_acquire(void *object, spinlock_t **lock);
78void ref_discard(u32 ref);
79
80
81/**
82 * ref_lock - lock referenced object and return pointer to it
83 */
84
85static inline void *ref_lock(u32 ref)
86{
87 if (likely(ref_table.entries)) {
88 struct reference *r =
89 &ref_table.entries[ref & ref_table.index_mask];
90
91 spin_lock_bh(&r->lock);
92 if (likely(r->data.reference == ref))
93 return r->object;
94 spin_unlock_bh(&r->lock);
95 }
96 return 0;
97}
98
99/**
100 * ref_unlock - unlock referenced object
101 */
102
103static inline void ref_unlock(u32 ref)
104{
105 if (likely(ref_table.entries)) {
106 struct reference *r =
107 &ref_table.entries[ref & ref_table.index_mask];
108
109 if (likely(r->data.reference == ref))
110 spin_unlock_bh(&r->lock);
111 else
112 err("ref_unlock() invoked using obsolete reference\n");
113 }
114}
115
116/**
117 * ref_deref - return pointer referenced object (without locking it)
118 */
119
120static inline void *ref_deref(u32 ref)
121{
122 if (likely(ref_table.entries)) {
123 struct reference *r =
124 &ref_table.entries[ref & ref_table.index_mask];
125
126 if (likely(r->data.reference == ref))
127 return r->object;
128 }
129 return 0;
130}
131
132#endif