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1/*
2 * net/tipc/ref.h: Include file for TIPC object registry code
3 *
4 * Copyright (c) 1991-2006, Ericsson AB
5 * Copyright (c) 2005, Wind River Systems
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions are met:
10 *
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.
19 *
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
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
47struct 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 tipc_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
64struct ref_table {
65 struct reference *entries;
66 u32 index_mask;
67 u32 first_free;
68 u32 last_free;
69};
70
71extern struct ref_table tipc_ref_table;
72
73int tipc_ref_table_init(u32 requested_size, u32 start);
74void tipc_ref_table_stop(void);
75
76u32 tipc_ref_acquire(void *object, spinlock_t **lock);
77void tipc_ref_discard(u32 ref);
78
79
80/**
81 * tipc_ref_lock - lock referenced object and return pointer to it
82 */
83
84static inline void *tipc_ref_lock(u32 ref)
85{
86 if (likely(tipc_ref_table.entries)) {
87 struct reference *r =
88 &tipc_ref_table.entries[ref & tipc_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 NULL;
96}
97
98/**
99 * tipc_ref_unlock - unlock referenced object
100 */
101
102static inline void tipc_ref_unlock(u32 ref)
103{
104 if (likely(tipc_ref_table.entries)) {
105 struct reference *r =
106 &tipc_ref_table.entries[ref & tipc_ref_table.index_mask];
107
108 if (likely(r->data.reference == ref))
109 spin_unlock_bh(&r->lock);
110 else
111 err("tipc_ref_unlock() invoked using obsolete reference\n");
112 }
113}
114
115/**
116 * tipc_ref_deref - return pointer referenced object (without locking it)
117 */
118
119static inline void *tipc_ref_deref(u32 ref)
120{
121 if (likely(tipc_ref_table.entries)) {
122 struct reference *r =
123 &tipc_ref_table.entries[ref & tipc_ref_table.index_mask];
124
125 if (likely(r->data.reference == ref))
126 return r->object;
127 }
128 return NULL;
129}
130
131#endif