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authorPer Liden <per.liden@nospam.ericsson.com>2006-01-02 13:04:38 -0500
committerDavid S. Miller <davem@sunset.davemloft.net>2006-01-12 17:06:31 -0500
commitb97bf3fd8f6a16966d4f18983b2c40993ff937d4 (patch)
tree59959f8a0f3087455efdcb430846686f303c5991 /net/tipc/ref.c
parent58cba4650a7a414eabd2b40cc9d8e45fcdf192d9 (diff)
[TIPC] Initial merge
TIPC (Transparent Inter Process Communication) is a protocol designed for intra cluster communication. For more information see http://tipc.sourceforge.net Signed-off-by: Per Liden <per.liden@nospam.ericsson.com>
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diff --git a/net/tipc/ref.c b/net/tipc/ref.c
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1/*
2 * net/tipc/ref.c: TIPC object registry code
3 *
4 * Copyright (c) 2003-2005, Ericsson Research Canada
5 * Copyright (c) 2004-2005, 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#include "core.h"
35#include "ref.h"
36#include "port.h"
37#include "subscr.h"
38#include "name_distr.h"
39#include "name_table.h"
40#include "config.h"
41#include "discover.h"
42#include "bearer.h"
43#include "node.h"
44#include "bcast.h"
45
46/*
47 * Object reference table consists of 2**N entries.
48 *
49 * A used entry has object ptr != 0, reference == XXXX|own index
50 * (XXXX changes each time entry is acquired)
51 * A free entry has object ptr == 0, reference == YYYY|next free index
52 * (YYYY is one more than last used XXXX)
53 *
54 * Free list is initially chained from entry (2**N)-1 to entry 1.
55 * Entry 0 is not used to allow index 0 to indicate the end of the free list.
56 *
57 * Note: Any accidental reference of the form XXXX|0--0 won't match entry 0
58 * because entry 0's reference field has the form XXXX|1--1.
59 */
60
61struct ref_table ref_table = { 0 };
62
63rwlock_t reftbl_lock = RW_LOCK_UNLOCKED;
64
65/**
66 * ref_table_init - create reference table for objects
67 */
68
69int ref_table_init(u32 requested_size, u32 start)
70{
71 struct reference *table;
72 u32 sz = 1 << 4;
73 u32 index_mask;
74 int i;
75
76 while (sz < requested_size) {
77 sz <<= 1;
78 }
79 table = (struct reference *)vmalloc(sz * sizeof(struct reference));
80 if (table == NULL)
81 return -ENOMEM;
82
83 write_lock_bh(&reftbl_lock);
84 index_mask = sz - 1;
85 for (i = sz - 1; i >= 0; i--) {
86 table[i].object = 0;
87 table[i].lock = SPIN_LOCK_UNLOCKED;
88 table[i].data.next_plus_upper = (start & ~index_mask) + i - 1;
89 }
90 ref_table.entries = table;
91 ref_table.index_mask = index_mask;
92 ref_table.first_free = sz - 1;
93 ref_table.last_free = 1;
94 write_unlock_bh(&reftbl_lock);
95 return TIPC_OK;
96}
97
98/**
99 * ref_table_stop - destroy reference table for objects
100 */
101
102void ref_table_stop(void)
103{
104 if (!ref_table.entries)
105 return;
106
107 vfree(ref_table.entries);
108 ref_table.entries = 0;
109}
110
111/**
112 * ref_acquire - create reference to an object
113 *
114 * Return a unique reference value which can be translated back to the pointer
115 * 'object' at a later time. Also, pass back a pointer to the lock protecting
116 * the object, but without locking it.
117 */
118
119u32 ref_acquire(void *object, spinlock_t **lock)
120{
121 struct reference *entry;
122 u32 index;
123 u32 index_mask;
124 u32 next_plus_upper;
125 u32 reference = 0;
126
127 assert(ref_table.entries && object);
128
129 write_lock_bh(&reftbl_lock);
130 if (ref_table.first_free) {
131 index = ref_table.first_free;
132 entry = &(ref_table.entries[index]);
133 index_mask = ref_table.index_mask;
134 /* take lock in case a previous user of entry still holds it */
135 spin_lock_bh(&entry->lock);
136 next_plus_upper = entry->data.next_plus_upper;
137 ref_table.first_free = next_plus_upper & index_mask;
138 reference = (next_plus_upper & ~index_mask) + index;
139 entry->data.reference = reference;
140 entry->object = object;
141 if (lock != 0)
142 *lock = &entry->lock;
143 spin_unlock_bh(&entry->lock);
144 }
145 write_unlock_bh(&reftbl_lock);
146 return reference;
147}
148
149/**
150 * ref_discard - invalidate references to an object
151 *
152 * Disallow future references to an object and free up the entry for re-use.
153 * Note: The entry's spin_lock may still be busy after discard
154 */
155
156void ref_discard(u32 ref)
157{
158 struct reference *entry;
159 u32 index;
160 u32 index_mask;
161
162 assert(ref_table.entries);
163 assert(ref != 0);
164
165 write_lock_bh(&reftbl_lock);
166 index_mask = ref_table.index_mask;
167 index = ref & index_mask;
168 entry = &(ref_table.entries[index]);
169 assert(entry->object != 0);
170 assert(entry->data.reference == ref);
171
172 /* mark entry as unused */
173 entry->object = 0;
174 if (ref_table.first_free == 0)
175 ref_table.first_free = index;
176 else
177 /* next_plus_upper is always XXXX|0--0 for last free entry */
178 ref_table.entries[ref_table.last_free].data.next_plus_upper
179 |= index;
180 ref_table.last_free = index;
181
182 /* increment upper bits of entry to invalidate subsequent references */
183 entry->data.next_plus_upper = (ref & ~index_mask) + (index_mask + 1);
184 write_unlock_bh(&reftbl_lock);
185}
186