Linux kernel mirror (for testing)
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1/*
2 * net/tipc/ref.c: TIPC object registry code
3 *
4 * Copyright (c) 1991-2006, Ericsson AB
5 * Copyright (c) 2004-2005, 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#include "core.h"
38#include "ref.h"
39#include "port.h"
40#include "subscr.h"
41#include "name_distr.h"
42#include "name_table.h"
43#include "config.h"
44#include "discover.h"
45#include "bearer.h"
46#include "node.h"
47#include "bcast.h"
48
49/*
50 * Object reference table consists of 2**N entries.
51 *
52 * A used entry has object ptr != 0, reference == XXXX|own index
53 * (XXXX changes each time entry is acquired)
54 * A free entry has object ptr == 0, reference == YYYY|next free index
55 * (YYYY is one more than last used XXXX)
56 *
57 * Free list is initially chained from entry (2**N)-1 to entry 1.
58 * Entry 0 is not used to allow index 0 to indicate the end of the free list.
59 *
60 * Note: Any accidental reference of the form XXXX|0--0 won't match entry 0
61 * because entry 0's reference field has the form XXXX|1--1.
62 */
63
64struct ref_table tipc_ref_table = { NULL };
65
66static DEFINE_RWLOCK(ref_table_lock);
67
68/**
69 * tipc_ref_table_init - create reference table for objects
70 */
71
72int tipc_ref_table_init(u32 requested_size, u32 start)
73{
74 struct reference *table;
75 u32 sz = 1 << 4;
76 u32 index_mask;
77 int i;
78
79 while (sz < requested_size) {
80 sz <<= 1;
81 }
82 table = vmalloc(sz * sizeof(*table));
83 if (table == NULL)
84 return -ENOMEM;
85
86 write_lock_bh(&ref_table_lock);
87 index_mask = sz - 1;
88 for (i = sz - 1; i >= 0; i--) {
89 table[i].object = NULL;
90 spin_lock_init(&table[i].lock);
91 table[i].data.next_plus_upper = (start & ~index_mask) + i - 1;
92 }
93 tipc_ref_table.entries = table;
94 tipc_ref_table.index_mask = index_mask;
95 tipc_ref_table.first_free = sz - 1;
96 tipc_ref_table.last_free = 1;
97 write_unlock_bh(&ref_table_lock);
98 return TIPC_OK;
99}
100
101/**
102 * tipc_ref_table_stop - destroy reference table for objects
103 */
104
105void tipc_ref_table_stop(void)
106{
107 if (!tipc_ref_table.entries)
108 return;
109
110 vfree(tipc_ref_table.entries);
111 tipc_ref_table.entries = NULL;
112}
113
114/**
115 * tipc_ref_acquire - create reference to an object
116 *
117 * Return a unique reference value which can be translated back to the pointer
118 * 'object' at a later time. Also, pass back a pointer to the lock protecting
119 * the object, but without locking it.
120 */
121
122u32 tipc_ref_acquire(void *object, spinlock_t **lock)
123{
124 struct reference *entry;
125 u32 index;
126 u32 index_mask;
127 u32 next_plus_upper;
128 u32 reference = 0;
129
130 if (!object) {
131 err("Attempt to acquire reference to non-existent object\n");
132 return 0;
133 }
134 if (!tipc_ref_table.entries) {
135 err("Reference table not found during acquisition attempt\n");
136 return 0;
137 }
138
139 write_lock_bh(&ref_table_lock);
140 if (tipc_ref_table.first_free) {
141 index = tipc_ref_table.first_free;
142 entry = &(tipc_ref_table.entries[index]);
143 index_mask = tipc_ref_table.index_mask;
144 /* take lock in case a previous user of entry still holds it */
145 spin_lock_bh(&entry->lock);
146 next_plus_upper = entry->data.next_plus_upper;
147 tipc_ref_table.first_free = next_plus_upper & index_mask;
148 reference = (next_plus_upper & ~index_mask) + index;
149 entry->data.reference = reference;
150 entry->object = object;
151 if (lock != 0)
152 *lock = &entry->lock;
153 spin_unlock_bh(&entry->lock);
154 }
155 write_unlock_bh(&ref_table_lock);
156 return reference;
157}
158
159/**
160 * tipc_ref_discard - invalidate references to an object
161 *
162 * Disallow future references to an object and free up the entry for re-use.
163 * Note: The entry's spin_lock may still be busy after discard
164 */
165
166void tipc_ref_discard(u32 ref)
167{
168 struct reference *entry;
169 u32 index;
170 u32 index_mask;
171
172 if (!ref) {
173 err("Attempt to discard reference 0\n");
174 return;
175 }
176 if (!tipc_ref_table.entries) {
177 err("Reference table not found during discard attempt\n");
178 return;
179 }
180
181 write_lock_bh(&ref_table_lock);
182 index_mask = tipc_ref_table.index_mask;
183 index = ref & index_mask;
184 entry = &(tipc_ref_table.entries[index]);
185
186 if (!entry->object) {
187 err("Attempt to discard reference to non-existent object\n");
188 goto exit;
189 }
190 if (entry->data.reference != ref) {
191 err("Attempt to discard non-existent reference\n");
192 goto exit;
193 }
194
195 /* mark entry as unused */
196 entry->object = NULL;
197 if (tipc_ref_table.first_free == 0)
198 tipc_ref_table.first_free = index;
199 else
200 /* next_plus_upper is always XXXX|0--0 for last free entry */
201 tipc_ref_table.entries[tipc_ref_table.last_free].data.next_plus_upper
202 |= index;
203 tipc_ref_table.last_free = index;
204
205 /* increment upper bits of entry to invalidate subsequent references */
206 entry->data.next_plus_upper = (ref & ~index_mask) + (index_mask + 1);
207exit:
208 write_unlock_bh(&ref_table_lock);
209}
210