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Commit | Line | Data |
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b97bf3fd PL |
1 | /* |
2 | * net/tipc/ref.c: TIPC object registry code | |
c4307285 | 3 | * |
593a5f22 | 4 | * Copyright (c) 1991-2006, Ericsson AB |
4784b7c3 | 5 | * Copyright (c) 2004-2007, Wind River Systems |
b97bf3fd PL |
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: | |
9ea1fd3c PL |
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. | |
b97bf3fd PL |
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" | |
b97bf3fd | 39 | |
4784b7c3 AS |
40 | /** |
41 | * struct reference - TIPC object reference entry | |
42 | * @object: pointer to object associated with reference entry | |
43 | * @lock: spinlock controlling access to object | |
bcff122d | 44 | * @ref: reference value for object (combines instance & array index info) |
4784b7c3 | 45 | */ |
4784b7c3 AS |
46 | struct reference { |
47 | void *object; | |
48 | spinlock_t lock; | |
bcff122d | 49 | u32 ref; |
4784b7c3 AS |
50 | }; |
51 | ||
52 | /** | |
53 | * struct tipc_ref_table - table of TIPC object reference entries | |
54 | * @entries: pointer to array of reference entries | |
00895098 AS |
55 | * @capacity: array index of first unusable entry |
56 | * @init_point: array index of first uninitialized entry | |
4784b7c3 AS |
57 | * @first_free: array index of first unused object reference entry |
58 | * @last_free: array index of last unused object reference entry | |
00895098 AS |
59 | * @index_mask: bitmask for array index portion of reference values |
60 | * @start_mask: initial value for instance value portion of reference values | |
4784b7c3 | 61 | */ |
4784b7c3 AS |
62 | struct ref_table { |
63 | struct reference *entries; | |
00895098 AS |
64 | u32 capacity; |
65 | u32 init_point; | |
4784b7c3 AS |
66 | u32 first_free; |
67 | u32 last_free; | |
00895098 AS |
68 | u32 index_mask; |
69 | u32 start_mask; | |
4784b7c3 AS |
70 | }; |
71 | ||
b97bf3fd PL |
72 | /* |
73 | * Object reference table consists of 2**N entries. | |
74 | * | |
00895098 AS |
75 | * State Object ptr Reference |
76 | * ----- ---------- --------- | |
77 | * In use non-NULL XXXX|own index | |
78 | * (XXXX changes each time entry is acquired) | |
79 | * Free NULL YYYY|next free index | |
80 | * (YYYY is one more than last used XXXX) | |
81 | * Uninitialized NULL 0 | |
b97bf3fd | 82 | * |
00895098 | 83 | * Entry 0 is not used; this allows index 0 to denote the end of the free list. |
b97bf3fd | 84 | * |
00895098 AS |
85 | * Note that a reference value of 0 does not necessarily indicate that an |
86 | * entry is uninitialized, since the last entry in the free list could also | |
87 | * have a reference value of 0 (although this is unlikely). | |
b97bf3fd PL |
88 | */ |
89 | ||
e3ec9c7d | 90 | static struct ref_table tipc_ref_table; |
b97bf3fd | 91 | |
34af946a | 92 | static DEFINE_RWLOCK(ref_table_lock); |
b97bf3fd PL |
93 | |
94 | /** | |
4323add6 | 95 | * tipc_ref_table_init - create reference table for objects |
b97bf3fd | 96 | */ |
4323add6 | 97 | int tipc_ref_table_init(u32 requested_size, u32 start) |
b97bf3fd PL |
98 | { |
99 | struct reference *table; | |
00895098 | 100 | u32 actual_size; |
b97bf3fd | 101 | |
00895098 AS |
102 | /* account for unused entry, then round up size to a power of 2 */ |
103 | ||
104 | requested_size++; | |
105 | for (actual_size = 16; actual_size < requested_size; actual_size <<= 1) | |
106 | /* do nothing */ ; | |
107 | ||
108 | /* allocate table & mark all entries as uninitialized */ | |
966567b7 | 109 | table = vzalloc(actual_size * sizeof(struct reference)); |
b97bf3fd PL |
110 | if (table == NULL) |
111 | return -ENOMEM; | |
112 | ||
4323add6 | 113 | tipc_ref_table.entries = table; |
00895098 AS |
114 | tipc_ref_table.capacity = requested_size; |
115 | tipc_ref_table.init_point = 1; | |
116 | tipc_ref_table.first_free = 0; | |
117 | tipc_ref_table.last_free = 0; | |
118 | tipc_ref_table.index_mask = actual_size - 1; | |
119 | tipc_ref_table.start_mask = start & ~tipc_ref_table.index_mask; | |
120 | ||
0e35fd5e | 121 | return 0; |
b97bf3fd PL |
122 | } |
123 | ||
124 | /** | |
4323add6 | 125 | * tipc_ref_table_stop - destroy reference table for objects |
b97bf3fd | 126 | */ |
4323add6 | 127 | void tipc_ref_table_stop(void) |
b97bf3fd | 128 | { |
4323add6 | 129 | if (!tipc_ref_table.entries) |
b97bf3fd PL |
130 | return; |
131 | ||
4323add6 | 132 | vfree(tipc_ref_table.entries); |
1fc54d8f | 133 | tipc_ref_table.entries = NULL; |
b97bf3fd PL |
134 | } |
135 | ||
136 | /** | |
4323add6 | 137 | * tipc_ref_acquire - create reference to an object |
c4307285 | 138 | * |
7ef43eba AS |
139 | * Register an object pointer in reference table and lock the object. |
140 | * Returns a unique reference value that is used from then on to retrieve the | |
141 | * object pointer, or to determine that the object has been deregistered. | |
142 | * | |
143 | * Note: The object is returned in the locked state so that the caller can | |
144 | * register a partially initialized object, without running the risk that | |
145 | * the object will be accessed before initialization is complete. | |
b97bf3fd | 146 | */ |
4323add6 | 147 | u32 tipc_ref_acquire(void *object, spinlock_t **lock) |
b97bf3fd | 148 | { |
b97bf3fd PL |
149 | u32 index; |
150 | u32 index_mask; | |
151 | u32 next_plus_upper; | |
bcff122d | 152 | u32 ref; |
a2f46ee1 | 153 | struct reference *entry = NULL; |
b97bf3fd | 154 | |
f131072c | 155 | if (!object) { |
2cf8aa19 | 156 | pr_err("Attempt to acquire ref. to non-existent obj\n"); |
f131072c AS |
157 | return 0; |
158 | } | |
159 | if (!tipc_ref_table.entries) { | |
2cf8aa19 | 160 | pr_err("Ref. table not found in acquisition attempt\n"); |
f131072c AS |
161 | return 0; |
162 | } | |
b97bf3fd | 163 | |
00895098 | 164 | /* take a free entry, if available; otherwise initialize a new entry */ |
4323add6 PL |
165 | write_lock_bh(&ref_table_lock); |
166 | if (tipc_ref_table.first_free) { | |
167 | index = tipc_ref_table.first_free; | |
168 | entry = &(tipc_ref_table.entries[index]); | |
169 | index_mask = tipc_ref_table.index_mask; | |
bcff122d | 170 | next_plus_upper = entry->ref; |
4323add6 | 171 | tipc_ref_table.first_free = next_plus_upper & index_mask; |
bcff122d | 172 | ref = (next_plus_upper & ~index_mask) + index; |
0e65967e | 173 | } else if (tipc_ref_table.init_point < tipc_ref_table.capacity) { |
00895098 AS |
174 | index = tipc_ref_table.init_point++; |
175 | entry = &(tipc_ref_table.entries[index]); | |
176 | spin_lock_init(&entry->lock); | |
bcff122d | 177 | ref = tipc_ref_table.start_mask + index; |
0e65967e | 178 | } else { |
bcff122d | 179 | ref = 0; |
b97bf3fd | 180 | } |
4323add6 | 181 | write_unlock_bh(&ref_table_lock); |
00895098 | 182 | |
a2f46ee1 NH |
183 | /* |
184 | * Grab the lock so no one else can modify this entry | |
185 | * While we assign its ref value & object pointer | |
186 | */ | |
187 | if (entry) { | |
188 | spin_lock_bh(&entry->lock); | |
189 | entry->ref = ref; | |
190 | entry->object = object; | |
191 | *lock = &entry->lock; | |
192 | /* | |
193 | * keep it locked, the caller is responsible | |
194 | * for unlocking this when they're done with it | |
195 | */ | |
196 | } | |
197 | ||
bcff122d | 198 | return ref; |
b97bf3fd PL |
199 | } |
200 | ||
201 | /** | |
4323add6 | 202 | * tipc_ref_discard - invalidate references to an object |
c4307285 | 203 | * |
b97bf3fd PL |
204 | * Disallow future references to an object and free up the entry for re-use. |
205 | * Note: The entry's spin_lock may still be busy after discard | |
206 | */ | |
4323add6 | 207 | void tipc_ref_discard(u32 ref) |
b97bf3fd PL |
208 | { |
209 | struct reference *entry; | |
c4307285 | 210 | u32 index; |
b97bf3fd PL |
211 | u32 index_mask; |
212 | ||
f131072c | 213 | if (!tipc_ref_table.entries) { |
2cf8aa19 | 214 | pr_err("Ref. table not found during discard attempt\n"); |
f131072c AS |
215 | return; |
216 | } | |
b97bf3fd | 217 | |
4323add6 | 218 | index_mask = tipc_ref_table.index_mask; |
b97bf3fd | 219 | index = ref & index_mask; |
4323add6 | 220 | entry = &(tipc_ref_table.entries[index]); |
f131072c | 221 | |
00895098 AS |
222 | write_lock_bh(&ref_table_lock); |
223 | ||
f131072c | 224 | if (!entry->object) { |
2cf8aa19 | 225 | pr_err("Attempt to discard ref. to non-existent obj\n"); |
f131072c AS |
226 | goto exit; |
227 | } | |
bcff122d | 228 | if (entry->ref != ref) { |
2cf8aa19 | 229 | pr_err("Attempt to discard non-existent reference\n"); |
f131072c AS |
230 | goto exit; |
231 | } | |
b97bf3fd | 232 | |
00895098 | 233 | /* |
bcff122d | 234 | * mark entry as unused; increment instance part of entry's reference |
00895098 AS |
235 | * to invalidate any subsequent references |
236 | */ | |
1fc54d8f | 237 | entry->object = NULL; |
bcff122d | 238 | entry->ref = (ref & ~index_mask) + (index_mask + 1); |
00895098 AS |
239 | |
240 | /* append entry to free entry list */ | |
4323add6 PL |
241 | if (tipc_ref_table.first_free == 0) |
242 | tipc_ref_table.first_free = index; | |
b97bf3fd | 243 | else |
bcff122d | 244 | tipc_ref_table.entries[tipc_ref_table.last_free].ref |= index; |
4323add6 | 245 | tipc_ref_table.last_free = index; |
b97bf3fd | 246 | |
f131072c | 247 | exit: |
4323add6 | 248 | write_unlock_bh(&ref_table_lock); |
b97bf3fd PL |
249 | } |
250 | ||
4784b7c3 AS |
251 | /** |
252 | * tipc_ref_lock - lock referenced object and return pointer to it | |
253 | */ | |
4784b7c3 AS |
254 | void *tipc_ref_lock(u32 ref) |
255 | { | |
256 | if (likely(tipc_ref_table.entries)) { | |
bcff122d AS |
257 | struct reference *entry; |
258 | ||
259 | entry = &tipc_ref_table.entries[ref & | |
260 | tipc_ref_table.index_mask]; | |
261 | if (likely(entry->ref != 0)) { | |
262 | spin_lock_bh(&entry->lock); | |
263 | if (likely((entry->ref == ref) && (entry->object))) | |
264 | return entry->object; | |
265 | spin_unlock_bh(&entry->lock); | |
00895098 | 266 | } |
4784b7c3 AS |
267 | } |
268 | return NULL; | |
269 | } | |
270 | ||
4784b7c3 AS |
271 | |
272 | /** | |
273 | * tipc_ref_deref - return pointer referenced object (without locking it) | |
274 | */ | |
4784b7c3 AS |
275 | void *tipc_ref_deref(u32 ref) |
276 | { | |
277 | if (likely(tipc_ref_table.entries)) { | |
bcff122d | 278 | struct reference *entry; |
4784b7c3 | 279 | |
bcff122d AS |
280 | entry = &tipc_ref_table.entries[ref & |
281 | tipc_ref_table.index_mask]; | |
282 | if (likely(entry->ref == ref)) | |
283 | return entry->object; | |
4784b7c3 AS |
284 | } |
285 | return NULL; | |
286 | } |