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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 AS |
45 | */ |
46 | ||
47 | struct reference { | |
48 | void *object; | |
49 | spinlock_t lock; | |
bcff122d | 50 | u32 ref; |
4784b7c3 AS |
51 | }; |
52 | ||
53 | /** | |
54 | * struct tipc_ref_table - table of TIPC object reference entries | |
55 | * @entries: pointer to array of reference entries | |
00895098 AS |
56 | * @capacity: array index of first unusable entry |
57 | * @init_point: array index of first uninitialized entry | |
4784b7c3 AS |
58 | * @first_free: array index of first unused object reference entry |
59 | * @last_free: array index of last unused object reference entry | |
00895098 AS |
60 | * @index_mask: bitmask for array index portion of reference values |
61 | * @start_mask: initial value for instance value portion of reference values | |
4784b7c3 AS |
62 | */ |
63 | ||
64 | struct ref_table { | |
65 | struct reference *entries; | |
00895098 AS |
66 | u32 capacity; |
67 | u32 init_point; | |
4784b7c3 AS |
68 | u32 first_free; |
69 | u32 last_free; | |
00895098 AS |
70 | u32 index_mask; |
71 | u32 start_mask; | |
4784b7c3 AS |
72 | }; |
73 | ||
b97bf3fd PL |
74 | /* |
75 | * Object reference table consists of 2**N entries. | |
76 | * | |
00895098 AS |
77 | * State Object ptr Reference |
78 | * ----- ---------- --------- | |
79 | * In use non-NULL XXXX|own index | |
80 | * (XXXX changes each time entry is acquired) | |
81 | * Free NULL YYYY|next free index | |
82 | * (YYYY is one more than last used XXXX) | |
83 | * Uninitialized NULL 0 | |
b97bf3fd | 84 | * |
00895098 | 85 | * Entry 0 is not used; this allows index 0 to denote the end of the free list. |
b97bf3fd | 86 | * |
00895098 AS |
87 | * Note that a reference value of 0 does not necessarily indicate that an |
88 | * entry is uninitialized, since the last entry in the free list could also | |
89 | * have a reference value of 0 (although this is unlikely). | |
b97bf3fd PL |
90 | */ |
91 | ||
4784b7c3 | 92 | static struct ref_table tipc_ref_table = { NULL }; |
b97bf3fd | 93 | |
34af946a | 94 | static DEFINE_RWLOCK(ref_table_lock); |
b97bf3fd PL |
95 | |
96 | /** | |
4323add6 | 97 | * tipc_ref_table_init - create reference table for objects |
b97bf3fd PL |
98 | */ |
99 | ||
4323add6 | 100 | int tipc_ref_table_init(u32 requested_size, u32 start) |
b97bf3fd PL |
101 | { |
102 | struct reference *table; | |
00895098 | 103 | u32 actual_size; |
b97bf3fd | 104 | |
00895098 AS |
105 | /* account for unused entry, then round up size to a power of 2 */ |
106 | ||
107 | requested_size++; | |
108 | for (actual_size = 16; actual_size < requested_size; actual_size <<= 1) | |
109 | /* do nothing */ ; | |
110 | ||
111 | /* allocate table & mark all entries as uninitialized */ | |
112 | ||
113 | table = __vmalloc(actual_size * sizeof(struct reference), | |
114 | GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, PAGE_KERNEL); | |
b97bf3fd PL |
115 | if (table == NULL) |
116 | return -ENOMEM; | |
117 | ||
4323add6 | 118 | tipc_ref_table.entries = table; |
00895098 AS |
119 | tipc_ref_table.capacity = requested_size; |
120 | tipc_ref_table.init_point = 1; | |
121 | tipc_ref_table.first_free = 0; | |
122 | tipc_ref_table.last_free = 0; | |
123 | tipc_ref_table.index_mask = actual_size - 1; | |
124 | tipc_ref_table.start_mask = start & ~tipc_ref_table.index_mask; | |
125 | ||
0e35fd5e | 126 | return 0; |
b97bf3fd PL |
127 | } |
128 | ||
129 | /** | |
4323add6 | 130 | * tipc_ref_table_stop - destroy reference table for objects |
b97bf3fd PL |
131 | */ |
132 | ||
4323add6 | 133 | void tipc_ref_table_stop(void) |
b97bf3fd | 134 | { |
4323add6 | 135 | if (!tipc_ref_table.entries) |
b97bf3fd PL |
136 | return; |
137 | ||
4323add6 | 138 | vfree(tipc_ref_table.entries); |
1fc54d8f | 139 | tipc_ref_table.entries = NULL; |
b97bf3fd PL |
140 | } |
141 | ||
142 | /** | |
4323add6 | 143 | * tipc_ref_acquire - create reference to an object |
c4307285 | 144 | * |
7ef43eba AS |
145 | * Register an object pointer in reference table and lock the object. |
146 | * Returns a unique reference value that is used from then on to retrieve the | |
147 | * object pointer, or to determine that the object has been deregistered. | |
148 | * | |
149 | * Note: The object is returned in the locked state so that the caller can | |
150 | * register a partially initialized object, without running the risk that | |
151 | * the object will be accessed before initialization is complete. | |
b97bf3fd PL |
152 | */ |
153 | ||
4323add6 | 154 | u32 tipc_ref_acquire(void *object, spinlock_t **lock) |
b97bf3fd | 155 | { |
b97bf3fd PL |
156 | u32 index; |
157 | u32 index_mask; | |
158 | u32 next_plus_upper; | |
bcff122d | 159 | u32 ref; |
a2f46ee1 | 160 | struct reference *entry = NULL; |
b97bf3fd | 161 | |
f131072c AS |
162 | if (!object) { |
163 | err("Attempt to acquire reference to non-existent object\n"); | |
164 | return 0; | |
165 | } | |
166 | if (!tipc_ref_table.entries) { | |
167 | err("Reference table not found during acquisition attempt\n"); | |
168 | return 0; | |
169 | } | |
b97bf3fd | 170 | |
00895098 AS |
171 | /* take a free entry, if available; otherwise initialize a new entry */ |
172 | ||
4323add6 PL |
173 | write_lock_bh(&ref_table_lock); |
174 | if (tipc_ref_table.first_free) { | |
175 | index = tipc_ref_table.first_free; | |
176 | entry = &(tipc_ref_table.entries[index]); | |
177 | index_mask = tipc_ref_table.index_mask; | |
bcff122d | 178 | next_plus_upper = entry->ref; |
4323add6 | 179 | tipc_ref_table.first_free = next_plus_upper & index_mask; |
bcff122d | 180 | ref = (next_plus_upper & ~index_mask) + index; |
00895098 AS |
181 | } |
182 | else if (tipc_ref_table.init_point < tipc_ref_table.capacity) { | |
183 | index = tipc_ref_table.init_point++; | |
184 | entry = &(tipc_ref_table.entries[index]); | |
185 | spin_lock_init(&entry->lock); | |
bcff122d | 186 | ref = tipc_ref_table.start_mask + index; |
00895098 AS |
187 | } |
188 | else { | |
bcff122d | 189 | ref = 0; |
b97bf3fd | 190 | } |
4323add6 | 191 | write_unlock_bh(&ref_table_lock); |
00895098 | 192 | |
a2f46ee1 NH |
193 | /* |
194 | * Grab the lock so no one else can modify this entry | |
195 | * While we assign its ref value & object pointer | |
196 | */ | |
197 | if (entry) { | |
198 | spin_lock_bh(&entry->lock); | |
199 | entry->ref = ref; | |
200 | entry->object = object; | |
201 | *lock = &entry->lock; | |
202 | /* | |
203 | * keep it locked, the caller is responsible | |
204 | * for unlocking this when they're done with it | |
205 | */ | |
206 | } | |
207 | ||
bcff122d | 208 | return ref; |
b97bf3fd PL |
209 | } |
210 | ||
211 | /** | |
4323add6 | 212 | * tipc_ref_discard - invalidate references to an object |
c4307285 | 213 | * |
b97bf3fd PL |
214 | * Disallow future references to an object and free up the entry for re-use. |
215 | * Note: The entry's spin_lock may still be busy after discard | |
216 | */ | |
217 | ||
4323add6 | 218 | void tipc_ref_discard(u32 ref) |
b97bf3fd PL |
219 | { |
220 | struct reference *entry; | |
c4307285 | 221 | u32 index; |
b97bf3fd PL |
222 | u32 index_mask; |
223 | ||
f131072c AS |
224 | if (!tipc_ref_table.entries) { |
225 | err("Reference table not found during discard attempt\n"); | |
226 | return; | |
227 | } | |
b97bf3fd | 228 | |
4323add6 | 229 | index_mask = tipc_ref_table.index_mask; |
b97bf3fd | 230 | index = ref & index_mask; |
4323add6 | 231 | entry = &(tipc_ref_table.entries[index]); |
f131072c | 232 | |
00895098 AS |
233 | write_lock_bh(&ref_table_lock); |
234 | ||
f131072c AS |
235 | if (!entry->object) { |
236 | err("Attempt to discard reference to non-existent object\n"); | |
237 | goto exit; | |
238 | } | |
bcff122d | 239 | if (entry->ref != ref) { |
f131072c AS |
240 | err("Attempt to discard non-existent reference\n"); |
241 | goto exit; | |
242 | } | |
b97bf3fd | 243 | |
00895098 | 244 | /* |
bcff122d | 245 | * mark entry as unused; increment instance part of entry's reference |
00895098 AS |
246 | * to invalidate any subsequent references |
247 | */ | |
248 | ||
1fc54d8f | 249 | entry->object = NULL; |
bcff122d | 250 | entry->ref = (ref & ~index_mask) + (index_mask + 1); |
00895098 AS |
251 | |
252 | /* append entry to free entry list */ | |
253 | ||
4323add6 PL |
254 | if (tipc_ref_table.first_free == 0) |
255 | tipc_ref_table.first_free = index; | |
b97bf3fd | 256 | else |
bcff122d | 257 | tipc_ref_table.entries[tipc_ref_table.last_free].ref |= index; |
4323add6 | 258 | tipc_ref_table.last_free = index; |
b97bf3fd | 259 | |
f131072c | 260 | exit: |
4323add6 | 261 | write_unlock_bh(&ref_table_lock); |
b97bf3fd PL |
262 | } |
263 | ||
4784b7c3 AS |
264 | /** |
265 | * tipc_ref_lock - lock referenced object and return pointer to it | |
266 | */ | |
267 | ||
268 | void *tipc_ref_lock(u32 ref) | |
269 | { | |
270 | if (likely(tipc_ref_table.entries)) { | |
bcff122d AS |
271 | struct reference *entry; |
272 | ||
273 | entry = &tipc_ref_table.entries[ref & | |
274 | tipc_ref_table.index_mask]; | |
275 | if (likely(entry->ref != 0)) { | |
276 | spin_lock_bh(&entry->lock); | |
277 | if (likely((entry->ref == ref) && (entry->object))) | |
278 | return entry->object; | |
279 | spin_unlock_bh(&entry->lock); | |
00895098 | 280 | } |
4784b7c3 AS |
281 | } |
282 | return NULL; | |
283 | } | |
284 | ||
285 | /** | |
286 | * tipc_ref_unlock - unlock referenced object | |
287 | */ | |
288 | ||
289 | void tipc_ref_unlock(u32 ref) | |
290 | { | |
291 | if (likely(tipc_ref_table.entries)) { | |
bcff122d | 292 | struct reference *entry; |
00895098 | 293 | |
bcff122d AS |
294 | entry = &tipc_ref_table.entries[ref & |
295 | tipc_ref_table.index_mask]; | |
296 | if (likely((entry->ref == ref) && (entry->object))) | |
297 | spin_unlock_bh(&entry->lock); | |
4784b7c3 | 298 | else |
bcff122d | 299 | err("Attempt to unlock non-existent reference\n"); |
4784b7c3 AS |
300 | } |
301 | } | |
302 | ||
303 | /** | |
304 | * tipc_ref_deref - return pointer referenced object (without locking it) | |
305 | */ | |
306 | ||
307 | void *tipc_ref_deref(u32 ref) | |
308 | { | |
309 | if (likely(tipc_ref_table.entries)) { | |
bcff122d | 310 | struct reference *entry; |
4784b7c3 | 311 | |
bcff122d AS |
312 | entry = &tipc_ref_table.entries[ref & |
313 | tipc_ref_table.index_mask]; | |
314 | if (likely(entry->ref == ref)) | |
315 | return entry->object; | |
4784b7c3 AS |
316 | } |
317 | return NULL; | |
318 | } | |
319 |