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Per Lidenb97bf3f2006-01-02 19:04:38 +01001/*
2 * net/tipc/ref.c: TIPC object registry code
YOSHIFUJI Hideakic4307282007-02-09 23:25:21 +09003 *
Per Liden593a5f22006-01-11 19:14:19 +01004 * Copyright (c) 1991-2006, Ericsson AB
Allan Stephens4784b7c2008-04-16 18:21:16 -07005 * Copyright (c) 2004-2007, Wind River Systems
Per Lidenb97bf3f2006-01-02 19:04:38 +01006 * 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:
Per Liden9ea1fd32006-01-11 13:30:43 +010010 *
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.
Per Lidenb97bf3f2006-01-02 19:04:38 +010023 *
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"
Per Lidenb97bf3f2006-01-02 19:04:38 +010039
Allan Stephens4784b7c2008-04-16 18:21:16 -070040/**
41 * struct reference - TIPC object reference entry
42 * @object: pointer to object associated with reference entry
43 * @lock: spinlock controlling access to object
Allan Stephensbcff1222008-04-16 18:22:20 -070044 * @ref: reference value for object (combines instance & array index info)
Allan Stephens4784b7c2008-04-16 18:21:16 -070045 */
46
47struct reference {
48 void *object;
49 spinlock_t lock;
Allan Stephensbcff1222008-04-16 18:22:20 -070050 u32 ref;
Allan Stephens4784b7c2008-04-16 18:21:16 -070051};
52
53/**
54 * struct tipc_ref_table - table of TIPC object reference entries
55 * @entries: pointer to array of reference entries
Allan Stephens00895092008-04-16 18:21:47 -070056 * @capacity: array index of first unusable entry
57 * @init_point: array index of first uninitialized entry
Allan Stephens4784b7c2008-04-16 18:21:16 -070058 * @first_free: array index of first unused object reference entry
59 * @last_free: array index of last unused object reference entry
Allan Stephens00895092008-04-16 18:21:47 -070060 * @index_mask: bitmask for array index portion of reference values
61 * @start_mask: initial value for instance value portion of reference values
Allan Stephens4784b7c2008-04-16 18:21:16 -070062 */
63
64struct ref_table {
65 struct reference *entries;
Allan Stephens00895092008-04-16 18:21:47 -070066 u32 capacity;
67 u32 init_point;
Allan Stephens4784b7c2008-04-16 18:21:16 -070068 u32 first_free;
69 u32 last_free;
Allan Stephens00895092008-04-16 18:21:47 -070070 u32 index_mask;
71 u32 start_mask;
Allan Stephens4784b7c2008-04-16 18:21:16 -070072};
73
Per Lidenb97bf3f2006-01-02 19:04:38 +010074/*
75 * Object reference table consists of 2**N entries.
76 *
Allan Stephens00895092008-04-16 18:21:47 -070077 * 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
Per Lidenb97bf3f2006-01-02 19:04:38 +010084 *
Allan Stephens00895092008-04-16 18:21:47 -070085 * Entry 0 is not used; this allows index 0 to denote the end of the free list.
Per Lidenb97bf3f2006-01-02 19:04:38 +010086 *
Allan Stephens00895092008-04-16 18:21:47 -070087 * 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).
Per Lidenb97bf3f2006-01-02 19:04:38 +010090 */
91
Allan Stephens4784b7c2008-04-16 18:21:16 -070092static struct ref_table tipc_ref_table = { NULL };
Per Lidenb97bf3f2006-01-02 19:04:38 +010093
Ingo Molnar34af9462006-06-27 02:53:55 -070094static DEFINE_RWLOCK(ref_table_lock);
Per Lidenb97bf3f2006-01-02 19:04:38 +010095
96/**
Per Liden4323add2006-01-18 00:38:21 +010097 * tipc_ref_table_init - create reference table for objects
Per Lidenb97bf3f2006-01-02 19:04:38 +010098 */
99
Per Liden4323add2006-01-18 00:38:21 +0100100int tipc_ref_table_init(u32 requested_size, u32 start)
Per Lidenb97bf3f2006-01-02 19:04:38 +0100101{
102 struct reference *table;
Allan Stephens00895092008-04-16 18:21:47 -0700103 u32 actual_size;
Per Lidenb97bf3f2006-01-02 19:04:38 +0100104
Allan Stephens00895092008-04-16 18:21:47 -0700105 /* 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);
Per Lidenb97bf3f2006-01-02 19:04:38 +0100115 if (table == NULL)
116 return -ENOMEM;
117
Per Liden4323add2006-01-18 00:38:21 +0100118 tipc_ref_table.entries = table;
Allan Stephens00895092008-04-16 18:21:47 -0700119 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
Allan Stephens0e35fd52008-07-14 22:44:01 -0700126 return 0;
Per Lidenb97bf3f2006-01-02 19:04:38 +0100127}
128
129/**
Per Liden4323add2006-01-18 00:38:21 +0100130 * tipc_ref_table_stop - destroy reference table for objects
Per Lidenb97bf3f2006-01-02 19:04:38 +0100131 */
132
Per Liden4323add2006-01-18 00:38:21 +0100133void tipc_ref_table_stop(void)
Per Lidenb97bf3f2006-01-02 19:04:38 +0100134{
Per Liden4323add2006-01-18 00:38:21 +0100135 if (!tipc_ref_table.entries)
Per Lidenb97bf3f2006-01-02 19:04:38 +0100136 return;
137
Per Liden4323add2006-01-18 00:38:21 +0100138 vfree(tipc_ref_table.entries);
Sam Ravnborg1fc54d82006-03-20 22:36:47 -0800139 tipc_ref_table.entries = NULL;
Per Lidenb97bf3f2006-01-02 19:04:38 +0100140}
141
142/**
Per Liden4323add2006-01-18 00:38:21 +0100143 * tipc_ref_acquire - create reference to an object
YOSHIFUJI Hideakic4307282007-02-09 23:25:21 +0900144 *
Allan Stephens7ef43eb2008-05-12 15:42:28 -0700145 * 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.
Per Lidenb97bf3f2006-01-02 19:04:38 +0100152 */
153
Per Liden4323add2006-01-18 00:38:21 +0100154u32 tipc_ref_acquire(void *object, spinlock_t **lock)
Per Lidenb97bf3f2006-01-02 19:04:38 +0100155{
Per Lidenb97bf3f2006-01-02 19:04:38 +0100156 u32 index;
157 u32 index_mask;
158 u32 next_plus_upper;
Allan Stephensbcff1222008-04-16 18:22:20 -0700159 u32 ref;
Neil Hormana2f46ee2010-03-16 08:14:33 +0000160 struct reference *entry = NULL;
Per Lidenb97bf3f2006-01-02 19:04:38 +0100161
Allan Stephensf1310722006-06-25 23:51:37 -0700162 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 }
Per Lidenb97bf3f2006-01-02 19:04:38 +0100170
Allan Stephens00895092008-04-16 18:21:47 -0700171 /* take a free entry, if available; otherwise initialize a new entry */
172
Per Liden4323add2006-01-18 00:38:21 +0100173 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;
Allan Stephensbcff1222008-04-16 18:22:20 -0700178 next_plus_upper = entry->ref;
Per Liden4323add2006-01-18 00:38:21 +0100179 tipc_ref_table.first_free = next_plus_upper & index_mask;
Allan Stephensbcff1222008-04-16 18:22:20 -0700180 ref = (next_plus_upper & ~index_mask) + index;
Allan Stephens00895092008-04-16 18:21:47 -0700181 }
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);
Allan Stephensbcff1222008-04-16 18:22:20 -0700186 ref = tipc_ref_table.start_mask + index;
Allan Stephens00895092008-04-16 18:21:47 -0700187 }
188 else {
Allan Stephensbcff1222008-04-16 18:22:20 -0700189 ref = 0;
Per Lidenb97bf3f2006-01-02 19:04:38 +0100190 }
Per Liden4323add2006-01-18 00:38:21 +0100191 write_unlock_bh(&ref_table_lock);
Allan Stephens00895092008-04-16 18:21:47 -0700192
Neil Hormana2f46ee2010-03-16 08:14:33 +0000193 /*
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
Allan Stephensbcff1222008-04-16 18:22:20 -0700208 return ref;
Per Lidenb97bf3f2006-01-02 19:04:38 +0100209}
210
211/**
Per Liden4323add2006-01-18 00:38:21 +0100212 * tipc_ref_discard - invalidate references to an object
YOSHIFUJI Hideakic4307282007-02-09 23:25:21 +0900213 *
Per Lidenb97bf3f2006-01-02 19:04:38 +0100214 * 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
Per Liden4323add2006-01-18 00:38:21 +0100218void tipc_ref_discard(u32 ref)
Per Lidenb97bf3f2006-01-02 19:04:38 +0100219{
220 struct reference *entry;
YOSHIFUJI Hideakic4307282007-02-09 23:25:21 +0900221 u32 index;
Per Lidenb97bf3f2006-01-02 19:04:38 +0100222 u32 index_mask;
223
Allan Stephensf1310722006-06-25 23:51:37 -0700224 if (!tipc_ref_table.entries) {
225 err("Reference table not found during discard attempt\n");
226 return;
227 }
Per Lidenb97bf3f2006-01-02 19:04:38 +0100228
Per Liden4323add2006-01-18 00:38:21 +0100229 index_mask = tipc_ref_table.index_mask;
Per Lidenb97bf3f2006-01-02 19:04:38 +0100230 index = ref & index_mask;
Per Liden4323add2006-01-18 00:38:21 +0100231 entry = &(tipc_ref_table.entries[index]);
Allan Stephensf1310722006-06-25 23:51:37 -0700232
Allan Stephens00895092008-04-16 18:21:47 -0700233 write_lock_bh(&ref_table_lock);
234
Allan Stephensf1310722006-06-25 23:51:37 -0700235 if (!entry->object) {
236 err("Attempt to discard reference to non-existent object\n");
237 goto exit;
238 }
Allan Stephensbcff1222008-04-16 18:22:20 -0700239 if (entry->ref != ref) {
Allan Stephensf1310722006-06-25 23:51:37 -0700240 err("Attempt to discard non-existent reference\n");
241 goto exit;
242 }
Per Lidenb97bf3f2006-01-02 19:04:38 +0100243
Allan Stephens00895092008-04-16 18:21:47 -0700244 /*
Allan Stephensbcff1222008-04-16 18:22:20 -0700245 * mark entry as unused; increment instance part of entry's reference
Allan Stephens00895092008-04-16 18:21:47 -0700246 * to invalidate any subsequent references
247 */
248
Sam Ravnborg1fc54d82006-03-20 22:36:47 -0800249 entry->object = NULL;
Allan Stephensbcff1222008-04-16 18:22:20 -0700250 entry->ref = (ref & ~index_mask) + (index_mask + 1);
Allan Stephens00895092008-04-16 18:21:47 -0700251
252 /* append entry to free entry list */
253
Per Liden4323add2006-01-18 00:38:21 +0100254 if (tipc_ref_table.first_free == 0)
255 tipc_ref_table.first_free = index;
Per Lidenb97bf3f2006-01-02 19:04:38 +0100256 else
Allan Stephensbcff1222008-04-16 18:22:20 -0700257 tipc_ref_table.entries[tipc_ref_table.last_free].ref |= index;
Per Liden4323add2006-01-18 00:38:21 +0100258 tipc_ref_table.last_free = index;
Per Lidenb97bf3f2006-01-02 19:04:38 +0100259
Allan Stephensf1310722006-06-25 23:51:37 -0700260exit:
Per Liden4323add2006-01-18 00:38:21 +0100261 write_unlock_bh(&ref_table_lock);
Per Lidenb97bf3f2006-01-02 19:04:38 +0100262}
263
Allan Stephens4784b7c2008-04-16 18:21:16 -0700264/**
265 * tipc_ref_lock - lock referenced object and return pointer to it
266 */
267
268void *tipc_ref_lock(u32 ref)
269{
270 if (likely(tipc_ref_table.entries)) {
Allan Stephensbcff1222008-04-16 18:22:20 -0700271 struct reference *entry;
Allan Stephens4784b7c2008-04-16 18:21:16 -0700272
Allan Stephensbcff1222008-04-16 18:22:20 -0700273 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);
Allan Stephens00895092008-04-16 18:21:47 -0700280 }
Allan Stephens4784b7c2008-04-16 18:21:16 -0700281 }
282 return NULL;
283}
284
285/**
286 * tipc_ref_unlock - unlock referenced object
287 */
288
289void tipc_ref_unlock(u32 ref)
290{
291 if (likely(tipc_ref_table.entries)) {
Allan Stephensbcff1222008-04-16 18:22:20 -0700292 struct reference *entry;
Allan Stephens4784b7c2008-04-16 18:21:16 -0700293
Allan Stephensbcff1222008-04-16 18:22:20 -0700294 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);
Allan Stephens4784b7c2008-04-16 18:21:16 -0700298 else
Allan Stephensbcff1222008-04-16 18:22:20 -0700299 err("Attempt to unlock non-existent reference\n");
Allan Stephens4784b7c2008-04-16 18:21:16 -0700300 }
301}
302
303/**
304 * tipc_ref_deref - return pointer referenced object (without locking it)
305 */
306
307void *tipc_ref_deref(u32 ref)
308{
309 if (likely(tipc_ref_table.entries)) {
Allan Stephensbcff1222008-04-16 18:22:20 -0700310 struct reference *entry;
Allan Stephens4784b7c2008-04-16 18:21:16 -0700311
Allan Stephensbcff1222008-04-16 18:22:20 -0700312 entry = &tipc_ref_table.entries[ref &
313 tipc_ref_table.index_mask];
314 if (likely(entry->ref == ref))
315 return entry->object;
Allan Stephens4784b7c2008-04-16 18:21:16 -0700316 }
317 return NULL;
318}
319