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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 */
Allan Stephens4784b7c2008-04-16 18:21:16 -070046struct reference {
47 void *object;
48 spinlock_t lock;
Allan Stephensbcff1222008-04-16 18:22:20 -070049 u32 ref;
Allan Stephens4784b7c2008-04-16 18:21:16 -070050};
51
52/**
53 * struct tipc_ref_table - table of TIPC object reference entries
54 * @entries: pointer to array of reference entries
Allan Stephens00895092008-04-16 18:21:47 -070055 * @capacity: array index of first unusable entry
56 * @init_point: array index of first uninitialized entry
Allan Stephens4784b7c2008-04-16 18:21:16 -070057 * @first_free: array index of first unused object reference entry
58 * @last_free: array index of last unused object reference entry
Allan Stephens00895092008-04-16 18:21:47 -070059 * @index_mask: bitmask for array index portion of reference values
60 * @start_mask: initial value for instance value portion of reference values
Allan Stephens4784b7c2008-04-16 18:21:16 -070061 */
Allan Stephens4784b7c2008-04-16 18:21:16 -070062struct ref_table {
63 struct reference *entries;
Allan Stephens00895092008-04-16 18:21:47 -070064 u32 capacity;
65 u32 init_point;
Allan Stephens4784b7c2008-04-16 18:21:16 -070066 u32 first_free;
67 u32 last_free;
Allan Stephens00895092008-04-16 18:21:47 -070068 u32 index_mask;
69 u32 start_mask;
Allan Stephens4784b7c2008-04-16 18:21:16 -070070};
71
Per Lidenb97bf3f2006-01-02 19:04:38 +010072/*
73 * Object reference table consists of 2**N entries.
74 *
Allan Stephens00895092008-04-16 18:21:47 -070075 * 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
Per Lidenb97bf3f2006-01-02 19:04:38 +010082 *
Allan Stephens00895092008-04-16 18:21:47 -070083 * Entry 0 is not used; this allows index 0 to denote the end of the free list.
Per Lidenb97bf3f2006-01-02 19:04:38 +010084 *
Allan Stephens00895092008-04-16 18:21:47 -070085 * 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).
Per Lidenb97bf3f2006-01-02 19:04:38 +010088 */
89
Allan Stephense3ec9c72010-12-31 18:59:34 +000090static struct ref_table tipc_ref_table;
Per Lidenb97bf3f2006-01-02 19:04:38 +010091
Ingo Molnar34af9462006-06-27 02:53:55 -070092static DEFINE_RWLOCK(ref_table_lock);
Per Lidenb97bf3f2006-01-02 19:04:38 +010093
94/**
Per Liden4323add2006-01-18 00:38:21 +010095 * tipc_ref_table_init - create reference table for objects
Per Lidenb97bf3f2006-01-02 19:04:38 +010096 */
Per Liden4323add2006-01-18 00:38:21 +010097int tipc_ref_table_init(u32 requested_size, u32 start)
Per Lidenb97bf3f2006-01-02 19:04:38 +010098{
99 struct reference *table;
Allan Stephens00895092008-04-16 18:21:47 -0700100 u32 actual_size;
Per Lidenb97bf3f2006-01-02 19:04:38 +0100101
Allan Stephens00895092008-04-16 18:21:47 -0700102 /* 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 */
Eric Dumazet966567b2011-12-19 16:01:38 -0500109 table = vzalloc(actual_size * sizeof(struct reference));
Per Lidenb97bf3f2006-01-02 19:04:38 +0100110 if (table == NULL)
111 return -ENOMEM;
112
Per Liden4323add2006-01-18 00:38:21 +0100113 tipc_ref_table.entries = table;
Allan Stephens00895092008-04-16 18:21:47 -0700114 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
Allan Stephens0e35fd52008-07-14 22:44:01 -0700121 return 0;
Per Lidenb97bf3f2006-01-02 19:04:38 +0100122}
123
124/**
Per Liden4323add2006-01-18 00:38:21 +0100125 * tipc_ref_table_stop - destroy reference table for objects
Per Lidenb97bf3f2006-01-02 19:04:38 +0100126 */
Per Liden4323add2006-01-18 00:38:21 +0100127void tipc_ref_table_stop(void)
Per Lidenb97bf3f2006-01-02 19:04:38 +0100128{
Per Liden4323add2006-01-18 00:38:21 +0100129 if (!tipc_ref_table.entries)
Per Lidenb97bf3f2006-01-02 19:04:38 +0100130 return;
131
Per Liden4323add2006-01-18 00:38:21 +0100132 vfree(tipc_ref_table.entries);
Sam Ravnborg1fc54d82006-03-20 22:36:47 -0800133 tipc_ref_table.entries = NULL;
Per Lidenb97bf3f2006-01-02 19:04:38 +0100134}
135
136/**
Per Liden4323add2006-01-18 00:38:21 +0100137 * tipc_ref_acquire - create reference to an object
YOSHIFUJI Hideakic4307282007-02-09 23:25:21 +0900138 *
Allan Stephens7ef43eb2008-05-12 15:42:28 -0700139 * 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.
Per Lidenb97bf3f2006-01-02 19:04:38 +0100146 */
Per Liden4323add2006-01-18 00:38:21 +0100147u32 tipc_ref_acquire(void *object, spinlock_t **lock)
Per Lidenb97bf3f2006-01-02 19:04:38 +0100148{
Per Lidenb97bf3f2006-01-02 19:04:38 +0100149 u32 index;
150 u32 index_mask;
151 u32 next_plus_upper;
Allan Stephensbcff1222008-04-16 18:22:20 -0700152 u32 ref;
Neil Hormana2f46ee2010-03-16 08:14:33 +0000153 struct reference *entry = NULL;
Per Lidenb97bf3f2006-01-02 19:04:38 +0100154
Allan Stephensf1310722006-06-25 23:51:37 -0700155 if (!object) {
156 err("Attempt to acquire reference to non-existent object\n");
157 return 0;
158 }
159 if (!tipc_ref_table.entries) {
160 err("Reference table not found during acquisition attempt\n");
161 return 0;
162 }
Per Lidenb97bf3f2006-01-02 19:04:38 +0100163
Allan Stephens00895092008-04-16 18:21:47 -0700164 /* take a free entry, if available; otherwise initialize a new entry */
Per Liden4323add2006-01-18 00:38:21 +0100165 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;
Allan Stephensbcff1222008-04-16 18:22:20 -0700170 next_plus_upper = entry->ref;
Per Liden4323add2006-01-18 00:38:21 +0100171 tipc_ref_table.first_free = next_plus_upper & index_mask;
Allan Stephensbcff1222008-04-16 18:22:20 -0700172 ref = (next_plus_upper & ~index_mask) + index;
Allan Stephens0e659672010-12-31 18:59:32 +0000173 } else if (tipc_ref_table.init_point < tipc_ref_table.capacity) {
Allan Stephens00895092008-04-16 18:21:47 -0700174 index = tipc_ref_table.init_point++;
175 entry = &(tipc_ref_table.entries[index]);
176 spin_lock_init(&entry->lock);
Allan Stephensbcff1222008-04-16 18:22:20 -0700177 ref = tipc_ref_table.start_mask + index;
Allan Stephens0e659672010-12-31 18:59:32 +0000178 } else {
Allan Stephensbcff1222008-04-16 18:22:20 -0700179 ref = 0;
Per Lidenb97bf3f2006-01-02 19:04:38 +0100180 }
Per Liden4323add2006-01-18 00:38:21 +0100181 write_unlock_bh(&ref_table_lock);
Allan Stephens00895092008-04-16 18:21:47 -0700182
Neil Hormana2f46ee2010-03-16 08:14:33 +0000183 /*
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
Allan Stephensbcff1222008-04-16 18:22:20 -0700198 return ref;
Per Lidenb97bf3f2006-01-02 19:04:38 +0100199}
200
201/**
Per Liden4323add2006-01-18 00:38:21 +0100202 * tipc_ref_discard - invalidate references to an object
YOSHIFUJI Hideakic4307282007-02-09 23:25:21 +0900203 *
Per Lidenb97bf3f2006-01-02 19:04:38 +0100204 * 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 */
Per Liden4323add2006-01-18 00:38:21 +0100207void tipc_ref_discard(u32 ref)
Per Lidenb97bf3f2006-01-02 19:04:38 +0100208{
209 struct reference *entry;
YOSHIFUJI Hideakic4307282007-02-09 23:25:21 +0900210 u32 index;
Per Lidenb97bf3f2006-01-02 19:04:38 +0100211 u32 index_mask;
212
Allan Stephensf1310722006-06-25 23:51:37 -0700213 if (!tipc_ref_table.entries) {
214 err("Reference table not found during discard attempt\n");
215 return;
216 }
Per Lidenb97bf3f2006-01-02 19:04:38 +0100217
Per Liden4323add2006-01-18 00:38:21 +0100218 index_mask = tipc_ref_table.index_mask;
Per Lidenb97bf3f2006-01-02 19:04:38 +0100219 index = ref & index_mask;
Per Liden4323add2006-01-18 00:38:21 +0100220 entry = &(tipc_ref_table.entries[index]);
Allan Stephensf1310722006-06-25 23:51:37 -0700221
Allan Stephens00895092008-04-16 18:21:47 -0700222 write_lock_bh(&ref_table_lock);
223
Allan Stephensf1310722006-06-25 23:51:37 -0700224 if (!entry->object) {
225 err("Attempt to discard reference to non-existent object\n");
226 goto exit;
227 }
Allan Stephensbcff1222008-04-16 18:22:20 -0700228 if (entry->ref != ref) {
Allan Stephensf1310722006-06-25 23:51:37 -0700229 err("Attempt to discard non-existent reference\n");
230 goto exit;
231 }
Per Lidenb97bf3f2006-01-02 19:04:38 +0100232
Allan Stephens00895092008-04-16 18:21:47 -0700233 /*
Allan Stephensbcff1222008-04-16 18:22:20 -0700234 * mark entry as unused; increment instance part of entry's reference
Allan Stephens00895092008-04-16 18:21:47 -0700235 * to invalidate any subsequent references
236 */
Sam Ravnborg1fc54d82006-03-20 22:36:47 -0800237 entry->object = NULL;
Allan Stephensbcff1222008-04-16 18:22:20 -0700238 entry->ref = (ref & ~index_mask) + (index_mask + 1);
Allan Stephens00895092008-04-16 18:21:47 -0700239
240 /* append entry to free entry list */
Per Liden4323add2006-01-18 00:38:21 +0100241 if (tipc_ref_table.first_free == 0)
242 tipc_ref_table.first_free = index;
Per Lidenb97bf3f2006-01-02 19:04:38 +0100243 else
Allan Stephensbcff1222008-04-16 18:22:20 -0700244 tipc_ref_table.entries[tipc_ref_table.last_free].ref |= index;
Per Liden4323add2006-01-18 00:38:21 +0100245 tipc_ref_table.last_free = index;
Per Lidenb97bf3f2006-01-02 19:04:38 +0100246
Allan Stephensf1310722006-06-25 23:51:37 -0700247exit:
Per Liden4323add2006-01-18 00:38:21 +0100248 write_unlock_bh(&ref_table_lock);
Per Lidenb97bf3f2006-01-02 19:04:38 +0100249}
250
Allan Stephens4784b7c2008-04-16 18:21:16 -0700251/**
252 * tipc_ref_lock - lock referenced object and return pointer to it
253 */
Allan Stephens4784b7c2008-04-16 18:21:16 -0700254void *tipc_ref_lock(u32 ref)
255{
256 if (likely(tipc_ref_table.entries)) {
Allan Stephensbcff1222008-04-16 18:22:20 -0700257 struct reference *entry;
Allan Stephens4784b7c2008-04-16 18:21:16 -0700258
Allan Stephensbcff1222008-04-16 18:22:20 -0700259 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);
Allan Stephens00895092008-04-16 18:21:47 -0700266 }
Allan Stephens4784b7c2008-04-16 18:21:16 -0700267 }
268 return NULL;
269}
270
Allan Stephens4784b7c2008-04-16 18:21:16 -0700271
272/**
273 * tipc_ref_deref - return pointer referenced object (without locking it)
274 */
Allan Stephens4784b7c2008-04-16 18:21:16 -0700275void *tipc_ref_deref(u32 ref)
276{
277 if (likely(tipc_ref_table.entries)) {
Allan Stephensbcff1222008-04-16 18:22:20 -0700278 struct reference *entry;
Allan Stephens4784b7c2008-04-16 18:21:16 -0700279
Allan Stephensbcff1222008-04-16 18:22:20 -0700280 entry = &tipc_ref_table.entries[ref &
281 tipc_ref_table.index_mask];
282 if (likely(entry->ref == ref))
283 return entry->object;
Allan Stephens4784b7c2008-04-16 18:21:16 -0700284 }
285 return NULL;
286}