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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
Jon Paul Maloy978813e2014-03-12 11:31:07 -040092static DEFINE_SPINLOCK(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 vfree(tipc_ref_table.entries);
Sam Ravnborg1fc54d82006-03-20 22:36:47 -0800130 tipc_ref_table.entries = NULL;
Per Lidenb97bf3f2006-01-02 19:04:38 +0100131}
132
133/**
Per Liden4323add2006-01-18 00:38:21 +0100134 * tipc_ref_acquire - create reference to an object
YOSHIFUJI Hideakic4307282007-02-09 23:25:21 +0900135 *
Allan Stephens7ef43eb2008-05-12 15:42:28 -0700136 * Register an object pointer in reference table and lock the object.
137 * Returns a unique reference value that is used from then on to retrieve the
138 * object pointer, or to determine that the object has been deregistered.
139 *
140 * Note: The object is returned in the locked state so that the caller can
141 * register a partially initialized object, without running the risk that
142 * the object will be accessed before initialization is complete.
Per Lidenb97bf3f2006-01-02 19:04:38 +0100143 */
Per Liden4323add2006-01-18 00:38:21 +0100144u32 tipc_ref_acquire(void *object, spinlock_t **lock)
Per Lidenb97bf3f2006-01-02 19:04:38 +0100145{
Per Lidenb97bf3f2006-01-02 19:04:38 +0100146 u32 index;
147 u32 index_mask;
148 u32 next_plus_upper;
Allan Stephensbcff1222008-04-16 18:22:20 -0700149 u32 ref;
Neil Hormana2f46ee2010-03-16 08:14:33 +0000150 struct reference *entry = NULL;
Per Lidenb97bf3f2006-01-02 19:04:38 +0100151
Allan Stephensf1310722006-06-25 23:51:37 -0700152 if (!object) {
Erik Hugne2cf8aa12012-06-29 00:16:37 -0400153 pr_err("Attempt to acquire ref. to non-existent obj\n");
Allan Stephensf1310722006-06-25 23:51:37 -0700154 return 0;
155 }
156 if (!tipc_ref_table.entries) {
Erik Hugne2cf8aa12012-06-29 00:16:37 -0400157 pr_err("Ref. table not found in acquisition attempt\n");
Allan Stephensf1310722006-06-25 23:51:37 -0700158 return 0;
159 }
Per Lidenb97bf3f2006-01-02 19:04:38 +0100160
Allan Stephens00895092008-04-16 18:21:47 -0700161 /* take a free entry, if available; otherwise initialize a new entry */
Jon Paul Maloy978813e2014-03-12 11:31:07 -0400162 spin_lock_bh(&ref_table_lock);
Per Liden4323add2006-01-18 00:38:21 +0100163 if (tipc_ref_table.first_free) {
164 index = tipc_ref_table.first_free;
165 entry = &(tipc_ref_table.entries[index]);
166 index_mask = tipc_ref_table.index_mask;
Allan Stephensbcff1222008-04-16 18:22:20 -0700167 next_plus_upper = entry->ref;
Per Liden4323add2006-01-18 00:38:21 +0100168 tipc_ref_table.first_free = next_plus_upper & index_mask;
Allan Stephensbcff1222008-04-16 18:22:20 -0700169 ref = (next_plus_upper & ~index_mask) + index;
Allan Stephens0e659672010-12-31 18:59:32 +0000170 } else if (tipc_ref_table.init_point < tipc_ref_table.capacity) {
Allan Stephens00895092008-04-16 18:21:47 -0700171 index = tipc_ref_table.init_point++;
172 entry = &(tipc_ref_table.entries[index]);
173 spin_lock_init(&entry->lock);
Allan Stephensbcff1222008-04-16 18:22:20 -0700174 ref = tipc_ref_table.start_mask + index;
Allan Stephens0e659672010-12-31 18:59:32 +0000175 } else {
Allan Stephensbcff1222008-04-16 18:22:20 -0700176 ref = 0;
Per Lidenb97bf3f2006-01-02 19:04:38 +0100177 }
Jon Paul Maloy978813e2014-03-12 11:31:07 -0400178 spin_unlock_bh(&ref_table_lock);
Allan Stephens00895092008-04-16 18:21:47 -0700179
Neil Hormana2f46ee2010-03-16 08:14:33 +0000180 /*
181 * Grab the lock so no one else can modify this entry
182 * While we assign its ref value & object pointer
183 */
184 if (entry) {
185 spin_lock_bh(&entry->lock);
186 entry->ref = ref;
187 entry->object = object;
188 *lock = &entry->lock;
189 /*
190 * keep it locked, the caller is responsible
191 * for unlocking this when they're done with it
192 */
193 }
194
Allan Stephensbcff1222008-04-16 18:22:20 -0700195 return ref;
Per Lidenb97bf3f2006-01-02 19:04:38 +0100196}
197
198/**
Per Liden4323add2006-01-18 00:38:21 +0100199 * tipc_ref_discard - invalidate references to an object
YOSHIFUJI Hideakic4307282007-02-09 23:25:21 +0900200 *
Per Lidenb97bf3f2006-01-02 19:04:38 +0100201 * Disallow future references to an object and free up the entry for re-use.
202 * Note: The entry's spin_lock may still be busy after discard
203 */
Per Liden4323add2006-01-18 00:38:21 +0100204void tipc_ref_discard(u32 ref)
Per Lidenb97bf3f2006-01-02 19:04:38 +0100205{
206 struct reference *entry;
YOSHIFUJI Hideakic4307282007-02-09 23:25:21 +0900207 u32 index;
Per Lidenb97bf3f2006-01-02 19:04:38 +0100208 u32 index_mask;
209
Allan Stephensf1310722006-06-25 23:51:37 -0700210 if (!tipc_ref_table.entries) {
Erik Hugne2cf8aa12012-06-29 00:16:37 -0400211 pr_err("Ref. table not found during discard attempt\n");
Allan Stephensf1310722006-06-25 23:51:37 -0700212 return;
213 }
Per Lidenb97bf3f2006-01-02 19:04:38 +0100214
Per Liden4323add2006-01-18 00:38:21 +0100215 index_mask = tipc_ref_table.index_mask;
Per Lidenb97bf3f2006-01-02 19:04:38 +0100216 index = ref & index_mask;
Per Liden4323add2006-01-18 00:38:21 +0100217 entry = &(tipc_ref_table.entries[index]);
Allan Stephensf1310722006-06-25 23:51:37 -0700218
Jon Paul Maloy978813e2014-03-12 11:31:07 -0400219 spin_lock_bh(&ref_table_lock);
Allan Stephens00895092008-04-16 18:21:47 -0700220
Allan Stephensf1310722006-06-25 23:51:37 -0700221 if (!entry->object) {
Erik Hugne2cf8aa12012-06-29 00:16:37 -0400222 pr_err("Attempt to discard ref. to non-existent obj\n");
Allan Stephensf1310722006-06-25 23:51:37 -0700223 goto exit;
224 }
Allan Stephensbcff1222008-04-16 18:22:20 -0700225 if (entry->ref != ref) {
Erik Hugne2cf8aa12012-06-29 00:16:37 -0400226 pr_err("Attempt to discard non-existent reference\n");
Allan Stephensf1310722006-06-25 23:51:37 -0700227 goto exit;
228 }
Per Lidenb97bf3f2006-01-02 19:04:38 +0100229
Allan Stephens00895092008-04-16 18:21:47 -0700230 /*
Allan Stephensbcff1222008-04-16 18:22:20 -0700231 * mark entry as unused; increment instance part of entry's reference
Allan Stephens00895092008-04-16 18:21:47 -0700232 * to invalidate any subsequent references
233 */
Sam Ravnborg1fc54d82006-03-20 22:36:47 -0800234 entry->object = NULL;
Allan Stephensbcff1222008-04-16 18:22:20 -0700235 entry->ref = (ref & ~index_mask) + (index_mask + 1);
Allan Stephens00895092008-04-16 18:21:47 -0700236
237 /* append entry to free entry list */
Per Liden4323add2006-01-18 00:38:21 +0100238 if (tipc_ref_table.first_free == 0)
239 tipc_ref_table.first_free = index;
Per Lidenb97bf3f2006-01-02 19:04:38 +0100240 else
Allan Stephensbcff1222008-04-16 18:22:20 -0700241 tipc_ref_table.entries[tipc_ref_table.last_free].ref |= index;
Per Liden4323add2006-01-18 00:38:21 +0100242 tipc_ref_table.last_free = index;
Per Lidenb97bf3f2006-01-02 19:04:38 +0100243
Allan Stephensf1310722006-06-25 23:51:37 -0700244exit:
Jon Paul Maloy978813e2014-03-12 11:31:07 -0400245 spin_unlock_bh(&ref_table_lock);
Per Lidenb97bf3f2006-01-02 19:04:38 +0100246}
247
Allan Stephens4784b7c2008-04-16 18:21:16 -0700248/**
249 * tipc_ref_lock - lock referenced object and return pointer to it
250 */
Allan Stephens4784b7c2008-04-16 18:21:16 -0700251void *tipc_ref_lock(u32 ref)
252{
253 if (likely(tipc_ref_table.entries)) {
Allan Stephensbcff1222008-04-16 18:22:20 -0700254 struct reference *entry;
Allan Stephens4784b7c2008-04-16 18:21:16 -0700255
Allan Stephensbcff1222008-04-16 18:22:20 -0700256 entry = &tipc_ref_table.entries[ref &
257 tipc_ref_table.index_mask];
258 if (likely(entry->ref != 0)) {
259 spin_lock_bh(&entry->lock);
260 if (likely((entry->ref == ref) && (entry->object)))
261 return entry->object;
262 spin_unlock_bh(&entry->lock);
Allan Stephens00895092008-04-16 18:21:47 -0700263 }
Allan Stephens4784b7c2008-04-16 18:21:16 -0700264 }
265 return NULL;
266}