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1 | /* |
2 | * net/tipc/ref.c: TIPC object registry code | |
3 | * | |
4 | * Copyright (c) 2003-2005, Ericsson Research Canada | |
5 | * Copyright (c) 2004-2005, Wind River Systems | |
6 | * Copyright (c) 2005-2006, Ericsson AB | |
7 | * All rights reserved. | |
8 | * | |
9 | * Redistribution and use in source and binary forms, with or without | |
10 | * modification, are permitted provided that the following conditions are met: | |
11 | * | |
12 | * Redistributions of source code must retain the above copyright notice, this | |
13 | * list of conditions and the following disclaimer. | |
14 | * Redistributions in binary form must reproduce the above copyright notice, | |
15 | * this list of conditions and the following disclaimer in the documentation | |
16 | * and/or other materials provided with the distribution. | |
17 | * Neither the names of the copyright holders nor the names of its | |
18 | * contributors may be used to endorse or promote products derived from this | |
19 | * software without specific prior written permission. | |
20 | * | |
21 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" | |
22 | * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
23 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
24 | * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE | |
25 | * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR | |
26 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF | |
27 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS | |
28 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN | |
29 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | |
30 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE | |
31 | * POSSIBILITY OF SUCH DAMAGE. | |
32 | */ | |
33 | ||
34 | #include "core.h" | |
35 | #include "ref.h" | |
36 | #include "port.h" | |
37 | #include "subscr.h" | |
38 | #include "name_distr.h" | |
39 | #include "name_table.h" | |
40 | #include "config.h" | |
41 | #include "discover.h" | |
42 | #include "bearer.h" | |
43 | #include "node.h" | |
44 | #include "bcast.h" | |
45 | ||
46 | /* | |
47 | * Object reference table consists of 2**N entries. | |
48 | * | |
49 | * A used entry has object ptr != 0, reference == XXXX|own index | |
50 | * (XXXX changes each time entry is acquired) | |
51 | * A free entry has object ptr == 0, reference == YYYY|next free index | |
52 | * (YYYY is one more than last used XXXX) | |
53 | * | |
54 | * Free list is initially chained from entry (2**N)-1 to entry 1. | |
55 | * Entry 0 is not used to allow index 0 to indicate the end of the free list. | |
56 | * | |
57 | * Note: Any accidental reference of the form XXXX|0--0 won't match entry 0 | |
58 | * because entry 0's reference field has the form XXXX|1--1. | |
59 | */ | |
60 | ||
61 | struct ref_table ref_table = { 0 }; | |
62 | ||
63 | rwlock_t reftbl_lock = RW_LOCK_UNLOCKED; | |
64 | ||
65 | /** | |
66 | * ref_table_init - create reference table for objects | |
67 | */ | |
68 | ||
69 | int ref_table_init(u32 requested_size, u32 start) | |
70 | { | |
71 | struct reference *table; | |
72 | u32 sz = 1 << 4; | |
73 | u32 index_mask; | |
74 | int i; | |
75 | ||
76 | while (sz < requested_size) { | |
77 | sz <<= 1; | |
78 | } | |
79 | table = (struct reference *)vmalloc(sz * sizeof(struct reference)); | |
80 | if (table == NULL) | |
81 | return -ENOMEM; | |
82 | ||
83 | write_lock_bh(&reftbl_lock); | |
84 | index_mask = sz - 1; | |
85 | for (i = sz - 1; i >= 0; i--) { | |
86 | table[i].object = 0; | |
87 | table[i].lock = SPIN_LOCK_UNLOCKED; | |
88 | table[i].data.next_plus_upper = (start & ~index_mask) + i - 1; | |
89 | } | |
90 | ref_table.entries = table; | |
91 | ref_table.index_mask = index_mask; | |
92 | ref_table.first_free = sz - 1; | |
93 | ref_table.last_free = 1; | |
94 | write_unlock_bh(&reftbl_lock); | |
95 | return TIPC_OK; | |
96 | } | |
97 | ||
98 | /** | |
99 | * ref_table_stop - destroy reference table for objects | |
100 | */ | |
101 | ||
102 | void ref_table_stop(void) | |
103 | { | |
104 | if (!ref_table.entries) | |
105 | return; | |
106 | ||
107 | vfree(ref_table.entries); | |
108 | ref_table.entries = 0; | |
109 | } | |
110 | ||
111 | /** | |
112 | * ref_acquire - create reference to an object | |
113 | * | |
114 | * Return a unique reference value which can be translated back to the pointer | |
115 | * 'object' at a later time. Also, pass back a pointer to the lock protecting | |
116 | * the object, but without locking it. | |
117 | */ | |
118 | ||
119 | u32 ref_acquire(void *object, spinlock_t **lock) | |
120 | { | |
121 | struct reference *entry; | |
122 | u32 index; | |
123 | u32 index_mask; | |
124 | u32 next_plus_upper; | |
125 | u32 reference = 0; | |
126 | ||
127 | assert(ref_table.entries && object); | |
128 | ||
129 | write_lock_bh(&reftbl_lock); | |
130 | if (ref_table.first_free) { | |
131 | index = ref_table.first_free; | |
132 | entry = &(ref_table.entries[index]); | |
133 | index_mask = ref_table.index_mask; | |
134 | /* take lock in case a previous user of entry still holds it */ | |
135 | spin_lock_bh(&entry->lock); | |
136 | next_plus_upper = entry->data.next_plus_upper; | |
137 | ref_table.first_free = next_plus_upper & index_mask; | |
138 | reference = (next_plus_upper & ~index_mask) + index; | |
139 | entry->data.reference = reference; | |
140 | entry->object = object; | |
141 | if (lock != 0) | |
142 | *lock = &entry->lock; | |
143 | spin_unlock_bh(&entry->lock); | |
144 | } | |
145 | write_unlock_bh(&reftbl_lock); | |
146 | return reference; | |
147 | } | |
148 | ||
149 | /** | |
150 | * ref_discard - invalidate references to an object | |
151 | * | |
152 | * Disallow future references to an object and free up the entry for re-use. | |
153 | * Note: The entry's spin_lock may still be busy after discard | |
154 | */ | |
155 | ||
156 | void ref_discard(u32 ref) | |
157 | { | |
158 | struct reference *entry; | |
159 | u32 index; | |
160 | u32 index_mask; | |
161 | ||
162 | assert(ref_table.entries); | |
163 | assert(ref != 0); | |
164 | ||
165 | write_lock_bh(&reftbl_lock); | |
166 | index_mask = ref_table.index_mask; | |
167 | index = ref & index_mask; | |
168 | entry = &(ref_table.entries[index]); | |
169 | assert(entry->object != 0); | |
170 | assert(entry->data.reference == ref); | |
171 | ||
172 | /* mark entry as unused */ | |
173 | entry->object = 0; | |
174 | if (ref_table.first_free == 0) | |
175 | ref_table.first_free = index; | |
176 | else | |
177 | /* next_plus_upper is always XXXX|0--0 for last free entry */ | |
178 | ref_table.entries[ref_table.last_free].data.next_plus_upper | |
179 | |= index; | |
180 | ref_table.last_free = index; | |
181 | ||
182 | /* increment upper bits of entry to invalidate subsequent references */ | |
183 | entry->data.next_plus_upper = (ref & ~index_mask) + (index_mask + 1); | |
184 | write_unlock_bh(&reftbl_lock); | |
185 | } | |
186 |