1 /*
2 * Basic general purpose allocator for managing special purpose memory
3 * not managed by the regular kmalloc/kfree interface.
4 * Uses for this includes on-device special memory, uncached memory
5 * etc.
6 *
7 * Copyright 2005 (C) Jes Sorensen <jes@trained-monkey.org>
8 *
9 * This source code is licensed under the GNU General Public License,
10 * Version 2. See the file COPYING for more details.
11 */
12
13 #include <linux/module.h>
14 #include <linux/genalloc.h>
15
16
17 /**
18 * gen_pool_create - create a new special memory pool
19 * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents
20 * @nid: node id of the node the pool structure should be allocated on, or -1
21 *
22 * Create a new special memory pool that can be used to manage special purpose
23 * memory not managed by the regular kmalloc/kfree interface.
24 */
25 struct gen_pool *gen_pool_create(int min_alloc_order, int nid)
26 {
27 struct gen_pool *pool;
28
29 pool = kmalloc_node(sizeof(struct gen_pool), GFP_KERNEL, nid);
30 if (pool != NULL) {
31 rwlock_init(&pool->lock);
32 INIT_LIST_HEAD(&pool->chunks);
33 pool->min_alloc_order = min_alloc_order;
34 }
35 return pool;
36 }
37 EXPORT_SYMBOL(gen_pool_create);
38
39 /**
40 * gen_pool_add - add a new chunk of special memory to the pool
41 * @pool: pool to add new memory chunk to
42 * @addr: starting address of memory chunk to add to pool
43 * @size: size in bytes of the memory chunk to add to pool
44 * @nid: node id of the node the chunk structure and bitmap should be
45 * allocated on, or -1
46 *
47 * Add a new chunk of special memory to the specified pool.
48 */
49 int gen_pool_add(struct gen_pool *pool, unsigned long addr, size_t size,
50 int nid)
51 {
52 struct gen_pool_chunk *chunk;
53 int nbits = size >> pool->min_alloc_order;
54 int nbytes = sizeof(struct gen_pool_chunk) +
55 (nbits + BITS_PER_BYTE - 1) / BITS_PER_BYTE;
56
57 chunk = kmalloc_node(nbytes, GFP_KERNEL | __GFP_ZERO, nid);
58 if (unlikely(chunk == NULL))
59 return -1;
60
61 spin_lock_init(&chunk->lock);
62 chunk->start_addr = addr;
63 chunk->end_addr = addr + size;
64
65 write_lock(&pool->lock);
66 list_add(&chunk->next_chunk, &pool->chunks);
67 write_unlock(&pool->lock);
68
69 return 0;
70 }
71 EXPORT_SYMBOL(gen_pool_add);
72
73 /**
74 * gen_pool_destroy - destroy a special memory pool
75 * @pool: pool to destroy
76 *
77 * Destroy the specified special memory pool. Verifies that there are no
78 * outstanding allocations.
79 */
80 void gen_pool_destroy(struct gen_pool *pool)
81 {
82 struct list_head *_chunk, *_next_chunk;
83 struct gen_pool_chunk *chunk;
84 int order = pool->min_alloc_order;
85 int bit, end_bit;
86
87
88 list_for_each_safe(_chunk, _next_chunk, &pool->chunks) {
89 chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
90 list_del(&chunk->next_chunk);
91
92 end_bit = (chunk->end_addr - chunk->start_addr) >> order;
93 bit = find_next_bit(chunk->bits, end_bit, 0);
94 BUG_ON(bit < end_bit);
95
96 kfree(chunk);
97 }
98 kfree(pool);
99 return;
100 }
101 EXPORT_SYMBOL(gen_pool_destroy);
102
103 /**
104 * gen_pool_alloc - allocate special memory from the pool
105 * @pool: pool to allocate from
106 * @size: number of bytes to allocate from the pool
107 *
108 * Allocate the requested number of bytes from the specified pool.
109 * Uses a first-fit algorithm.
110 */
111 unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size)
112 {
113 struct list_head *_chunk;
114 struct gen_pool_chunk *chunk;
115 unsigned long addr, flags;
116 int order = pool->min_alloc_order;
117 int nbits, bit, start_bit, end_bit;
118
119 if (size == 0)
120 return 0;
121
122 nbits = (size + (1UL << order) - 1) >> order;
123
124 read_lock(&pool->lock);
125 list_for_each(_chunk, &pool->chunks) {
126 chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
127
128 end_bit = (chunk->end_addr - chunk->start_addr) >> order;
129 end_bit -= nbits + 1;
130
131 spin_lock_irqsave(&chunk->lock, flags);
132 bit = -1;
133 while (bit + 1 < end_bit) {
134 bit = find_next_zero_bit(chunk->bits, end_bit, bit + 1);
135 if (bit >= end_bit)
136 break;
137
138 start_bit = bit;
139 if (nbits > 1) {
140 bit = find_next_bit(chunk->bits, bit + nbits,
141 bit + 1);
142 if (bit - start_bit < nbits)
143 continue;
144 }
145
146 addr = chunk->start_addr +
147 ((unsigned long)start_bit << order);
148 while (nbits--)
149 __set_bit(start_bit++, chunk->bits);
150 spin_unlock_irqrestore(&chunk->lock, flags);
151 read_unlock(&pool->lock);
152 return addr;
153 }
154 spin_unlock_irqrestore(&chunk->lock, flags);
155 }
156 read_unlock(&pool->lock);
157 return 0;
158 }
159 EXPORT_SYMBOL(gen_pool_alloc);
160
161 /**
162 * gen_pool_free - free allocated special memory back to the pool
163 * @pool: pool to free to
164 * @addr: starting address of memory to free back to pool
165 * @size: size in bytes of memory to free
166 *
167 * Free previously allocated special memory back to the specified pool.
168 */
169 void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size)
170 {
171 struct list_head *_chunk;
172 struct gen_pool_chunk *chunk;
173 unsigned long flags;
174 int order = pool->min_alloc_order;
175 int bit, nbits;
176
177 nbits = (size + (1UL << order) - 1) >> order;
178
179 read_lock(&pool->lock);
180 list_for_each(_chunk, &pool->chunks) {
181 chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
182
183 if (addr >= chunk->start_addr && addr < chunk->end_addr) {
184 BUG_ON(addr + size > chunk->end_addr);
185 spin_lock_irqsave(&chunk->lock, flags);
186 bit = (addr - chunk->start_addr) >> order;
187 while (nbits--)
188 __clear_bit(bit++, chunk->bits);
189 spin_unlock_irqrestore(&chunk->lock, flags);
190 break;
191 }
192 }
193 BUG_ON(nbits > 0);
194 read_unlock(&pool->lock);
195 }
196 EXPORT_SYMBOL(gen_pool_free);
197
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