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
7 * Copyright 2005 (C) Jes Sorensen <jes@trained-monkey.org>
9 * This source code is licensed under the GNU General Public License,
10 * Version 2. See the file COPYING for more details.
13 #include <linux/module.h>
14 #include <linux/genalloc.h>
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
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.
25 struct gen_pool
*gen_pool_create(int min_alloc_order
, int nid
)
27 struct gen_pool
*pool
;
29 pool
= kmalloc_node(sizeof(struct gen_pool
), GFP_KERNEL
, nid
);
31 rwlock_init(&pool
->lock
);
32 INIT_LIST_HEAD(&pool
->chunks
);
33 pool
->min_alloc_order
= min_alloc_order
;
37 EXPORT_SYMBOL(gen_pool_create
);
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
47 * Add a new chunk of special memory to the specified pool.
49 int gen_pool_add(struct gen_pool
*pool
, unsigned long addr
, size_t size
,
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
;
57 chunk
= kmalloc_node(nbytes
, GFP_KERNEL
| __GFP_ZERO
, nid
);
58 if (unlikely(chunk
== NULL
))
61 spin_lock_init(&chunk
->lock
);
62 chunk
->start_addr
= addr
;
63 chunk
->end_addr
= addr
+ size
;
65 write_lock(&pool
->lock
);
66 list_add(&chunk
->next_chunk
, &pool
->chunks
);
67 write_unlock(&pool
->lock
);
71 EXPORT_SYMBOL(gen_pool_add
);
74 * gen_pool_destroy - destroy a special memory pool
75 * @pool: pool to destroy
77 * Destroy the specified special memory pool. Verifies that there are no
78 * outstanding allocations.
80 void gen_pool_destroy(struct gen_pool
*pool
)
82 struct list_head
*_chunk
, *_next_chunk
;
83 struct gen_pool_chunk
*chunk
;
84 int order
= pool
->min_alloc_order
;
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
);
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
);
101 EXPORT_SYMBOL(gen_pool_destroy
);
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
108 * Allocate the requested number of bytes from the specified pool.
109 * Uses a first-fit algorithm.
111 unsigned long gen_pool_alloc(struct gen_pool
*pool
, size_t size
)
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
;
122 nbits
= (size
+ (1UL << order
) - 1) >> order
;
124 read_lock(&pool
->lock
);
125 list_for_each(_chunk
, &pool
->chunks
) {
126 chunk
= list_entry(_chunk
, struct gen_pool_chunk
, next_chunk
);
128 end_bit
= (chunk
->end_addr
- chunk
->start_addr
) >> order
;
129 end_bit
-= nbits
+ 1;
131 spin_lock_irqsave(&chunk
->lock
, flags
);
133 while (bit
+ 1 < end_bit
) {
134 bit
= find_next_zero_bit(chunk
->bits
, end_bit
, bit
+ 1);
140 bit
= find_next_bit(chunk
->bits
, bit
+ nbits
,
142 if (bit
- start_bit
< nbits
)
146 addr
= chunk
->start_addr
+
147 ((unsigned long)start_bit
<< order
);
149 __set_bit(start_bit
++, chunk
->bits
);
150 spin_unlock_irqrestore(&chunk
->lock
, flags
);
151 read_unlock(&pool
->lock
);
154 spin_unlock_irqrestore(&chunk
->lock
, flags
);
156 read_unlock(&pool
->lock
);
159 EXPORT_SYMBOL(gen_pool_alloc
);
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
167 * Free previously allocated special memory back to the specified pool.
169 void gen_pool_free(struct gen_pool
*pool
, unsigned long addr
, size_t size
)
171 struct list_head
*_chunk
;
172 struct gen_pool_chunk
*chunk
;
174 int order
= pool
->min_alloc_order
;
177 nbits
= (size
+ (1UL << order
) - 1) >> order
;
179 read_lock(&pool
->lock
);
180 list_for_each(_chunk
, &pool
->chunks
) {
181 chunk
= list_entry(_chunk
, struct gen_pool_chunk
, next_chunk
);
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
;
188 __clear_bit(bit
++, chunk
->bits
);
189 spin_unlock_irqrestore(&chunk
->lock
, flags
);
194 read_unlock(&pool
->lock
);
196 EXPORT_SYMBOL(gen_pool_free
);
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