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