Root/lib/genalloc.c

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 */
27struct 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}
39EXPORT_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 */
51int 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}
73EXPORT_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 */
82void 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}
103EXPORT_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 */
113unsigned 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}
150EXPORT_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 */
160void 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}
187EXPORT_SYMBOL(gen_pool_free);
188

Archive Download this file



interactive