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/module.h>
  14 #include <linux/bitmap.h>
  15 #include <linux/genalloc.h>
  16
  17
  18 /**
  19  * gen_pool_create - create a new special memory pool
  20  * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents
  21  * @nid: node id of the node the pool structure should be allocated on, or -1
  22  *
  23  * Create a new special memory pool that can be used to manage special purpose
  24  * memory not managed by the regular kmalloc/kfree interface.
  25  */
  26 struct gen_pool *gen_pool_create(int min_alloc_order, int nid)
  27 {
  28         struct gen_pool *pool;
  29
  30         pool = kmalloc_node(sizeof(struct gen_pool), GFP_KERNEL, nid);
  31         if (pool != NULL) {
  32                 rwlock_init(&pool->lock);
  33                 INIT_LIST_HEAD(&pool->chunks);
  34                 pool->min_alloc_order = min_alloc_order;
  35         }
  36         return pool;
  37 }
  38 EXPORT_SYMBOL(gen_pool_create);
  39
  40 /**
  41  * gen_pool_add - add a new chunk of special memory to the pool
  42  * @pool: pool to add new memory chunk to
  43  * @addr: starting address of memory chunk to add to pool
  44  * @size: size in bytes of the memory chunk to add to pool
  45  * @nid: node id of the node the chunk structure and bitmap should be
  46  *       allocated on, or -1
  47  *
  48  * Add a new chunk of special memory to the specified pool.
  49  */
  50 int gen_pool_add(struct gen_pool *pool, unsigned long addr, size_t size,
  51                  int nid)
  52 {
  53         struct gen_pool_chunk *chunk;
  54         int nbits = size >> pool->min_alloc_order;
  55         int nbytes = sizeof(struct gen_pool_chunk) +
  56                                 (nbits + BITS_PER_BYTE - 1) / BITS_PER_BYTE;
  57
  58         chunk = kmalloc_node(nbytes, GFP_KERNEL | __GFP_ZERO, nid);
  59         if (unlikely(chunk == NULL))
  60                 return -1;
  61
  62         spin_lock_init(&chunk->lock);
  63         chunk->start_addr = addr;
  64         chunk->end_addr = addr + size;
  65
  66         write_lock(&pool->lock);
  67         list_add(&chunk->next_chunk, &pool->chunks);
  68         write_unlock(&pool->lock);
  69
  70         return 0;
  71 }
  72 EXPORT_SYMBOL(gen_pool_add);
  73
  74 /**
  75  * gen_pool_destroy - destroy a special memory pool
  76  * @pool: pool to destroy
  77  *
  78  * Destroy the specified special memory pool. Verifies that there are no
  79  * outstanding allocations.
  80  */
  81 void gen_pool_destroy(struct gen_pool *pool)
  82 {
  83         struct list_head *_chunk, *_next_chunk;
  84         struct gen_pool_chunk *chunk;
  85         int order = pool->min_alloc_order;
  86         int bit, end_bit;
  87
  88
  89         list_for_each_safe(_chunk, _next_chunk, &pool->chunks) {
  90                 chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
  91                 list_del(&chunk->next_chunk);
  92
  93                 end_bit = (chunk->end_addr - chunk->start_addr) >> order;
  94                 bit = find_next_bit(chunk->bits, end_bit, 0);
  95                 BUG_ON(bit < end_bit);
  96
  97                 kfree(chunk);
  98         }
  99         kfree(pool);
 100         return;
 101 }
 102 EXPORT_SYMBOL(gen_pool_destroy);
 103
 104 /**
 105  * gen_pool_alloc - allocate special memory from the pool
 106  * @pool: pool to allocate from
 107  * @size: number of bytes to allocate from the pool
 108  *
 109  * Allocate the requested number of bytes from the specified pool.
 110  * Uses a first-fit algorithm.
 111  */
 112 unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size)
 113 {
 114         struct list_head *_chunk;
 115         struct gen_pool_chunk *chunk;
 116         unsigned long addr, flags;
 117         int order = pool->min_alloc_order;
 118         int nbits, start_bit, end_bit;
 119
 120         if (size == 0)
 121                 return 0;
 122
 123         nbits = (size + (1UL << order) - 1) >> order;
 124
 125         read_lock(&pool->lock);
 126         list_for_each(_chunk, &pool->chunks) {
 127                 chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
 128
 129                 end_bit = (chunk->end_addr - chunk->start_addr) >> order;
 130                 end_bit -= nbits + 1;
 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);