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/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         write_lock(&pool->lock);
  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, bit, 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                 bit = -1;
 134                 while (bit + 1 < end_bit) {
 135                         bit = find_next_zero_bit(chunk->bits, end_bit, bit + 1);
 136                         if (bit >= end_bit)
 137                                 break;
 138
 139                         start_bit = bit;
 140                         if (nbits > 1) {
 141                                 bit = find_next_bit(chunk->bits, bit + nbits,
 142                                                         bit + 1);
 143                                 if (bit - start_bit < nbits)
 144                                         continue;
 145                         }
 146
 147                         addr = chunk->start_addr +
 148                                             ((unsigned long)start_bit << order);
 149                         while (nbits--)
 150                                 __set_bit(start_bit++, chunk->bits);
 151                         spin_unlock_irqrestore(&chunk->lock, flags);
 152                         read_unlock(&pool->lock);
 153                         return addr;
 154                 }
 155                 spin_unlock_irqrestore(&chunk->lock, flags);
 156         }
 157         read_unlock(&pool->lock);
 158         return 0;
 159 }
 160 EXPORT_SYMBOL(gen_pool_alloc);
 161
 162 /**
 163  * gen_pool_free - free allocated special memory back to the pool
 164  * @pool: pool to free to
 165  * @addr: starting address of memory to free back to pool
 166  * @size: size in bytes of memory to free
 167  *
 168  * Free previously allocated special memory back to the specified pool.
 169  */
 170 void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size)
 171 {
 172         struct list_head *_chunk;
 173         struct gen_pool_chunk *chunk;
 174         unsigned long flags;
 175         int order = pool->min_alloc_order;
 176         int bit, nbits;
 177
 178         nbits = (size + (1UL << order) - 1) >> order;
 179
 180         read_lock(&pool->lock);
 181         list_for_each(_chunk, &pool->chunks) {
 182                 chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
 183
 184                 if (addr >= chunk->start_addr && addr < chunk->end_addr) {
 185                         BUG_ON(addr + size > chunk->end_addr);
 186                         spin_lock_irqsave(&chunk->lock, flags);
 187                         bit = (addr - chunk->start_addr) >> order;
 188                         while (nbits--)
 189                                 __clear_bit(bit++, chunk->bits);
 190                         spin_unlock_irqrestore(&chunk->lock, flags);
 191                         break;
 192                 }
 193         }
 194         BUG_ON(nbits > 0);
 195         read_unlock(&pool->lock);
 196 }
 197 EXPORT_SYMBOL(gen_pool_free);