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, nid);
  58         if (unlikely(chunk == NULL))
  59                 return -1;
  60
  61         memset(chunk, 0, nbytes);
  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         write_lock(&pool->lock);
  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, bit, 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                 end_bit -= nbits + 1;
 132
 133                 spin_lock_irqsave(&chunk->lock, flags);
 134                 bit = -1;
 135                 while (bit + 1 < end_bit) {
 136                         bit = find_next_zero_bit(chunk->bits, end_bit, bit + 1);
 137                         if (bit >= end_bit)
 138                                 break;
 139
 140                         start_bit = bit;
 141                         if (nbits > 1) {
 142                                 bit = find_next_bit(chunk->bits, bit + nbits,
 143                                                         bit + 1);
 144                                 if (bit - start_bit < nbits)
 145                                         continue;
 146                         }
 147
 148                         addr = chunk->start_addr +
 149                                             ((unsigned long)start_bit << order);
 150                         while (nbits--)
 151                                 __set_bit(start_bit++, chunk->bits);
 152                         spin_unlock_irqrestore(&chunk->lock, flags);
 153                         read_unlock(&pool->lock);
 154                         return addr;
 155                 }
 156                 spin_unlock_irqrestore(&chunk->lock, flags);
 157         }
 158         read_unlock(&pool->lock);
 159         return 0;
 160 }
 161 EXPORT_SYMBOL(gen_pool_alloc);
 162
 163 /**
 164  * gen_pool_free - free allocated special memory back to the pool
 165  * @pool: pool to free to
 166  * @addr: starting address of memory to free back to pool
 167  * @size: size in bytes of memory to free
 168  *
 169  * Free previously allocated special memory back to the specified pool.
 170  */
 171 void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size)
 172 {
 173         struct list_head *_chunk;
 174         struct gen_pool_chunk *chunk;
 175         unsigned long flags;
 176         int order = pool->min_alloc_order;
 177         int bit, nbits;
 178
 179         nbits = (size + (1UL << order) - 1) >> order;
 180
 181         read_lock(&pool->lock);
 182         list_for_each(_chunk, &pool->chunks) {
 183                 chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
 184
 185                 if (addr >= chunk->start_addr && addr < chunk->end_addr) {
 186                         BUG_ON(addr + size > chunk->end_addr);
 187                         spin_lock_irqsave(&chunk->lock, flags);
 188                         bit = (addr - chunk->start_addr) >> order;
 189                         while (nbits--)
 190                                 __clear_bit(bit++, chunk->bits);
 191                         spin_unlock_irqrestore(&chunk->lock, flags);
 192                         break;
 193                 }
 194         }
 195         BUG_ON(nbits > 0);
 196         read_unlock(&pool->lock);
 197 }
 198 EXPORT_SYMBOL(gen_pool_free);