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         list_for_each_safe(_chunk, _next_chunk, &pool->chunks) {
  89                 chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
  90                 list_del(&chunk->next_chunk);
  91
  92                 end_bit = (chunk->end_addr - chunk->start_addr) >> order;
  93                 bit = find_next_bit(chunk->bits, end_bit, 0);
  94                 BUG_ON(bit < end_bit);
  95
  96                 kfree(chunk);
  97         }
  98         kfree(pool);
  99         return;
 100 }
 101 EXPORT_SYMBOL(gen_pool_destroy);
 102
 103 /**
 104  * gen_pool_alloc - allocate special memory from the pool
 105  * @pool: pool to allocate from
 106  * @size: number of bytes to allocate from the pool
 107  *
 108  * Allocate the requested number of bytes from the specified pool.
 109  * Uses a first-fit algorithm.
 110  */
 111 unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size)
 112 {
 113         struct list_head *_chunk;
 114         struct gen_pool_chunk *chunk;
 115         unsigned long addr, flags;
 116         int order = pool->min_alloc_order;
 117         int nbits, bit, start_bit, end_bit;
 118
 119         if (size == 0)
 120                 return 0;
 121
 122         nbits = (size + (1UL << order) - 1) >> order;
 123
 124         read_lock(&pool->lock);
 125         list_for_each(_chunk, &pool->chunks) {
 126                 chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
 127
 128                 end_bit = (chunk->end_addr - chunk->start_addr) >> order;
 129                 end_bit -= nbits + 1;
 130
 131                 spin_lock_irqsave(&chunk->lock, flags);
 132                 bit = -1;
 133                 while (bit + 1 < end_bit) {
 134                         bit = find_next_zero_bit(chunk->bits, end_bit, bit + 1);
 135                         if (bit >= end_bit)
 136                                 break;
 137
 138                         start_bit = bit;
 139                         if (nbits > 1) {
 140                                 bit = find_next_bit(chunk->bits, bit + nbits,
 141                                                         bit + 1);
 142                                 if (bit - start_bit < nbits)
 143                                         continue;
 144                         }
 145
 146                         addr = chunk->start_addr +
 147                                             ((unsigned long)start_bit << order);
 148                         while (nbits--)
 149                                 __set_bit(start_bit++, chunk->bits);
 150                         spin_unlock_irqrestore(&chunk->lock, flags);
 151                         read_unlock(&pool->lock);
 152                         return addr;
 153                 }
 154                 spin_unlock_irqrestore(&chunk->lock, flags);
 155         }
 156         read_unlock(&pool->lock);
 157         return 0;
 158 }
 159 EXPORT_SYMBOL(gen_pool_alloc);
 160
 161 /**
 162  * gen_pool_free - free allocated special memory back to the pool
 163  * @pool: pool to free to
 164  * @addr: starting address of memory to free back to pool
 165  * @size: size in bytes of memory to free
 166  *
 167  * Free previously allocated special memory back to the specified pool.
 168  */
 169 void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size)
 170 {
 171         struct list_head *_chunk;
 172         struct gen_pool_chunk *chunk;
 173         unsigned long flags;
 174         int order = pool->min_alloc_order;
 175         int bit, nbits;
 176
 177         nbits = (size + (1UL << order) - 1) >> order;
 178
 179         read_lock(&pool->lock);
 180         list_for_each(_chunk, &pool->chunks) {
 181                 chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
 182
 183                 if (addr >= chunk->start_addr && addr < chunk->end_addr) {
 184                         BUG_ON(addr + size > chunk->end_addr);
 185                         spin_lock_irqsave(&chunk->lock, flags);
 186                         bit = (addr - chunk->start_addr) >> order;
 187                         while (nbits--)
 188                                 __clear_bit(bit++, chunk->bits);
 189                         spin_unlock_irqrestore(&chunk->lock, flags);
 190                         break;
 191                 }
 192         }
 193         BUG_ON(nbits > 0);
 194         read_unlock(&pool->lock);
 195 }
 196 EXPORT_SYMBOL(gen_pool_free);