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); 199