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); 198