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/slab.h> 14 #include <linux/module.h> 15 #include <linux/bitmap.h> 16 #include <linux/genalloc.h> 17 18 19 /** 20 * gen_pool_create - create a new special memory pool 21 * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents 22 * @nid: node id of the node the pool structure should be allocated on, or -1 23 * 24 * Create a new special memory pool that can be used to manage special purpose 25 * memory not managed by the regular kmalloc/kfree interface. 26 */ 27 struct gen_pool *gen_pool_create(int min_alloc_order, int nid) 28 { 29 struct gen_pool *pool; 30 31 pool = kmalloc_node(sizeof(struct gen_pool), GFP_KERNEL, nid); 32 if (pool != NULL) { 33 rwlock_init(&pool->lock); 34 INIT_LIST_HEAD(&pool->chunks); 35 pool->min_alloc_order = min_alloc_order; 36 } 37 return pool; 38 } 39 EXPORT_SYMBOL(gen_pool_create); 40 41 /** 42 * gen_pool_add - add a new chunk of special memory to the pool 43 * @pool: pool to add new memory chunk to 44 * @addr: starting address of memory chunk to add to pool 45 * @size: size in bytes of the memory chunk to add to pool 46 * @nid: node id of the node the chunk structure and bitmap should be 47 * allocated on, or -1 48 * 49 * Add a new chunk of special memory to the specified pool. 50 */ 51 int gen_pool_add(struct gen_pool *pool, unsigned long addr, size_t size, 52 int nid) 53 { 54 struct gen_pool_chunk *chunk; 55 int nbits = size >> pool->min_alloc_order; 56 int nbytes = sizeof(struct gen_pool_chunk) + 57 (nbits + BITS_PER_BYTE - 1) / BITS_PER_BYTE; 58 59 chunk = kmalloc_node(nbytes, GFP_KERNEL | __GFP_ZERO, nid); 60 if (unlikely(chunk == NULL)) 61 return -1; 62 63 spin_lock_init(&chunk->lock); 64 chunk->start_addr = addr; 65 chunk->end_addr = addr + size; 66 67 write_lock(&pool->lock); 68 list_add(&chunk->next_chunk, &pool->chunks); 69 write_unlock(&pool->lock); 70 71 return 0; 72 } 73 EXPORT_SYMBOL(gen_pool_add); 74 75 /** 76 * gen_pool_destroy - destroy a special memory pool 77 * @pool: pool to destroy 78 * 79 * Destroy the specified special memory pool. Verifies that there are no 80 * outstanding allocations. 81 */ 82 void gen_pool_destroy(struct gen_pool *pool) 83 { 84 struct list_head *_chunk, *_next_chunk; 85 struct gen_pool_chunk *chunk; 86 int order = pool->min_alloc_order; 87 int bit, end_bit; 88 89 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, 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; 131 132 spin_lock_irqsave(&chunk->lock, flags); 133 start_bit = bitmap_find_next_zero_area(chunk->bits, end_bit, 0, 134 nbits, 0); 135 if (start_bit >= end_bit) { 136 spin_unlock_irqrestore(&chunk->lock, flags); 137 continue; 138 } 139 140 addr = chunk->start_addr + ((unsigned long)start_bit << order); 141 142 bitmap_set(chunk->bits, start_bit, nbits); 143 spin_unlock_irqrestore(&chunk->lock, flags); 144 read_unlock(&pool->lock); 145 return addr; 146 } 147 read_unlock(&pool->lock); 148 return 0; 149 } 150 EXPORT_SYMBOL(gen_pool_alloc); 151 152 /** 153 * gen_pool_free - free allocated special memory back to the pool 154 * @pool: pool to free to 155 * @addr: starting address of memory to free back to pool 156 * @size: size in bytes of memory to free 157 * 158 * Free previously allocated special memory back to the specified pool. 159 */ 160 void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size) 161 { 162 struct list_head *_chunk; 163 struct gen_pool_chunk *chunk; 164 unsigned long flags; 165 int order = pool->min_alloc_order; 166 int bit, nbits; 167 168 nbits = (size + (1UL << order) - 1) >> order; 169 170 read_lock(&pool->lock); 171 list_for_each(_chunk, &pool->chunks) { 172 chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk); 173 174 if (addr >= chunk->start_addr && addr < chunk->end_addr) { 175 BUG_ON(addr + size > chunk->end_addr); 176 spin_lock_irqsave(&chunk->lock, flags); 177 bit = (addr - chunk->start_addr) >> order; 178 while (nbits--) 179 __clear_bit(bit++, chunk->bits); 180 spin_unlock_irqrestore(&chunk->lock, flags); 181 break; 182 } 183 } 184 BUG_ON(nbits > 0); 185 read_unlock(&pool->lock); 186 } 187 EXPORT_SYMBOL(gen_pool_free); 188