/* * Basic general purpose allocator for managing special purpose memory * not managed by the regular kmalloc/kfree interface. * Uses for this includes on-device special memory, uncached memory * etc. * * Copyright 2005 (C) Jes Sorensen <jes@trained-monkey.org> * * This source code is licensed under the GNU General Public License, * Version 2. See the file COPYING for more details. */ #include <linux/slab.h> #include <linux/module.h> #include <linux/bitmap.h> #include <linux/genalloc.h> /** * gen_pool_create - create a new special memory pool * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents * @nid: node id of the node the pool structure should be allocated on, or -1 * * Create a new special memory pool that can be used to manage special purpose * memory not managed by the regular kmalloc/kfree interface. */ struct gen_pool *gen_pool_create(int min_alloc_order, int nid) { struct gen_pool *pool; pool = kmalloc_node(sizeof(struct gen_pool), GFP_KERNEL, nid); if (pool != NULL) { rwlock_init(&pool->lock); INIT_LIST_HEAD(&pool->chunks); pool->min_alloc_order = min_alloc_order; } return pool; } EXPORT_SYMBOL(gen_pool_create); /** * gen_pool_add - add a new chunk of special memory to the pool * @pool: pool to add new memory chunk to * @addr: starting address of memory chunk to add to pool * @size: size in bytes of the memory chunk to add to pool * @nid: node id of the node the chunk structure and bitmap should be * allocated on, or -1 * * Add a new chunk of special memory to the specified pool. */ int gen_pool_add(struct gen_pool *pool, unsigned long addr, size_t size, int nid) { struct gen_pool_chunk *chunk; int nbits = size >> pool->min_alloc_order; int nbytes = sizeof(struct gen_pool_chunk) + (nbits + BITS_PER_BYTE - 1) / BITS_PER_BYTE; chunk = kmalloc_node(nbytes, GFP_KERNEL | __GFP_ZERO, nid); if (unlikely(chunk == NULL)) return -1; spin_lock_init(&chunk->lock); chunk->start_addr = addr; chunk->end_addr = addr + size; write_lock(&pool->lock); list_add(&chunk->next_chunk, &pool->chunks); write_unlock(&pool->lock); return 0; } EXPORT_SYMBOL(gen_pool_add); /** * gen_pool_destroy - destroy a special memory pool * @pool: pool to destroy * * Destroy the specified special memory pool. Verifies that there are no * outstanding allocations. */ void gen_pool_destroy(struct gen_pool *pool) { struct list_head *_chunk, *_next_chunk; struct gen_pool_chunk *chunk; int order = pool->min_alloc_order; int bit, end_bit; list_for_each_safe(_chunk, _next_chunk, &pool->chunks) { chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk); list_del(&chunk->next_chunk); end_bit = (chunk->end_addr - chunk->start_addr) >> order; bit = find_next_bit(chunk->bits, end_bit, 0); BUG_ON(bit < end_bit); kfree(chunk); } kfree(pool); return; } EXPORT_SYMBOL(gen_pool_destroy); /** * gen_pool_alloc - allocate special memory from the pool * @pool: pool to allocate from * @size: number of bytes to allocate from the pool * * Allocate the requested number of bytes from the specified pool. * Uses a first-fit algorithm. */ unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size) { struct list_head *_chunk; struct gen_pool_chunk *chunk; unsigned long addr, flags; int order = pool->min_alloc_order; int nbits, start_bit, end_bit; if (size == 0) return 0; nbits = (size + (1UL << order) - 1) >> order; read_lock(&pool->lock); list_for_each(_chunk, &pool->chunks) { chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk); end_bit = (chunk->end_addr - chunk->start_addr) >> order; spin_lock_irqsave(&chunk->lock, flags); start_bit = bitmap_find_next_zero_area(chunk->bits, end_bit, 0, nbits, 0); if (start_bit >= end_bit) { spin_unlock_irqrestore(&chunk->lock, flags); continue; } addr = chunk->start_addr + ((unsigned long)start_bit << order); bitmap_set(chunk->bits, start_bit, nbits); spin_unlock_irqrestore(&chunk->lock, flags); read_unlock(&pool->lock); return addr; } read_unlock(&pool->lock); return 0; } EXPORT_SYMBOL(gen_pool_alloc); /** * gen_pool_free - free allocated special memory back to the pool * @pool: pool to free to * @addr: starting address of memory to free back to pool * @size: size in bytes of memory to free * * Free previously allocated special memory back to the specified pool. */ void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size) { struct list_head *_chunk; struct gen_pool_chunk *chunk; unsigned long flags; int order = pool->min_alloc_order; int bit, nbits; nbits = (size + (1UL << order) - 1) >> order; read_lock(&pool->lock); list_for_each(_chunk, &pool->chunks) { chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk); if (addr >= chunk->start_addr && addr < chunk->end_addr) { BUG_ON(addr + size > chunk->end_addr); spin_lock_irqsave(&chunk->lock, flags); bit = (addr - chunk->start_addr) >> order; while (nbits--) __clear_bit(bit++, chunk->bits); spin_unlock_irqrestore(&chunk->lock, flags); break; } } BUG_ON(nbits > 0); read_unlock(&pool->lock); } EXPORT_SYMBOL(gen_pool_free);