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lib/genalloc.c
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/* * 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. * |
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* 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/module.h> |
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#include <linux/genalloc.h> |
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/* * 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 */ struct gen_pool *gen_pool_create(int min_alloc_order, int nid) |
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{ |
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struct gen_pool *pool; |
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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; |
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} EXPORT_SYMBOL(gen_pool_create); /* |
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* Add a new chunk of memory to the specified 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 |
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*/ |
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int gen_pool_add(struct gen_pool *pool, unsigned long addr, size_t size, int nid) |
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{ |
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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; |
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chunk = kmalloc_node(nbytes, GFP_KERNEL, nid); if (unlikely(chunk == NULL)) return -1; |
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memset(chunk, 0, nbytes); spin_lock_init(&chunk->lock); chunk->start_addr = addr; chunk->end_addr = addr + size; |
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write_lock(&pool->lock); list_add(&chunk->next_chunk, &pool->chunks); write_unlock(&pool->lock); return 0; |
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} |
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EXPORT_SYMBOL(gen_pool_add); |
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/* |
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* Allocate the requested number of bytes from the specified pool. * Uses a first-fit algorithm. * * @pool: pool to allocate from * @size: number of bytes to allocate from the pool |
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*/ |
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unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size) |
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{ |
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struct list_head *_chunk; struct gen_pool_chunk *chunk; unsigned long addr, flags; int order = pool->min_alloc_order; int nbits, bit, start_bit, end_bit; |
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if (size == 0) return 0; |
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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; end_bit -= nbits + 1; spin_lock_irqsave(&chunk->lock, flags); bit = -1; while (bit + 1 < end_bit) { bit = find_next_zero_bit(chunk->bits, end_bit, bit + 1); if (bit >= end_bit) break; start_bit = bit; if (nbits > 1) { bit = find_next_bit(chunk->bits, bit + nbits, bit + 1); if (bit - start_bit < nbits) continue; } addr = chunk->start_addr + ((unsigned long)start_bit << order); while (nbits--) __set_bit(start_bit++, &chunk->bits); spin_unlock_irqrestore(&chunk->lock, flags); read_unlock(&pool->lock); return addr; |
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} |
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spin_unlock_irqrestore(&chunk->lock, flags); } read_unlock(&pool->lock); return 0; } EXPORT_SYMBOL(gen_pool_alloc); |
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/* * Free the specified memory back to the specified pool. * * @pool: pool to free to * @addr: starting address of memory to free back to pool * @size: size in bytes of memory to free */ 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); |
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break; } |
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} |
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BUG_ON(nbits > 0); read_unlock(&pool->lock); |
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} EXPORT_SYMBOL(gen_pool_free); |