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929f97276b
Modify the gen_pool allocator (lib/genalloc.c) to utilize a bitmap scheme instead of the buddy scheme. The purpose of this change is to eliminate the touching of the actual memory being allocated. Since the change modifies the interface, a change to the uncached allocator (arch/ia64/kernel/uncached.c) is also required. Both Andrey Volkov and Jes Sorenson have expressed a desire that the gen_pool allocator not write to the memory being managed. See the following: http://marc.theaimsgroup.com/?l=linux-kernel&m=113518602713125&w=2 http://marc.theaimsgroup.com/?l=linux-kernel&m=113533568827916&w=2 Signed-off-by: Dean Nelson <dcn@sgi.com> Cc: Andrey Volkov <avolkov@varma-el.com> Acked-by: Jes Sorensen <jes@trained-monkey.org> Cc: "Luck, Tony" <tony.luck@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
166 lines
4.2 KiB
C
166 lines
4.2 KiB
C
/*
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* Basic general purpose allocator for managing special purpose memory
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* not managed by the regular kmalloc/kfree interface.
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* Uses for this includes on-device special memory, uncached memory
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* etc.
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*
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* Copyright 2005 (C) Jes Sorensen <jes@trained-monkey.org>
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*
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* This source code is licensed under the GNU General Public License,
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* Version 2. See the file COPYING for more details.
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*/
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#include <linux/module.h>
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#include <linux/genalloc.h>
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/*
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* Create a new special memory pool.
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*
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* @min_alloc_order: log base 2 of number of bytes each bitmap bit represents
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* @nid: node id of the node the pool structure should be allocated on, or -1
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*/
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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);
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if (pool != NULL) {
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rwlock_init(&pool->lock);
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INIT_LIST_HEAD(&pool->chunks);
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pool->min_alloc_order = min_alloc_order;
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}
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return pool;
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}
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EXPORT_SYMBOL(gen_pool_create);
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/*
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* Add a new chunk of memory to the specified pool.
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*
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* @pool: pool to add new memory chunk to
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* @addr: starting address of memory chunk to add to pool
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* @size: size in bytes of the memory chunk to add to pool
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* @nid: node id of the node the chunk structure and bitmap should be
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* 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,
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int nid)
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{
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struct gen_pool_chunk *chunk;
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int nbits = size >> pool->min_alloc_order;
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int nbytes = sizeof(struct gen_pool_chunk) +
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(nbits + BITS_PER_BYTE - 1) / BITS_PER_BYTE;
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chunk = kmalloc_node(nbytes, GFP_KERNEL, nid);
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if (unlikely(chunk == NULL))
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return -1;
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memset(chunk, 0, nbytes);
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spin_lock_init(&chunk->lock);
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chunk->start_addr = addr;
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chunk->end_addr = addr + size;
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write_lock(&pool->lock);
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list_add(&chunk->next_chunk, &pool->chunks);
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write_unlock(&pool->lock);
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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.
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* Uses a first-fit algorithm.
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*
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* @pool: pool to allocate from
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* @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;
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struct gen_pool_chunk *chunk;
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unsigned long addr, flags;
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int order = pool->min_alloc_order;
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int nbits, bit, start_bit, end_bit;
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if (size == 0)
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return 0;
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nbits = (size + (1UL << order) - 1) >> order;
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read_lock(&pool->lock);
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list_for_each(_chunk, &pool->chunks) {
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chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
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end_bit = (chunk->end_addr - chunk->start_addr) >> order;
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end_bit -= nbits + 1;
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spin_lock_irqsave(&chunk->lock, flags);
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bit = -1;
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while (bit + 1 < end_bit) {
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bit = find_next_zero_bit(chunk->bits, end_bit, bit + 1);
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if (bit >= end_bit)
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break;
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start_bit = bit;
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if (nbits > 1) {
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bit = find_next_bit(chunk->bits, bit + nbits,
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bit + 1);
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if (bit - start_bit < nbits)
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continue;
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}
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addr = chunk->start_addr +
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((unsigned long)start_bit << order);
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while (nbits--)
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__set_bit(start_bit++, &chunk->bits);
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spin_unlock_irqrestore(&chunk->lock, flags);
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read_unlock(&pool->lock);
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return addr;
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}
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spin_unlock_irqrestore(&chunk->lock, flags);
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}
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read_unlock(&pool->lock);
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return 0;
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}
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EXPORT_SYMBOL(gen_pool_alloc);
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/*
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* Free the specified memory back to the specified pool.
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*
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* @pool: pool to free to
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* @addr: starting address of memory to free back to pool
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* @size: size in bytes of memory to free
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*/
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void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size)
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{
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struct list_head *_chunk;
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struct gen_pool_chunk *chunk;
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unsigned long flags;
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int order = pool->min_alloc_order;
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int bit, nbits;
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nbits = (size + (1UL << order) - 1) >> order;
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read_lock(&pool->lock);
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list_for_each(_chunk, &pool->chunks) {
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chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
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if (addr >= chunk->start_addr && addr < chunk->end_addr) {
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BUG_ON(addr + size > chunk->end_addr);
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spin_lock_irqsave(&chunk->lock, flags);
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bit = (addr - chunk->start_addr) >> order;
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while (nbits--)
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__clear_bit(bit++, &chunk->bits);
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spin_unlock_irqrestore(&chunk->lock, flags);
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break;
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}
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}
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BUG_ON(nbits > 0);
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read_unlock(&pool->lock);
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}
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EXPORT_SYMBOL(gen_pool_free);
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