mm/dmapool.c - third_party/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * DMA Pool allocator
  *
  * Copyright 2001 David Brownell
  * Copyright 2007 Intel Corporation
  *   Author: Matthew Wilcox <willy@linux.intel.com>
  *
  * This allocator returns small blocks of a given size which are DMA-able by
  * the given device.  It uses the dma_alloc_coherent page allocator to get
  * new pages, then splits them up into blocks of the required size.
  * Many older drivers still have their own code to do this.
  *
  * The current design of this allocator is fairly simple.  The pool is
  * represented by the 'struct dma_pool' which keeps a doubly-linked list of
  * allocated pages.  Each page in the page_list is split into blocks of at
  * least 'size' bytes.  Free blocks are tracked in an unsorted singly-linked
  * list of free blocks across all pages.  Used blocks aren't tracked, but we
  * keep a count of how many are currently allocated from each page.
  */

 #include <linux/device.h>
 #include <linux/dma-mapping.h>
 #include <linux/dmapool.h>
 #include <linux/kernel.h>
 #include <linux/list.h>
 #include <linux/export.h>
 #include <linux/mutex.h>
 #include <linux/poison.h>
 #include <linux/sched.h>
 #include <linux/sched/mm.h>
 #include <linux/slab.h>
 #include <linux/stat.h>
 #include <linux/spinlock.h>
 #include <linux/string.h>
 #include <linux/types.h>
 #include <linux/wait.h>

 #ifdef CONFIG_SLUB_DEBUG_ON
 #define DMAPOOL_DEBUG 1
 #endif

 struct dma_block {
 	struct dma_block *next_block;
 	dma_addr_t dma;
 };

 struct dma_pool {		/* the pool */
 	struct list_head page_list;
 	spinlock_t lock;
 	struct dma_block *next_block;
 	size_t nr_blocks;
 	size_t nr_active;
 	size_t nr_pages;
 	struct device *dev;
 	unsigned int size;
 	unsigned int allocation;
 	unsigned int boundary;
 	char name[32];
 	struct list_head pools;
 };

 struct dma_page {		/* cacheable header for 'allocation' bytes */
 	struct list_head page_list;
 	void *vaddr;
 	dma_addr_t dma;
 };

 static DEFINE_MUTEX(pools_lock);
 static DEFINE_MUTEX(pools_reg_lock);

 static ssize_t pools_show(struct device *dev, struct device_attribute *attr, char *buf)
 {
 	struct dma_pool *pool;
 	unsigned size;

 	size = sysfs_emit(buf, "poolinfo - 0.1\n");

 	mutex_lock(&pools_lock);
 	list_for_each_entry(pool, &dev->dma_pools, pools) {
 		/* per-pool info, no real statistics yet */
 		size += sysfs_emit_at(buf, size, "%-16s %4zu %4zu %4u %2zu\n",
 				      pool->name, pool->nr_active,
 				      pool->nr_blocks, pool->size,
 				      pool->nr_pages);
 	}
 	mutex_unlock(&pools_lock);

 	return size;
 }

 static DEVICE_ATTR_RO(pools);

 #ifdef DMAPOOL_DEBUG
 static void pool_check_block(struct dma_pool *pool, struct dma_block *block,
 			     gfp_t mem_flags)
 {
 	u8 *data = (void *)block;
 	int i;

 	for (i = sizeof(struct dma_block); i < pool->size; i++) {
 		if (data[i] == POOL_POISON_FREED)
 			continue;
 		dev_err(pool->dev, "%s %s, %p (corrupted)\n", __func__,
 			pool->name, block);

 		/*
 		 * Dump the first 4 bytes even if they are not
 		 * POOL_POISON_FREED
 		 */
 		print_hex_dump(KERN_ERR, "", DUMP_PREFIX_OFFSET, 16, 1,
 				data, pool->size, 1);
 		break;
 	}

 	if (!want_init_on_alloc(mem_flags))
 		memset(block, POOL_POISON_ALLOCATED, pool->size);
 }

 static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
 {
 	struct dma_page *page;

 	list_for_each_entry(page, &pool->page_list, page_list) {
 		if (dma < page->dma)
 			continue;
 		if ((dma - page->dma) < pool->allocation)
 			return page;
 	}
 	return NULL;
 }

 static bool pool_block_err(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
 {
 	struct dma_block *block = pool->next_block;
 	struct dma_page *page;

 	page = pool_find_page(pool, dma);
 	if (!page) {
 		dev_err(pool->dev, "%s %s, %p/%pad (bad dma)\n",
 			__func__, pool->name, vaddr, &dma);
 		return true;
 	}

 	while (block) {
 		if (block != vaddr) {
 			block = block->next_block;
 			continue;
 		}
 		dev_err(pool->dev, "%s %s, dma %pad already free\n",
 			__func__, pool->name, &dma);
 		return true;
 	}

 	memset(vaddr, POOL_POISON_FREED, pool->size);
 	return false;
 }

 static void pool_init_page(struct dma_pool *pool, struct dma_page *page)
 {
 	memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
 }
 #else
 static void pool_check_block(struct dma_pool *pool, struct dma_block *block,
 			     gfp_t mem_flags)
 {
 }

 static bool pool_block_err(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
 {
 	if (want_init_on_free())
 		memset(vaddr, 0, pool->size);
 	return false;
 }

 static void pool_init_page(struct dma_pool *pool, struct dma_page *page)
 {
 }
 #endif

 static struct dma_block *pool_block_pop(struct dma_pool *pool)
 {
 	struct dma_block *block = pool->next_block;

 	if (block) {
 		pool->next_block = block->next_block;
 		pool->nr_active++;
 	}
 	return block;
 }

 static void pool_block_push(struct dma_pool *pool, struct dma_block *block,
 			    dma_addr_t dma)
 {
 	block->dma = dma;
 	block->next_block = pool->next_block;
 	pool->next_block = block;
 }


 /**
  * dma_pool_create - Creates a pool of consistent memory blocks, for dma.
  * @name: name of pool, for diagnostics
  * @dev: device that will be doing the DMA
  * @size: size of the blocks in this pool.
  * @align: alignment requirement for blocks; must be a power of two
  * @boundary: returned blocks won't cross this power of two boundary
  * Context: not in_interrupt()
  *
  * Given one of these pools, dma_pool_alloc()
  * may be used to allocate memory.  Such memory will all have "consistent"
  * DMA mappings, accessible by the device and its driver without using
  * cache flushing primitives.  The actual size of blocks allocated may be
  * larger than requested because of alignment.
  *
  * If @boundary is nonzero, objects returned from dma_pool_alloc() won't
  * cross that size boundary.  This is useful for devices which have
  * addressing restrictions on individual DMA transfers, such as not crossing
  * boundaries of 4KBytes.
  *
  * Return: a dma allocation pool with the requested characteristics, or
  * %NULL if one can't be created.
  */
 struct dma_pool *dma_pool_create(const char *name, struct device *dev,
 				 size_t size, size_t align, size_t boundary)
 {
 	struct dma_pool *retval;
 	size_t allocation;
 	bool empty;

 	if (!dev)
 		return NULL;

 	if (align == 0)
 		align = 1;
 	else if (align & (align - 1))
 		return NULL;

 	if (size == 0 || size > INT_MAX)
 		return NULL;
 	if (size < sizeof(struct dma_block))
 		size = sizeof(struct dma_block);

 	size = ALIGN(size, align);
 	allocation = max_t(size_t, size, PAGE_SIZE);

 	if (!boundary)
 		boundary = allocation;
 	else if ((boundary < size) || (boundary & (boundary - 1)))
 		return NULL;

 	boundary = min(boundary, allocation);

 	retval = kzalloc(sizeof(*retval), GFP_KERNEL);
 	if (!retval)
 		return retval;

 	strscpy(retval->name, name, sizeof(retval->name));

 	retval->dev = dev;

 	INIT_LIST_HEAD(&retval->page_list);
 	spin_lock_init(&retval->lock);
 	retval->size = size;
 	retval->boundary = boundary;
 	retval->allocation = allocation;
 	INIT_LIST_HEAD(&retval->pools);

 	/*
 	 * pools_lock ensures that the ->dma_pools list does not get corrupted.
 	 * pools_reg_lock ensures that there is not a race between
 	 * dma_pool_create() and dma_pool_destroy() or within dma_pool_create()
 	 * when the first invocation of dma_pool_create() failed on
 	 * device_create_file() and the second assumes that it has been done (I
 	 * know it is a short window).
 	 */
 	mutex_lock(&pools_reg_lock);
 	mutex_lock(&pools_lock);
 	empty = list_empty(&dev->dma_pools);
 	list_add(&retval->pools, &dev->dma_pools);
 	mutex_unlock(&pools_lock);
 	if (empty) {
 		int err;

 		err = device_create_file(dev, &dev_attr_pools);
 		if (err) {
 			mutex_lock(&pools_lock);
 			list_del(&retval->pools);
 			mutex_unlock(&pools_lock);
 			mutex_unlock(&pools_reg_lock);
 			kfree(retval);
 			return NULL;
 		}
 	}
 	mutex_unlock(&pools_reg_lock);
 	return retval;
 }
 EXPORT_SYMBOL(dma_pool_create);

 static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
 {
 	unsigned int next_boundary = pool->boundary, offset = 0;
 	struct dma_block *block, *first = NULL, *last = NULL;

 	pool_init_page(pool, page);
 	while (offset + pool->size <= pool->allocation) {
 		if (offset + pool->size > next_boundary) {
 			offset = next_boundary;
 			next_boundary += pool->boundary;
 			continue;
 		}

 		block = page->vaddr + offset;
 		block->dma = page->dma + offset;
 		block->next_block = NULL;

 		if (last)
 			last->next_block = block;
 		else
 			first = block;
 		last = block;

 		offset += pool->size;
 		pool->nr_blocks++;
 	}

 	last->next_block = pool->next_block;
 	pool->next_block = first;

 	list_add(&page->page_list, &pool->page_list);
 	pool->nr_pages++;
 }

 static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
 {
 	struct dma_page *page;

 	page = kmalloc(sizeof(*page), mem_flags);
 	if (!page)
 		return NULL;

 	page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
 					 &page->dma, mem_flags);
 	if (!page->vaddr) {
 		kfree(page);
 		return NULL;
 	}

 	return page;
 }

 /**
  * dma_pool_destroy - destroys a pool of dma memory blocks.
  * @pool: dma pool that will be destroyed
  * Context: !in_interrupt()
  *
  * Caller guarantees that no more memory from the pool is in use,
  * and that nothing will try to use the pool after this call.
  */
 void dma_pool_destroy(struct dma_pool *pool)
 {
 	struct dma_page *page, *tmp;
 	bool empty, busy = false;

 	if (unlikely(!pool))
 		return;

 	mutex_lock(&pools_reg_lock);
 	mutex_lock(&pools_lock);
 	list_del(&pool->pools);
 	empty = list_empty(&pool->dev->dma_pools);
 	mutex_unlock(&pools_lock);
 	if (empty)
 		device_remove_file(pool->dev, &dev_attr_pools);
 	mutex_unlock(&pools_reg_lock);

 	if (pool->nr_active) {
 		dev_err(pool->dev, "%s %s busy\n", __func__, pool->name);
 		busy = true;
 	}

 	list_for_each_entry_safe(page, tmp, &pool->page_list, page_list) {
 		if (!busy)
 			dma_free_coherent(pool->dev, pool->allocation,
 					  page->vaddr, page->dma);
 		list_del(&page->page_list);
 		kfree(page);
 	}

 	kfree(pool);
 }
 EXPORT_SYMBOL(dma_pool_destroy);

 /**
  * dma_pool_alloc - get a block of consistent memory
  * @pool: dma pool that will produce the block
  * @mem_flags: GFP_* bitmask
  * @handle: pointer to dma address of block
  *
  * Return: the kernel virtual address of a currently unused block,
  * and reports its dma address through the handle.
  * If such a memory block can't be allocated, %NULL is returned.
  */
 void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
 		     dma_addr_t *handle)
 {
 	struct dma_block *block;
 	struct dma_page *page;
 	unsigned long flags;

 	might_alloc(mem_flags);

 	spin_lock_irqsave(&pool->lock, flags);
 	block = pool_block_pop(pool);
 	if (!block) {
 		/*
 		 * pool_alloc_page() might sleep, so temporarily drop
 		 * &pool->lock
 		 */
 		spin_unlock_irqrestore(&pool->lock, flags);

 		page = pool_alloc_page(pool, mem_flags & (~__GFP_ZERO));
 		if (!page)
 			return NULL;

 		spin_lock_irqsave(&pool->lock, flags);
 		pool_initialise_page(pool, page);
 		block = pool_block_pop(pool);
 	}
 	spin_unlock_irqrestore(&pool->lock, flags);

 	*handle = block->dma;
 	pool_check_block(pool, block, mem_flags);
 	if (want_init_on_alloc(mem_flags))
 		memset(block, 0, pool->size);

 	return block;
 }
 EXPORT_SYMBOL(dma_pool_alloc);

 /**
  * dma_pool_free - put block back into dma pool
  * @pool: the dma pool holding the block
  * @vaddr: virtual address of block
  * @dma: dma address of block
  *
  * Caller promises neither device nor driver will again touch this block
  * unless it is first re-allocated.
  */
 void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
 {
 	struct dma_block *block = vaddr;
 	unsigned long flags;

 	spin_lock_irqsave(&pool->lock, flags);
 	if (!pool_block_err(pool, vaddr, dma)) {
 		pool_block_push(pool, block, dma);
 		pool->nr_active--;
 	}
 	spin_unlock_irqrestore(&pool->lock, flags);
 }
 EXPORT_SYMBOL(dma_pool_free);

 /*
  * Managed DMA pool
  */
 static void dmam_pool_release(struct device *dev, void *res)
 {
 	struct dma_pool *pool = *(struct dma_pool **)res;

 	dma_pool_destroy(pool);
 }

 static int dmam_pool_match(struct device *dev, void *res, void *match_data)
 {
 	return *(struct dma_pool **)res == match_data;
 }

 /**
  * dmam_pool_create - Managed dma_pool_create()
  * @name: name of pool, for diagnostics
  * @dev: device that will be doing the DMA
  * @size: size of the blocks in this pool.
  * @align: alignment requirement for blocks; must be a power of two
  * @allocation: returned blocks won't cross this boundary (or zero)
  *
  * Managed dma_pool_create().  DMA pool created with this function is
  * automatically destroyed on driver detach.
  *
  * Return: a managed dma allocation pool with the requested
  * characteristics, or %NULL if one can't be created.
  */
 struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
 				  size_t size, size_t align, size_t allocation)
 {
 	struct dma_pool **ptr, *pool;

 	ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
 	if (!ptr)
 		return NULL;

 	pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
 	if (pool)
 		devres_add(dev, ptr);
 	else
 		devres_free(ptr);

 	return pool;
 }
 EXPORT_SYMBOL(dmam_pool_create);

 /**
  * dmam_pool_destroy - Managed dma_pool_destroy()
  * @pool: dma pool that will be destroyed
  *
  * Managed dma_pool_destroy().
  */
 void dmam_pool_destroy(struct dma_pool *pool)
 {
 	struct device *dev = pool->dev;

 	WARN_ON(devres_release(dev, dmam_pool_release, dmam_pool_match, pool));
 }
 EXPORT_SYMBOL(dmam_pool_destroy);
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* DMA Pool allocator
	*
	* Copyright 2001 David Brownell
	* Copyright 2007 Intel Corporation
	* Author: Matthew Wilcox <willy@linux.intel.com>
	*
	* This allocator returns small blocks of a given size which are DMA-able by
	* the given device. It uses the dma_alloc_coherent page allocator to get
	* new pages, then splits them up into blocks of the required size.
	* Many older drivers still have their own code to do this.
	*
	* The current design of this allocator is fairly simple. The pool is
	* represented by the 'struct dma_pool' which keeps a doubly-linked list of
	* allocated pages. Each page in the page_list is split into blocks of at
	* least 'size' bytes. Free blocks are tracked in an unsorted singly-linked
	* list of free blocks across all pages. Used blocks aren't tracked, but we
	* keep a count of how many are currently allocated from each page.
	*/

	#include <linux/device.h>
	#include <linux/dma-mapping.h>
	#include <linux/dmapool.h>
	#include <linux/kernel.h>
	#include <linux/list.h>
	#include <linux/export.h>
	#include <linux/mutex.h>
	#include <linux/poison.h>
	#include <linux/sched.h>
	#include <linux/sched/mm.h>
	#include <linux/slab.h>
	#include <linux/stat.h>
	#include <linux/spinlock.h>
	#include <linux/string.h>
	#include <linux/types.h>
	#include <linux/wait.h>

	#ifdef CONFIG_SLUB_DEBUG_ON
	#define DMAPOOL_DEBUG 1
	#endif

	struct dma_block {
	struct dma_block *next_block;
	dma_addr_t dma;
	};

	struct dma_pool { /* the pool */
	struct list_head page_list;
	spinlock_t lock;
	struct dma_block *next_block;
	size_t nr_blocks;
	size_t nr_active;
	size_t nr_pages;
	struct device *dev;
	unsigned int size;
	unsigned int allocation;
	unsigned int boundary;
	char name[32];
	struct list_head pools;
	};

	struct dma_page { /* cacheable header for 'allocation' bytes */
	struct list_head page_list;
	void *vaddr;
	dma_addr_t dma;
	};

	static DEFINE_MUTEX(pools_lock);
	static DEFINE_MUTEX(pools_reg_lock);

	static ssize_t pools_show(struct device dev, struct device_attribute attr, char *buf)
	{
	struct dma_pool *pool;
	unsigned size;

	size = sysfs_emit(buf, "poolinfo - 0.1\n");

	mutex_lock(&pools_lock);
	list_for_each_entry(pool, &dev->dma_pools, pools) {
	/* per-pool info, no real statistics yet */
	size += sysfs_emit_at(buf, size, "%-16s %4zu %4zu %4u %2zu\n",
	pool->name, pool->nr_active,
	pool->nr_blocks, pool->size,
	pool->nr_pages);
	}
	mutex_unlock(&pools_lock);

	return size;
	}

	static DEVICE_ATTR_RO(pools);

	#ifdef DMAPOOL_DEBUG
	static void pool_check_block(struct dma_pool pool, struct dma_block block,
	gfp_t mem_flags)
	{
	u8 data = (void )block;
	int i;

	for (i = sizeof(struct dma_block); i < pool->size; i++) {
	if (data[i] == POOL_POISON_FREED)
	continue;
	dev_err(pool->dev, "%s %s, %p (corrupted)\n", __func__,
	pool->name, block);

	/*
	* Dump the first 4 bytes even if they are not
	* POOL_POISON_FREED
	*/
	print_hex_dump(KERN_ERR, "", DUMP_PREFIX_OFFSET, 16, 1,
	data, pool->size, 1);
	break;
	}

	if (!want_init_on_alloc(mem_flags))
	memset(block, POOL_POISON_ALLOCATED, pool->size);
	}

	static struct dma_page pool_find_page(struct dma_pool pool, dma_addr_t dma)
	{
	struct dma_page *page;

	list_for_each_entry(page, &pool->page_list, page_list) {
	if (dma < page->dma)
	continue;
	if ((dma - page->dma) < pool->allocation)
	return page;
	}
	return NULL;
	}

	static bool pool_block_err(struct dma_pool pool, void vaddr, dma_addr_t dma)
	{
	struct dma_block *block = pool->next_block;
	struct dma_page *page;

	page = pool_find_page(pool, dma);
	if (!page) {
	dev_err(pool->dev, "%s %s, %p/%pad (bad dma)\n",
	__func__, pool->name, vaddr, &dma);
	return true;
	}

	while (block) {
	if (block != vaddr) {
	block = block->next_block;
	continue;
	}
	dev_err(pool->dev, "%s %s, dma %pad already free\n",
	__func__, pool->name, &dma);
	return true;
	}

	memset(vaddr, POOL_POISON_FREED, pool->size);
	return false;
	}

	static void pool_init_page(struct dma_pool pool, struct dma_page page)
	{
	memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
	}
	#else
	static void pool_check_block(struct dma_pool pool, struct dma_block block,
	gfp_t mem_flags)
	{
	}

	static bool pool_block_err(struct dma_pool pool, void vaddr, dma_addr_t dma)
	{
	if (want_init_on_free())
	memset(vaddr, 0, pool->size);
	return false;
	}

	static void pool_init_page(struct dma_pool pool, struct dma_page page)
	{
	}
	#endif

	static struct dma_block pool_block_pop(struct dma_pool pool)
	{
	struct dma_block *block = pool->next_block;

	if (block) {
	pool->next_block = block->next_block;
	pool->nr_active++;
	}
	return block;
	}

	static void pool_block_push(struct dma_pool pool, struct dma_block block,
	dma_addr_t dma)
	{
	block->dma = dma;
	block->next_block = pool->next_block;
	pool->next_block = block;
	}


	/**
	* dma_pool_create - Creates a pool of consistent memory blocks, for dma.
	* @name: name of pool, for diagnostics
	* @dev: device that will be doing the DMA
	* @size: size of the blocks in this pool.
	* @align: alignment requirement for blocks; must be a power of two
	* @boundary: returned blocks won't cross this power of two boundary
	* Context: not in_interrupt()
	*
	* Given one of these pools, dma_pool_alloc()
	* may be used to allocate memory. Such memory will all have "consistent"
	* DMA mappings, accessible by the device and its driver without using
	* cache flushing primitives. The actual size of blocks allocated may be
	* larger than requested because of alignment.
	*
	* If @boundary is nonzero, objects returned from dma_pool_alloc() won't
	* cross that size boundary. This is useful for devices which have
	* addressing restrictions on individual DMA transfers, such as not crossing
	* boundaries of 4KBytes.
	*
	* Return: a dma allocation pool with the requested characteristics, or
	* %NULL if one can't be created.
	*/
	struct dma_pool dma_pool_create(const char name, struct device *dev,
	size_t size, size_t align, size_t boundary)
	{
	struct dma_pool *retval;
	size_t allocation;
	bool empty;

	if (!dev)
	return NULL;

	if (align == 0)
	align = 1;
	else if (align & (align - 1))
	return NULL;

	if (size == 0 \|\| size > INT_MAX)
	return NULL;
	if (size < sizeof(struct dma_block))
	size = sizeof(struct dma_block);

	size = ALIGN(size, align);
	allocation = max_t(size_t, size, PAGE_SIZE);

	if (!boundary)
	boundary = allocation;
	else if ((boundary < size) \|\| (boundary & (boundary - 1)))
	return NULL;

	boundary = min(boundary, allocation);

	retval = kzalloc(sizeof(*retval), GFP_KERNEL);
	if (!retval)
	return retval;

	strscpy(retval->name, name, sizeof(retval->name));

	retval->dev = dev;

	INIT_LIST_HEAD(&retval->page_list);
	spin_lock_init(&retval->lock);
	retval->size = size;
	retval->boundary = boundary;
	retval->allocation = allocation;
	INIT_LIST_HEAD(&retval->pools);

	/*
	* pools_lock ensures that the ->dma_pools list does not get corrupted.
	* pools_reg_lock ensures that there is not a race between
	* dma_pool_create() and dma_pool_destroy() or within dma_pool_create()
	* when the first invocation of dma_pool_create() failed on
	* device_create_file() and the second assumes that it has been done (I
	* know it is a short window).
	*/
	mutex_lock(&pools_reg_lock);
	mutex_lock(&pools_lock);
	empty = list_empty(&dev->dma_pools);
	list_add(&retval->pools, &dev->dma_pools);
	mutex_unlock(&pools_lock);
	if (empty) {
	int err;

	err = device_create_file(dev, &dev_attr_pools);
	if (err) {
	mutex_lock(&pools_lock);
	list_del(&retval->pools);
	mutex_unlock(&pools_lock);
	mutex_unlock(&pools_reg_lock);
	kfree(retval);
	return NULL;
	}
	}
	mutex_unlock(&pools_reg_lock);
	return retval;
	}
	EXPORT_SYMBOL(dma_pool_create);

	static void pool_initialise_page(struct dma_pool pool, struct dma_page page)
	{
	unsigned int next_boundary = pool->boundary, offset = 0;
	struct dma_block block, first = NULL, *last = NULL;

	pool_init_page(pool, page);
	while (offset + pool->size <= pool->allocation) {
	if (offset + pool->size > next_boundary) {
	offset = next_boundary;
	next_boundary += pool->boundary;
	continue;
	}

	block = page->vaddr + offset;
	block->dma = page->dma + offset;
	block->next_block = NULL;

	if (last)
	last->next_block = block;
	else
	first = block;
	last = block;

	offset += pool->size;
	pool->nr_blocks++;
	}

	last->next_block = pool->next_block;
	pool->next_block = first;

	list_add(&page->page_list, &pool->page_list);
	pool->nr_pages++;
	}

	static struct dma_page pool_alloc_page(struct dma_pool pool, gfp_t mem_flags)
	{
	struct dma_page *page;

	page = kmalloc(sizeof(*page), mem_flags);
	if (!page)
	return NULL;

	page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
	&page->dma, mem_flags);
	if (!page->vaddr) {
	kfree(page);
	return NULL;
	}

	return page;
	}

	/**
	* dma_pool_destroy - destroys a pool of dma memory blocks.
	* @pool: dma pool that will be destroyed
	* Context: !in_interrupt()
	*
	* Caller guarantees that no more memory from the pool is in use,
	* and that nothing will try to use the pool after this call.
	*/
	void dma_pool_destroy(struct dma_pool *pool)
	{
	struct dma_page page, tmp;
	bool empty, busy = false;

	if (unlikely(!pool))
	return;

	mutex_lock(&pools_reg_lock);
	mutex_lock(&pools_lock);
	list_del(&pool->pools);
	empty = list_empty(&pool->dev->dma_pools);
	mutex_unlock(&pools_lock);
	if (empty)
	device_remove_file(pool->dev, &dev_attr_pools);
	mutex_unlock(&pools_reg_lock);

	if (pool->nr_active) {
	dev_err(pool->dev, "%s %s busy\n", __func__, pool->name);
	busy = true;
	}

	list_for_each_entry_safe(page, tmp, &pool->page_list, page_list) {
	if (!busy)
	dma_free_coherent(pool->dev, pool->allocation,
	page->vaddr, page->dma);
	list_del(&page->page_list);
	kfree(page);
	}

	kfree(pool);
	}
	EXPORT_SYMBOL(dma_pool_destroy);

	/**
	* dma_pool_alloc - get a block of consistent memory
	* @pool: dma pool that will produce the block
	* @mem_flags: GFP_* bitmask
	* @handle: pointer to dma address of block
	*
	* Return: the kernel virtual address of a currently unused block,
	* and reports its dma address through the handle.
	* If such a memory block can't be allocated, %NULL is returned.
	*/
	void dma_pool_alloc(struct dma_pool pool, gfp_t mem_flags,
	dma_addr_t *handle)
	{
	struct dma_block *block;
	struct dma_page *page;
	unsigned long flags;

	might_alloc(mem_flags);

	spin_lock_irqsave(&pool->lock, flags);
	block = pool_block_pop(pool);
	if (!block) {
	/*
	* pool_alloc_page() might sleep, so temporarily drop
	* &pool->lock
	*/
	spin_unlock_irqrestore(&pool->lock, flags);

	page = pool_alloc_page(pool, mem_flags & (~__GFP_ZERO));
	if (!page)
	return NULL;

	spin_lock_irqsave(&pool->lock, flags);
	pool_initialise_page(pool, page);
	block = pool_block_pop(pool);
	}
	spin_unlock_irqrestore(&pool->lock, flags);

	*handle = block->dma;
	pool_check_block(pool, block, mem_flags);
	if (want_init_on_alloc(mem_flags))
	memset(block, 0, pool->size);

	return block;
	}
	EXPORT_SYMBOL(dma_pool_alloc);

	/**
	* dma_pool_free - put block back into dma pool
	* @pool: the dma pool holding the block
	* @vaddr: virtual address of block
	* @dma: dma address of block
	*
	* Caller promises neither device nor driver will again touch this block
	* unless it is first re-allocated.
	*/
	void dma_pool_free(struct dma_pool pool, void vaddr, dma_addr_t dma)
	{
	struct dma_block *block = vaddr;
	unsigned long flags;

	spin_lock_irqsave(&pool->lock, flags);
	if (!pool_block_err(pool, vaddr, dma)) {
	pool_block_push(pool, block, dma);
	pool->nr_active--;
	}
	spin_unlock_irqrestore(&pool->lock, flags);
	}
	EXPORT_SYMBOL(dma_pool_free);

	/*
	* Managed DMA pool
	*/
	static void dmam_pool_release(struct device dev, void res)
	{
	struct dma_pool pool = (struct dma_pool **)res;

	dma_pool_destroy(pool);
	}

	static int dmam_pool_match(struct device dev, void res, void *match_data)
	{
	return (struct dma_pool *)res == match_data;
	}

	/**
	* dmam_pool_create - Managed dma_pool_create()
	* @name: name of pool, for diagnostics
	* @dev: device that will be doing the DMA
	* @size: size of the blocks in this pool.
	* @align: alignment requirement for blocks; must be a power of two
	* @allocation: returned blocks won't cross this boundary (or zero)
	*
	* Managed dma_pool_create(). DMA pool created with this function is
	* automatically destroyed on driver detach.
	*
	* Return: a managed dma allocation pool with the requested
	* characteristics, or %NULL if one can't be created.
	*/
	struct dma_pool dmam_pool_create(const char name, struct device *dev,
	size_t size, size_t align, size_t allocation)
	{
	struct dma_pool *ptr, pool;

	ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
	if (!ptr)
	return NULL;

	pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
	if (pool)
	devres_add(dev, ptr);
	else
	devres_free(ptr);

	return pool;
	}
	EXPORT_SYMBOL(dmam_pool_create);

	/**
	* dmam_pool_destroy - Managed dma_pool_destroy()
	* @pool: dma pool that will be destroyed
	*
	* Managed dma_pool_destroy().
	*/
	void dmam_pool_destroy(struct dma_pool *pool)
	{
	struct device *dev = pool->dev;

	WARN_ON(devres_release(dev, dmam_pool_release, dmam_pool_match, pool));
	}
	EXPORT_SYMBOL(dmam_pool_destroy);