Merge branch 'dmapool' of git://git.kernel.org/pub/scm/linux/kernel/git/willy/misc

* 'dmapool' of git://git.kernel.org/pub/scm/linux/kernel/git/willy/misc:
  pool: Improve memory usage for devices which can't cross boundaries
  Change dmapool free block management
  dmapool: Tidy up includes and add comments
  dmapool: Validate parameters to dma_pool_create
  Avoid taking waitqueue lock in dmapool
  dmapool: Fix style problems
  Move dmapool.c to mm/ directory

4 files changed, 502 insertions, 482 deletions

diff --git a/drivers/base/Makefile b/drivers/base/Makefile
index 63e09c015ca..c66637392bb 100644
--- a/drivers/base/Makefile
+++ b/drivers/base/Makefile
@@ -5,7 +5,7 @@ obj-y			:= core.o sys.o bus.o dd.o \
 			   cpu.o firmware.o init.o map.o devres.o \
 			   attribute_container.o transport_class.o
 obj-y			+= power/
-obj-$(CONFIG_HAS_DMA)	+= dma-mapping.o dmapool.o
+obj-$(CONFIG_HAS_DMA)	+= dma-mapping.o
 obj-$(CONFIG_ISA)	+= isa.o
 obj-$(CONFIG_FW_LOADER)	+= firmware_class.o
 obj-$(CONFIG_NUMA)	+= node.o
diff --git a/drivers/base/dmapool.c b/drivers/base/dmapool.c
deleted file mode 100644
index b5034dc72a0..00000000000
--- a/drivers/base/dmapool.c
+++ /dev/null
@@ -1,481 +0,0 @@
-
-#include <linux/device.h>
-#include <linux/mm.h>
-#include <asm/io.h>		/* Needed for i386 to build */
-#include <linux/dma-mapping.h>
-#include <linux/dmapool.h>
-#include <linux/slab.h>
-#include <linux/module.h>
-#include <linux/poison.h>
-#include <linux/sched.h>
-
-/*
- * Pool allocator ... wraps the dma_alloc_coherent page allocator, so
- * small blocks are easily used by drivers for bus mastering controllers.
- * This should probably be sharing the guts of the slab allocator.
- */
-
-struct dma_pool {	/* the pool */
-	struct list_head	page_list;
-	spinlock_t		lock;
-	size_t			blocks_per_page;
-	size_t			size;
-	struct device		*dev;
-	size_t			allocation;
-	char			name [32];
-	wait_queue_head_t	waitq;
-	struct list_head	pools;
-};
-
-struct dma_page {	/* cacheable header for 'allocation' bytes */
-	struct list_head	page_list;
-	void			*vaddr;
-	dma_addr_t		dma;
-	unsigned		in_use;
-	unsigned long		bitmap [0];
-};
-
-#define	POOL_TIMEOUT_JIFFIES	((100 /* msec */ * HZ) / 1000)
-
-static DEFINE_MUTEX (pools_lock);
-
-static ssize_t
-show_pools (struct device *dev, struct device_attribute *attr, char *buf)
-{
-	unsigned temp;
-	unsigned size;
-	char *next;
-	struct dma_page *page;
-	struct dma_pool *pool;
-
-	next = buf;
-	size = PAGE_SIZE;
-
-	temp = scnprintf(next, size, "poolinfo - 0.1\n");
-	size -= temp;
-	next += temp;
-
-	mutex_lock(&pools_lock);
-	list_for_each_entry(pool, &dev->dma_pools, pools) {
-		unsigned pages = 0;
-		unsigned blocks = 0;
-
-		list_for_each_entry(page, &pool->page_list, page_list) {
-			pages++;
-			blocks += page->in_use;
-		}
-
-		/* per-pool info, no real statistics yet */
-		temp = scnprintf(next, size, "%-16s %4u %4Zu %4Zu %2u\n",
-				pool->name,
-				blocks, pages * pool->blocks_per_page,
-				pool->size, pages);
-		size -= temp;
-		next += temp;
-	}
-	mutex_unlock(&pools_lock);
-
-	return PAGE_SIZE - size;
-}
-static DEVICE_ATTR (pools, S_IRUGO, show_pools, NULL);
-
-/**
- * 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
- * @allocation: returned blocks won't cross this boundary (or zero)
- * Context: !in_interrupt()
- *
- * Returns a dma allocation pool with the requested characteristics, or
- * null if one can't be created.  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 allocation 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.
- */
-struct dma_pool *
-dma_pool_create (const char *name, struct device *dev,
-	size_t size, size_t align, size_t allocation)
-{
-	struct dma_pool		*retval;
-
-	if (align == 0)
-		align = 1;
-	if (size == 0)
-		return NULL;
-	else if (size < align)
-		size = align;
-	else if ((size % align) != 0) {
-		size += align + 1;
-		size &= ~(align - 1);
-	}
-
-	if (allocation == 0) {
-		if (PAGE_SIZE < size)
-			allocation = size;
-		else
-			allocation = PAGE_SIZE;
-		// FIXME: round up for less fragmentation
-	} else if (allocation < size)
-		return NULL;
-
-	if (!(retval = kmalloc_node (sizeof *retval, GFP_KERNEL, dev_to_node(dev))))
-		return retval;
-
-	strlcpy (retval->name, name, sizeof retval->name);
-
-	retval->dev = dev;
-
-	INIT_LIST_HEAD (&retval->page_list);
-	spin_lock_init (&retval->lock);
-	retval->size = size;
-	retval->allocation = allocation;
-	retval->blocks_per_page = allocation / size;
-	init_waitqueue_head (&retval->waitq);
-
-	if (dev) {
-		int ret;
-
-		mutex_lock(&pools_lock);
-		if (list_empty (&dev->dma_pools))
-			ret = device_create_file (dev, &dev_attr_pools);
-		else
-			ret = 0;
-		/* note:  not currently insisting "name" be unique */
-		if (!ret)
-			list_add (&retval->pools, &dev->dma_pools);
-		else {
-			kfree(retval);
-			retval = NULL;
-		}
-		mutex_unlock(&pools_lock);
-	} else
-		INIT_LIST_HEAD (&retval->pools);
-
-	return retval;
-}
-
-
-static struct dma_page *
-pool_alloc_page (struct dma_pool *pool, gfp_t mem_flags)
-{
-	struct dma_page	*page;
-	int		mapsize;
-
-	mapsize = pool->blocks_per_page;
-	mapsize = (mapsize + BITS_PER_LONG - 1) / BITS_PER_LONG;
-	mapsize *= sizeof (long);
-
-	page = kmalloc(mapsize + sizeof *page, mem_flags);
-	if (!page)
-		return NULL;
-	page->vaddr = dma_alloc_coherent (pool->dev,
-					    pool->allocation,
-					    &page->dma,
-					    mem_flags);
-	if (page->vaddr) {
-		memset (page->bitmap, 0xff, mapsize);	// bit set == free
-#ifdef	CONFIG_DEBUG_SLAB
-		memset (page->vaddr, POOL_POISON_FREED, pool->allocation);
-#endif
-		list_add (&page->page_list, &pool->page_list);
-		page->in_use = 0;
-	} else {
-		kfree (page);
-		page = NULL;
-	}
-	return page;
-}
-
-
-static inline int
-is_page_busy (int blocks, unsigned long *bitmap)
-{
-	while (blocks > 0) {
-		if (*bitmap++ != ~0UL)
-			return 1;
-		blocks -= BITS_PER_LONG;
-	}
-	return 0;
-}
-
-static void
-pool_free_page (struct dma_pool *pool, struct dma_page *page)
-{
-	dma_addr_t	dma = page->dma;
-
-#ifdef	CONFIG_DEBUG_SLAB
-	memset (page->vaddr, POOL_POISON_FREED, pool->allocation);
-#endif
-	dma_free_coherent (pool->dev, pool->allocation, page->vaddr, dma);
-	list_del (&page->page_list);
-	kfree (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)
-{
-	mutex_lock(&pools_lock);
-	list_del (&pool->pools);
-	if (pool->dev && list_empty (&pool->dev->dma_pools))
-		device_remove_file (pool->dev, &dev_attr_pools);
-	mutex_unlock(&pools_lock);
-
-	while (!list_empty (&pool->page_list)) {
-		struct dma_page		*page;
-		page = list_entry (pool->page_list.next,
-				struct dma_page, page_list);
-		if (is_page_busy (pool->blocks_per_page, page->bitmap)) {
-			if (pool->dev)
-				dev_err(pool->dev, "dma_pool_destroy %s, %p busy\n",
-					pool->name, page->vaddr);
-			else
-				printk (KERN_ERR "dma_pool_destroy %s, %p busy\n",
-					pool->name, page->vaddr);
-			/* leak the still-in-use consistent memory */
-			list_del (&page->page_list);
-			kfree (page);
-		} else
-			pool_free_page (pool, page);
-	}
-
-	kfree (pool);
-}
-
-
-/**
- * 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
- *
- * This returns 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)
-{
-	unsigned long		flags;
-	struct dma_page		*page;
-	int			map, block;
-	size_t			offset;
-	void			*retval;
-
-restart:
-	spin_lock_irqsave (&pool->lock, flags);
-	list_for_each_entry(page, &pool->page_list, page_list) {
-		int		i;
-		/* only cachable accesses here ... */
-		for (map = 0, i = 0;
-				i < pool->blocks_per_page;
-				i += BITS_PER_LONG, map++) {
-			if (page->bitmap [map] == 0)
-				continue;
-			block = ffz (~ page->bitmap [map]);
-			if ((i + block) < pool->blocks_per_page) {
-				clear_bit (block, &page->bitmap [map]);
-				offset = (BITS_PER_LONG * map) + block;
-				offset *= pool->size;
-				goto ready;
-			}
-		}
-	}
-	if (!(page = pool_alloc_page (pool, GFP_ATOMIC))) {
-		if (mem_flags & __GFP_WAIT) {
-			DECLARE_WAITQUEUE (wait, current);
-
-			__set_current_state(TASK_INTERRUPTIBLE);
-			add_wait_queue (&pool->waitq, &wait);
-			spin_unlock_irqrestore (&pool->lock, flags);
-
-			schedule_timeout (POOL_TIMEOUT_JIFFIES);
-
-			remove_wait_queue (&pool->waitq, &wait);
-			goto restart;
-		}
-		retval = NULL;
-		goto done;
-	}
-
-	clear_bit (0, &page->bitmap [0]);
-	offset = 0;
-ready:
-	page->in_use++;
-	retval = offset + page->vaddr;
-	*handle = offset + page->dma;
-#ifdef	CONFIG_DEBUG_SLAB
-	memset (retval, POOL_POISON_ALLOCATED, pool->size);
-#endif
-done:
-	spin_unlock_irqrestore (&pool->lock, flags);
-	return retval;
-}
-
-
-static struct dma_page *
-pool_find_page (struct dma_pool *pool, dma_addr_t dma)
-{
-	unsigned long		flags;
-	struct dma_page		*page;
-
-	spin_lock_irqsave (&pool->lock, flags);
-	list_for_each_entry(page, &pool->page_list, page_list) {
-		if (dma < page->dma)
-			continue;
-		if (dma < (page->dma + pool->allocation))
-			goto done;
-	}
-	page = NULL;
-done:
-	spin_unlock_irqrestore (&pool->lock, flags);
-	return page;
-}
-
-
-/**
- * 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_page		*page;
-	unsigned long		flags;
-	int			map, block;
-
-	if ((page = pool_find_page(pool, dma)) == NULL) {
-		if (pool->dev)
-			dev_err(pool->dev, "dma_pool_free %s, %p/%lx (bad dma)\n",
-				pool->name, vaddr, (unsigned long) dma);
-		else
-			printk (KERN_ERR "dma_pool_free %s, %p/%lx (bad dma)\n",
-				pool->name, vaddr, (unsigned long) dma);
-		return;
-	}
-
-	block = dma - page->dma;
-	block /= pool->size;
-	map = block / BITS_PER_LONG;
-	block %= BITS_PER_LONG;
-
-#ifdef	CONFIG_DEBUG_SLAB
-	if (((dma - page->dma) + (void *)page->vaddr) != vaddr) {
-		if (pool->dev)
-			dev_err(pool->dev, "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
-				pool->name, vaddr, (unsigned long long) dma);
-		else
-			printk (KERN_ERR "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
-				pool->name, vaddr, (unsigned long long) dma);
-		return;
-	}
-	if (page->bitmap [map] & (1UL << block)) {
-		if (pool->dev)
-			dev_err(pool->dev, "dma_pool_free %s, dma %Lx already free\n",
-				pool->name, (unsigned long long)dma);
-		else
-			printk (KERN_ERR "dma_pool_free %s, dma %Lx already free\n",
-				pool->name, (unsigned long long)dma);
-		return;
-	}
-	memset (vaddr, POOL_POISON_FREED, pool->size);
-#endif
-
-	spin_lock_irqsave (&pool->lock, flags);
-	page->in_use--;
-	set_bit (block, &page->bitmap [map]);
-	if (waitqueue_active (&pool->waitq))
-		wake_up (&pool->waitq);
-	/*
-	 * Resist a temptation to do
-	 *    if (!is_page_busy(bpp, page->bitmap)) pool_free_page(pool, page);
-	 * Better have a few empty pages hang around.
-	 */
-	spin_unlock_irqrestore (&pool->lock, flags);
-}
-
-/*
- * 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.
- */
-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;
-}
-
-/**
- * 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;
-
-	dma_pool_destroy(pool);
-	WARN_ON(devres_destroy(dev, dmam_pool_release, dmam_pool_match, pool));
-}
-
-EXPORT_SYMBOL (dma_pool_create);
-EXPORT_SYMBOL (dma_pool_destroy);
-EXPORT_SYMBOL (dma_pool_alloc);
-EXPORT_SYMBOL (dma_pool_free);
-EXPORT_SYMBOL (dmam_pool_create);
-EXPORT_SYMBOL (dmam_pool_destroy);
diff --git a/mm/Makefile b/mm/Makefile
index 44e2528af70..4af5dff3727 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -16,6 +16,7 @@ obj-y			:= bootmem.o filemap.o mempool.o oom_kill.o fadvise.o \
 obj-$(CONFIG_PROC_PAGE_MONITOR) += pagewalk.o
 obj-$(CONFIG_BOUNCE)	+= bounce.o
 obj-$(CONFIG_SWAP)	+= page_io.o swap_state.o swapfile.o thrash.o
+obj-$(CONFIG_HAS_DMA)	+= dmapool.o
 obj-$(CONFIG_HUGETLBFS)	+= hugetlb.o
 obj-$(CONFIG_NUMA) 	+= mempolicy.o
 obj-$(CONFIG_SPARSEMEM)	+= sparse.o
diff --git a/mm/dmapool.c b/mm/dmapool.c
new file mode 100644
index 00000000000..34aaac451a9
--- /dev/null
+++ b/mm/dmapool.c
@@ -0,0 +1,500 @@
+/*
+ * DMA Pool allocator
+ *
+ * Copyright 2001 David Brownell
+ * Copyright 2007 Intel Corporation
+ *   Author: Matthew Wilcox <willy@linux.intel.com>
+ *
+ * This software may be redistributed and/or modified under the terms of
+ * the GNU General Public License ("GPL") version 2 as published by the
+ * Free Software Foundation.
+ *
+ * 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 within the page.  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/module.h>
+#include <linux/mutex.h>
+#include <linux/poison.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/wait.h>
+
+struct dma_pool {		/* the pool */
+	struct list_head page_list;
+	spinlock_t lock;
+	size_t size;
+	struct device *dev;
+	size_t allocation;
+	size_t boundary;
+	char name[32];
+	wait_queue_head_t waitq;
+	struct list_head pools;
+};
+
+struct dma_page {		/* cacheable header for 'allocation' bytes */
+	struct list_head page_list;
+	void *vaddr;
+	dma_addr_t dma;
+	unsigned int in_use;
+	unsigned int offset;
+};
+
+#define	POOL_TIMEOUT_JIFFIES	((100 /* msec */ * HZ) / 1000)
+
+static DEFINE_MUTEX(pools_lock);
+
+static ssize_t
+show_pools(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	unsigned temp;
+	unsigned size;
+	char *next;
+	struct dma_page *page;
+	struct dma_pool *pool;
+
+	next = buf;
+	size = PAGE_SIZE;
+
+	temp = scnprintf(next, size, "poolinfo - 0.1\n");
+	size -= temp;
+	next += temp;
+
+	mutex_lock(&pools_lock);
+	list_for_each_entry(pool, &dev->dma_pools, pools) {
+		unsigned pages = 0;
+		unsigned blocks = 0;
+
+		list_for_each_entry(page, &pool->page_list, page_list) {
+			pages++;
+			blocks += page->in_use;
+		}
+
+		/* per-pool info, no real statistics yet */
+		temp = scnprintf(next, size, "%-16s %4u %4Zu %4Zu %2u\n",
+				 pool->name, blocks,
+				 pages * (pool->allocation / pool->size),
+				 pool->size, pages);
+		size -= temp;
+		next += temp;
+	}
+	mutex_unlock(&pools_lock);
+
+	return PAGE_SIZE - size;
+}
+
+static DEVICE_ATTR(pools, S_IRUGO, show_pools, NULL);
+
+/**
+ * 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: !in_interrupt()
+ *
+ * Returns a dma allocation pool with the requested characteristics, or
+ * null if one can't be created.  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.
+ */
+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;
+
+	if (align == 0) {
+		align = 1;
+	} else if (align & (align - 1)) {
+		return NULL;
+	}
+
+	if (size == 0) {
+		return NULL;
+	} else if (size < 4) {
+		size = 4;
+	}
+
+	if ((size % align) != 0)
+		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;
+	}
+
+	retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, dev_to_node(dev));
+	if (!retval)
+		return retval;
+
+	strlcpy(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_waitqueue_head(&retval->waitq);
+
+	if (dev) {
+		int ret;
+
+		mutex_lock(&pools_lock);
+		if (list_empty(&dev->dma_pools))
+			ret = device_create_file(dev, &dev_attr_pools);
+		else
+			ret = 0;
+		/* note:  not currently insisting "name" be unique */
+		if (!ret)
+			list_add(&retval->pools, &dev->dma_pools);
+		else {
+			kfree(retval);
+			retval = NULL;
+		}
+		mutex_unlock(&pools_lock);
+	} else
+		INIT_LIST_HEAD(&retval->pools);
+
+	return retval;
+}
+EXPORT_SYMBOL(dma_pool_create);
+
+static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
+{
+	unsigned int offset = 0;
+	unsigned int next_boundary = pool->boundary;
+
+	do {
+		unsigned int next = offset + pool->size;
+		if (unlikely((next + pool->size) >= next_boundary)) {
+			next = next_boundary;
+			next_boundary += pool->boundary;
+		}
+		*(int *)(page->vaddr + offset) = next;
+		offset = next;
+	} while (offset < pool->allocation);
+}
+
+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) {
+#ifdef	CONFIG_DEBUG_SLAB
+		memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
+#endif
+		pool_initialise_page(pool, page);
+		list_add(&page->page_list, &pool->page_list);
+		page->in_use = 0;
+		page->offset = 0;
+	} else {
+		kfree(page);
+		page = NULL;
+	}
+	return page;
+}
+
+static inline int is_page_busy(struct dma_page *page)
+{
+	return page->in_use != 0;
+}
+
+static void pool_free_page(struct dma_pool *pool, struct dma_page *page)
+{
+	dma_addr_t dma = page->dma;
+
+#ifdef	CONFIG_DEBUG_SLAB
+	memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
+#endif
+	dma_free_coherent(pool->dev, pool->allocation, page->vaddr, dma);
+	list_del(&page->page_list);
+	kfree(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)
+{
+	mutex_lock(&pools_lock);
+	list_del(&pool->pools);
+	if (pool->dev && list_empty(&pool->dev->dma_pools))
+		device_remove_file(pool->dev, &dev_attr_pools);
+	mutex_unlock(&pools_lock);
+
+	while (!list_empty(&pool->page_list)) {
+		struct dma_page *page;
+		page = list_entry(pool->page_list.next,
+				  struct dma_page, page_list);
+		if (is_page_busy(page)) {
+			if (pool->dev)
+				dev_err(pool->dev,
+					"dma_pool_destroy %s, %p busy\n",
+					pool->name, page->vaddr);
+			else
+				printk(KERN_ERR
+				       "dma_pool_destroy %s, %p busy\n",
+				       pool->name, page->vaddr);
+			/* leak the still-in-use consistent memory */
+			list_del(&page->page_list);
+			kfree(page);
+		} else
+			pool_free_page(pool, 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
+ *
+ * This returns 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)
+{
+	unsigned long flags;
+	struct dma_page *page;
+	size_t offset;
+	void *retval;
+
+	spin_lock_irqsave(&pool->lock, flags);
+ restart:
+	list_for_each_entry(page, &pool->page_list, page_list) {
+		if (page->offset < pool->allocation)
+			goto ready;
+	}
+	page = pool_alloc_page(pool, GFP_ATOMIC);
+	if (!page) {
+		if (mem_flags & __GFP_WAIT) {
+			DECLARE_WAITQUEUE(wait, current);
+
+			__set_current_state(TASK_INTERRUPTIBLE);
+			__add_wait_queue(&pool->waitq, &wait);
+			spin_unlock_irqrestore(&pool->lock, flags);
+
+			schedule_timeout(POOL_TIMEOUT_JIFFIES);
+
+			spin_lock_irqsave(&pool->lock, flags);
+			__remove_wait_queue(&pool->waitq, &wait);
+			goto restart;
+		}
+		retval = NULL;
+		goto done;
+	}
+
+ ready:
+	page->in_use++;
+	offset = page->offset;
+	page->offset = *(int *)(page->vaddr + offset);
+	retval = offset + page->vaddr;
+	*handle = offset + page->dma;
+#ifdef	CONFIG_DEBUG_SLAB
+	memset(retval, POOL_POISON_ALLOCATED, pool->size);
+#endif
+ done:
+	spin_unlock_irqrestore(&pool->lock, flags);
+	return retval;
+}
+EXPORT_SYMBOL(dma_pool_alloc);
+
+static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
+{
+	unsigned long flags;
+	struct dma_page *page;
+
+	spin_lock_irqsave(&pool->lock, flags);
+	list_for_each_entry(page, &pool->page_list, page_list) {
+		if (dma < page->dma)
+			continue;
+		if (dma < (page->dma + pool->allocation))
+			goto done;
+	}
+	page = NULL;
+ done:
+	spin_unlock_irqrestore(&pool->lock, flags);
+	return page;
+}
+
+/**
+ * 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_page *page;
+	unsigned long flags;
+	unsigned int offset;
+
+	page = pool_find_page(pool, dma);
+	if (!page) {
+		if (pool->dev)
+			dev_err(pool->dev,
+				"dma_pool_free %s, %p/%lx (bad dma)\n",
+				pool->name, vaddr, (unsigned long)dma);
+		else
+			printk(KERN_ERR "dma_pool_free %s, %p/%lx (bad dma)\n",
+			       pool->name, vaddr, (unsigned long)dma);
+		return;
+	}
+
+	offset = vaddr - page->vaddr;
+#ifdef	CONFIG_DEBUG_SLAB
+	if ((dma - page->dma) != offset) {
+		if (pool->dev)
+			dev_err(pool->dev,
+				"dma_pool_free %s, %p (bad vaddr)/%Lx\n",
+				pool->name, vaddr, (unsigned long long)dma);
+		else
+			printk(KERN_ERR
+			       "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
+			       pool->name, vaddr, (unsigned long long)dma);
+		return;
+	}
+	{
+		unsigned int chain = page->offset;
+		while (chain < pool->allocation) {
+			if (chain != offset) {
+				chain = *(int *)(page->vaddr + chain);
+				continue;
+			}
+			if (pool->dev)
+				dev_err(pool->dev, "dma_pool_free %s, dma %Lx "
+					"already free\n", pool->name,
+					(unsigned long long)dma);
+			else
+				printk(KERN_ERR "dma_pool_free %s, dma %Lx "
+					"already free\n", pool->name,
+					(unsigned long long)dma);
+			return;
+		}
+	}
+	memset(vaddr, POOL_POISON_FREED, pool->size);
+#endif
+
+	spin_lock_irqsave(&pool->lock, flags);
+	page->in_use--;
+	*(int *)vaddr = page->offset;
+	page->offset = offset;
+	if (waitqueue_active(&pool->waitq))
+		wake_up_locked(&pool->waitq);
+	/*
+	 * Resist a temptation to do
+	 *    if (!is_page_busy(page)) pool_free_page(pool, page);
+	 * Better have a few empty pages hang around.
+	 */
+	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.
+ */
+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;
+
+	dma_pool_destroy(pool);
+	WARN_ON(devres_destroy(dev, dmam_pool_release, dmam_pool_match, pool));
+}
+EXPORT_SYMBOL(dmam_pool_destroy);