drivers/gpu/drm/drm_mm.c - kernel/skids - Git at Google

 /**************************************************************************
  *
  * Copyright 2006 Tungsten Graphics, Inc., Bismarck, ND., USA.
  * All Rights Reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the
  * "Software"), to deal in the Software without restriction, including
  * without limitation the rights to use, copy, modify, merge, publish,
  * distribute, sub license, and/or sell copies of the Software, and to
  * permit persons to whom the Software is furnished to do so, subject to
  * the following conditions:
  *
  * The above copyright notice and this permission notice (including the
  * next paragraph) shall be included in all copies or substantial portions
  * of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
  * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  * USE OR OTHER DEALINGS IN THE SOFTWARE.
  *
  *
  **************************************************************************/

 /*
  * Generic simple memory manager implementation. Intended to be used as a base
  * class implementation for more advanced memory managers.
  *
  * Note that the algorithm used is quite simple and there might be substantial
  * performance gains if a smarter free list is implemented. Currently it is just an
  * unordered stack of free regions. This could easily be improved if an RB-tree
  * is used instead. At least if we expect heavy fragmentation.
  *
  * Aligned allocations can also see improvement.
  *
  * Authors:
  * Thomas Hellström <thomas-at-tungstengraphics-dot-com>
  */

 #include "drmP.h"
 #include "drm_mm.h"
 #include <linux/slab.h>
 #include <linux/seq_file.h>

 #define MM_UNUSED_TARGET 4

 unsigned long drm_mm_tail_space(struct drm_mm *mm)
 {
 	struct list_head *tail_node;
 	struct drm_mm_node *entry;

 	tail_node = mm->ml_entry.prev;
 	entry = list_entry(tail_node, struct drm_mm_node, ml_entry);
 	if (!entry->free)
 		return 0;

 	return entry->size;
 }

 int drm_mm_remove_space_from_tail(struct drm_mm *mm, unsigned long size)
 {
 	struct list_head *tail_node;
 	struct drm_mm_node *entry;

 	tail_node = mm->ml_entry.prev;
 	entry = list_entry(tail_node, struct drm_mm_node, ml_entry);
 	if (!entry->free)
 		return -ENOMEM;

 	if (entry->size <= size)
 		return -ENOMEM;

 	entry->size -= size;
 	return 0;
 }

 static struct drm_mm_node *drm_mm_kmalloc(struct drm_mm *mm, int atomic)
 {
 	struct drm_mm_node *child;

 	if (atomic)
 		child = kmalloc(sizeof(*child), GFP_ATOMIC);
 	else
 		child = kmalloc(sizeof(*child), GFP_KERNEL);

 	if (unlikely(child == NULL)) {
 		spin_lock(&mm->unused_lock);
 		if (list_empty(&mm->unused_nodes))
 			child = NULL;
 		else {
 			child =
 			    list_entry(mm->unused_nodes.next,
 				       struct drm_mm_node, fl_entry);
 			list_del(&child->fl_entry);
 			--mm->num_unused;
 		}
 		spin_unlock(&mm->unused_lock);
 	}
 	return child;
 }

 /* drm_mm_pre_get() - pre allocate drm_mm_node structure
  * drm_mm:	memory manager struct we are pre-allocating for
  *
  * Returns 0 on success or -ENOMEM if allocation fails.
  */
 int drm_mm_pre_get(struct drm_mm *mm)
 {
 	struct drm_mm_node *node;

 	spin_lock(&mm->unused_lock);
 	while (mm->num_unused < MM_UNUSED_TARGET) {
 		spin_unlock(&mm->unused_lock);
 		node = kmalloc(sizeof(*node), GFP_KERNEL);
 		spin_lock(&mm->unused_lock);

 		if (unlikely(node == NULL)) {
 			int ret = (mm->num_unused < 2) ? -ENOMEM : 0;
 			spin_unlock(&mm->unused_lock);
 			return ret;
 		}
 		++mm->num_unused;
 		list_add_tail(&node->fl_entry, &mm->unused_nodes);
 	}
 	spin_unlock(&mm->unused_lock);
 	return 0;
 }
 EXPORT_SYMBOL(drm_mm_pre_get);

 static int drm_mm_create_tail_node(struct drm_mm *mm,
 				   unsigned long start,
 				   unsigned long size, int atomic)
 {
 	struct drm_mm_node *child;

 	child = drm_mm_kmalloc(mm, atomic);
 	if (unlikely(child == NULL))
 		return -ENOMEM;

 	child->free = 1;
 	child->size = size;
 	child->start = start;
 	child->mm = mm;

 	list_add_tail(&child->ml_entry, &mm->ml_entry);
 	list_add_tail(&child->fl_entry, &mm->fl_entry);

 	return 0;
 }

 int drm_mm_add_space_to_tail(struct drm_mm *mm, unsigned long size, int atomic)
 {
 	struct list_head *tail_node;
 	struct drm_mm_node *entry;

 	tail_node = mm->ml_entry.prev;
 	entry = list_entry(tail_node, struct drm_mm_node, ml_entry);
 	if (!entry->free) {
 		return drm_mm_create_tail_node(mm, entry->start + entry->size,
 					       size, atomic);
 	}
 	entry->size += size;
 	return 0;
 }

 static struct drm_mm_node *drm_mm_split_at_start(struct drm_mm_node *parent,
 						 unsigned long size,
 						 int atomic)
 {
 	struct drm_mm_node *child;

 	child = drm_mm_kmalloc(parent->mm, atomic);
 	if (unlikely(child == NULL))
 		return NULL;

 	INIT_LIST_HEAD(&child->fl_entry);

 	child->free = 0;
 	child->size = size;
 	child->start = parent->start;
 	child->mm = parent->mm;

 	list_add_tail(&child->ml_entry, &parent->ml_entry);
 	INIT_LIST_HEAD(&child->fl_entry);

 	parent->size -= size;
 	parent->start += size;
 	return child;
 }


 struct drm_mm_node *drm_mm_get_block_generic(struct drm_mm_node *node,
 					     unsigned long size,
 					     unsigned alignment,
 					     int atomic)
 {

 	struct drm_mm_node *align_splitoff = NULL;
 	unsigned tmp = 0;

 	if (alignment)
 		tmp = node->start % alignment;

 	if (tmp) {
 		align_splitoff =
 		    drm_mm_split_at_start(node, alignment - tmp, atomic);
 		if (unlikely(align_splitoff == NULL))
 			return NULL;
 	}

 	if (node->size == size) {
 		list_del_init(&node->fl_entry);
 		node->free = 0;
 	} else {
 		node = drm_mm_split_at_start(node, size, atomic);
 	}

 	if (align_splitoff)
 		drm_mm_put_block(align_splitoff);

 	return node;
 }
 EXPORT_SYMBOL(drm_mm_get_block_generic);

 struct drm_mm_node *drm_mm_get_block_range_generic(struct drm_mm_node *node,
 						unsigned long size,
 						unsigned alignment,
 						unsigned long start,
 						unsigned long end,
 						int atomic)
 {
 	struct drm_mm_node *align_splitoff = NULL;
 	unsigned tmp = 0;
 	unsigned wasted = 0;

 	if (node->start < start)
 		wasted += start - node->start;
 	if (alignment)
 		tmp = ((node->start + wasted) % alignment);

 	if (tmp)
 		wasted += alignment - tmp;
 	if (wasted) {
 		align_splitoff = drm_mm_split_at_start(node, wasted, atomic);
 		if (unlikely(align_splitoff == NULL))
 			return NULL;
 	}

 	if (node->size == size) {
 		list_del_init(&node->fl_entry);
 		node->free = 0;
 	} else {
 		node = drm_mm_split_at_start(node, size, atomic);
 	}

 	if (align_splitoff)
 		drm_mm_put_block(align_splitoff);

 	return node;
 }
 EXPORT_SYMBOL(drm_mm_get_block_range_generic);

 /*
  * Put a block. Merge with the previous and / or next block if they are free.
  * Otherwise add to the free stack.
  */

 void drm_mm_put_block(struct drm_mm_node *cur)
 {

 	struct drm_mm *mm = cur->mm;
 	struct list_head *cur_head = &cur->ml_entry;
 	struct list_head *root_head = &mm->ml_entry;
 	struct drm_mm_node *prev_node = NULL;
 	struct drm_mm_node *next_node;

 	int merged = 0;

 	if (cur_head->prev != root_head) {
 		prev_node =
 		    list_entry(cur_head->prev, struct drm_mm_node, ml_entry);
 		if (prev_node->free) {
 			prev_node->size += cur->size;
 			merged = 1;
 		}
 	}
 	if (cur_head->next != root_head) {
 		next_node =
 		    list_entry(cur_head->next, struct drm_mm_node, ml_entry);
 		if (next_node->free) {
 			if (merged) {
 				prev_node->size += next_node->size;
 				list_del(&next_node->ml_entry);
 				list_del(&next_node->fl_entry);
 				spin_lock(&mm->unused_lock);
 				if (mm->num_unused < MM_UNUSED_TARGET) {
 					list_add(&next_node->fl_entry,
 						 &mm->unused_nodes);
 					++mm->num_unused;
 				} else
 					kfree(next_node);
 				spin_unlock(&mm->unused_lock);
 			} else {
 				next_node->size += cur->size;
 				next_node->start = cur->start;
 				merged = 1;
 			}
 		}
 	}
 	if (!merged) {
 		cur->free = 1;
 		list_add(&cur->fl_entry, &mm->fl_entry);
 	} else {
 		list_del(&cur->ml_entry);
 		spin_lock(&mm->unused_lock);
 		if (mm->num_unused < MM_UNUSED_TARGET) {
 			list_add(&cur->fl_entry, &mm->unused_nodes);
 			++mm->num_unused;
 		} else
 			kfree(cur);
 		spin_unlock(&mm->unused_lock);
 	}
 }

 EXPORT_SYMBOL(drm_mm_put_block);

 struct drm_mm_node *drm_mm_search_free(const struct drm_mm *mm,
 				       unsigned long size,
 				       unsigned alignment, int best_match)
 {
 	struct list_head *list;
 	const struct list_head *free_stack = &mm->fl_entry;
 	struct drm_mm_node *entry;
 	struct drm_mm_node *best;
 	unsigned long best_size;
 	unsigned wasted;

 	best = NULL;
 	best_size = ~0UL;

 	list_for_each(list, free_stack) {
 		entry = list_entry(list, struct drm_mm_node, fl_entry);
 		wasted = 0;

 		if (entry->size < size)
 			continue;

 		if (alignment) {
 			register unsigned tmp = entry->start % alignment;
 			if (tmp)
 				wasted += alignment - tmp;
 		}

 		if (entry->size >= size + wasted) {
 			if (!best_match)
 				return entry;
 			if (entry->size < best_size) {
 				best = entry;
 				best_size = entry->size;
 			}
 		}
 	}

 	return best;
 }
 EXPORT_SYMBOL(drm_mm_search_free);

 struct drm_mm_node *drm_mm_search_free_in_range(const struct drm_mm *mm,
 						unsigned long size,
 						unsigned alignment,
 						unsigned long start,
 						unsigned long end,
 						int best_match)
 {
 	struct list_head *list;
 	const struct list_head *free_stack = &mm->fl_entry;
 	struct drm_mm_node *entry;
 	struct drm_mm_node *best;
 	unsigned long best_size;
 	unsigned wasted;

 	best = NULL;
 	best_size = ~0UL;

 	list_for_each(list, free_stack) {
 		entry = list_entry(list, struct drm_mm_node, fl_entry);
 		wasted = 0;

 		if (entry->size < size)
 			continue;

 		if (entry->start > end || (entry->start+entry->size) < start)
 			continue;

 		if (entry->start < start)
 			wasted += start - entry->start;

 		if (alignment) {
 			register unsigned tmp = (entry->start + wasted) % alignment;
 			if (tmp)
 				wasted += alignment - tmp;
 		}

 		if (entry->size >= size + wasted &&
 		    (entry->start + wasted + size) <= end) {
 			if (!best_match)
 				return entry;
 			if (entry->size < best_size) {
 				best = entry;
 				best_size = entry->size;
 			}
 		}
 	}

 	return best;
 }
 EXPORT_SYMBOL(drm_mm_search_free_in_range);

 int drm_mm_clean(struct drm_mm * mm)
 {
 	struct list_head *head = &mm->ml_entry;

 	return (head->next->next == head);
 }
 EXPORT_SYMBOL(drm_mm_clean);

 int drm_mm_init(struct drm_mm * mm, unsigned long start, unsigned long size)
 {
 	INIT_LIST_HEAD(&mm->ml_entry);
 	INIT_LIST_HEAD(&mm->fl_entry);
 	INIT_LIST_HEAD(&mm->unused_nodes);
 	mm->num_unused = 0;
 	spin_lock_init(&mm->unused_lock);

 	return drm_mm_create_tail_node(mm, start, size, 0);
 }
 EXPORT_SYMBOL(drm_mm_init);

 void drm_mm_takedown(struct drm_mm * mm)
 {
 	struct list_head *bnode = mm->fl_entry.next;
 	struct drm_mm_node *entry;
 	struct drm_mm_node *next;

 	entry = list_entry(bnode, struct drm_mm_node, fl_entry);

 	if (entry->ml_entry.next != &mm->ml_entry ||
 	    entry->fl_entry.next != &mm->fl_entry) {
 		DRM_ERROR("Memory manager not clean. Delaying takedown\n");
 		return;
 	}

 	list_del(&entry->fl_entry);
 	list_del(&entry->ml_entry);
 	kfree(entry);

 	spin_lock(&mm->unused_lock);
 	list_for_each_entry_safe(entry, next, &mm->unused_nodes, fl_entry) {
 		list_del(&entry->fl_entry);
 		kfree(entry);
 		--mm->num_unused;
 	}
 	spin_unlock(&mm->unused_lock);

 	BUG_ON(mm->num_unused != 0);
 }
 EXPORT_SYMBOL(drm_mm_takedown);

 void drm_mm_debug_table(struct drm_mm *mm, const char *prefix)
 {
 	struct drm_mm_node *entry;
 	int total_used = 0, total_free = 0, total = 0;

 	list_for_each_entry(entry, &mm->ml_entry, ml_entry) {
 		printk(KERN_DEBUG "%s 0x%08lx-0x%08lx: %8ld: %s\n",
 			prefix, entry->start, entry->start + entry->size,
 			entry->size, entry->free ? "free" : "used");
 		total += entry->size;
 		if (entry->free)
 			total_free += entry->size;
 		else
 			total_used += entry->size;
 	}
 	printk(KERN_DEBUG "%s total: %d, used %d free %d\n", prefix, total,
 		total_used, total_free);
 }
 EXPORT_SYMBOL(drm_mm_debug_table);

 #if defined(CONFIG_DEBUG_FS)
 int drm_mm_dump_table(struct seq_file *m, struct drm_mm *mm)
 {
 	struct drm_mm_node *entry;
 	int total_used = 0, total_free = 0, total = 0;

 	list_for_each_entry(entry, &mm->ml_entry, ml_entry) {
 		seq_printf(m, "0x%08lx-0x%08lx: 0x%08lx: %s\n", entry->start, entry->start + entry->size, entry->size, entry->free ? "free" : "used");
 		total += entry->size;
 		if (entry->free)
 			total_free += entry->size;
 		else
 			total_used += entry->size;
 	}
 	seq_printf(m, "total: %d, used %d free %d\n", total, total_used, total_free);
 	return 0;
 }
 EXPORT_SYMBOL(drm_mm_dump_table);
 #endif
	/**************************************************************************
	*
	* Copyright 2006 Tungsten Graphics, Inc., Bismarck, ND., USA.
	* All Rights Reserved.
	*
	* Permission is hereby granted, free of charge, to any person obtaining a
	* copy of this software and associated documentation files (the
	* "Software"), to deal in the Software without restriction, including
	* without limitation the rights to use, copy, modify, merge, publish,
	* distribute, sub license, and/or sell copies of the Software, and to
	* permit persons to whom the Software is furnished to do so, subject to
	* the following conditions:
	*
	* The above copyright notice and this permission notice (including the
	* next paragraph) shall be included in all copies or substantial portions
	* of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
	* THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
	* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
	* OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
	* USE OR OTHER DEALINGS IN THE SOFTWARE.
	*
	*
	**************************************************************************/

	/*
	* Generic simple memory manager implementation. Intended to be used as a base
	* class implementation for more advanced memory managers.
	*
	* Note that the algorithm used is quite simple and there might be substantial
	* performance gains if a smarter free list is implemented. Currently it is just an
	* unordered stack of free regions. This could easily be improved if an RB-tree
	* is used instead. At least if we expect heavy fragmentation.
	*
	* Aligned allocations can also see improvement.
	*
	* Authors:
	* Thomas Hellström <thomas-at-tungstengraphics-dot-com>
	*/

	#include "drmP.h"
	#include "drm_mm.h"
	#include <linux/slab.h>
	#include <linux/seq_file.h>

	#define MM_UNUSED_TARGET 4

	unsigned long drm_mm_tail_space(struct drm_mm *mm)
	{
	struct list_head *tail_node;
	struct drm_mm_node *entry;

	tail_node = mm->ml_entry.prev;
	entry = list_entry(tail_node, struct drm_mm_node, ml_entry);
	if (!entry->free)
	return 0;

	return entry->size;
	}

	int drm_mm_remove_space_from_tail(struct drm_mm *mm, unsigned long size)
	{
	struct list_head *tail_node;
	struct drm_mm_node *entry;

	tail_node = mm->ml_entry.prev;
	entry = list_entry(tail_node, struct drm_mm_node, ml_entry);
	if (!entry->free)
	return -ENOMEM;

	if (entry->size <= size)
	return -ENOMEM;

	entry->size -= size;
	return 0;
	}

	static struct drm_mm_node drm_mm_kmalloc(struct drm_mm mm, int atomic)
	{
	struct drm_mm_node *child;

	if (atomic)
	child = kmalloc(sizeof(*child), GFP_ATOMIC);
	else
	child = kmalloc(sizeof(*child), GFP_KERNEL);

	if (unlikely(child == NULL)) {
	spin_lock(&mm->unused_lock);
	if (list_empty(&mm->unused_nodes))
	child = NULL;
	else {
	child =
	list_entry(mm->unused_nodes.next,
	struct drm_mm_node, fl_entry);
	list_del(&child->fl_entry);
	--mm->num_unused;
	}
	spin_unlock(&mm->unused_lock);
	}
	return child;
	}

	/* drm_mm_pre_get() - pre allocate drm_mm_node structure
	* drm_mm: memory manager struct we are pre-allocating for
	*
	* Returns 0 on success or -ENOMEM if allocation fails.
	*/
	int drm_mm_pre_get(struct drm_mm *mm)
	{
	struct drm_mm_node *node;

	spin_lock(&mm->unused_lock);
	while (mm->num_unused < MM_UNUSED_TARGET) {
	spin_unlock(&mm->unused_lock);
	node = kmalloc(sizeof(*node), GFP_KERNEL);
	spin_lock(&mm->unused_lock);

	if (unlikely(node == NULL)) {
	int ret = (mm->num_unused < 2) ? -ENOMEM : 0;
	spin_unlock(&mm->unused_lock);
	return ret;
	}
	++mm->num_unused;
	list_add_tail(&node->fl_entry, &mm->unused_nodes);
	}
	spin_unlock(&mm->unused_lock);
	return 0;
	}
	EXPORT_SYMBOL(drm_mm_pre_get);

	static int drm_mm_create_tail_node(struct drm_mm *mm,
	unsigned long start,
	unsigned long size, int atomic)
	{
	struct drm_mm_node *child;

	child = drm_mm_kmalloc(mm, atomic);
	if (unlikely(child == NULL))
	return -ENOMEM;

	child->free = 1;
	child->size = size;
	child->start = start;
	child->mm = mm;

	list_add_tail(&child->ml_entry, &mm->ml_entry);
	list_add_tail(&child->fl_entry, &mm->fl_entry);

	return 0;
	}

	int drm_mm_add_space_to_tail(struct drm_mm *mm, unsigned long size, int atomic)
	{
	struct list_head *tail_node;
	struct drm_mm_node *entry;

	tail_node = mm->ml_entry.prev;
	entry = list_entry(tail_node, struct drm_mm_node, ml_entry);
	if (!entry->free) {
	return drm_mm_create_tail_node(mm, entry->start + entry->size,
	size, atomic);
	}
	entry->size += size;
	return 0;
	}

	static struct drm_mm_node drm_mm_split_at_start(struct drm_mm_node parent,
	unsigned long size,
	int atomic)
	{
	struct drm_mm_node *child;

	child = drm_mm_kmalloc(parent->mm, atomic);
	if (unlikely(child == NULL))
	return NULL;

	INIT_LIST_HEAD(&child->fl_entry);

	child->free = 0;
	child->size = size;
	child->start = parent->start;
	child->mm = parent->mm;

	list_add_tail(&child->ml_entry, &parent->ml_entry);
	INIT_LIST_HEAD(&child->fl_entry);

	parent->size -= size;
	parent->start += size;
	return child;
	}


	struct drm_mm_node drm_mm_get_block_generic(struct drm_mm_node node,
	unsigned long size,
	unsigned alignment,
	int atomic)
	{

	struct drm_mm_node *align_splitoff = NULL;
	unsigned tmp = 0;

	if (alignment)
	tmp = node->start % alignment;

	if (tmp) {
	align_splitoff =
	drm_mm_split_at_start(node, alignment - tmp, atomic);
	if (unlikely(align_splitoff == NULL))
	return NULL;
	}

	if (node->size == size) {
	list_del_init(&node->fl_entry);
	node->free = 0;
	} else {
	node = drm_mm_split_at_start(node, size, atomic);
	}

	if (align_splitoff)
	drm_mm_put_block(align_splitoff);

	return node;
	}
	EXPORT_SYMBOL(drm_mm_get_block_generic);

	struct drm_mm_node drm_mm_get_block_range_generic(struct drm_mm_node node,
	unsigned long size,
	unsigned alignment,
	unsigned long start,
	unsigned long end,
	int atomic)
	{
	struct drm_mm_node *align_splitoff = NULL;
	unsigned tmp = 0;
	unsigned wasted = 0;

	if (node->start < start)
	wasted += start - node->start;
	if (alignment)
	tmp = ((node->start + wasted) % alignment);

	if (tmp)
	wasted += alignment - tmp;
	if (wasted) {
	align_splitoff = drm_mm_split_at_start(node, wasted, atomic);
	if (unlikely(align_splitoff == NULL))
	return NULL;
	}

	if (node->size == size) {
	list_del_init(&node->fl_entry);
	node->free = 0;
	} else {
	node = drm_mm_split_at_start(node, size, atomic);
	}

	if (align_splitoff)
	drm_mm_put_block(align_splitoff);

	return node;
	}
	EXPORT_SYMBOL(drm_mm_get_block_range_generic);

	/*
	* Put a block. Merge with the previous and / or next block if they are free.
	* Otherwise add to the free stack.
	*/

	void drm_mm_put_block(struct drm_mm_node *cur)
	{

	struct drm_mm *mm = cur->mm;
	struct list_head *cur_head = &cur->ml_entry;
	struct list_head *root_head = &mm->ml_entry;
	struct drm_mm_node *prev_node = NULL;
	struct drm_mm_node *next_node;

	int merged = 0;

	if (cur_head->prev != root_head) {
	prev_node =
	list_entry(cur_head->prev, struct drm_mm_node, ml_entry);
	if (prev_node->free) {
	prev_node->size += cur->size;
	merged = 1;
	}
	}
	if (cur_head->next != root_head) {
	next_node =
	list_entry(cur_head->next, struct drm_mm_node, ml_entry);
	if (next_node->free) {
	if (merged) {
	prev_node->size += next_node->size;
	list_del(&next_node->ml_entry);
	list_del(&next_node->fl_entry);
	spin_lock(&mm->unused_lock);
	if (mm->num_unused < MM_UNUSED_TARGET) {
	list_add(&next_node->fl_entry,
	&mm->unused_nodes);
	++mm->num_unused;
	} else
	kfree(next_node);
	spin_unlock(&mm->unused_lock);
	} else {
	next_node->size += cur->size;
	next_node->start = cur->start;
	merged = 1;
	}
	}
	}
	if (!merged) {
	cur->free = 1;
	list_add(&cur->fl_entry, &mm->fl_entry);
	} else {
	list_del(&cur->ml_entry);
	spin_lock(&mm->unused_lock);
	if (mm->num_unused < MM_UNUSED_TARGET) {
	list_add(&cur->fl_entry, &mm->unused_nodes);
	++mm->num_unused;
	} else
	kfree(cur);
	spin_unlock(&mm->unused_lock);
	}
	}

	EXPORT_SYMBOL(drm_mm_put_block);

	struct drm_mm_node drm_mm_search_free(const struct drm_mm mm,
	unsigned long size,
	unsigned alignment, int best_match)
	{
	struct list_head *list;
	const struct list_head *free_stack = &mm->fl_entry;
	struct drm_mm_node *entry;
	struct drm_mm_node *best;
	unsigned long best_size;
	unsigned wasted;

	best = NULL;
	best_size = ~0UL;

	list_for_each(list, free_stack) {
	entry = list_entry(list, struct drm_mm_node, fl_entry);
	wasted = 0;

	if (entry->size < size)
	continue;

	if (alignment) {
	register unsigned tmp = entry->start % alignment;
	if (tmp)
	wasted += alignment - tmp;
	}

	if (entry->size >= size + wasted) {
	if (!best_match)
	return entry;
	if (entry->size < best_size) {
	best = entry;
	best_size = entry->size;
	}
	}
	}

	return best;
	}
	EXPORT_SYMBOL(drm_mm_search_free);

	struct drm_mm_node drm_mm_search_free_in_range(const struct drm_mm mm,
	unsigned long size,
	unsigned alignment,
	unsigned long start,
	unsigned long end,
	int best_match)
	{
	struct list_head *list;
	const struct list_head *free_stack = &mm->fl_entry;
	struct drm_mm_node *entry;
	struct drm_mm_node *best;
	unsigned long best_size;
	unsigned wasted;

	best = NULL;
	best_size = ~0UL;

	list_for_each(list, free_stack) {
	entry = list_entry(list, struct drm_mm_node, fl_entry);
	wasted = 0;

	if (entry->size < size)
	continue;

	if (entry->start > end \|\| (entry->start+entry->size) < start)
	continue;

	if (entry->start < start)
	wasted += start - entry->start;

	if (alignment) {
	register unsigned tmp = (entry->start + wasted) % alignment;
	if (tmp)
	wasted += alignment - tmp;
	}

	if (entry->size >= size + wasted &&
	(entry->start + wasted + size) <= end) {
	if (!best_match)
	return entry;
	if (entry->size < best_size) {
	best = entry;
	best_size = entry->size;
	}
	}
	}

	return best;
	}
	EXPORT_SYMBOL(drm_mm_search_free_in_range);

	int drm_mm_clean(struct drm_mm * mm)
	{
	struct list_head *head = &mm->ml_entry;

	return (head->next->next == head);
	}
	EXPORT_SYMBOL(drm_mm_clean);

	int drm_mm_init(struct drm_mm * mm, unsigned long start, unsigned long size)
	{
	INIT_LIST_HEAD(&mm->ml_entry);
	INIT_LIST_HEAD(&mm->fl_entry);
	INIT_LIST_HEAD(&mm->unused_nodes);
	mm->num_unused = 0;
	spin_lock_init(&mm->unused_lock);

	return drm_mm_create_tail_node(mm, start, size, 0);
	}
	EXPORT_SYMBOL(drm_mm_init);

	void drm_mm_takedown(struct drm_mm * mm)
	{
	struct list_head *bnode = mm->fl_entry.next;
	struct drm_mm_node *entry;
	struct drm_mm_node *next;

	entry = list_entry(bnode, struct drm_mm_node, fl_entry);

	if (entry->ml_entry.next != &mm->ml_entry \|\|
	entry->fl_entry.next != &mm->fl_entry) {
	DRM_ERROR("Memory manager not clean. Delaying takedown\n");
	return;
	}

	list_del(&entry->fl_entry);
	list_del(&entry->ml_entry);
	kfree(entry);

	spin_lock(&mm->unused_lock);
	list_for_each_entry_safe(entry, next, &mm->unused_nodes, fl_entry) {
	list_del(&entry->fl_entry);
	kfree(entry);
	--mm->num_unused;
	}
	spin_unlock(&mm->unused_lock);

	BUG_ON(mm->num_unused != 0);
	}
	EXPORT_SYMBOL(drm_mm_takedown);

	void drm_mm_debug_table(struct drm_mm mm, const char prefix)
	{
	struct drm_mm_node *entry;
	int total_used = 0, total_free = 0, total = 0;

	list_for_each_entry(entry, &mm->ml_entry, ml_entry) {
	printk(KERN_DEBUG "%s 0x%08lx-0x%08lx: %8ld: %s\n",
	prefix, entry->start, entry->start + entry->size,
	entry->size, entry->free ? "free" : "used");
	total += entry->size;
	if (entry->free)
	total_free += entry->size;
	else
	total_used += entry->size;
	}
	printk(KERN_DEBUG "%s total: %d, used %d free %d\n", prefix, total,
	total_used, total_free);
	}
	EXPORT_SYMBOL(drm_mm_debug_table);

	#if defined(CONFIG_DEBUG_FS)
	int drm_mm_dump_table(struct seq_file m, struct drm_mm mm)
	{
	struct drm_mm_node *entry;
	int total_used = 0, total_free = 0, total = 0;

	list_for_each_entry(entry, &mm->ml_entry, ml_entry) {
	seq_printf(m, "0x%08lx-0x%08lx: 0x%08lx: %s\n", entry->start, entry->start + entry->size, entry->size, entry->free ? "free" : "used");
	total += entry->size;
	if (entry->free)
	total_free += entry->size;
	else
	total_used += entry->size;
	}
	seq_printf(m, "total: %d, used %d free %d\n", total, total_used, total_free);
	return 0;
	}
	EXPORT_SYMBOL(drm_mm_dump_table);
	#endif