drivers/char/drm/drm_mm.c - maze/linux - 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 <linux/slab.h>

 unsigned long drm_mm_tail_space(drm_mm_t *mm)
 {
 	struct list_head *tail_node;
 	drm_mm_node_t *entry;

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

 	return entry->size;
 }

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

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

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

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


 static int drm_mm_create_tail_node(drm_mm_t *mm,
 			    unsigned long start,
 			    unsigned long size)
 {
 	drm_mm_node_t *child;

 	child = (drm_mm_node_t *)
 		drm_alloc(sizeof(*child), DRM_MEM_MM);
 	if (!child)
 		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(drm_mm_t *mm, unsigned long size)
 {
 	struct list_head *tail_node;
 	drm_mm_node_t *entry;

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

 static drm_mm_node_t *drm_mm_split_at_start(drm_mm_node_t *parent,
 					    unsigned long size)
 {
 	drm_mm_node_t *child;

 	child = (drm_mm_node_t *)
 		drm_alloc(sizeof(*child), DRM_MEM_MM);
 	if (!child)
 		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;
 }


 drm_mm_node_t *drm_mm_get_block(drm_mm_node_t * parent,
 				unsigned long size, unsigned alignment)
 {

 	drm_mm_node_t *align_splitoff = NULL;
 	drm_mm_node_t *child;
 	unsigned tmp = 0;

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

 	if (tmp) {
 		align_splitoff = drm_mm_split_at_start(parent, alignment - tmp);
 		if (!align_splitoff)
 			return NULL;
 	}

 	if (parent->size == size) {
 		list_del_init(&parent->fl_entry);
 		parent->free = 0;
 		return parent;
 	} else {
 		child = drm_mm_split_at_start(parent, size);
 	}

 	if (align_splitoff)
 		drm_mm_put_block(align_splitoff);

 	return child;
 }

 /*
  * 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(drm_mm_node_t * cur)
 {

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

 	int merged = 0;

 	if (cur_head->prev != root_head) {
 		prev_node = list_entry(cur_head->prev, drm_mm_node_t, 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, drm_mm_node_t, 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);
 				drm_free(next_node, sizeof(*next_node),
 					 DRM_MEM_MM);
 			} 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);
 		drm_free(cur, sizeof(*cur), DRM_MEM_MM);
 	}
 }

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

 	best = NULL;
 	best_size = ~0UL;

 	list_for_each(list, free_stack) {
 		entry = list_entry(list, drm_mm_node_t, 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 (size < best_size) {
 				best = entry;
 				best_size = entry->size;
 			}
 		}
 	}

 	return best;
 }

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

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

 int drm_mm_init(drm_mm_t * mm, unsigned long start, unsigned long size)
 {
 	INIT_LIST_HEAD(&mm->ml_entry);
 	INIT_LIST_HEAD(&mm->fl_entry);

 	return drm_mm_create_tail_node(mm, start, size);
 }

 EXPORT_SYMBOL(drm_mm_init);

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

 	entry = list_entry(bnode, drm_mm_node_t, 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);

 	drm_free(entry, sizeof(*entry), DRM_MEM_MM);
 }

 EXPORT_SYMBOL(drm_mm_takedown);
	/**************************************************************************
	*
	* 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 <linux/slab.h>

	unsigned long drm_mm_tail_space(drm_mm_t *mm)
	{
	struct list_head *tail_node;
	drm_mm_node_t *entry;

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

	return entry->size;
	}

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

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

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

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


	static int drm_mm_create_tail_node(drm_mm_t *mm,
	unsigned long start,
	unsigned long size)
	{
	drm_mm_node_t *child;

	child = (drm_mm_node_t *)
	drm_alloc(sizeof(*child), DRM_MEM_MM);
	if (!child)
	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(drm_mm_t *mm, unsigned long size)
	{
	struct list_head *tail_node;
	drm_mm_node_t *entry;

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

	static drm_mm_node_t drm_mm_split_at_start(drm_mm_node_t parent,
	unsigned long size)
	{
	drm_mm_node_t *child;

	child = (drm_mm_node_t *)
	drm_alloc(sizeof(*child), DRM_MEM_MM);
	if (!child)
	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;
	}



	drm_mm_node_t drm_mm_get_block(drm_mm_node_t parent,
	unsigned long size, unsigned alignment)
	{

	drm_mm_node_t *align_splitoff = NULL;
	drm_mm_node_t *child;
	unsigned tmp = 0;

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

	if (tmp) {
	align_splitoff = drm_mm_split_at_start(parent, alignment - tmp);
	if (!align_splitoff)
	return NULL;
	}

	if (parent->size == size) {
	list_del_init(&parent->fl_entry);
	parent->free = 0;
	return parent;
	} else {
	child = drm_mm_split_at_start(parent, size);
	}

	if (align_splitoff)
	drm_mm_put_block(align_splitoff);

	return child;
	}

	/*
	* 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(drm_mm_node_t * cur)
	{

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

	int merged = 0;

	if (cur_head->prev != root_head) {
	prev_node = list_entry(cur_head->prev, drm_mm_node_t, 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, drm_mm_node_t, 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);
	drm_free(next_node, sizeof(*next_node),
	DRM_MEM_MM);
	} 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);
	drm_free(cur, sizeof(*cur), DRM_MEM_MM);
	}
	}

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

	best = NULL;
	best_size = ~0UL;

	list_for_each(list, free_stack) {
	entry = list_entry(list, drm_mm_node_t, 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 (size < best_size) {
	best = entry;
	best_size = entry->size;
	}
	}
	}

	return best;
	}

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

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

	int drm_mm_init(drm_mm_t * mm, unsigned long start, unsigned long size)
	{
	INIT_LIST_HEAD(&mm->ml_entry);
	INIT_LIST_HEAD(&mm->fl_entry);

	return drm_mm_create_tail_node(mm, start, size);
	}

	EXPORT_SYMBOL(drm_mm_init);

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

	entry = list_entry(bnode, drm_mm_node_t, 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);

	drm_free(entry, sizeof(*entry), DRM_MEM_MM);
	}

	EXPORT_SYMBOL(drm_mm_takedown);