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/**************************************************************************

 *

 * 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 

 */

#include "drmP.h"

#include "drm_mm.h"

#include 

#include 

#define MM_UNUSED_TARGET 4

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

{

	struct drm_mm_node *child;

	if (atomic)

		child = kzalloc(sizeof(*child), GFP_ATOMIC);

	else

		child = kzalloc(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, node_list);

			list_del(&child->node_list);

			--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 = kzalloc(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->node_list, &mm->unused_nodes);

	}

	spin_unlock(&mm->unused_lock);

	return 0;

}

EXPORT_SYMBOL(drm_mm_pre_get);

static inline unsigned long drm_mm_hole_node_start(struct drm_mm_node *hole_node)

{

	return hole_node->start + hole_node->size;

}

static inline unsigned long drm_mm_hole_node_end(struct drm_mm_node *hole_node)

{

	struct drm_mm_node *next_node =

		list_entry(hole_node->node_list.next, struct drm_mm_node,

			   node_list);

	return next_node->start;

}

static void drm_mm_insert_helper(struct drm_mm_node *hole_node,

				 struct drm_mm_node *node,

				 unsigned long size, unsigned alignment)

{

	struct drm_mm *mm = hole_node->mm;

	unsigned long tmp = 0, wasted = 0;

	unsigned long hole_start = drm_mm_hole_node_start(hole_node);

	unsigned long hole_end = drm_mm_hole_node_end(hole_node);

	BUG_ON(!hole_node->hole_follows || node->allocated);

	if (alignment)

		tmp = hole_start % alignment;

	if (!tmp) {

		hole_node->hole_follows = 0;

		list_del_init(&hole_node->hole_stack);

	} else

		wasted = alignment - tmp;

	node->start = hole_start + wasted;

	node->size = size;

	node->mm = mm;

	node->allocated = 1;

	INIT_LIST_HEAD(&node->hole_stack);

	list_add(&node->node_list, &hole_node->node_list);

	BUG_ON(node->start + node->size > hole_end);

	if (node->start + node->size < hole_end) {

		list_add(&node->hole_stack, &mm->hole_stack);

		node->hole_follows = 1;

	} else {

		node->hole_follows = 0;

	}

}

struct drm_mm_node *drm_mm_get_block_generic(struct drm_mm_node *hole_node,

						 unsigned long size,

					     unsigned alignment,

						 int atomic)

{

	struct drm_mm_node *node;

	node = drm_mm_kmalloc(hole_node->mm, atomic);

	if (unlikely(node == NULL))

		return NULL;

	drm_mm_insert_helper(hole_node, node, size, alignment);

	return node;

}

EXPORT_SYMBOL(drm_mm_get_block_generic);

/**

 * Search for free space and insert a preallocated memory node. Returns

 * -ENOSPC if no suitable free area is available. The preallocated memory node

 * must be cleared.

 */

int drm_mm_insert_node(struct drm_mm *mm, struct drm_mm_node *node,

		       unsigned long size, unsigned alignment)

{

	struct drm_mm_node *hole_node;

	hole_node = drm_mm_search_free(mm, size, alignment, 0);

	if (!hole_node)

		return -ENOSPC;

	drm_mm_insert_helper(hole_node, node, size, alignment);

	return 0;

}

EXPORT_SYMBOL(drm_mm_insert_node);

static void drm_mm_insert_helper_range(struct drm_mm_node *hole_node,

				       struct drm_mm_node *node,

				       unsigned long size, unsigned alignment,

				       unsigned long start, unsigned long end)

{

	struct drm_mm *mm = hole_node->mm;

	unsigned long tmp = 0, wasted = 0;

	unsigned long hole_start = drm_mm_hole_node_start(hole_node);

	unsigned long hole_end = drm_mm_hole_node_end(hole_node);

	BUG_ON(!hole_node->hole_follows || node->allocated);

	if (hole_start < start)

		wasted += start - hole_start;

	if (alignment)

		tmp = (hole_start + wasted) % alignment;

	if (tmp)

		wasted += alignment - tmp;

	if (!wasted) {

		hole_node->hole_follows = 0;

		list_del_init(&hole_node->hole_stack);

	}

	node->start = hole_start + wasted;

	node->size = size;

	node->mm = mm;

	node->allocated = 1;

	INIT_LIST_HEAD(&node->hole_stack);

	list_add(&node->node_list, &hole_node->node_list);

	BUG_ON(node->start + node->size > hole_end);

	BUG_ON(node->start + node->size > end);

	if (node->start + node->size < hole_end) {

		list_add(&node->hole_stack, &mm->hole_stack);

		node->hole_follows = 1;

	} else {

		node->hole_follows = 0;

	}

}

struct drm_mm_node *drm_mm_get_block_range_generic(struct drm_mm_node *hole_node,

						unsigned long size,

						unsigned alignment,

						unsigned long start,

						unsigned long end,

						int atomic)

{

	struct drm_mm_node *node;

	node = drm_mm_kmalloc(hole_node->mm, atomic);

	if (unlikely(node == NULL))

			return NULL;

	drm_mm_insert_helper_range(hole_node, node, size, alignment,

				   start, end);

	return node;

}

EXPORT_SYMBOL(drm_mm_get_block_range_generic);

/**

 * Search for free space and insert a preallocated memory node. Returns

 * -ENOSPC if no suitable free area is available. This is for range

 * restricted allocations. The preallocated memory node must be cleared.

 */

int drm_mm_insert_node_in_range(struct drm_mm *mm, struct drm_mm_node *node,

				unsigned long size, unsigned alignment,

				unsigned long start, unsigned long end)

{

	struct drm_mm_node *hole_node;

	hole_node = drm_mm_search_free_in_range(mm, size, alignment,

						start, end, 0);

	if (!hole_node)

		return -ENOSPC;

	drm_mm_insert_helper_range(hole_node, node, size, alignment,

				   start, end);

	return 0;

}

EXPORT_SYMBOL(drm_mm_insert_node_in_range);

/**

 * Remove a memory node from the allocator.

 */

void drm_mm_remove_node(struct drm_mm_node *node)

{

	struct drm_mm *mm = node->mm;

	struct drm_mm_node *prev_node;

	BUG_ON(node->scanned_block || node->scanned_prev_free

				   || node->scanned_next_free);

	prev_node =

	    list_entry(node->node_list.prev, struct drm_mm_node, node_list);

	if (node->hole_follows) {

		BUG_ON(drm_mm_hole_node_start(node)

				== drm_mm_hole_node_end(node));

		list_del(&node->hole_stack);

	} else

		BUG_ON(drm_mm_hole_node_start(node)

				!= drm_mm_hole_node_end(node));

	if (!prev_node->hole_follows) {

		prev_node->hole_follows = 1;

		list_add(&prev_node->hole_stack, &mm->hole_stack);

				} else

		list_move(&prev_node->hole_stack, &mm->hole_stack);

	list_del(&node->node_list);

	node->allocated = 0;

}

EXPORT_SYMBOL(drm_mm_remove_node);

/*

 * Remove a memory node from the allocator and free the allocated struct

 * drm_mm_node. Only to be used on a struct drm_mm_node obtained by one of the

 * drm_mm_get_block functions.

 */

void drm_mm_put_block(struct drm_mm_node *node)

{

	struct drm_mm *mm = node->mm;

	drm_mm_remove_node(node);

		spin_lock(&mm->unused_lock);

		if (mm->num_unused < MM_UNUSED_TARGET) {

		list_add(&node->node_list, &mm->unused_nodes);

			++mm->num_unused;

		} else

		kfree(node);

		spin_unlock(&mm->unused_lock);

}

EXPORT_SYMBOL(drm_mm_put_block);

static int check_free_hole(unsigned long start, unsigned long end,

			   unsigned long size, unsigned alignment)

{

	unsigned wasted = 0;

	if (end - start < size)

		return 0;

	if (alignment) {

		unsigned tmp = start % alignment;

		if (tmp)

			wasted = alignment - tmp;

	}

	if (end >= start + size + wasted) {

		return 1;

	}

	return 0;

}

struct drm_mm_node *drm_mm_search_free(const struct drm_mm *mm,

				       unsigned long size,

				       unsigned alignment, int best_match)

{

	struct drm_mm_node *entry;

	struct drm_mm_node *best;

	unsigned long best_size;

	BUG_ON(mm->scanned_blocks);

	best = NULL;

	best_size = ~0UL;

	list_for_each_entry(entry, &mm->hole_stack, hole_stack) {

		BUG_ON(!entry->hole_follows);

		if (!check_free_hole(drm_mm_hole_node_start(entry),

				     drm_mm_hole_node_end(entry),

				     size, alignment))

			continue;

			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 drm_mm_node *entry;

	struct drm_mm_node *best;

	unsigned long best_size;

	BUG_ON(mm->scanned_blocks);

	best = NULL;

	best_size = ~0UL;

	list_for_each_entry(entry, &mm->hole_stack, hole_stack) {

		unsigned long adj_start = drm_mm_hole_node_start(entry) < start ?

			start : drm_mm_hole_node_start(entry);

		unsigned long adj_end = drm_mm_hole_node_end(entry) > end ?

			end : drm_mm_hole_node_end(entry);

		BUG_ON(!entry->hole_follows);

		if (!check_free_hole(adj_start, adj_end, size, alignment))

			continue;

			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);

/**

 * Moves an allocation. To be used with embedded struct drm_mm_node.

 */

void drm_mm_replace_node(struct drm_mm_node *old, struct drm_mm_node *new)

{

	list_replace(&old->node_list, &new->node_list);

	list_replace(&old->hole_stack, &new->hole_stack);

	new->hole_follows = old->hole_follows;

	new->mm = old->mm;

	new->start = old->start;

	new->size = old->size;

	old->allocated = 0;

	new->allocated = 1;

}

EXPORT_SYMBOL(drm_mm_replace_node);

/**

 * Initializa lru scanning.

 *

 * This simply sets up the scanning routines with the parameters for the desired

 * hole.

 *

 * Warning: As long as the scan list is non-empty, no other operations than

 * adding/removing nodes to/from the scan list are allowed.

 */

void drm_mm_init_scan(struct drm_mm *mm, unsigned long size,

		      unsigned alignment)

{

	mm->scan_alignment = alignment;

	mm->scan_size = size;

	mm->scanned_blocks = 0;

	mm->scan_hit_start = 0;

	mm->scan_hit_size = 0;

	mm->scan_check_range = 0;

	mm->prev_scanned_node = NULL;

}

EXPORT_SYMBOL(drm_mm_init_scan);

/**

 * Initializa lru scanning.

 *

 * This simply sets up the scanning routines with the parameters for the desired

 * hole. This version is for range-restricted scans.

 *

 * Warning: As long as the scan list is non-empty, no other operations than

 * adding/removing nodes to/from the scan list are allowed.

 */

void drm_mm_init_scan_with_range(struct drm_mm *mm, unsigned long size,

				 unsigned alignment,

				 unsigned long start,

				 unsigned long end)

{

	mm->scan_alignment = alignment;

	mm->scan_size = size;

	mm->scanned_blocks = 0;

	mm->scan_hit_start = 0;

	mm->scan_hit_size = 0;

	mm->scan_start = start;

	mm->scan_end = end;

	mm->scan_check_range = 1;

	mm->prev_scanned_node = NULL;

}

EXPORT_SYMBOL(drm_mm_init_scan_with_range);

/**

 * Add a node to the scan list that might be freed to make space for the desired

 * hole.

 *

 * Returns non-zero, if a hole has been found, zero otherwise.

 */

int drm_mm_scan_add_block(struct drm_mm_node *node)

{

	struct drm_mm *mm = node->mm;

	struct drm_mm_node *prev_node;

	unsigned long hole_start, hole_end;

	unsigned long adj_start;

	unsigned long adj_end;

	mm->scanned_blocks++;

	BUG_ON(node->scanned_block);

	node->scanned_block = 1;

		prev_node = list_entry(node->node_list.prev, struct drm_mm_node,

				       node_list);

	node->scanned_preceeds_hole = prev_node->hole_follows;

	prev_node->hole_follows = 1;

	list_del(&node->node_list);

	node->node_list.prev = &prev_node->node_list;

	node->node_list.next = &mm->prev_scanned_node->node_list;

	mm->prev_scanned_node = node;

	hole_start = drm_mm_hole_node_start(prev_node);

	hole_end = drm_mm_hole_node_end(prev_node);

	if (mm->scan_check_range) {

		adj_start = hole_start < mm->scan_start ?

			mm->scan_start : hole_start;

		adj_end = hole_end > mm->scan_end ?

			mm->scan_end : hole_end;

	} else {

		adj_start = hole_start;

		adj_end = hole_end;

	}

	if (check_free_hole(adj_start , adj_end,

			    mm->scan_size, mm->scan_alignment)) {

		mm->scan_hit_start = hole_start;

		mm->scan_hit_size = hole_end;

		return 1;

	}

	return 0;

}

EXPORT_SYMBOL(drm_mm_scan_add_block);

/**

 * Remove a node from the scan list.

 *

 * Nodes _must_ be removed in the exact same order from the scan list as they

 * have been added, otherwise the internal state of the memory manager will be

 * corrupted.

 *

 * When the scan list is empty, the selected memory nodes can be freed. An

 * immediately following drm_mm_search_free with best_match = 0 will then return

 * the just freed block (because its at the top of the free_stack list).

 *

 * Returns one if this block should be evicted, zero otherwise. Will always

 * return zero when no hole has been found.

 */

int drm_mm_scan_remove_block(struct drm_mm_node *node)

{

	struct drm_mm *mm = node->mm;

	struct drm_mm_node *prev_node;

	mm->scanned_blocks--;

	BUG_ON(!node->scanned_block);

	node->scanned_block = 0;

	prev_node = list_entry(node->node_list.prev, struct drm_mm_node,

			       node_list);

	prev_node->hole_follows = node->scanned_preceeds_hole;

	INIT_LIST_HEAD(&node->node_list);

	list_add(&node->node_list, &prev_node->node_list);

	/* Only need to check for containement because start&size for the

	 * complete resulting free block (not just the desired part) is

	 * stored. */

	if (node->start >= mm->scan_hit_start &&

	    node->start + node->size

	    		<= mm->scan_hit_start + mm->scan_hit_size) {

		return 1;

	}

	return 0;

}

EXPORT_SYMBOL(drm_mm_scan_remove_block);

int drm_mm_clean(struct drm_mm * mm)

{

	struct list_head *head = &mm->head_node.node_list;

	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->hole_stack);

	INIT_LIST_HEAD(&mm->unused_nodes);

	mm->num_unused = 0;

	mm->scanned_blocks = 0;

	spin_lock_init(&mm->unused_lock);

	/* Clever trick to avoid a special case in the free hole tracking. */

	INIT_LIST_HEAD(&mm->head_node.node_list);

	INIT_LIST_HEAD(&mm->head_node.hole_stack);

	mm->head_node.hole_follows = 1;

	mm->head_node.scanned_block = 0;

	mm->head_node.scanned_prev_free = 0;

	mm->head_node.scanned_next_free = 0;

	mm->head_node.mm = mm;

	mm->head_node.start = start + size;

	mm->head_node.size = start - mm->head_node.start;

	list_add_tail(&mm->head_node.hole_stack, &mm->hole_stack);

	return 0;

}

EXPORT_SYMBOL(drm_mm_init);

void drm_mm_takedown(struct drm_mm * mm)

{

	struct drm_mm_node *entry, *next;

	if (!list_empty(&mm->head_node.node_list)) {

		DRM_ERROR("Memory manager not clean. Delaying takedown\n");

		return;

	}

	spin_lock(&mm->unused_lock);

	list_for_each_entry_safe(entry, next, &mm->unused_nodes, node_list) {

	list_del(&entry->node_list);

	kfree(entry);

		--mm->num_unused;

	}

	spin_unlock(&mm->unused_lock);

	BUG_ON(mm->num_unused != 0);

}

EXPORT_SYMBOL(drm_mm_takedown);