1 files changed, 587 insertions, 390 deletions

diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
index c59515ba7e6..04a209e2b66 100644
--- a/drivers/gpu/drm/drm_mm.c
+++ b/drivers/gpu/drm/drm_mm.c
@@ -41,277 +41,377 @@
  * Thomas Hellström <thomas-at-tungstengraphics-dot-com>
  */
 
-#include "drmP.h"
-#include "drm_mm.h"
+#include <drm/drmP.h>
+#include <drm/drm_mm.h>
 #include <linux/slab.h>
 #include <linux/seq_file.h>
+#include <linux/export.h>
 
-#define MM_UNUSED_TARGET 4
+/**
+ * DOC: Overview
+ *
+ * drm_mm provides a simple range allocator. The drivers are free to use the
+ * resource allocator from the linux core if it suits them, the upside of drm_mm
+ * is that it's in the DRM core. Which means that it's easier to extend for
+ * some of the crazier special purpose needs of gpus.
+ *
+ * The main data struct is &drm_mm, allocations are tracked in &drm_mm_node.
+ * Drivers are free to embed either of them into their own suitable
+ * datastructures. drm_mm itself will not do any allocations of its own, so if
+ * drivers choose not to embed nodes they need to still allocate them
+ * themselves.
+ *
+ * The range allocator also supports reservation of preallocated blocks. This is
+ * useful for taking over initial mode setting configurations from the firmware,
+ * where an object needs to be created which exactly matches the firmware's
+ * scanout target. As long as the range is still free it can be inserted anytime
+ * after the allocator is initialized, which helps with avoiding looped
+ * depencies in the driver load sequence.
+ *
+ * drm_mm maintains a stack of most recently freed holes, which of all
+ * simplistic datastructures seems to be a fairly decent approach to clustering
+ * allocations and avoiding too much fragmentation. This means free space
+ * searches are O(num_holes). Given that all the fancy features drm_mm supports
+ * something better would be fairly complex and since gfx thrashing is a fairly
+ * steep cliff not a real concern. Removing a node again is O(1).
+ *
+ * drm_mm supports a few features: Alignment and range restrictions can be
+ * supplied. Further more every &drm_mm_node has a color value (which is just an
+ * opaqua unsigned long) which in conjunction with a driver callback can be used
+ * to implement sophisticated placement restrictions. The i915 DRM driver uses
+ * this to implement guard pages between incompatible caching domains in the
+ * graphics TT.
+ *
+ * Two behaviors are supported for searching and allocating: bottom-up and top-down.
+ * The default is bottom-up. Top-down allocation can be used if the memory area
+ * has different restrictions, or just to reduce fragmentation.
+ *
+ * Finally iteration helpers to walk all nodes and all holes are provided as are
+ * some basic allocator dumpers for debugging.
+ */
 
-static struct drm_mm_node *drm_mm_kmalloc(struct drm_mm *mm, int atomic)
+static struct drm_mm_node *drm_mm_search_free_generic(const struct drm_mm *mm,
+						unsigned long size,
+						unsigned alignment,
+						unsigned long color,
+						enum drm_mm_search_flags flags);
+static struct drm_mm_node *drm_mm_search_free_in_range_generic(const struct drm_mm *mm,
+						unsigned long size,
+						unsigned alignment,
+						unsigned long color,
+						unsigned long start,
+						unsigned long end,
+						enum drm_mm_search_flags flags);
+
+static void drm_mm_insert_helper(struct drm_mm_node *hole_node,
+				 struct drm_mm_node *node,
+				 unsigned long size, unsigned alignment,
+				 unsigned long color,
+				 enum drm_mm_allocator_flags flags)
 {
-	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, free_stack);
-			list_del(&child->free_stack);
-			--mm->num_unused;
+	struct drm_mm *mm = hole_node->mm;
+	unsigned long hole_start = drm_mm_hole_node_start(hole_node);
+	unsigned long hole_end = drm_mm_hole_node_end(hole_node);
+	unsigned long adj_start = hole_start;
+	unsigned long adj_end = hole_end;
+
+	BUG_ON(node->allocated);
+
+	if (mm->color_adjust)
+		mm->color_adjust(hole_node, color, &adj_start, &adj_end);
+
+	if (flags & DRM_MM_CREATE_TOP)
+		adj_start = adj_end - size;
+
+	if (alignment) {
+		unsigned tmp = adj_start % alignment;
+		if (tmp) {
+			if (flags & DRM_MM_CREATE_TOP)
+				adj_start -= tmp;
+			else
+				adj_start += alignment - tmp;
 		}
-		spin_unlock(&mm->unused_lock);
 	}
-	return child;
+
+	BUG_ON(adj_start < hole_start);
+	BUG_ON(adj_end > hole_end);
+
+	if (adj_start == hole_start) {
+		hole_node->hole_follows = 0;
+		list_del(&hole_node->hole_stack);
+	}
+
+	node->start = adj_start;
+	node->size = size;
+	node->mm = mm;
+	node->color = color;
+	node->allocated = 1;
+
+	INIT_LIST_HEAD(&node->hole_stack);
+	list_add(&node->node_list, &hole_node->node_list);
+
+	BUG_ON(node->start + node->size > adj_end);
+
+	node->hole_follows = 0;
+	if (__drm_mm_hole_node_start(node) < hole_end) {
+		list_add(&node->hole_stack, &mm->hole_stack);
+		node->hole_follows = 1;
+	}
 }
 
-/* drm_mm_pre_get() - pre allocate drm_mm_node structure
- * drm_mm:	memory manager struct we are pre-allocating for
+/**
+ * drm_mm_reserve_node - insert an pre-initialized node
+ * @mm: drm_mm allocator to insert @node into
+ * @node: drm_mm_node to insert
+ *
+ * This functions inserts an already set-up drm_mm_node into the allocator,
+ * meaning that start, size and color must be set by the caller. This is useful
+ * to initialize the allocator with preallocated objects which must be set-up
+ * before the range allocator can be set-up, e.g. when taking over a firmware
+ * framebuffer.
  *
- * Returns 0 on success or -ENOMEM if allocation fails.
+ * Returns:
+ * 0 on success, -ENOSPC if there's no hole where @node is.
  */
-int drm_mm_pre_get(struct drm_mm *mm)
+int drm_mm_reserve_node(struct drm_mm *mm, struct drm_mm_node *node)
 {
-	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->free_stack, &mm->unused_nodes);
-	}
-	spin_unlock(&mm->unused_lock);
-	return 0;
-}
-EXPORT_SYMBOL(drm_mm_pre_get);
+	struct drm_mm_node *hole;
+	unsigned long end = node->start + node->size;
+	unsigned long hole_start;
+	unsigned long hole_end;
 
-static int drm_mm_create_tail_node(struct drm_mm *mm,
-				   unsigned long start,
-				   unsigned long size, int atomic)
-{
-	struct drm_mm_node *child;
+	BUG_ON(node == NULL);
 
-	child = drm_mm_kmalloc(mm, atomic);
-	if (unlikely(child == NULL))
-		return -ENOMEM;
+	/* Find the relevant hole to add our node to */
+	drm_mm_for_each_hole(hole, mm, hole_start, hole_end) {
+		if (hole_start > node->start || hole_end < end)
+			continue;
 
-	child->free = 1;
-	child->size = size;
-	child->start = start;
-	child->mm = mm;
+		node->mm = mm;
+		node->allocated = 1;
 
-	list_add_tail(&child->node_list, &mm->node_list);
-	list_add_tail(&child->free_stack, &mm->free_stack);
+		INIT_LIST_HEAD(&node->hole_stack);
+		list_add(&node->node_list, &hole->node_list);
 
-	return 0;
-}
+		if (node->start == hole_start) {
+			hole->hole_follows = 0;
+			list_del_init(&hole->hole_stack);
+		}
 
-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;
+		node->hole_follows = 0;
+		if (end != hole_end) {
+			list_add(&node->hole_stack, &mm->hole_stack);
+			node->hole_follows = 1;
+		}
 
-	child = drm_mm_kmalloc(parent->mm, atomic);
-	if (unlikely(child == NULL))
-		return NULL;
+		return 0;
+	}
 
-	INIT_LIST_HEAD(&child->free_stack);
+	return -ENOSPC;
+}
+EXPORT_SYMBOL(drm_mm_reserve_node);
 
-	child->size = size;
-	child->start = parent->start;
-	child->mm = parent->mm;
+/**
+ * drm_mm_insert_node_generic - search for space and insert @node
+ * @mm: drm_mm to allocate from
+ * @node: preallocate node to insert
+ * @size: size of the allocation
+ * @alignment: alignment of the allocation
+ * @color: opaque tag value to use for this node
+ * @sflags: flags to fine-tune the allocation search
+ * @aflags: flags to fine-tune the allocation behavior
+ *
+ * The preallocated node must be cleared to 0.
+ *
+ * Returns:
+ * 0 on success, -ENOSPC if there's no suitable hole.
+ */
+int drm_mm_insert_node_generic(struct drm_mm *mm, struct drm_mm_node *node,
+			       unsigned long size, unsigned alignment,
+			       unsigned long color,
+			       enum drm_mm_search_flags sflags,
+			       enum drm_mm_allocator_flags aflags)
+{
+	struct drm_mm_node *hole_node;
 
-	list_add_tail(&child->node_list, &parent->node_list);
-	INIT_LIST_HEAD(&child->free_stack);
+	hole_node = drm_mm_search_free_generic(mm, size, alignment,
+					       color, sflags);
+	if (!hole_node)
+		return -ENOSPC;
 
-	parent->size -= size;
-	parent->start += size;
-	return child;
+	drm_mm_insert_helper(hole_node, node, size, alignment, color, aflags);
+	return 0;
 }
+EXPORT_SYMBOL(drm_mm_insert_node_generic);
+
+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 color,
+				       unsigned long start, unsigned long end,
+				       enum drm_mm_allocator_flags flags)
+{
+	struct drm_mm *mm = hole_node->mm;
+	unsigned long hole_start = drm_mm_hole_node_start(hole_node);
+	unsigned long hole_end = drm_mm_hole_node_end(hole_node);
+	unsigned long adj_start = hole_start;
+	unsigned long adj_end = hole_end;
 
+	BUG_ON(!hole_node->hole_follows || node->allocated);
 
-struct drm_mm_node *drm_mm_get_block_generic(struct drm_mm_node *node,
-					     unsigned long size,
-					     unsigned alignment,
-					     int atomic)
-{
+	if (adj_start < start)
+		adj_start = start;
+	if (adj_end > end)
+		adj_end = end;
 
-	struct drm_mm_node *align_splitoff = NULL;
-	unsigned tmp = 0;
+	if (flags & DRM_MM_CREATE_TOP)
+		adj_start = adj_end - size;
 
-	if (alignment)
-		tmp = node->start % alignment;
+	if (mm->color_adjust)
+		mm->color_adjust(hole_node, color, &adj_start, &adj_end);
 
-	if (tmp) {
-		align_splitoff =
-		    drm_mm_split_at_start(node, alignment - tmp, atomic);
-		if (unlikely(align_splitoff == NULL))
-			return NULL;
+	if (alignment) {
+		unsigned tmp = adj_start % alignment;
+		if (tmp) {
+			if (flags & DRM_MM_CREATE_TOP)
+				adj_start -= tmp;
+			else
+				adj_start += alignment - tmp;
+		}
 	}
 
-	if (node->size == size) {
-		list_del_init(&node->free_stack);
-		node->free = 0;
-	} else {
-		node = drm_mm_split_at_start(node, size, atomic);
+	if (adj_start == hole_start) {
+		hole_node->hole_follows = 0;
+		list_del(&hole_node->hole_stack);
 	}
 
-	if (align_splitoff)
-		drm_mm_put_block(align_splitoff);
+	node->start = adj_start;
+	node->size = size;
+	node->mm = mm;
+	node->color = color;
+	node->allocated = 1;
 
-	return node;
-}
-EXPORT_SYMBOL(drm_mm_get_block_generic);
+	INIT_LIST_HEAD(&node->hole_stack);
+	list_add(&node->node_list, &hole_node->node_list);
 
-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;
-	}
+	BUG_ON(node->start < start);
+	BUG_ON(node->start < adj_start);
+	BUG_ON(node->start + node->size > adj_end);
+	BUG_ON(node->start + node->size > end);
 
-	if (node->size == size) {
-		list_del_init(&node->free_stack);
-		node->free = 0;
-	} else {
-		node = drm_mm_split_at_start(node, size, atomic);
+	node->hole_follows = 0;
+	if (__drm_mm_hole_node_start(node) < hole_end) {
+		list_add(&node->hole_stack, &mm->hole_stack);
+		node->hole_follows = 1;
 	}
+}
+
+/**
+ * drm_mm_insert_node_in_range_generic - ranged search for space and insert @node
+ * @mm: drm_mm to allocate from
+ * @node: preallocate node to insert
+ * @size: size of the allocation
+ * @alignment: alignment of the allocation
+ * @color: opaque tag value to use for this node
+ * @start: start of the allowed range for this node
+ * @end: end of the allowed range for this node
+ * @sflags: flags to fine-tune the allocation search
+ * @aflags: flags to fine-tune the allocation behavior
+ *
+ * The preallocated node must be cleared to 0.
+ *
+ * Returns:
+ * 0 on success, -ENOSPC if there's no suitable hole.
+ */
+int drm_mm_insert_node_in_range_generic(struct drm_mm *mm, struct drm_mm_node *node,
+					unsigned long size, unsigned alignment,
+					unsigned long color,
+					unsigned long start, unsigned long end,
+					enum drm_mm_search_flags sflags,
+					enum drm_mm_allocator_flags aflags)
+{
+	struct drm_mm_node *hole_node;
 
-	if (align_splitoff)
-		drm_mm_put_block(align_splitoff);
+	hole_node = drm_mm_search_free_in_range_generic(mm,
+							size, alignment, color,
+							start, end, sflags);
+	if (!hole_node)
+		return -ENOSPC;
 
-	return node;
+	drm_mm_insert_helper_range(hole_node, node,
+				   size, alignment, color,
+				   start, end, aflags);
+	return 0;
 }
-EXPORT_SYMBOL(drm_mm_get_block_range_generic);
+EXPORT_SYMBOL(drm_mm_insert_node_in_range_generic);
 
-/*
- * Put a block. Merge with the previous and / or next block if they are free.
- * Otherwise add to the free stack.
+/**
+ * drm_mm_remove_node - Remove a memory node from the allocator.
+ * @node: drm_mm_node to remove
+ *
+ * This just removes a node from its drm_mm allocator. The node does not need to
+ * be cleared again before it can be re-inserted into this or any other drm_mm
+ * allocator. It is a bug to call this function on a un-allocated node.
  */
-
-void drm_mm_put_block(struct drm_mm_node *cur)
+void drm_mm_remove_node(struct drm_mm_node *node)
 {
+	struct drm_mm *mm = node->mm;
+	struct drm_mm_node *prev_node;
 
-	struct drm_mm *mm = cur->mm;
-	struct list_head *cur_head = &cur->node_list;
-	struct list_head *root_head = &mm->node_list;
-	struct drm_mm_node *prev_node = NULL;
-	struct drm_mm_node *next_node;
+	if (WARN_ON(!node->allocated))
+		return;
 
-	int merged = 0;
+	BUG_ON(node->scanned_block || node->scanned_prev_free
+				   || node->scanned_next_free);
 
-	BUG_ON(cur->scanned_block || cur->scanned_prev_free
-				  || cur->scanned_next_free);
+	prev_node =
+	    list_entry(node->node_list.prev, struct drm_mm_node, node_list);
 
-	if (cur_head->prev != root_head) {
-		prev_node =
-		    list_entry(cur_head->prev, struct drm_mm_node, node_list);
-		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, node_list);
-		if (next_node->free) {
-			if (merged) {
-				prev_node->size += next_node->size;
-				list_del(&next_node->node_list);
-				list_del(&next_node->free_stack);
-				spin_lock(&mm->unused_lock);
-				if (mm->num_unused < MM_UNUSED_TARGET) {
-					list_add(&next_node->free_stack,
-						 &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->free_stack, &mm->free_stack);
-	} else {
-		list_del(&cur->node_list);
-		spin_lock(&mm->unused_lock);
-		if (mm->num_unused < MM_UNUSED_TARGET) {
-			list_add(&cur->free_stack, &mm->unused_nodes);
-			++mm->num_unused;
-		} else
-			kfree(cur);
-		spin_unlock(&mm->unused_lock);
-	}
-}
+	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);
 
-EXPORT_SYMBOL(drm_mm_put_block);
+	list_del(&node->node_list);
+	node->allocated = 0;
+}
+EXPORT_SYMBOL(drm_mm_remove_node);
 
 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;
+			start += alignment - tmp;
 	}
 
-	if (end >= start + size + wasted) {
-		return 1;
-	}
-
-	return 0;
+	return end >= start + size;
 }
 
-struct drm_mm_node *drm_mm_search_free(const struct drm_mm *mm,
-				       unsigned long size,
-				       unsigned alignment, int best_match)
+static struct drm_mm_node *drm_mm_search_free_generic(const struct drm_mm *mm,
+						      unsigned long size,
+						      unsigned alignment,
+						      unsigned long color,
+						      enum drm_mm_search_flags flags)
 {
 	struct drm_mm_node *entry;
 	struct drm_mm_node *best;
+	unsigned long adj_start;
+	unsigned long adj_end;
 	unsigned long best_size;
 
 	BUG_ON(mm->scanned_blocks);
@@ -319,33 +419,43 @@ struct drm_mm_node *drm_mm_search_free(const struct drm_mm *mm,
 	best = NULL;
 	best_size = ~0UL;
 
-	list_for_each_entry(entry, &mm->free_stack, free_stack) {
-		if (!check_free_hole(entry->start, entry->start + entry->size,
-				     size, alignment))
+	__drm_mm_for_each_hole(entry, mm, adj_start, adj_end,
+			       flags & DRM_MM_SEARCH_BELOW) {
+		unsigned long hole_size = adj_end - adj_start;
+
+		if (mm->color_adjust) {
+			mm->color_adjust(entry, color, &adj_start, &adj_end);
+			if (adj_end <= adj_start)
+				continue;
+		}
+
+		if (!check_free_hole(adj_start, adj_end, size, alignment))
 			continue;
 
-		if (!best_match)
+		if (!(flags & DRM_MM_SEARCH_BEST))
 			return entry;
 
-		if (entry->size < best_size) {
+		if (hole_size < best_size) {
 			best = entry;
-			best_size = entry->size;
+			best_size = hole_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)
+static struct drm_mm_node *drm_mm_search_free_in_range_generic(const struct drm_mm *mm,
+							unsigned long size,
+							unsigned alignment,
+							unsigned long color,
+							unsigned long start,
+							unsigned long end,
+							enum drm_mm_search_flags flags)
 {
 	struct drm_mm_node *entry;
 	struct drm_mm_node *best;
+	unsigned long adj_start;
+	unsigned long adj_end;
 	unsigned long best_size;
 
 	BUG_ON(mm->scanned_blocks);
@@ -353,305 +463,392 @@ struct drm_mm_node *drm_mm_search_free_in_range(const struct drm_mm *mm,
 	best = NULL;
 	best_size = ~0UL;
 
-	list_for_each_entry(entry, &mm->free_stack, free_stack) {
-		unsigned long adj_start = entry->start < start ?
-			start : entry->start;
-		unsigned long adj_end = entry->start + entry->size > end ?
-			end : entry->start + entry->size;
+	__drm_mm_for_each_hole(entry, mm, adj_start, adj_end,
+			       flags & DRM_MM_SEARCH_BELOW) {
+		unsigned long hole_size = adj_end - adj_start;
+
+		if (adj_start < start)
+			adj_start = start;
+		if (adj_end > end)
+			adj_end = end;
+
+		if (mm->color_adjust) {
+			mm->color_adjust(entry, color, &adj_start, &adj_end);
+			if (adj_end <= adj_start)
+				continue;
+		}
 
 		if (!check_free_hole(adj_start, adj_end, size, alignment))
 			continue;
 
-		if (!best_match)
+		if (!(flags & DRM_MM_SEARCH_BEST))
 			return entry;
 
-		if (entry->size < best_size) {
+		if (hole_size < best_size) {
 			best = entry;
-			best_size = entry->size;
+			best_size = hole_size;
 		}
 	}
 
 	return best;
 }
-EXPORT_SYMBOL(drm_mm_search_free_in_range);
 
 /**
- * Initializa lru scanning.
+ * drm_mm_replace_node - move an allocation from @old to @new
+ * @old: drm_mm_node to remove from the allocator
+ * @new: drm_mm_node which should inherit @old's allocation
+ *
+ * This is useful for when drivers embed the drm_mm_node structure and hence
+ * can't move allocations by reassigning pointers. It's a combination of remove
+ * and insert with the guarantee that the allocation start will match.
+ */
+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;
+	new->color = old->color;
+
+	old->allocated = 0;
+	new->allocated = 1;
+}
+EXPORT_SYMBOL(drm_mm_replace_node);
+
+/**
+ * DOC: lru scan roaster
+ *
+ * Very often GPUs need to have continuous allocations for a given object. When
+ * evicting objects to make space for a new one it is therefore not most
+ * efficient when we simply start to select all objects from the tail of an LRU
+ * until there's a suitable hole: Especially for big objects or nodes that
+ * otherwise have special allocation constraints there's a good chance we evict
+ * lots of (smaller) objects unecessarily.
+ *
+ * The DRM range allocator supports this use-case through the scanning
+ * interfaces. First a scan operation needs to be initialized with
+ * drm_mm_init_scan() or drm_mm_init_scan_with_range(). The the driver adds
+ * objects to the roaster (probably by walking an LRU list, but this can be
+ * freely implemented) until a suitable hole is found or there's no further
+ * evitable object.
+ *
+ * The the driver must walk through all objects again in exactly the reverse
+ * order to restore the allocator state. Note that while the allocator is used
+ * in the scan mode no other operation is allowed.
+ *
+ * Finally the driver evicts all objects selected in the scan. Adding and
+ * removing an object is O(1), and since freeing a node is also O(1) the overall
+ * complexity is O(scanned_objects). So like the free stack which needs to be
+ * walked before a scan operation even begins this is linear in the number of
+ * objects. It doesn't seem to hurt badly.
+ */
+
+/**
+ * drm_mm_init_scan - initialize lru scanning
+ * @mm: drm_mm to scan
+ * @size: size of the allocation
+ * @alignment: alignment of the allocation
+ * @color: opaque tag value to use for the allocation
  *
  * This simply sets up the scanning routines with the parameters for the desired
- * hole.
+ * hole. Note that there's no need to specify allocation flags, since they only
+ * change the place a node is allocated from within a suitable hole.
  *
- * Warning: As long as the scan list is non-empty, no other operations than
+ * 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)
+void drm_mm_init_scan(struct drm_mm *mm,
+		      unsigned long size,
+		      unsigned alignment,
+		      unsigned long color)
 {
+	mm->scan_color = color;
 	mm->scan_alignment = alignment;
 	mm->scan_size = size;
 	mm->scanned_blocks = 0;
 	mm->scan_hit_start = 0;
-	mm->scan_hit_size = 0;
+	mm->scan_hit_end = 0;
 	mm->scan_check_range = 0;
+	mm->prev_scanned_node = NULL;
 }
 EXPORT_SYMBOL(drm_mm_init_scan);
 
 /**
- * Initializa lru scanning.
+ * drm_mm_init_scan - initialize range-restricted lru scanning
+ * @mm: drm_mm to scan
+ * @size: size of the allocation
+ * @alignment: alignment of the allocation
+ * @color: opaque tag value to use for the allocation
+ * @start: start of the allowed range for the allocation
+ * @end: end of the allowed range for the allocation
  *
  * This simply sets up the scanning routines with the parameters for the desired
- * hole. This version is for range-restricted scans.
+ * hole. Note that there's no need to specify allocation flags, since they only
+ * change the place a node is allocated from within a suitable hole.
  *
- * Warning: As long as the scan list is non-empty, no other operations than
+ * 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,
+void drm_mm_init_scan_with_range(struct drm_mm *mm,
+				 unsigned long size,
 				 unsigned alignment,
+				 unsigned long color,
 				 unsigned long start,
 				 unsigned long end)
 {
+	mm->scan_color = color;
 	mm->scan_alignment = alignment;
 	mm->scan_size = size;
 	mm->scanned_blocks = 0;
 	mm->scan_hit_start = 0;
-	mm->scan_hit_size = 0;
+	mm->scan_hit_end = 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);
 
 /**
+ * drm_mm_scan_add_block - add a node to the scan list
+ * @node: drm_mm_node to add
+ *
  * 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.
+ * Returns:
+ * True if a hole has been found, false otherwise.
  */
-int drm_mm_scan_add_block(struct drm_mm_node *node)
+bool drm_mm_scan_add_block(struct drm_mm_node *node)
 {
 	struct drm_mm *mm = node->mm;
-	struct list_head *prev_free, *next_free;
-	struct drm_mm_node *prev_node, *next_node;
-	unsigned long adj_start;
-	unsigned long adj_end;
+	struct drm_mm_node *prev_node;
+	unsigned long hole_start, hole_end;
+	unsigned long adj_start, adj_end;
 
 	mm->scanned_blocks++;
 
-	prev_free = next_free = NULL;
-
-	BUG_ON(node->free);
+	BUG_ON(node->scanned_block);
 	node->scanned_block = 1;
-	node->free = 1;
-
-	if (node->node_list.prev != &mm->node_list) {
-		prev_node = list_entry(node->node_list.prev, struct drm_mm_node,
-				       node_list);
-
-		if (prev_node->free) {
-			list_del(&prev_node->node_list);
 
-			node->start = prev_node->start;
-			node->size += prev_node->size;
+	prev_node = list_entry(node->node_list.prev, struct drm_mm_node,
+			       node_list);
 
-			prev_node->scanned_prev_free = 1;
-
-			prev_free = &prev_node->free_stack;
-		}
-	}
+	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;
 
-	if (node->node_list.next != &mm->node_list) {
-		next_node = list_entry(node->node_list.next, struct drm_mm_node,
-				       node_list);
-
-		if (next_node->free) {
-			list_del(&next_node->node_list);
-
-			node->size += next_node->size;
-
-			next_node->scanned_next_free = 1;
-
-			next_free = &next_node->free_stack;
-		}
-	}
-
-	/* The free_stack list is not used for allocated objects, so these two
-	 * pointers can be abused (as long as no allocations in this memory
-	 * manager happens). */
-	node->free_stack.prev = prev_free;
-	node->free_stack.next = next_free;
+	adj_start = hole_start = drm_mm_hole_node_start(prev_node);
+	adj_end = hole_end = drm_mm_hole_node_end(prev_node);
 
 	if (mm->scan_check_range) {
-		adj_start = node->start < mm->scan_start ?
-			mm->scan_start : node->start;
-		adj_end = node->start + node->size > mm->scan_end ?
-			mm->scan_end : node->start + node->size;
-	} else {
-		adj_start = node->start;
-		adj_end = node->start + node->size;
+		if (adj_start < mm->scan_start)
+			adj_start = mm->scan_start;
+		if (adj_end > mm->scan_end)
+			adj_end = mm->scan_end;
 	}
 
-	if (check_free_hole(adj_start , adj_end,
-			    mm->scan_size, mm->scan_alignment)) {
-		mm->scan_hit_start = node->start;
-		mm->scan_hit_size = node->size;
+	if (mm->color_adjust)
+		mm->color_adjust(prev_node, mm->scan_color,
+				 &adj_start, &adj_end);
 
-		return 1;
+	if (check_free_hole(adj_start, adj_end,
+			    mm->scan_size, mm->scan_alignment)) {
+		mm->scan_hit_start = hole_start;
+		mm->scan_hit_end = hole_end;
+		return true;
 	}
 
-	return 0;
+	return false;
 }
 EXPORT_SYMBOL(drm_mm_scan_add_block);
 
 /**
- * Remove a node from the scan list.
+ * drm_mm_scan_remove_block - remove a node from the scan list
+ * @node: drm_mm_node to remove
  *
  * 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
- * immediatly 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).
+ * immediately following drm_mm_search_free with !DRM_MM_SEARCH_BEST 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.
+ * Returns:
+ * True if this block should be evicted, false otherwise. Will always
+ * return false when no hole has been found.
  */
-int drm_mm_scan_remove_block(struct drm_mm_node *node)
+bool drm_mm_scan_remove_block(struct drm_mm_node *node)
 {
 	struct drm_mm *mm = node->mm;
-	struct drm_mm_node *prev_node, *next_node;
+	struct drm_mm_node *prev_node;
 
 	mm->scanned_blocks--;
 
 	BUG_ON(!node->scanned_block);
 	node->scanned_block = 0;
-	node->free = 0;
-
-	prev_node = list_entry(node->free_stack.prev, struct drm_mm_node,
-			       free_stack);
-	next_node = list_entry(node->free_stack.next, struct drm_mm_node,
-			       free_stack);
 
-	if (prev_node) {
-		BUG_ON(!prev_node->scanned_prev_free);
-		prev_node->scanned_prev_free = 0;
+	prev_node = list_entry(node->node_list.prev, struct drm_mm_node,
+			       node_list);
 
-		list_add_tail(&prev_node->node_list, &node->node_list);
+	prev_node->hole_follows = node->scanned_preceeds_hole;
+	list_add(&node->node_list, &prev_node->node_list);
 
-		node->start = prev_node->start + prev_node->size;
-		node->size -= prev_node->size;
-	}
-
-	if (next_node) {
-		BUG_ON(!next_node->scanned_next_free);
-		next_node->scanned_next_free = 0;
-
-		list_add(&next_node->node_list, &node->node_list);
-
-		node->size -= next_node->size;
-	}
-
-	INIT_LIST_HEAD(&node->free_stack);
-
-	/* 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;
+	 return (drm_mm_hole_node_end(node) > mm->scan_hit_start &&
+		 node->start < mm->scan_hit_end);
 }
 EXPORT_SYMBOL(drm_mm_scan_remove_block);
 
-int drm_mm_clean(struct drm_mm * mm)
+/**
+ * drm_mm_clean - checks whether an allocator is clean
+ * @mm: drm_mm allocator to check
+ *
+ * Returns:
+ * True if the allocator is completely free, false if there's still a node
+ * allocated in it.
+ */
+bool drm_mm_clean(struct drm_mm * mm)
 {
-	struct list_head *head = &mm->node_list;
+	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)
+/**
+ * drm_mm_init - initialize a drm-mm allocator
+ * @mm: the drm_mm structure to initialize
+ * @start: start of the range managed by @mm
+ * @size: end of the range managed by @mm
+ *
+ * Note that @mm must be cleared to 0 before calling this function.
+ */
+void drm_mm_init(struct drm_mm * mm, unsigned long start, unsigned long size)
 {
-	INIT_LIST_HEAD(&mm->node_list);
-	INIT_LIST_HEAD(&mm->free_stack);
-	INIT_LIST_HEAD(&mm->unused_nodes);
-	mm->num_unused = 0;
+	INIT_LIST_HEAD(&mm->hole_stack);
 	mm->scanned_blocks = 0;
-	spin_lock_init(&mm->unused_lock);
 
-	return drm_mm_create_tail_node(mm, start, size, 0);
+	/* 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);
+
+	mm->color_adjust = NULL;
 }
 EXPORT_SYMBOL(drm_mm_init);
 
+/**
+ * drm_mm_takedown - clean up a drm_mm allocator
+ * @mm: drm_mm allocator to clean up
+ *
+ * Note that it is a bug to call this function on an allocator which is not
+ * clean.
+ */
 void drm_mm_takedown(struct drm_mm * mm)
 {
-	struct list_head *bnode = mm->free_stack.next;
-	struct drm_mm_node *entry;
-	struct drm_mm_node *next;
-
-	entry = list_entry(bnode, struct drm_mm_node, free_stack);
-
-	if (entry->node_list.next != &mm->node_list ||
-	    entry->free_stack.next != &mm->free_stack) {
-		DRM_ERROR("Memory manager not clean. Delaying takedown\n");
-		return;
-	}
-
-	list_del(&entry->free_stack);
-	list_del(&entry->node_list);
-	kfree(entry);
+	WARN(!list_empty(&mm->head_node.node_list),
+	     "Memory manager not clean during takedown.\n");
+}
+EXPORT_SYMBOL(drm_mm_takedown);
 
-	spin_lock(&mm->unused_lock);
-	list_for_each_entry_safe(entry, next, &mm->unused_nodes, free_stack) {
-		list_del(&entry->free_stack);
-		kfree(entry);
-		--mm->num_unused;
+static unsigned long drm_mm_debug_hole(struct drm_mm_node *entry,
+				       const char *prefix)
+{
+	unsigned long hole_start, hole_end, hole_size;
+
+	if (entry->hole_follows) {
+		hole_start = drm_mm_hole_node_start(entry);
+		hole_end = drm_mm_hole_node_end(entry);
+		hole_size = hole_end - hole_start;
+		printk(KERN_DEBUG "%s 0x%08lx-0x%08lx: %8lu: free\n",
+			prefix, hole_start, hole_end,
+			hole_size);
+		return hole_size;
 	}
-	spin_unlock(&mm->unused_lock);
 
-	BUG_ON(mm->num_unused != 0);
+	return 0;
 }
-EXPORT_SYMBOL(drm_mm_takedown);
 
+/**
+ * drm_mm_debug_table - dump allocator state to dmesg
+ * @mm: drm_mm allocator to dump
+ * @prefix: prefix to use for dumping to dmesg
+ */
 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;
+	unsigned long total_used = 0, total_free = 0, total = 0;
 
-	list_for_each_entry(entry, &mm->node_list, node_list) {
-		printk(KERN_DEBUG "%s 0x%08lx-0x%08lx: %8ld: %s\n",
+	total_free += drm_mm_debug_hole(&mm->head_node, prefix);
+
+	drm_mm_for_each_node(entry, mm) {
+		printk(KERN_DEBUG "%s 0x%08lx-0x%08lx: %8lu: used\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;
+			entry->size);
+		total_used += entry->size;
+		total_free += drm_mm_debug_hole(entry, prefix);
 	}
-	printk(KERN_DEBUG "%s total: %d, used %d free %d\n", prefix, total,
+	total = total_free + total_used;
+
+	printk(KERN_DEBUG "%s total: %lu, used %lu free %lu\n", prefix, total,
 		total_used, total_free);
 }
 EXPORT_SYMBOL(drm_mm_debug_table);
 
 #if defined(CONFIG_DEBUG_FS)
+static unsigned long drm_mm_dump_hole(struct seq_file *m, struct drm_mm_node *entry)
+{
+	unsigned long hole_start, hole_end, hole_size;
+
+	if (entry->hole_follows) {
+		hole_start = drm_mm_hole_node_start(entry);
+		hole_end = drm_mm_hole_node_end(entry);
+		hole_size = hole_end - hole_start;
+		seq_printf(m, "0x%08lx-0x%08lx: 0x%08lx: free\n",
+				hole_start, hole_end, hole_size);
+		return hole_size;
+	}
+
+	return 0;
+}
+
+/**
+ * drm_mm_dump_table - dump allocator state to a seq_file
+ * @m: seq_file to dump to
+ * @mm: drm_mm allocator to dump
+ */
 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->node_list, node_list) {
-		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;
+	unsigned long total_used = 0, total_free = 0, total = 0;
+
+	total_free += drm_mm_dump_hole(m, &mm->head_node);
+
+	drm_mm_for_each_node(entry, mm) {
+		seq_printf(m, "0x%08lx-0x%08lx: 0x%08lx: used\n",
+				entry->start, entry->start + entry->size,
+				entry->size);
+		total_used += entry->size;
+		total_free += drm_mm_dump_hole(m, entry);
 	}
-	seq_printf(m, "total: %d, used %d free %d\n", total, total_used, total_free);
+	total = total_free + total_used;
+
+	seq_printf(m, "total: %lu, used %lu free %lu\n", total, total_used, total_free);
 	return 0;
 }
 EXPORT_SYMBOL(drm_mm_dump_table);