[PATCH v4 3/3] drm/buddy: Add defragmentation support

[Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@xxxxxxx>]

Add a function to support defragmentation.

Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@xxxxxxx>
Suggested-by: Matthew Auld <matthew.auld@xxxxxxxxx>
---
 drivers/gpu/drm/drm_buddy.c | 48 ++++++++++++++++++++++++++++---------
 1 file changed, 37 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c
index d44172f23f05..3cffa9cc12d7 100644
--- a/drivers/gpu/drm/drm_buddy.c
+++ b/drivers/gpu/drm/drm_buddy.c
@@ -277,7 +277,8 @@ drm_get_buddy(struct drm_buddy_block *block)
 EXPORT_SYMBOL(drm_get_buddy);
 
 static void __drm_buddy_free(struct drm_buddy *mm,
-			     struct drm_buddy_block *block)
+			     struct drm_buddy_block *block,
+			     bool defrag)
 {
 	struct drm_buddy_block *parent;
 
@@ -289,12 +290,14 @@ static void __drm_buddy_free(struct drm_buddy *mm,
 		if (!drm_buddy_block_is_free(buddy))
 			break;
 
-		if (drm_buddy_block_is_clear(block) !=
-		    drm_buddy_block_is_clear(buddy))
-			break;
+		if (!defrag) {
+			if (drm_buddy_block_is_clear(block) !=
+			    drm_buddy_block_is_clear(buddy))
+				break;
 
-		if (drm_buddy_block_is_clear(block))
-			mark_cleared(parent);
+			if (drm_buddy_block_is_clear(block))
+				mark_cleared(parent);
+		}
 
 		list_del(&buddy->link);
 
@@ -307,6 +310,19 @@ static void __drm_buddy_free(struct drm_buddy *mm,
 	mark_free(mm, block);
 }
 
+static void drm_buddy_defrag(struct drm_buddy *mm)
+{
+	struct drm_buddy_block *block;
+	struct list_head *list;
+
+	list = &mm->free_list[0];
+	if (list_empty(list))
+		return;
+
+	list_for_each_entry_reverse(block, list, link)
+		__drm_buddy_free(mm, block, 1);
+}
+
 /**
  * drm_buddy_free_block - free a block
  *
@@ -321,7 +337,7 @@ void drm_buddy_free_block(struct drm_buddy *mm,
 	if (drm_buddy_block_is_clear(block))
 		mm->clear_avail += drm_buddy_block_size(mm, block);
 
-	__drm_buddy_free(mm, block);
+	__drm_buddy_free(mm, block, 0);
 }
 EXPORT_SYMBOL(drm_buddy_free_block);
 
@@ -447,7 +463,7 @@ __alloc_range_bias(struct drm_buddy *mm,
 	if (buddy &&
 	    (drm_buddy_block_is_free(block) &&
 	     drm_buddy_block_is_free(buddy)))
-		__drm_buddy_free(mm, block);
+		__drm_buddy_free(mm, block, 0);
 	return ERR_PTR(err);
 }
 
@@ -577,7 +593,7 @@ alloc_from_freelist(struct drm_buddy *mm,
 
 err_undo:
 	if (tmp != order)
-		__drm_buddy_free(mm, block);
+		__drm_buddy_free(mm, block, 0);
 	return ERR_PTR(err);
 }
 
@@ -657,7 +673,7 @@ static int __alloc_range(struct drm_buddy *mm,
 	if (buddy &&
 	    (drm_buddy_block_is_free(block) &&
 	     drm_buddy_block_is_free(buddy)))
-		__drm_buddy_free(mm, block);
+		__drm_buddy_free(mm, block, 0);
 
 err_free:
 	if (err == -ENOSPC && total_allocated_on_err) {
@@ -903,7 +919,7 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
 
 			if (order-- == min_order) {
 				if (flags & DRM_BUDDY_CONTIGUOUS_ALLOCATION &&
-				    !(flags & DRM_BUDDY_RANGE_ALLOCATION))
+				    !(flags & DRM_BUDDY_RANGE_ALLOCATION)) {
 					/*
 					 * Try contiguous block allocation through
 					 * try harder method
@@ -912,6 +928,16 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
 									 original_size,
 									 original_min_size,
 									 blocks);
+
+					/*
+					 * Defragment the freelist and try contiguous block
+					 * allocation
+					 */
+					drm_buddy_defrag(mm);
+					if (!IS_ERR(alloc_from_freelist(mm, min_order, flags)))
+						break;
+				}
+
 				err = -ENOSPC;
 				goto err_free;
 			}
-- 
2.25.1