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

[Arunpravin Paneer Selvam]

Add a function to support defragmentation.

Signed-off-by: Arunpravin Paneer Selvam <arunpravin.paneersel...@amd.com>
Suggested-by: Matthew Auld <matthew.a...@intel.com>
---
 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