[PATCH 29/31] drm: Simplify drm_mm scan-list manipulation

[Chris Wilson]

Since we mandate a strict reverse-order of drm_mm_scan_remove_block()
after drm_mm_scan_add_block() we can further simplify the list
manipulations when generating the temporary scan-hole.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/drm_mm.c | 27 ++++-----------------------
 include/drm/drm_mm.h     |  6 ------
 2 files changed, 4 insertions(+), 29 deletions(-)

diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
index 7f7f7ee4f0c1..4eab82f2a1ef 100644
--- a/drivers/gpu/drm/drm_mm.c
+++ b/drivers/gpu/drm/drm_mm.c
@@ -526,10 +526,6 @@ void drm_mm_remove_node(struct drm_mm_node *node)
 	if (WARN_ON(!node->allocated))
 		return;
 
-	MM_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);
 
@@ -763,8 +759,6 @@ void drm_mm_scan_init_with_range(struct drm_mm_scan *scan,
 
 	scan->hit_start = 0;
 	scan->hit_end = 0;
-
-	scan->prev_scanned_node = NULL;
 }
 EXPORT_SYMBOL(drm_mm_scan_init_with_range);
 
@@ -788,17 +782,10 @@ bool drm_mm_scan_add_block(struct drm_mm_scan *scan,
 	u64 adj_start, adj_end;
 
 	MM_BUG_ON(!node->allocated);
-	MM_BUG_ON(node->scanned_block);
-	node->scanned_block = true;
 
 	hole = list_prev_entry(node, node_list);
-
-	node->scanned_preceeds_hole = hole->hole_follows;
-	hole->hole_follows = 1;
-	list_del(&node->node_list);
-	node->node_list.prev = &hole->node_list;
-	node->node_list.next = &scan->prev_scanned_node->node_list;
-	scan->prev_scanned_node = node;
+	MM_BUG_ON(list_next_entry(hole, node_list) != node);
+	__list_del_entry(&node->node_list);
 
 	hole_start = __drm_mm_hole_node_start(hole);
 	hole_end = __drm_mm_hole_node_end(hole);
@@ -882,12 +869,9 @@ bool drm_mm_scan_remove_block(struct drm_mm_scan *scan,
 {
 	struct drm_mm_node *prev_node;
 
-	MM_BUG_ON(!node->scanned_block);
-	node->scanned_block = false;
-
 	prev_node = list_prev_entry(node, node_list);
-
-	prev_node->hole_follows = node->scanned_preceeds_hole;
+	MM_BUG_ON(list_next_entry(prev_node, node_list) !=
+		  list_next_entry(node, node_list));
 	list_add(&node->node_list, &prev_node->node_list);
 
 	return (node->start + node->size > scan->hit_start &&
@@ -911,9 +895,6 @@ void drm_mm_init(struct drm_mm *mm, u64 start, u64 size)
 	INIT_LIST_HEAD(&mm->head_node.node_list);
 	mm->head_node.allocated = 0;
 	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;
diff --git a/include/drm/drm_mm.h b/include/drm/drm_mm.h
index 19e7bde5c95b..c6844d153783 100644
--- a/include/drm/drm_mm.h
+++ b/include/drm/drm_mm.h
@@ -67,10 +67,6 @@ struct drm_mm_node {
 	struct list_head hole_stack;
 	struct rb_node rb;
 	unsigned hole_follows : 1;
-	unsigned scanned_block : 1;
-	unsigned scanned_prev_free : 1;
-	unsigned scanned_next_free : 1;
-	unsigned scanned_preceeds_hole : 1;
 	unsigned allocated : 1;
 	unsigned long color;
 	u64 start;
@@ -111,8 +107,6 @@ struct drm_mm_scan {
 	u64 hit_start;
 	u64 hit_end;
 
-	struct drm_mm_node *prev_scanned_node;
-
 	unsigned long color;
 	unsigned int flags;
 };
-- 
2.11.0