lib/rbtree,drm/mm: add rbtree_replace_node_cached()

Add a variant of rbtree_replace_node() that maintains the leftmost cache of struct rbtree_root_cached when replacing nodes within the rbtree. As drm_mm is the only rb_replace_node() being used on an interval tree, the mistake looks fairly self-contained. Furthermore the only user of drm_mm_replace_node() is its testsuite... Testcase: igt/drm_mm/replace Link: http://lkml.kernel.org/r/[email protected] Link: https://patchwork.freedesktop.org/patch/msgid/[email protected] Fixes: f808c13 ("lib/interval_tree: fast overlap detection") Signed-off-by: Chris Wilson <[email protected]> Reviewed-by: Joonas Lahtinen <[email protected]> Acked-by: Davidlohr Bueso <[email protected]> Cc: Jérôme Glisse <[email protected]> Cc: Joonas Lahtinen <[email protected]> Cc: Daniel Vetter <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
chewitt · Dec 15, 2017 · 338f1d9 · 338f1d9
1 parent c47d7f5
commit 338f1d9
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Showing 3 changed files with 17 additions and 3 deletions.
diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
@@ -575,21 +575,23 @@ EXPORT_SYMBOL(drm_mm_remove_node);
  */
 void drm_mm_replace_node(struct drm_mm_node *old, struct drm_mm_node *new)
 {
+	struct drm_mm *mm = old->mm;
+
 	DRM_MM_BUG_ON(!old->allocated);
 
 	*new = *old;
 
 	list_replace(&old->node_list, &new->node_list);
-	rb_replace_node(&old->rb, &new->rb, &old->mm->interval_tree.rb_root);
+	rb_replace_node_cached(&old->rb, &new->rb, &mm->interval_tree);
 
 	if (drm_mm_hole_follows(old)) {
 		list_replace(&old->hole_stack, &new->hole_stack);
 		rb_replace_node(&old->rb_hole_size,
 				&new->rb_hole_size,
-				&old->mm->holes_size);
+				&mm->holes_size);
 		rb_replace_node(&old->rb_hole_addr,
 				&new->rb_hole_addr,
-				&old->mm->holes_addr);
+				&mm->holes_addr);
 	}
 
 	old->allocated = false;

diff --git a/include/linux/rbtree.h b/include/linux/rbtree.h
@@ -99,6 +99,8 @@ extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
 			    struct rb_root *root);
 extern void rb_replace_node_rcu(struct rb_node *victim, struct rb_node *new,
 				struct rb_root *root);
+extern void rb_replace_node_cached(struct rb_node *victim, struct rb_node *new,
+				   struct rb_root_cached *root);
 
 static inline void rb_link_node(struct rb_node *node, struct rb_node *parent,
 				struct rb_node **rb_link)

diff --git a/lib/rbtree.c b/lib/rbtree.c
@@ -603,6 +603,16 @@ void rb_replace_node(struct rb_node *victim, struct rb_node *new,
 }
 EXPORT_SYMBOL(rb_replace_node);
 
+void rb_replace_node_cached(struct rb_node *victim, struct rb_node *new,
+			    struct rb_root_cached *root)
+{
+	rb_replace_node(victim, new, &root->rb_root);
+
+	if (root->rb_leftmost == victim)
+		root->rb_leftmost = new;
+}
+EXPORT_SYMBOL(rb_replace_node_cached);
+
 void rb_replace_node_rcu(struct rb_node *victim, struct rb_node *new,
 			 struct rb_root *root)
 {