diff mbox

drm/mm: Fix caching of leftmost node in the interval tree

Message ID 20180215113651.21038-1-chris@chris-wilson.co.uk (mailing list archive)
State New, archived
Headers show

Commit Message

Chris Wilson Feb. 15, 2018, 11:36 a.m. UTC 
When we descend the tree to find our slot, if we step to the right, we
are no longer the leftmost node.

Fixes: f808c13fd373 ("lib/interval_tree: fast overlap detection")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: <stable@vger.kernel.org> # v4.14+
---
 drivers/gpu/drm/drm_mm.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

Comments

Chris Wilson Feb. 15, 2018, 12:26 p.m. UTC | #1 
Quoting Chris Wilson (2018-02-15 11:36:51)
> When we descend the tree to find our slot, if we step to the right, we
> are no longer the leftmost node.

Fortunately, the cached leftmost node is unused here and no drm_mm API
exposes it. So probably doesn't make sense to send it to stable@ as no
bug exists.
 
> Fixes: f808c13fd373 ("lib/interval_tree: fast overlap detection")
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Davidlohr Bueso <dbueso@suse.de>
> Cc: Jérôme Glisse <jglisse@redhat.com>
> Cc: Christian König <christian.koenig@amd.com>
> Cc: <stable@vger.kernel.org> # v4.14+
diff mbox

Patch

diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
index 186c4e90cc1c..a351bd888a61 100644
--- a/drivers/gpu/drm/drm_mm.c
+++ b/drivers/gpu/drm/drm_mm.c
@@ -180,7 +180,7 @@  static void drm_mm_interval_tree_add_node(struct drm_mm_node *hole_node,
 	struct drm_mm *mm = hole_node->mm;
 	struct rb_node **link, *rb;
 	struct drm_mm_node *parent;
-	bool leftmost = true;
+	bool leftmost;
 
 	node->__subtree_last = LAST(node);
 
@@ -201,6 +201,7 @@  static void drm_mm_interval_tree_add_node(struct drm_mm_node *hole_node,
 	} else {
 		rb = NULL;
 		link = &mm->interval_tree.rb_root.rb_node;
+		leftmost = true;
 	}
 
 	while (*link) {
@@ -208,11 +209,11 @@  static void drm_mm_interval_tree_add_node(struct drm_mm_node *hole_node,
 		parent = rb_entry(rb, struct drm_mm_node, rb);
 		if (parent->__subtree_last < node->__subtree_last)
 			parent->__subtree_last = node->__subtree_last;
-		if (node->start < parent->start)
+		if (node->start < parent->start) {
 			link = &parent->rb.rb_left;
-		else {
+		} else {
 			link = &parent->rb.rb_right;
-			leftmost = true;
+			leftmost = false;
 		}
 	}