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

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>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Acked-by: Christian König <christian.koenig@amd.com> for now.
Link: https://patchwork.freedesktop.org/patch/msgid/20180220093738.1461-1-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
index 186c4e90cc1cd25e06a19a89da1bf88a7d9e0cf7..a351bd888a6187bf34e45d987b7abc68d1145003 100644 (file)
--- 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;
                }
        }