rbtree: API changes. Remove rbtree control node from RBTree_Next.

The implementation of RBTree_Next was using an awkward construction to detect
and avoid accessing the false root of the red-black tree. To deal with the
false root, RBTree_Next was comparing node parents with the control node.
Instead the false root can be detected by checking if the grandparent of a
node exists; the grandparent of the tree's true root is NULL by definition
so the root of the tree is found while walking up the tree by checking for
the non-existence of a grandparent.

This change propagates into the predecessor/successor and iterate functions.

1 files changed, 4 insertions, 8 deletions

diff --git a/cpukit/score/inline/rtems/score/rbtree.inl b/cpukit/score/inline/rtems/score/rbtree.inl
index a079745290..c5187a02ae 100644
--- a/cpukit/score/inline/rtems/score/rbtree.inl
+++ b/cpukit/score/inline/rtems/score/rbtree.inl
@@ -384,11 +384,10 @@ RTEMS_INLINE_ROUTINE RBTree_Node *_RBTree_Find_unprotected(
  * @retval otherwise The predecessor node.
  */
 RTEMS_INLINE_ROUTINE RBTree_Node *_RBTree_Predecessor_unprotected(
-  const RBTree_Control *rbtree,
   const RBTree_Node *node
 )
 {
-  return _RBTree_Next_unprotected( rbtree, node, RBT_LEFT );
+  return _RBTree_Next_unprotected( node, RBT_LEFT );
 }
 
 /**
@@ -397,11 +396,10 @@ RTEMS_INLINE_ROUTINE RBTree_Node *_RBTree_Predecessor_unprotected(
  * The function disables the interrupts protect the operation.
  */
 RTEMS_INLINE_ROUTINE RBTree_Node *_RBTree_Predecessor(
-  const RBTree_Control *rbtree,
   const RBTree_Node *node
 )
 {
-  return _RBTree_Next( rbtree, node, RBT_LEFT );
+  return _RBTree_Next( node, RBT_LEFT );
 }
 
 /**
@@ -414,11 +412,10 @@ RTEMS_INLINE_ROUTINE RBTree_Node *_RBTree_Predecessor(
  * @retval otherwise The successor node.
  */
 RTEMS_INLINE_ROUTINE RBTree_Node *_RBTree_Successor_unprotected(
-  const RBTree_Control *rbtree,
   const RBTree_Node *node
 )
 {
-  return _RBTree_Next_unprotected( rbtree, node, RBT_RIGHT );
+  return _RBTree_Next_unprotected( node, RBT_RIGHT );
 }
 
 /**
@@ -427,11 +424,10 @@ RTEMS_INLINE_ROUTINE RBTree_Node *_RBTree_Successor_unprotected(
  * The function disables the interrupts protect the operation.
  */
 RTEMS_INLINE_ROUTINE RBTree_Node *_RBTree_Successor(
-  const RBTree_Control *rbtree,
   const RBTree_Node *node
 )
 {
-  return _RBTree_Next( rbtree, node, RBT_RIGHT );
+  return _RBTree_Next( node, RBT_RIGHT );
 }
 
 /** @brief Get the First Node (unprotected)