prio_tree: remove unnecessary code in prio_tree_replace

index ccfd850..423eba8 100644
@@ -151,7 +151,6 @@ struct prio_tree_node *prio_tree_replace(struct prio_tree_root *root,
 		 * We can reduce root->index_bits here. However, it is complex
 		 * and does not help much to improve performance (IMO).
 		 */
-		node->parent = node;
 		root->prio_tree_node = node;
 	} else {
 		node->parent = old->parent;

index 423eba8..888e8b3 100644
@@ -304,6 +304,40 @@ void prio_tree_remove(struct prio_tree_root *root, struct prio_tree_node *node)
 		cur = prio_tree_replace(root, cur->parent, cur);
 }
 
+static void iter_walk_down(struct prio_tree_iter *iter)
+{
+	iter->mask >>= 1;
+	if (iter->mask) {
+		if (iter->size_level)
+			iter->size_level++;
+		return;
+	}
+
+	if (iter->size_level) {
+		BUG_ON(!prio_tree_left_empty(iter->cur));
+		BUG_ON(!prio_tree_right_empty(iter->cur));
+		iter->size_level++;
+		iter->mask = ULONG_MAX;
+	} else {
+		iter->size_level = 1;
+		iter->mask = 1UL << (BITS_PER_LONG - 1);
+	}
+}
+
+static void iter_walk_up(struct prio_tree_iter *iter)
+{
+	if (iter->mask == ULONG_MAX)
+		iter->mask = 1UL;
+	else if (iter->size_level == 1)
+		iter->mask = 1UL;
+	else
+		iter->mask <<= 1;
+	if (iter->size_level)
+		iter->size_level--;
+	if (!iter->size_level && (iter->value & iter->mask))
+		iter->value ^= iter->mask;
+}
+
 /*
  * Following functions help to enumerate all prio_tree_nodes in the tree that
  * overlap with the input interval X [radix_index, heap_index]. The enumeration

@@ -322,21 +356,7 @@ static struct prio_tree_node *prio_tree_left(struct prio_tree_iter *iter,
 
 	if (iter->r_index <= *h_index) {
 		iter->cur = iter->cur->left;
-		iter->mask >>= 1;
-		if (iter->mask) {
-			if (iter->size_level)
-				iter->size_level++;
-		} else {
-			if (iter->size_level) {
-				BUG_ON(!prio_tree_left_empty(iter->cur));
-				BUG_ON(!prio_tree_right_empty(iter->cur));
-				iter->size_level++;
-				iter->mask = ULONG_MAX;
-			} else {
-				iter->size_level = 1;
-				iter->mask = 1UL << (BITS_PER_LONG - 1);
-			}
-		}
+		iter_walk_down(iter);
 		return iter->cur;
 	}
 

@@ -363,22 +383,7 @@ static struct prio_tree_node *prio_tree_right(struct prio_tree_iter *iter,
 
 	if (iter->r_index <= *h_index) {
 		iter->cur = iter->cur->right;
-		iter->mask >>= 1;
-		iter->value = value;
-		if (iter->mask) {
-			if (iter->size_level)
-				iter->size_level++;
-		} else {
-			if (iter->size_level) {
-				BUG_ON(!prio_tree_left_empty(iter->cur));
-				BUG_ON(!prio_tree_right_empty(iter->cur));
-				iter->size_level++;
-				iter->mask = ULONG_MAX;
-			} else {
-				iter->size_level = 1;
-				iter->mask = 1UL << (BITS_PER_LONG - 1);
-			}
-		}
+		iter_walk_down(iter);
 		return iter->cur;
 	}
 

@@ -388,16 +393,7 @@ static struct prio_tree_node *prio_tree_right(struct prio_tree_iter *iter,
 static struct prio_tree_node *prio_tree_parent(struct prio_tree_iter *iter)
 {
 	iter->cur = iter->cur->parent;
-	if (iter->mask == ULONG_MAX)
-		iter->mask = 1UL;
-	else if (iter->size_level == 1)
-		iter->mask = 1UL;
-	else
-		iter->mask <<= 1;
-	if (iter->size_level)
-		iter->size_level--;
-	if (!iter->size_level && (iter->value & iter->mask))
-		iter->value ^= iter->mask;
+	iter_walk_up(iter);
 	return iter->cur;
 }
 

index 888e8b3..928482b 100644
@@ -94,43 +94,33 @@ static inline unsigned long prio_tree_maxindex(unsigned int bits)
 static struct prio_tree_node *prio_tree_expand(struct prio_tree_root *root,
 		struct prio_tree_node *node, unsigned long max_heap_index)
 {
-	struct prio_tree_node *first = NULL, *prev, *last = NULL;
+	struct prio_tree_node *prev;
 
 	if (max_heap_index > prio_tree_maxindex(root->index_bits))
 		root->index_bits++;
 
+	prev = node;
+	INIT_PRIO_TREE_NODE(node);
+
 	while (max_heap_index > prio_tree_maxindex(root->index_bits)) {
+		struct prio_tree_node *tmp = root->prio_tree_node;
+
 		root->index_bits++;
 
 		if (prio_tree_empty(root))
 			continue;
 
-		if (first == NULL) {
-			first = root->prio_tree_node;
-			prio_tree_remove(root, root->prio_tree_node);
-			INIT_PRIO_TREE_NODE(first);
-			last = first;
-		} else {
-			prev = last;
-			last = root->prio_tree_node;
-			prio_tree_remove(root, root->prio_tree_node);
-			INIT_PRIO_TREE_NODE(last);
-			prev->left = last;
-			last->parent = prev;
-		}
-	}
-
-	INIT_PRIO_TREE_NODE(node);
+		prio_tree_remove(root, root->prio_tree_node);
+		INIT_PRIO_TREE_NODE(tmp);
 
-	if (first) {
-		node->left = first;
-		first->parent = node;
-	} else
-		last = node;
+		prev->left = tmp;
+		tmp->parent = prev;
+		prev = tmp;
+	}
 
 	if (!prio_tree_empty(root)) {
-		last->left = root->prio_tree_node;
-		last->left->parent = last;
+		prev->left = root->prio_tree_node;
+		prev->left->parent = prev;
 	}
 
 	root->prio_tree_node = node;

index 928482b..8d443af 100644
@@ -85,6 +85,17 @@ static inline unsigned long prio_tree_maxindex(unsigned int bits)
 	return index_bits_to_maxindex[bits - 1];
 }
 
+static void prio_set_parent(struct prio_tree_node *parent,
+			    struct prio_tree_node *child, bool left)
+{
+	if (left)
+		parent->left = child;
+	else
+		parent->right = child;
+
+	child->parent = parent;
+}
+
 /*
  * Extend a priority search tree so that it can store a node with heap_index
  * max_heap_index. In the worst case, this algorithm takes O((log n)^2).

@@ -113,15 +124,12 @@ static struct prio_tree_node *prio_tree_expand(struct prio_tree_root *root,
 		prio_tree_remove(root, root->prio_tree_node);
 		INIT_PRIO_TREE_NODE(tmp);
 
-		prev->left = tmp;
-		tmp->parent = prev;
+		prio_set_parent(prev, tmp, true);
 		prev = tmp;
 	}
 
-	if (!prio_tree_empty(root)) {
-		prev->left = root->prio_tree_node;
-		prev->left->parent = prev;
-	}
+	if (!prio_tree_empty(root))
+		prio_set_parent(prev, root->prio_tree_node, true);
 
 	root->prio_tree_node = node;
 	return node;

@@ -142,23 +150,14 @@ struct prio_tree_node *prio_tree_replace(struct prio_tree_root *root,
 		 * and does not help much to improve performance (IMO).
 		 */
 		root->prio_tree_node = node;
-	} else {
-		node->parent = old->parent;
-		if (old->parent->left == old)
-			old->parent->left = node;
-		else
-			old->parent->right = node;
-	}
+	} else
+		prio_set_parent(old->parent, node, old->parent->left == old);
 
-	if (!prio_tree_left_empty(old)) {
-		node->left = old->left;
-		old->left->parent = node;
-	}
+	if (!prio_tree_left_empty(old))
+		prio_set_parent(node, old->left, true);
 
-	if (!prio_tree_right_empty(old)) {
-		node->right = old->right;
-		old->right->parent = node;
-	}
+	if (!prio_tree_right_empty(old))
+		prio_set_parent(node, old->right, false);
 
 	return old;
 }

@@ -218,16 +217,14 @@ struct prio_tree_node *prio_tree_insert(struct prio_tree_root *root,
 		if (index & mask) {
 			if (prio_tree_right_empty(cur)) {
 				INIT_PRIO_TREE_NODE(node);
-				cur->right = node;
-				node->parent = cur;
+				prio_set_parent(cur, node, false);
 				return res;
 			} else
 				cur = cur->right;
 		} else {
 			if (prio_tree_left_empty(cur)) {
 				INIT_PRIO_TREE_NODE(node);
-				cur->left = node;
-				node->parent = cur;
+				prio_set_parent(cur, node, true);
 				return res;
 			} else
 				cur = cur->left;