prio_tree: cleanup prio_tree_left()/prio_tree_right()

Introduce iter_walk_down()/iter_walk_up() to remove the common code
between prio_tree_left() and prio_tree_right().

Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/lib/prio_tree.c b/lib/prio_tree.c
index 423eba8..888e8b3 100644 (file)
--- a/lib/prio_tree.c
+++ b/lib/prio_tree.c
@@ -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;
 }