lib: do code optimization for radix_tree_lookup() and radix_tree_lookup_slot()
radix_tree_lookup() and radix_tree_lookup_slot() have much the
same code except for the return value.
Introduce radix_tree_lookup_element() to do the real work.
/*
* is_slot == 1 : search for the slot.
* is_slot == 0 : search for the node.
*/
static void * radix_tree_lookup_element(struct radix_tree_root *root,
unsigned long index, int is_slot);
Signed-off-by: Huang Shijie <shijie8@gmail.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 5301a52..23abbd9 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -351,20 +351,12 @@
}
EXPORT_SYMBOL(radix_tree_insert);
-/**
- * radix_tree_lookup_slot - lookup a slot in a radix tree
- * @root: radix tree root
- * @index: index key
- *
- * Returns: the slot corresponding to the position @index in the
- * radix tree @root. This is useful for update-if-exists operations.
- *
- * This function can be called under rcu_read_lock iff the slot is not
- * modified by radix_tree_replace_slot, otherwise it must be called
- * exclusive from other writers. Any dereference of the slot must be done
- * using radix_tree_deref_slot.
+/*
+ * is_slot == 1 : search for the slot.
+ * is_slot == 0 : search for the node.
*/
-void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index)
+static void *radix_tree_lookup_element(struct radix_tree_root *root,
+ unsigned long index, int is_slot)
{
unsigned int height, shift;
struct radix_tree_node *node, **slot;
@@ -376,7 +368,7 @@
if (!radix_tree_is_indirect_ptr(node)) {
if (index > 0)
return NULL;
- return (void **)&root->rnode;
+ return is_slot ? (void *)&root->rnode : node;
}
node = radix_tree_indirect_to_ptr(node);
@@ -397,7 +389,25 @@
height--;
} while (height > 0);
- return (void **)slot;
+ return is_slot ? (void *)slot:node;
+}
+
+/**
+ * radix_tree_lookup_slot - lookup a slot in a radix tree
+ * @root: radix tree root
+ * @index: index key
+ *
+ * Returns: the slot corresponding to the position @index in the
+ * radix tree @root. This is useful for update-if-exists operations.
+ *
+ * This function can be called under rcu_read_lock iff the slot is not
+ * modified by radix_tree_replace_slot, otherwise it must be called
+ * exclusive from other writers. Any dereference of the slot must be done
+ * using radix_tree_deref_slot.
+ */
+void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index)
+{
+ return (void **)radix_tree_lookup_element(root, index, 1);
}
EXPORT_SYMBOL(radix_tree_lookup_slot);
@@ -415,38 +425,7 @@
*/
void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
{
- unsigned int height, shift;
- struct radix_tree_node *node, **slot;
-
- node = rcu_dereference(root->rnode);
- if (node == NULL)
- return NULL;
-
- if (!radix_tree_is_indirect_ptr(node)) {
- if (index > 0)
- return NULL;
- return node;
- }
- node = radix_tree_indirect_to_ptr(node);
-
- height = node->height;
- if (index > radix_tree_maxindex(height))
- return NULL;
-
- shift = (height-1) * RADIX_TREE_MAP_SHIFT;
-
- do {
- slot = (struct radix_tree_node **)
- (node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK));
- node = rcu_dereference(*slot);
- if (node == NULL)
- return NULL;
-
- shift -= RADIX_TREE_MAP_SHIFT;
- height--;
- } while (height > 0);
-
- return node;
+ return radix_tree_lookup_element(root, index, 0);
}
EXPORT_SYMBOL(radix_tree_lookup);