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Commit b72b71c6 authored by Huang Shijie's avatar Huang Shijie Committed by Linus Torvalds
Browse files

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: default avatarHuang Shijie <shijie8@gmail.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 30639b6a

lib/radix-tree.c

+26 −47
Original line number Diff line number Diff line
@@ -351,20 +351,12 @@ int radix_tree_insert(struct radix_tree_root *root, 
}

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 @@ void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index) 
	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 @@ void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index) 
		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 @@ EXPORT_SYMBOL(radix_tree_lookup_slot); 
 */

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);