backport-include/linux/radix-tree.h - vendor/opensource/backports - Git at Google

 /*
  * Copyright (C) 2013 Konstantin Khlebnikov
  * Copyright (C) 2013 Luis R. Rodriguez <mcgrof@do-not-panic.com>
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License as
  * published by the Free Software Foundation; either version 2, or (at
  * your option) any later version.
  *
  */
 #ifndef BACKPORT_LINUX_RADIX_TREE_H
 #define BACKPORT_LINUX_RADIX_TREE_H

 #include_next <linux/radix-tree.h>

 #ifdef CPTCFG_BACKPORT_BUILD_RADIX_HELPERS

 /**
  * struct radix_tree_iter - radix tree iterator state
  *
  * @index:	index of current slot
  * @next_index:	next-to-last index for this chunk
  * @tags:	bit-mask for tag-iterating
  *
  * This radix tree iterator works in terms of "chunks" of slots.  A chunk is a
  * subinterval of slots contained within one radix tree leaf node.  It is
  * described by a pointer to its first slot and a struct radix_tree_iter
  * which holds the chunk's position in the tree and its size.  For tagged
  * iteration radix_tree_iter also holds the slots' bit-mask for one chosen
  * radix tree tag.
  */
 struct radix_tree_iter {
 	unsigned long	index;
 	unsigned long	next_index;
 	unsigned long	tags;
 };

 #define RADIX_TREE_ITER_TAG_MASK	0x00FF	/* tag index in lower byte */
 #define RADIX_TREE_ITER_TAGGED		0x0100	/* lookup tagged slots */
 #define RADIX_TREE_ITER_CONTIG		0x0200	/* stop at first hole */

 /**
  * radix_tree_iter_init - initialize radix tree iterator
  *
  * @iter:	pointer to iterator state
  * @start:	iteration starting index
  * Returns:	NULL
  */
 static __always_inline void **
 radix_tree_iter_init(struct radix_tree_iter *iter, unsigned long start)
 {
 	/*
 	 * Leave iter->tags uninitialized. radix_tree_next_chunk() will fill it
 	 * in the case of a successful tagged chunk lookup.  If the lookup was
 	 * unsuccessful or non-tagged then nobody cares about ->tags.
 	 *
 	 * Set index to zero to bypass next_index overflow protection.
 	 * See the comment in radix_tree_next_chunk() for details.
 	 */
 	iter->index = 0;
 	iter->next_index = start;
 	return NULL;
 }

 /**
  * radix_tree_next_chunk - find next chunk of slots for iteration
  *
  * @root:	radix tree root
  * @iter:	iterator state
  * @flags:	RADIX_TREE_ITER_* flags and tag index
  * Returns:	pointer to chunk first slot, or NULL if there no more left
  *
  * This function looks up the next chunk in the radix tree starting from
  * @iter->next_index.  It returns a pointer to the chunk's first slot.
  * Also it fills @iter with data about chunk: position in the tree (index),
  * its end (next_index), and constructs a bit mask for tagged iterating (tags).
  */
 void **radix_tree_next_chunk(struct radix_tree_root *root,
 			     struct radix_tree_iter *iter, unsigned flags);

 /**
  * radix_tree_chunk_size - get current chunk size
  *
  * @iter:	pointer to radix tree iterator
  * Returns:	current chunk size
  */
 static __always_inline unsigned
 radix_tree_chunk_size(struct radix_tree_iter *iter)
 {
 	return iter->next_index - iter->index;
 }

 /**
  * radix_tree_next_slot - find next slot in chunk
  *
  * @slot:	pointer to current slot
  * @iter:	pointer to interator state
  * @flags:	RADIX_TREE_ITER_*, should be constant
  * Returns:	pointer to next slot, or NULL if there no more left
  *
  * This function updates @iter->index in the case of a successful lookup.
  * For tagged lookup it also eats @iter->tags.
  */
 static __always_inline void **
 radix_tree_next_slot(void **slot, struct radix_tree_iter *iter, unsigned flags)
 {
 	if (flags & RADIX_TREE_ITER_TAGGED) {
 		iter->tags >>= 1;
 		if (likely(iter->tags & 1ul)) {
 			iter->index++;
 			return slot + 1;
 		}
 		if (!(flags & RADIX_TREE_ITER_CONTIG) && likely(iter->tags)) {
 			unsigned offset = __ffs(iter->tags);

 			iter->tags >>= offset;
 			iter->index += offset + 1;
 			return slot + offset + 1;
 		}
 	} else {
 		unsigned size = radix_tree_chunk_size(iter) - 1;

 		while (size--) {
 			slot++;
 			iter->index++;
 			if (likely(*slot))
 				return slot;
 			if (flags & RADIX_TREE_ITER_CONTIG) {
 				/* forbid switching to the next chunk */
 				iter->next_index = 0;
 				break;
 			}
 		}
 	}
 	return NULL;
 }

 /**
  * radix_tree_for_each_chunk - iterate over chunks
  *
  * @slot:	the void** variable for pointer to chunk first slot
  * @root:	the struct radix_tree_root pointer
  * @iter:	the struct radix_tree_iter pointer
  * @start:	iteration starting index
  * @flags:	RADIX_TREE_ITER_* and tag index
  *
  * Locks can be released and reacquired between iterations.
  */
 #define radix_tree_for_each_chunk(slot, root, iter, start, flags)	\
 	for (slot = radix_tree_iter_init(iter, start) ;			\
 	      (slot = radix_tree_next_chunk(root, iter, flags)) ;)

 /**
  * radix_tree_for_each_chunk_slot - iterate over slots in one chunk
  *
  * @slot:	the void** variable, at the beginning points to chunk first slot
  * @iter:	the struct radix_tree_iter pointer
  * @flags:	RADIX_TREE_ITER_*, should be constant
  *
  * This macro is designed to be nested inside radix_tree_for_each_chunk().
  * @slot points to the radix tree slot, @iter->index contains its index.
  */
 #define radix_tree_for_each_chunk_slot(slot, iter, flags)		\
 	for (; slot ; slot = radix_tree_next_slot(slot, iter, flags))

 /**
  * radix_tree_for_each_slot - iterate over non-empty slots
  *
  * @slot:	the void** variable for pointer to slot
  * @root:	the struct radix_tree_root pointer
  * @iter:	the struct radix_tree_iter pointer
  * @start:	iteration starting index
  *
  * @slot points to radix tree slot, @iter->index contains its index.
  */
 #define radix_tree_for_each_slot(slot, root, iter, start)		\
 	for (slot = radix_tree_iter_init(iter, start) ;			\
 	     slot || (slot = radix_tree_next_chunk(root, iter, 0)) ;	\
 	     slot = radix_tree_next_slot(slot, iter, 0))

 /**
  * radix_tree_for_each_contig - iterate over contiguous slots
  *
  * @slot:	the void** variable for pointer to slot
  * @root:	the struct radix_tree_root pointer
  * @iter:	the struct radix_tree_iter pointer
  * @start:	iteration starting index
  *
  * @slot points to radix tree slot, @iter->index contains its index.
  */
 #define radix_tree_for_each_contig(slot, root, iter, start)		\
 	for (slot = radix_tree_iter_init(iter, start) ;			\
 	     slot || (slot = radix_tree_next_chunk(root, iter,		\
 				RADIX_TREE_ITER_CONTIG)) ;		\
 	     slot = radix_tree_next_slot(slot, iter,			\
 				RADIX_TREE_ITER_CONTIG))

 /**
  * radix_tree_for_each_tagged - iterate over tagged slots
  *
  * @slot:	the void** variable for pointer to slot
  * @root:	the struct radix_tree_root pointer
  * @iter:	the struct radix_tree_iter pointer
  * @start:	iteration starting index
  * @tag:	tag index
  *
  * @slot points to radix tree slot, @iter->index contains its index.
  */
 #define radix_tree_for_each_tagged(slot, root, iter, start, tag)	\
 	for (slot = radix_tree_iter_init(iter, start) ;			\
 	     slot || (slot = radix_tree_next_chunk(root, iter,		\
 			      RADIX_TREE_ITER_TAGGED | tag)) ;		\
 	     slot = radix_tree_next_slot(slot, iter,			\
 				RADIX_TREE_ITER_TAGGED))

 #endif /* CPTCFG_BACKPORT_BUILD_RADIX_HELPERS */

 #endif /* BACKPORT_LINUX_RADIX_TREE_H */
	/*
	* Copyright (C) 2013 Konstantin Khlebnikov
	* Copyright (C) 2013 Luis R. Rodriguez <mcgrof@do-not-panic.com>
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public License as
	* published by the Free Software Foundation; either version 2, or (at
	* your option) any later version.
	*
	*/
	#ifndef BACKPORT_LINUX_RADIX_TREE_H
	#define BACKPORT_LINUX_RADIX_TREE_H

	#include_next <linux/radix-tree.h>

	#ifdef CPTCFG_BACKPORT_BUILD_RADIX_HELPERS

	/**
	* struct radix_tree_iter - radix tree iterator state
	*
	* @index: index of current slot
	* @next_index: next-to-last index for this chunk
	* @tags: bit-mask for tag-iterating
	*
	* This radix tree iterator works in terms of "chunks" of slots. A chunk is a
	* subinterval of slots contained within one radix tree leaf node. It is
	* described by a pointer to its first slot and a struct radix_tree_iter
	* which holds the chunk's position in the tree and its size. For tagged
	* iteration radix_tree_iter also holds the slots' bit-mask for one chosen
	* radix tree tag.
	*/
	struct radix_tree_iter {
	unsigned long index;
	unsigned long next_index;
	unsigned long tags;
	};

	#define RADIX_TREE_ITER_TAG_MASK 0x00FF /* tag index in lower byte */
	#define RADIX_TREE_ITER_TAGGED 0x0100 /* lookup tagged slots */
	#define RADIX_TREE_ITER_CONTIG 0x0200 /* stop at first hole */

	/**
	* radix_tree_iter_init - initialize radix tree iterator
	*
	* @iter: pointer to iterator state
	* @start: iteration starting index
	* Returns: NULL
	*/
	static __always_inline void **
	radix_tree_iter_init(struct radix_tree_iter *iter, unsigned long start)
	{
	/*
	* Leave iter->tags uninitialized. radix_tree_next_chunk() will fill it
	* in the case of a successful tagged chunk lookup. If the lookup was
	* unsuccessful or non-tagged then nobody cares about ->tags.
	*
	* Set index to zero to bypass next_index overflow protection.
	* See the comment in radix_tree_next_chunk() for details.
	*/
	iter->index = 0;
	iter->next_index = start;
	return NULL;
	}

	/**
	* radix_tree_next_chunk - find next chunk of slots for iteration
	*
	* @root: radix tree root
	* @iter: iterator state
	* @flags: RADIX_TREE_ITER_* flags and tag index
	* Returns: pointer to chunk first slot, or NULL if there no more left
	*
	* This function looks up the next chunk in the radix tree starting from
	* @iter->next_index. It returns a pointer to the chunk's first slot.
	* Also it fills @iter with data about chunk: position in the tree (index),
	* its end (next_index), and constructs a bit mask for tagged iterating (tags).
	*/
	void *radix_tree_next_chunk(struct radix_tree_root root,
	struct radix_tree_iter *iter, unsigned flags);

	/**
	* radix_tree_chunk_size - get current chunk size
	*
	* @iter: pointer to radix tree iterator
	* Returns: current chunk size
	*/
	static __always_inline unsigned
	radix_tree_chunk_size(struct radix_tree_iter *iter)
	{
	return iter->next_index - iter->index;
	}

	/**
	* radix_tree_next_slot - find next slot in chunk
	*
	* @slot: pointer to current slot
	* @iter: pointer to interator state
	* @flags: RADIX_TREE_ITER_*, should be constant
	* Returns: pointer to next slot, or NULL if there no more left
	*
	* This function updates @iter->index in the case of a successful lookup.
	* For tagged lookup it also eats @iter->tags.
	*/
	static __always_inline void **
	radix_tree_next_slot(void *slot, struct radix_tree_iter iter, unsigned flags)
	{
	if (flags & RADIX_TREE_ITER_TAGGED) {
	iter->tags >>= 1;
	if (likely(iter->tags & 1ul)) {
	iter->index++;
	return slot + 1;
	}
	if (!(flags & RADIX_TREE_ITER_CONTIG) && likely(iter->tags)) {
	unsigned offset = __ffs(iter->tags);

	iter->tags >>= offset;
	iter->index += offset + 1;
	return slot + offset + 1;
	}
	} else {
	unsigned size = radix_tree_chunk_size(iter) - 1;

	while (size--) {
	slot++;
	iter->index++;
	if (likely(*slot))
	return slot;
	if (flags & RADIX_TREE_ITER_CONTIG) {
	/* forbid switching to the next chunk */
	iter->next_index = 0;
	break;
	}
	}
	}
	return NULL;
	}

	/**
	* radix_tree_for_each_chunk - iterate over chunks
	*
	* @slot: the void** variable for pointer to chunk first slot
	* @root: the struct radix_tree_root pointer
	* @iter: the struct radix_tree_iter pointer
	* @start: iteration starting index
	* @flags: RADIX_TREE_ITER_* and tag index
	*
	* Locks can be released and reacquired between iterations.
	*/
	#define radix_tree_for_each_chunk(slot, root, iter, start, flags) \
	for (slot = radix_tree_iter_init(iter, start) ; \
	(slot = radix_tree_next_chunk(root, iter, flags)) ;)

	/**
	* radix_tree_for_each_chunk_slot - iterate over slots in one chunk
	*
	* @slot: the void** variable, at the beginning points to chunk first slot
	* @iter: the struct radix_tree_iter pointer
	* @flags: RADIX_TREE_ITER_*, should be constant
	*
	* This macro is designed to be nested inside radix_tree_for_each_chunk().
	* @slot points to the radix tree slot, @iter->index contains its index.
	*/
	#define radix_tree_for_each_chunk_slot(slot, iter, flags) \
	for (; slot ; slot = radix_tree_next_slot(slot, iter, flags))

	/**
	* radix_tree_for_each_slot - iterate over non-empty slots
	*
	* @slot: the void** variable for pointer to slot
	* @root: the struct radix_tree_root pointer
	* @iter: the struct radix_tree_iter pointer
	* @start: iteration starting index
	*
	* @slot points to radix tree slot, @iter->index contains its index.
	*/
	#define radix_tree_for_each_slot(slot, root, iter, start) \
	for (slot = radix_tree_iter_init(iter, start) ; \
	slot \|\| (slot = radix_tree_next_chunk(root, iter, 0)) ; \
	slot = radix_tree_next_slot(slot, iter, 0))

	/**
	* radix_tree_for_each_contig - iterate over contiguous slots
	*
	* @slot: the void** variable for pointer to slot
	* @root: the struct radix_tree_root pointer
	* @iter: the struct radix_tree_iter pointer
	* @start: iteration starting index
	*
	* @slot points to radix tree slot, @iter->index contains its index.
	*/
	#define radix_tree_for_each_contig(slot, root, iter, start) \
	for (slot = radix_tree_iter_init(iter, start) ; \
	slot \|\| (slot = radix_tree_next_chunk(root, iter, \
	RADIX_TREE_ITER_CONTIG)) ; \
	slot = radix_tree_next_slot(slot, iter, \
	RADIX_TREE_ITER_CONTIG))

	/**
	* radix_tree_for_each_tagged - iterate over tagged slots
	*
	* @slot: the void** variable for pointer to slot
	* @root: the struct radix_tree_root pointer
	* @iter: the struct radix_tree_iter pointer
	* @start: iteration starting index
	* @tag: tag index
	*
	* @slot points to radix tree slot, @iter->index contains its index.
	*/
	#define radix_tree_for_each_tagged(slot, root, iter, start, tag) \
	for (slot = radix_tree_iter_init(iter, start) ; \
	slot \|\| (slot = radix_tree_next_chunk(root, iter, \
	RADIX_TREE_ITER_TAGGED \| tag)) ; \
	slot = radix_tree_next_slot(slot, iter, \
	RADIX_TREE_ITER_TAGGED))

	#endif /* CPTCFG_BACKPORT_BUILD_RADIX_HELPERS */

	#endif /* BACKPORT_LINUX_RADIX_TREE_H */