[GitHub/mt8127/android_kernel_alcatel_ttab.git] / include / linux / radix-tree.h

/*
 * Copyright (C) 2001 Momchil Velikov
 * Portions Copyright (C) 2001 Christoph Hellwig
 * Copyright (C) 2006 Nick Piggin
 *
 * 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.
 * 
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
#ifndef _LINUX_RADIX_TREE_H
#define _LINUX_RADIX_TREE_H

#include <linux/preempt.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/rcupdate.h>

/*
 * An indirect pointer (root->rnode pointing to a radix_tree_node, rather
 * than a data item) is signalled by the low bit set in the root->rnode
 * pointer.
 *
 * In this case root->height is > 0, but the indirect pointer tests are
 * needed for RCU lookups (because root->height is unreliable). The only
 * time callers need worry about this is when doing a lookup_slot under
 * RCU.
 */
#define RADIX_TREE_INDIRECT_PTR	1
#define RADIX_TREE_RETRY ((void *)-1UL)

static inline void *radix_tree_ptr_to_indirect(void *ptr)
{
	return (void *)((unsigned long)ptr | RADIX_TREE_INDIRECT_PTR);
}

static inline void *radix_tree_indirect_to_ptr(void *ptr)
{
	return (void *)((unsigned long)ptr & ~RADIX_TREE_INDIRECT_PTR);
}

static inline int radix_tree_is_indirect_ptr(void *ptr)
{
	return (int)((unsigned long)ptr & RADIX_TREE_INDIRECT_PTR);
}

/*** radix-tree API starts here ***/

#define RADIX_TREE_MAX_TAGS 2

/* root tags are stored in gfp_mask, shifted by __GFP_BITS_SHIFT */
struct radix_tree_root {
	unsigned int		height;
	gfp_t			gfp_mask;
	struct radix_tree_node	*rnode;
};

#define RADIX_TREE_INIT(mask)	{					\
	.height = 0,							\
	.gfp_mask = (mask),						\
	.rnode = NULL,							\
}

#define RADIX_TREE(name, mask) \
	struct radix_tree_root name = RADIX_TREE_INIT(mask)

#define INIT_RADIX_TREE(root, mask)					\
do {									\
	(root)->height = 0;						\
	(root)->gfp_mask = (mask);					\
	(root)->rnode = NULL;						\
} while (0)

/**
 * Radix-tree synchronization
 *
 * The radix-tree API requires that users provide all synchronisation (with
 * specific exceptions, noted below).
 *
 * Synchronization of access to the data items being stored in the tree, and
 * management of their lifetimes must be completely managed by API users.
 *
 * For API usage, in general,
 * - any function _modifying_ the tree or tags (inserting or deleting
 *   items, setting or clearing tags must exclude other modifications, and
 *   exclude any functions reading the tree.
 * - any function _reading_ the tree or tags (looking up items or tags,
 *   gang lookups) must exclude modifications to the tree, but may occur
 *   concurrently with other readers.
 *
 * The notable exceptions to this rule are the following functions:
 * radix_tree_lookup
 * radix_tree_tag_get
 * radix_tree_gang_lookup
 * radix_tree_gang_lookup_tag
 * radix_tree_tagged
 *
 * The first 4 functions are able to be called locklessly, using RCU. The
 * caller must ensure calls to these functions are made within rcu_read_lock()
 * regions. Other readers (lock-free or otherwise) and modifications may be
 * running concurrently.
 *
 * It is still required that the caller manage the synchronization and lifetimes
 * of the items. So if RCU lock-free lookups are used, typically this would mean
 * that the items have their own locks, or are amenable to lock-free access; and
 * that the items are freed by RCU (or only freed after having been deleted from
 * the radix tree *and* a synchronize_rcu() grace period).
 *
 * (Note, rcu_assign_pointer and rcu_dereference are not needed to control
 * access to data items when inserting into or looking up from the radix tree)
 *
 * radix_tree_tagged is able to be called without locking or RCU.
 */

/**
 * radix_tree_deref_slot	- dereference a slot
 * @pslot:	pointer to slot, returned by radix_tree_lookup_slot
 * Returns:	item that was stored in that slot with any direct pointer flag
 *		removed.
 *
 * For use with radix_tree_lookup_slot().  Caller must hold tree at least read
 * locked across slot lookup and dereference.  More likely, will be used with
 * radix_tree_replace_slot(), as well, so caller will hold tree write locked.
 */
static inline void *radix_tree_deref_slot(void **pslot)
{
	void *ret = *pslot;
	if (unlikely(radix_tree_is_indirect_ptr(ret)))
		ret = RADIX_TREE_RETRY;
	return ret;
}
/**
 * radix_tree_replace_slot	- replace item in a slot
 * @pslot:	pointer to slot, returned by radix_tree_lookup_slot
 * @item:	new item to store in the slot.
 *
 * For use with radix_tree_lookup_slot().  Caller must hold tree write locked
 * across slot lookup and replacement.
 */
static inline void radix_tree_replace_slot(void **pslot, void *item)
{
	BUG_ON(radix_tree_is_indirect_ptr(item));
	rcu_assign_pointer(*pslot, item);
}

int radix_tree_insert(struct radix_tree_root *, unsigned long, void *);
void *radix_tree_lookup(struct radix_tree_root *, unsigned long);
void **radix_tree_lookup_slot(struct radix_tree_root *, unsigned long);
void *radix_tree_delete(struct radix_tree_root *, unsigned long);
unsigned int
radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
			unsigned long first_index, unsigned int max_items);
unsigned long radix_tree_next_hole(struct radix_tree_root *root,
				unsigned long index, unsigned long max_scan);
int radix_tree_preload(gfp_t gfp_mask);
void radix_tree_init(void);
void *radix_tree_tag_set(struct radix_tree_root *root,
			unsigned long index, unsigned int tag);
void *radix_tree_tag_clear(struct radix_tree_root *root,
			unsigned long index, unsigned int tag);
int radix_tree_tag_get(struct radix_tree_root *root,
			unsigned long index, unsigned int tag);
unsigned int
radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
		unsigned long first_index, unsigned int max_items,
		unsigned int tag);
int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag);

static inline void radix_tree_preload_end(void)
{
	preempt_enable();
}

#endif /* _LINUX_RADIX_TREE_H */
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Copyright (C) 2001 Momchil Velikov
	3	* Portions Copyright (C) 2001 Christoph Hellwig
7cf9c2c7	4	* Copyright (C) 2006 Nick Piggin
1da177e4 LT	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public License as
	8	* published by the Free Software Foundation; either version 2, or (at
	9	* your option) any later version.
	10	*
	11	* This program is distributed in the hope that it will be useful, but
	12	* WITHOUT ANY WARRANTY; without even the implied warranty of
	13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	14	* General Public License for more details.
	15	*
	16	* You should have received a copy of the GNU General Public License
	17	* along with this program; if not, write to the Free Software
	18	* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
	19	*/
	20	#ifndef _LINUX_RADIX_TREE_H
	21	#define _LINUX_RADIX_TREE_H
	22
	23	#include <linux/preempt.h>
	24	#include <linux/types.h>
7cf9c2c7 NP	25	#include <linux/kernel.h>
	26	#include <linux/rcupdate.h>
	27
	28	/*
c0bc9875 NP	29	* An indirect pointer (root->rnode pointing to a radix_tree_node, rather
	30	* than a data item) is signalled by the low bit set in the root->rnode
	31	* pointer.
7cf9c2c7	32	*
c0bc9875 NP	33	* In this case root->height is > 0, but the indirect pointer tests are
	34	* needed for RCU lookups (because root->height is unreliable). The only
	35	* time callers need worry about this is when doing a lookup_slot under
	36	* RCU.
7cf9c2c7	37	*/
c0bc9875 NP	38	#define RADIX_TREE_INDIRECT_PTR 1
c0bc9875 NP	39	#define RADIX_TREE_RETRY ((void *)-1UL)
7cf9c2c7	40
c0bc9875	41	static inline void radix_tree_ptr_to_indirect(void ptr)
7cf9c2c7	42	{
c0bc9875	43	return (void *)((unsigned long)ptr \| RADIX_TREE_INDIRECT_PTR);
7cf9c2c7 NP	44	}
7cf9c2c7 NP	45
c0bc9875	46	static inline void radix_tree_indirect_to_ptr(void ptr)
7cf9c2c7	47	{
c0bc9875	48	return (void *)((unsigned long)ptr & ~RADIX_TREE_INDIRECT_PTR);
7cf9c2c7 NP	49	}
7cf9c2c7 NP	50
c0bc9875	51	static inline int radix_tree_is_indirect_ptr(void *ptr)
7cf9c2c7	52	{
c0bc9875	53	return (int)((unsigned long)ptr & RADIX_TREE_INDIRECT_PTR);
7cf9c2c7 NP	54	}
	55
	56	/* radix-tree API starts here */
1da177e4	57
612d6c19 NP	58	#define RADIX_TREE_MAX_TAGS 2
	59
	60	/* root tags are stored in gfp_mask, shifted by __GFP_BITS_SHIFT */
1da177e4 LT	61	struct radix_tree_root {
1da177e4 LT	62	unsigned int height;
fd4f2df2	63	gfp_t gfp_mask;
1da177e4 LT	64	struct radix_tree_node *rnode;
	65	};
	66
	67	#define RADIX_TREE_INIT(mask) { \
	68	.height = 0, \
	69	.gfp_mask = (mask), \
	70	.rnode = NULL, \
	71	}
	72
	73	#define RADIX_TREE(name, mask) \
	74	struct radix_tree_root name = RADIX_TREE_INIT(mask)
	75
	76	#define INIT_RADIX_TREE(root, mask) \
	77	do { \
	78	(root)->height = 0; \
	79	(root)->gfp_mask = (mask); \
	80	(root)->rnode = NULL; \
	81	} while (0)
	82
7cf9c2c7 NP	83	/**
	84	* Radix-tree synchronization
	85	*
	86	* The radix-tree API requires that users provide all synchronisation (with
	87	* specific exceptions, noted below).
	88	*
	89	* Synchronization of access to the data items being stored in the tree, and
	90	* management of their lifetimes must be completely managed by API users.
	91	*
	92	* For API usage, in general,
59c51591	93	* - any function _modifying_ the tree or tags (inserting or deleting
7cf9c2c7 NP	94	* items, setting or clearing tags must exclude other modifications, and
7cf9c2c7 NP	95	* exclude any functions reading the tree.
59c51591	96	* - any function _reading_ the tree or tags (looking up items or tags,
7cf9c2c7 NP	97	* gang lookups) must exclude modifications to the tree, but may occur
	98	* concurrently with other readers.
	99	*
	100	* The notable exceptions to this rule are the following functions:
	101	* radix_tree_lookup
	102	* radix_tree_tag_get
	103	* radix_tree_gang_lookup
	104	* radix_tree_gang_lookup_tag
	105	* radix_tree_tagged
	106	*
	107	* The first 4 functions are able to be called locklessly, using RCU. The
	108	* caller must ensure calls to these functions are made within rcu_read_lock()
	109	* regions. Other readers (lock-free or otherwise) and modifications may be
	110	* running concurrently.
	111	*
	112	* It is still required that the caller manage the synchronization and lifetimes
	113	* of the items. So if RCU lock-free lookups are used, typically this would mean
	114	* that the items have their own locks, or are amenable to lock-free access; and
	115	* that the items are freed by RCU (or only freed after having been deleted from
	116	* the radix tree and a synchronize_rcu() grace period).
	117	*
	118	* (Note, rcu_assign_pointer and rcu_dereference are not needed to control
	119	* access to data items when inserting into or looking up from the radix tree)
	120	*
	121	* radix_tree_tagged is able to be called without locking or RCU.
	122	*/
	123
	124	/**
	125	* radix_tree_deref_slot - dereference a slot
	126	* @pslot: pointer to slot, returned by radix_tree_lookup_slot
	127	* Returns: item that was stored in that slot with any direct pointer flag
	128	* removed.
	129	*
	130	* For use with radix_tree_lookup_slot(). Caller must hold tree at least read
	131	* locked across slot lookup and dereference. More likely, will be used with
	132	* radix_tree_replace_slot(), as well, so caller will hold tree write locked.
	133	*/
	134	static inline void radix_tree_deref_slot(void *pslot)
	135	{
c0bc9875 NP	136	void ret = pslot;
	137	if (unlikely(radix_tree_is_indirect_ptr(ret)))
	138	ret = RADIX_TREE_RETRY;
	139	return ret;
7cf9c2c7 NP	140	}
	141	/**
	142	* radix_tree_replace_slot - replace item in a slot
	143	* @pslot: pointer to slot, returned by radix_tree_lookup_slot
	144	* @item: new item to store in the slot.
	145	*
	146	* For use with radix_tree_lookup_slot(). Caller must hold tree write locked
	147	* across slot lookup and replacement.
	148	*/
	149	static inline void radix_tree_replace_slot(void *pslot, void item)
	150	{
c0bc9875 NP	151	BUG_ON(radix_tree_is_indirect_ptr(item));
c0bc9875 NP	152	rcu_assign_pointer(*pslot, item);
7cf9c2c7 NP	153	}
7cf9c2c7 NP	154
1da177e4 LT	155	int radix_tree_insert(struct radix_tree_root , unsigned long, void );
1da177e4 LT	156	void radix_tree_lookup(struct radix_tree_root , unsigned long);
a4331366	157	void *radix_tree_lookup_slot(struct radix_tree_root , unsigned long);
1da177e4 LT	158	void radix_tree_delete(struct radix_tree_root , unsigned long);
	159	unsigned int
	160	radix_tree_gang_lookup(struct radix_tree_root root, void *results,
	161	unsigned long first_index, unsigned int max_items);
6df8ba4f FW	162	unsigned long radix_tree_next_hole(struct radix_tree_root *root,
6df8ba4f FW	163	unsigned long index, unsigned long max_scan);
dd0fc66f	164	int radix_tree_preload(gfp_t gfp_mask);
1da177e4 LT	165	void radix_tree_init(void);
1da177e4 LT	166	void radix_tree_tag_set(struct radix_tree_root root,
daff89f3	167	unsigned long index, unsigned int tag);
1da177e4	168	void radix_tree_tag_clear(struct radix_tree_root root,
daff89f3	169	unsigned long index, unsigned int tag);
1da177e4	170	int radix_tree_tag_get(struct radix_tree_root *root,
daff89f3	171	unsigned long index, unsigned int tag);
1da177e4 LT	172	unsigned int
1da177e4 LT	173	radix_tree_gang_lookup_tag(struct radix_tree_root root, void *results,
daff89f3 JC	174	unsigned long first_index, unsigned int max_items,
	175	unsigned int tag);
	176	int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag);
1da177e4 LT	177
	178	static inline void radix_tree_preload_end(void)
	179	{
	180	preempt_enable();
	181	}
	182
	183	#endif /* _LINUX_RADIX_TREE_H */