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/*

 * include/linux/idr.h

 *

 * 2002-10-18  written by Jim Houston jim.houston@ccur.com

 *	Copyright (C) 2002 by Concurrent Computer Corporation

 *	Distributed under the GNU GPL license version 2.

 *

 * Small id to pointer translation service avoiding fixed sized

 * tables.

 */

#ifndef __IDR_H__

#define __IDR_H__

#include 

#include 

#include 

#include 

/*

 * We want shallower trees and thus more bits covered at each layer.  8

 * bits gives us large enough first layer for most use cases and maximum

 * tree depth of 4.  Each idr_layer is slightly larger than 2k on 64bit and

 * 1k on 32bit.

 */

#define IDR_BITS 8

#define IDR_SIZE (1 << IDR_BITS)

#define IDR_MASK ((1 << IDR_BITS)-1)

struct idr_layer {

	int			prefix;	/* the ID prefix of this idr_layer */

	int			layer;	/* distance from leaf */

	struct idr_layer __rcu	*ary[1<

	int			count;	/* When zero, we can release it */

	union {

		/* A zero bit means "space here" */

		DECLARE_BITMAP(bitmap, IDR_SIZE);

		struct rcu_head		rcu_head;

	};

};

struct idr {

	struct idr_layer __rcu	*hint;	/* the last layer allocated from */

	struct idr_layer __rcu	*top;

	int			layers;	/* only valid w/o concurrent changes */

	int			cur;	/* current pos for cyclic allocation */

	spinlock_t		lock;

	int			id_free_cnt;

	struct idr_layer	*id_free;

};

#define IDR_INIT(name)							\

{									\

	.lock			= __SPIN_LOCK_UNLOCKED(name.lock),	\

}

#define DEFINE_IDR(name)	struct idr name = IDR_INIT(name)

/**

 * DOC: idr sync

 * idr synchronization (stolen from radix-tree.h)

 *

 * idr_find() is able to be called locklessly, using RCU. The caller must

 * ensure calls to this function 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 idr tree *and* a synchronize_rcu() grace

 * period).

 */

/*

 * This is what we export.

 */

void *idr_find_slowpath(struct idr *idp, int id);

void idr_preload(gfp_t gfp_mask);

int idr_alloc(struct idr *idp, void *ptr, int start, int end, gfp_t gfp_mask);

int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end, gfp_t gfp_mask);

int idr_for_each(struct idr *idp,

		 int (*fn)(int id, void *p, void *data), void *data);

void *idr_get_next(struct idr *idp, int *nextid);

void *idr_replace(struct idr *idp, void *ptr, int id);

void idr_remove(struct idr *idp, int id);

void idr_destroy(struct idr *idp);

void idr_init(struct idr *idp);

bool idr_is_empty(struct idr *idp);

/**

 * idr_preload_end - end preload section started with idr_preload()

 *

 * Each idr_preload() should be matched with an invocation of this

 * function.  See idr_preload() for details.

 */

static inline void idr_preload_end(void)

{

//	preempt_enable();

}

/**

 * idr_find - return pointer for given id

 * @idr: idr handle

 * @id: lookup key

 *

 * Return the pointer given the id it has been registered with.  A %NULL

 * return indicates that @id is not valid or you passed %NULL in

 * idr_get_new().

 *

 * This function can be called under rcu_read_lock(), given that the leaf

 * pointers lifetimes are correctly managed.

 */

static inline void *idr_find(struct idr *idr, int id)

{

	struct idr_layer *hint = rcu_dereference_raw(idr->hint);

	if (hint && (id & ~IDR_MASK) == hint->prefix)

		return rcu_dereference_raw(hint->ary[id & IDR_MASK]);

	return idr_find_slowpath(idr, id);

}

/**

 * idr_for_each_entry - iterate over an idr's elements of a given type

 * @idp:     idr handle

 * @entry:   the type * to use as cursor

 * @id:      id entry's key

 *

 * @entry and @id do not need to be initialized before the loop, and

 * after normal terminatinon @entry is left with the value NULL.  This

 * is convenient for a "not found" value.

 */

#define idr_for_each_entry(idp, entry, id)			\

	for (id = 0; ((entry) = idr_get_next(idp, &(id))) != NULL; ++id)

/*

 * IDA - IDR based id allocator, use when translation from id to

 * pointer isn't necessary.

 *

 * IDA_BITMAP_LONGS is calculated to be one less to accommodate

 * ida_bitmap->nr_busy so that the whole struct fits in 128 bytes.

 */

#define IDA_CHUNK_SIZE		128	/* 128 bytes per chunk */

#define IDA_BITMAP_LONGS	(IDA_CHUNK_SIZE / sizeof(long) - 1)

#define IDA_BITMAP_BITS 	(IDA_BITMAP_LONGS * sizeof(long) * 8)

struct ida_bitmap {

	long			nr_busy;

	unsigned long		bitmap[IDA_BITMAP_LONGS];

};

struct ida {

	struct idr		idr;

	struct ida_bitmap	*free_bitmap;

};

#define IDA_INIT(name)		{ .idr = IDR_INIT((name).idr), .free_bitmap = NULL, }

#define DEFINE_IDA(name)	struct ida name = IDA_INIT(name)

int ida_pre_get(struct ida *ida, gfp_t gfp_mask);

int ida_get_new_above(struct ida *ida, int starting_id, int *p_id);

void ida_remove(struct ida *ida, int id);

void ida_destroy(struct ida *ida);

void ida_init(struct ida *ida);

int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end,

		   gfp_t gfp_mask);

void ida_simple_remove(struct ida *ida, unsigned int id);

/**

 * ida_get_new - allocate new ID

 * @ida:	idr handle

 * @p_id:	pointer to the allocated handle

 *

 * Simple wrapper around ida_get_new_above() w/ @starting_id of zero.

 */

static inline int ida_get_new(struct ida *ida, int *p_id)

{

	return ida_get_new_above(ida, 0, p_id);

}

void __init idr_init_cache(void);

#endif /* __IDR_H__ */