[linux.git] / include / linux / idr.h

/*
 * include/linux/idr.h
 * 
 * 2002-10-18  written by Jim Houston [email protected]
 *	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 <linux/types.h>
#include <linux/bitops.h>
#include <linux/init.h>
#include <linux/rcupdate.h>

#if BITS_PER_LONG == 32
# define IDR_BITS 5
# define IDR_FULL 0xfffffffful
/* We can only use two of the bits in the top level because there is
   only one possible bit in the top level (5 bits * 7 levels = 35
   bits, but you only use 31 bits in the id). */
# define TOP_LEVEL_FULL (IDR_FULL >> 30)
#elif BITS_PER_LONG == 64
# define IDR_BITS 6
# define IDR_FULL 0xfffffffffffffffful
/* We can only use two of the bits in the top level because there is
   only one possible bit in the top level (6 bits * 6 levels = 36
   bits, but you only use 31 bits in the id). */
# define TOP_LEVEL_FULL (IDR_FULL >> 62)
#else
# error "BITS_PER_LONG is not 32 or 64"
#endif

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

#define MAX_ID_SHIFT (sizeof(int)*8 - 1)
#define MAX_ID_BIT (1U << MAX_ID_SHIFT)
#define MAX_ID_MASK (MAX_ID_BIT - 1)

/* Leave the possibility of an incomplete final layer */
#define MAX_LEVEL (MAX_ID_SHIFT + IDR_BITS - 1) / IDR_BITS

/* Number of id_layer structs to leave in free list */
#define IDR_FREE_MAX MAX_LEVEL + MAX_LEVEL

struct idr_layer {
	unsigned long		 bitmap; /* A zero bit means "space here" */
	struct idr_layer __rcu	*ary[1<<IDR_BITS];
	int			 count;	 /* When zero, we can release it */
	int			 layer;	 /* distance from leaf */
	struct rcu_head		 rcu_head;
};

struct idr {
	struct idr_layer __rcu *top;
	struct idr_layer *id_free;
	int		  layers; /* only valid without concurrent changes */
	int		  id_free_cnt;
	spinlock_t	  lock;
};

#define IDR_INIT(name)						\
{								\
	.top		= NULL,					\
	.id_free	= NULL,					\
	.layers 	= 0,					\
	.id_free_cnt	= 0,					\
	.lock		= __SPIN_LOCK_UNLOCKED(name.lock),	\
}
#define DEFINE_IDR(name)	struct idr name = IDR_INIT(name)

/* Actions to be taken after a call to _idr_sub_alloc */
#define IDR_NEED_TO_GROW -2
#define IDR_NOMORE_SPACE -3

#define _idr_rc_to_errno(rc) ((rc) == -1 ? -EAGAIN : -ENOSPC)

/**
 * 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(struct idr *idp, int id);
int idr_pre_get(struct idr *idp, gfp_t gfp_mask);
int idr_get_new(struct idr *idp, void *ptr, int *id);
int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id);
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_remove_all(struct idr *idp);
void idr_destroy(struct idr *idp);
void idr_init(struct idr *idp);


/*
 * 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), .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);
int ida_get_new(struct ida *ida, 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);

void __init idr_init_cache(void);

#endif /* __IDR_H__ */
Commit	Line	Data
1da177e4 LT	1	/*
	2	* include/linux/idr.h
	3	*
	4	* 2002-10-18 written by Jim Houston [email protected]
	5	* Copyright (C) 2002 by Concurrent Computer Corporation
	6	* Distributed under the GNU GPL license version 2.
	7	*
	8	* Small id to pointer translation service avoiding fixed sized
	9	* tables.
	10	*/
f668ab1a LT	11
	12	#ifndef __IDR_H__
	13	#define __IDR_H__
	14
1da177e4 LT	15	#include <linux/types.h>
1da177e4 LT	16	#include <linux/bitops.h>
199f0ca5	17	#include <linux/init.h>
2027d1ab	18	#include <linux/rcupdate.h>
1da177e4 LT	19
	20	#if BITS_PER_LONG == 32
	21	# define IDR_BITS 5
	22	# define IDR_FULL 0xfffffffful
	23	/* We can only use two of the bits in the top level because there is
	24	only one possible bit in the top level (5 bits * 7 levels = 35
	25	bits, but you only use 31 bits in the id). */
	26	# define TOP_LEVEL_FULL (IDR_FULL >> 30)
	27	#elif BITS_PER_LONG == 64
	28	# define IDR_BITS 6
	29	# define IDR_FULL 0xfffffffffffffffful
	30	/* We can only use two of the bits in the top level because there is
	31	only one possible bit in the top level (6 bits * 6 levels = 36
	32	bits, but you only use 31 bits in the id). */
	33	# define TOP_LEVEL_FULL (IDR_FULL >> 62)
	34	#else
	35	# error "BITS_PER_LONG is not 32 or 64"
	36	#endif
	37
	38	#define IDR_SIZE (1 << IDR_BITS)
	39	#define IDR_MASK ((1 << IDR_BITS)-1)
	40
	41	#define MAX_ID_SHIFT (sizeof(int)*8 - 1)
	42	#define MAX_ID_BIT (1U << MAX_ID_SHIFT)
	43	#define MAX_ID_MASK (MAX_ID_BIT - 1)
	44
	45	/* Leave the possibility of an incomplete final layer */
	46	#define MAX_LEVEL (MAX_ID_SHIFT + IDR_BITS - 1) / IDR_BITS
	47
	48	/* Number of id_layer structs to leave in free list */
	49	#define IDR_FREE_MAX MAX_LEVEL + MAX_LEVEL
	50
	51	struct idr_layer {
	52	unsigned long bitmap; /* A zero bit means "space here" */
d2c2486b	53	struct idr_layer __rcu *ary[1<<IDR_BITS];
1da177e4	54	int count; /* When zero, we can release it */
6ff2d39b	55	int layer; /* distance from leaf */
2027d1ab	56	struct rcu_head rcu_head;
1da177e4 LT	57	};
	58
	59	struct idr {
d2c2486b	60	struct idr_layer __rcu *top;
1da177e4	61	struct idr_layer *id_free;
6ff2d39b	62	int layers; /* only valid without concurrent changes */
1da177e4 LT	63	int id_free_cnt;
	64	spinlock_t lock;
	65	};
	66
	67	#define IDR_INIT(name) \
	68	{ \
	69	.top = NULL, \
	70	.id_free = NULL, \
	71	.layers = 0, \
	72	.id_free_cnt = 0, \
e4d91918	73	.lock = __SPIN_LOCK_UNLOCKED(name.lock), \
1da177e4 LT	74	}
	75	#define DEFINE_IDR(name) struct idr name = IDR_INIT(name)
	76
944ca05c ND	77	/* Actions to be taken after a call to _idr_sub_alloc */
	78	#define IDR_NEED_TO_GROW -2
	79	#define IDR_NOMORE_SPACE -3
	80
	81	#define _idr_rc_to_errno(rc) ((rc) == -1 ? -EAGAIN : -ENOSPC)
	82
f9c46d6e	83	/**
56083ab1	84	* DOC: idr sync
f9c46d6e ND	85	* idr synchronization (stolen from radix-tree.h)
	86	*
	87	* idr_find() is able to be called locklessly, using RCU. The caller must
	88	* ensure calls to this function are made within rcu_read_lock() regions.
	89	* Other readers (lock-free or otherwise) and modifications may be running
	90	* concurrently.
	91	*
	92	* It is still required that the caller manage the synchronization and
	93	* lifetimes of the items. So if RCU lock-free lookups are used, typically
	94	* this would mean that the items have their own locks, or are amenable to
	95	* lock-free access; and that the items are freed by RCU (or only freed after
	96	* having been deleted from the idr tree and a synchronize_rcu() grace
	97	* period).
	98	*/
	99
1da177e4 LT	100	/*
	101	* This is what we export.
	102	*/
	103
	104	void idr_find(struct idr idp, int id);
fd4f2df2	105	int idr_pre_get(struct idr *idp, gfp_t gfp_mask);
1da177e4 LT	106	int idr_get_new(struct idr idp, void ptr, int *id);
1da177e4 LT	107	int idr_get_new_above(struct idr idp, void ptr, int starting_id, int *id);
96d7fa42 KH	108	int idr_for_each(struct idr *idp,
96d7fa42 KH	109	int (fn)(int id, void p, void data), void data);
38460b48	110	void idr_get_next(struct idr idp, int *nextid);
5806f07c	111	void idr_replace(struct idr idp, void *ptr, int id);
1da177e4	112	void idr_remove(struct idr *idp, int id);
23936cc0	113	void idr_remove_all(struct idr *idp);
8d3b3591	114	void idr_destroy(struct idr *idp);
1da177e4	115	void idr_init(struct idr *idp);
f668ab1a	116
72dba584 TH	117
	118	/*
	119	* IDA - IDR based id allocator, use when translation from id to
	120	* pointer isn't necessary.
ed9f524a NK	121	*
	122	* IDA_BITMAP_LONGS is calculated to be one less to accommodate
	123	* ida_bitmap->nr_busy so that the whole struct fits in 128 bytes.
72dba584 TH	124	*/
72dba584 TH	125	#define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */
ed9f524a NK	126	#define IDA_BITMAP_LONGS (IDA_CHUNK_SIZE / sizeof(long) - 1)
ed9f524a NK	127	#define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8)
72dba584 TH	128
	129	struct ida_bitmap {
	130	long nr_busy;
	131	unsigned long bitmap[IDA_BITMAP_LONGS];
	132	};
	133
	134	struct ida {
	135	struct idr idr;
	136	struct ida_bitmap *free_bitmap;
	137	};
	138
	139	#define IDA_INIT(name) { .idr = IDR_INIT(name), .free_bitmap = NULL, }
	140	#define DEFINE_IDA(name) struct ida name = IDA_INIT(name)
	141
	142	int ida_pre_get(struct ida *ida, gfp_t gfp_mask);
	143	int ida_get_new_above(struct ida ida, int starting_id, int p_id);
	144	int ida_get_new(struct ida ida, int p_id);
	145	void ida_remove(struct ida *ida, int id);
	146	void ida_destroy(struct ida *ida);
	147	void ida_init(struct ida *ida);
	148
88eca020 RR	149	int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end,
	150	gfp_t gfp_mask);
	151	void ida_simple_remove(struct ida *ida, unsigned int id);
	152
199f0ca5 AM	153	void __init idr_init_cache(void);
199f0ca5 AM	154
f668ab1a	155	#endif /* __IDR_H__ */