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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * include/linux/idr.h
3 *
4 * 2002-10-18 written by Jim Houston jim.houston@ccur.com
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 */
Luben Tuikovf668ab12005-11-08 17:14:08 +010011
12#ifndef __IDR_H__
13#define __IDR_H__
14
Linus Torvalds1da177e2005-04-16 15:20:36 -070015#include <linux/types.h>
16#include <linux/bitops.h>
Akinobu Mita199f0ca2008-04-29 01:03:13 -070017#include <linux/init.h>
Nadia Derbey2027d1a2008-07-25 01:47:57 -070018#include <linux/rcupdate.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070019
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
51struct idr_layer {
52 unsigned long bitmap; /* A zero bit means "space here" */
53 struct idr_layer *ary[1<<IDR_BITS];
54 int count; /* When zero, we can release it */
Manfred Spraul6ff2d392008-12-01 13:14:02 -080055 int layer; /* distance from leaf */
Nadia Derbey2027d1a2008-07-25 01:47:57 -070056 struct rcu_head rcu_head;
Linus Torvalds1da177e2005-04-16 15:20:36 -070057};
58
59struct idr {
60 struct idr_layer *top;
61 struct idr_layer *id_free;
Manfred Spraul6ff2d392008-12-01 13:14:02 -080062 int layers; /* only valid without concurrent changes */
Linus Torvalds1da177e2005-04-16 15:20:36 -070063 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, \
Ingo Molnare4d91912006-07-03 00:24:34 -070073 .lock = __SPIN_LOCK_UNLOCKED(name.lock), \
Linus Torvalds1da177e2005-04-16 15:20:36 -070074}
75#define DEFINE_IDR(name) struct idr name = IDR_INIT(name)
76
Nadia Derbey944ca052008-07-25 01:47:59 -070077/* 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
Nadia Derbeyf9c46d62008-07-25 01:48:01 -070083/**
84 * idr synchronization (stolen from radix-tree.h)
85 *
86 * idr_find() is able to be called locklessly, using RCU. The caller must
87 * ensure calls to this function are made within rcu_read_lock() regions.
88 * Other readers (lock-free or otherwise) and modifications may be running
89 * concurrently.
90 *
91 * It is still required that the caller manage the synchronization and
92 * lifetimes of the items. So if RCU lock-free lookups are used, typically
93 * this would mean that the items have their own locks, or are amenable to
94 * lock-free access; and that the items are freed by RCU (or only freed after
95 * having been deleted from the idr tree *and* a synchronize_rcu() grace
96 * period).
97 */
98
Linus Torvalds1da177e2005-04-16 15:20:36 -070099/*
100 * This is what we export.
101 */
102
103void *idr_find(struct idr *idp, int id);
Al Virofd4f2df2005-10-21 03:18:50 -0400104int idr_pre_get(struct idr *idp, gfp_t gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105int idr_get_new(struct idr *idp, void *ptr, int *id);
106int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id);
Kristian Hoegsberg96d7fa42007-07-15 23:37:24 -0700107int idr_for_each(struct idr *idp,
108 int (*fn)(int id, void *p, void *data), void *data);
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700109void *idr_get_next(struct idr *idp, int *nextid);
Jeff Mahoney5806f072006-06-26 00:27:19 -0700110void *idr_replace(struct idr *idp, void *ptr, int id);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111void idr_remove(struct idr *idp, int id);
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700112void idr_remove_all(struct idr *idp);
Andrew Morton8d3b3592005-10-23 12:57:18 -0700113void idr_destroy(struct idr *idp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114void idr_init(struct idr *idp);
Luben Tuikovf668ab12005-11-08 17:14:08 +0100115
Tejun Heo72dba582007-06-14 03:45:13 +0900116
117/*
118 * IDA - IDR based id allocator, use when translation from id to
119 * pointer isn't necessary.
120 */
121#define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */
122#define IDA_BITMAP_LONGS (128 / sizeof(long) - 1)
123#define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8)
124
125struct ida_bitmap {
126 long nr_busy;
127 unsigned long bitmap[IDA_BITMAP_LONGS];
128};
129
130struct ida {
131 struct idr idr;
132 struct ida_bitmap *free_bitmap;
133};
134
135#define IDA_INIT(name) { .idr = IDR_INIT(name), .free_bitmap = NULL, }
136#define DEFINE_IDA(name) struct ida name = IDA_INIT(name)
137
138int ida_pre_get(struct ida *ida, gfp_t gfp_mask);
139int ida_get_new_above(struct ida *ida, int starting_id, int *p_id);
140int ida_get_new(struct ida *ida, int *p_id);
141void ida_remove(struct ida *ida, int id);
142void ida_destroy(struct ida *ida);
143void ida_init(struct ida *ida);
144
Akinobu Mita199f0ca2008-04-29 01:03:13 -0700145void __init idr_init_cache(void);
146
Luben Tuikovf668ab12005-11-08 17:14:08 +0100147#endif /* __IDR_H__ */