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1/*
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 */
11
12#ifndef __IDR_H__
13#define __IDR_H__
14
15#include <linux/types.h>
16#include <linux/bitops.h>
17#include <linux/init.h>
18
19#if BITS_PER_LONG == 32
20# define IDR_BITS 5
21# define IDR_FULL 0xfffffffful
22/* We can only use two of the bits in the top level because there is
23 only one possible bit in the top level (5 bits * 7 levels = 35
24 bits, but you only use 31 bits in the id). */
25# define TOP_LEVEL_FULL (IDR_FULL >> 30)
26#elif BITS_PER_LONG == 64
27# define IDR_BITS 6
28# define IDR_FULL 0xfffffffffffffffful
29/* We can only use two of the bits in the top level because there is
30 only one possible bit in the top level (6 bits * 6 levels = 36
31 bits, but you only use 31 bits in the id). */
32# define TOP_LEVEL_FULL (IDR_FULL >> 62)
33#else
34# error "BITS_PER_LONG is not 32 or 64"
35#endif
36
37#define IDR_SIZE (1 << IDR_BITS)
38#define IDR_MASK ((1 << IDR_BITS)-1)
39
40#define MAX_ID_SHIFT (sizeof(int)*8 - 1)
41#define MAX_ID_BIT (1U << MAX_ID_SHIFT)
42#define MAX_ID_MASK (MAX_ID_BIT - 1)
43
44/* Leave the possibility of an incomplete final layer */
45#define MAX_LEVEL (MAX_ID_SHIFT + IDR_BITS - 1) / IDR_BITS
46
47/* Number of id_layer structs to leave in free list */
48#define IDR_FREE_MAX MAX_LEVEL + MAX_LEVEL
49
50struct idr_layer {
51 unsigned long bitmap; /* A zero bit means "space here" */
52 struct idr_layer *ary[1<<IDR_BITS];
53 int count; /* When zero, we can release it */
54};
55
56struct idr {
57 struct idr_layer *top;
58 struct idr_layer *id_free;
59 int layers;
60 int id_free_cnt;
61 spinlock_t lock;
62};
63
64#define IDR_INIT(name) \
65{ \
66 .top = NULL, \
67 .id_free = NULL, \
68 .layers = 0, \
69 .id_free_cnt = 0, \
70 .lock = __SPIN_LOCK_UNLOCKED(name.lock), \
71}
72#define DEFINE_IDR(name) struct idr name = IDR_INIT(name)
73
74/*
75 * This is what we export.
76 */
77
78void *idr_find(struct idr *idp, int id);
79int idr_pre_get(struct idr *idp, gfp_t gfp_mask);
80int idr_get_new(struct idr *idp, void *ptr, int *id);
81int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id);
82int idr_for_each(struct idr *idp,
83 int (*fn)(int id, void *p, void *data), void *data);
84void *idr_replace(struct idr *idp, void *ptr, int id);
85void idr_remove(struct idr *idp, int id);
86void idr_remove_all(struct idr *idp);
87void idr_destroy(struct idr *idp);
88void idr_init(struct idr *idp);
89
90
91/*
92 * IDA - IDR based id allocator, use when translation from id to
93 * pointer isn't necessary.
94 */
95#define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */
96#define IDA_BITMAP_LONGS (128 / sizeof(long) - 1)
97#define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8)
98
99struct ida_bitmap {
100 long nr_busy;
101 unsigned long bitmap[IDA_BITMAP_LONGS];
102};
103
104struct ida {
105 struct idr idr;
106 struct ida_bitmap *free_bitmap;
107};
108
109#define IDA_INIT(name) { .idr = IDR_INIT(name), .free_bitmap = NULL, }
110#define DEFINE_IDA(name) struct ida name = IDA_INIT(name)
111
112int ida_pre_get(struct ida *ida, gfp_t gfp_mask);
113int ida_get_new_above(struct ida *ida, int starting_id, int *p_id);
114int ida_get_new(struct ida *ida, int *p_id);
115void ida_remove(struct ida *ida, int id);
116void ida_destroy(struct ida *ida);
117void ida_init(struct ida *ida);
118
119void __init idr_init_cache(void);
120
121#endif /* __IDR_H__ */