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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#include <linux/rcupdate.h>
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
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 */
55 struct rcu_head rcu_head;
56};
57
58struct idr {
59 struct idr_layer *top;
60 struct idr_layer *id_free;
61 int layers;
62 int id_free_cnt;
63 spinlock_t lock;
64};
65
66#define IDR_INIT(name) \
67{ \
68 .top = NULL, \
69 .id_free = NULL, \
70 .layers = 0, \
71 .id_free_cnt = 0, \
72 .lock = __SPIN_LOCK_UNLOCKED(name.lock), \
73}
74#define DEFINE_IDR(name) struct idr name = IDR_INIT(name)
75
76/* Actions to be taken after a call to _idr_sub_alloc */
77#define IDR_NEED_TO_GROW -2
78#define IDR_NOMORE_SPACE -3
79
80#define _idr_rc_to_errno(rc) ((rc) == -1 ? -EAGAIN : -ENOSPC)
81
82/**
83 * idr synchronization (stolen from radix-tree.h)
84 *
85 * idr_find() is able to be called locklessly, using RCU. The caller must
86 * ensure calls to this function are made within rcu_read_lock() regions.
87 * Other readers (lock-free or otherwise) and modifications may be running
88 * concurrently.
89 *
90 * It is still required that the caller manage the synchronization and
91 * lifetimes of the items. So if RCU lock-free lookups are used, typically
92 * this would mean that the items have their own locks, or are amenable to
93 * lock-free access; and that the items are freed by RCU (or only freed after
94 * having been deleted from the idr tree *and* a synchronize_rcu() grace
95 * period).
96 */
97
98/*
99 * This is what we export.
100 */
101
102void *idr_find(struct idr *idp, int id);
103int idr_pre_get(struct idr *idp, gfp_t gfp_mask);
104int idr_get_new(struct idr *idp, void *ptr, int *id);
105int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id);
106int idr_for_each(struct idr *idp,
107 int (*fn)(int id, void *p, void *data), void *data);
108void *idr_replace(struct idr *idp, void *ptr, int id);
109void idr_remove(struct idr *idp, int id);
110void idr_remove_all(struct idr *idp);
111void idr_destroy(struct idr *idp);
112void idr_init(struct idr *idp);
113
114
115/*
116 * IDA - IDR based id allocator, use when translation from id to
117 * pointer isn't necessary.
118 */
119#define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */
120#define IDA_BITMAP_LONGS (128 / sizeof(long) - 1)
121#define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8)
122
123struct ida_bitmap {
124 long nr_busy;
125 unsigned long bitmap[IDA_BITMAP_LONGS];
126};
127
128struct ida {
129 struct idr idr;
130 struct ida_bitmap *free_bitmap;
131};
132
133#define IDA_INIT(name) { .idr = IDR_INIT(name), .free_bitmap = NULL, }
134#define DEFINE_IDA(name) struct ida name = IDA_INIT(name)
135
136int ida_pre_get(struct ida *ida, gfp_t gfp_mask);
137int ida_get_new_above(struct ida *ida, int starting_id, int *p_id);
138int ida_get_new(struct ida *ida, int *p_id);
139void ida_remove(struct ida *ida, int id);
140void ida_destroy(struct ida *ida);
141void ida_init(struct ida *ida);
142
143void __init idr_init_cache(void);
144
145#endif /* __IDR_H__ */