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