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.
8 * Small id to pointer translation service avoiding fixed sized
15 #include <linux/types.h>
16 #include <linux/bitops.h>
17 #include <linux/init.h>
18 #include <linux/rcupdate.h>
20 #if BITS_PER_LONG == 32
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
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)
35 # error "BITS_PER_LONG is not 32 or 64"
38 #define IDR_SIZE (1 << IDR_BITS)
39 #define IDR_MASK ((1 << IDR_BITS)-1)
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)
45 /* Leave the possibility of an incomplete final layer */
46 #define MAX_LEVEL (MAX_ID_SHIFT + IDR_BITS - 1) / IDR_BITS
48 /* Number of id_layer structs to leave in free list */
49 #define IDR_FREE_MAX MAX_LEVEL + MAX_LEVEL
52 unsigned long bitmap
; /* A zero bit means "space here" */
53 struct idr_layer __rcu
*ary
[1<<IDR_BITS
];
54 int count
; /* When zero, we can release it */
55 int layer
; /* distance from leaf */
56 struct rcu_head rcu_head
;
60 struct idr_layer __rcu
*top
;
61 struct idr_layer
*id_free
;
62 int layers
; /* only valid without concurrent changes */
67 #define IDR_INIT(name) \
73 .lock = __SPIN_LOCK_UNLOCKED(name.lock), \
75 #define DEFINE_IDR(name) struct idr name = IDR_INIT(name)
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
81 #define _idr_rc_to_errno(rc) ((rc) == -1 ? -EAGAIN : -ENOSPC)
85 * idr synchronization (stolen from radix-tree.h)
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
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
101 * This is what we export.
104 void *idr_find(struct idr
*idp
, int id
);
105 int idr_pre_get(struct idr
*idp
, gfp_t gfp_mask
);
106 int idr_get_new(struct idr
*idp
, void *ptr
, int *id
);
107 int idr_get_new_above(struct idr
*idp
, void *ptr
, int starting_id
, int *id
);
108 int idr_for_each(struct idr
*idp
,
109 int (*fn
)(int id
, void *p
, void *data
), void *data
);
110 void *idr_get_next(struct idr
*idp
, int *nextid
);
111 void *idr_replace(struct idr
*idp
, void *ptr
, int id
);
112 void idr_remove(struct idr
*idp
, int id
);
113 void idr_remove_all(struct idr
*idp
);
114 void idr_destroy(struct idr
*idp
);
115 void idr_init(struct idr
*idp
);
119 * IDA - IDR based id allocator, use when translation from id to
120 * pointer isn't necessary.
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.
125 #define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */
126 #define IDA_BITMAP_LONGS (IDA_CHUNK_SIZE / sizeof(long) - 1)
127 #define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8)
131 unsigned long bitmap
[IDA_BITMAP_LONGS
];
136 struct ida_bitmap
*free_bitmap
;
139 #define IDA_INIT(name) { .idr = IDR_INIT(name), .free_bitmap = NULL, }
140 #define DEFINE_IDA(name) struct ida name = IDA_INIT(name)
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
);
149 void __init
idr_init_cache(void);
151 #endif /* __IDR_H__ */
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