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 *ary[1<<IDR_BITS];
54 int count; /* When zero, we can release it */
55 struct rcu_head rcu_head;
59 struct idr_layer *top;
60 struct idr_layer *id_free;
66 #define IDR_INIT(name) \
72 .lock = __SPIN_LOCK_UNLOCKED(name.lock), \
74 #define DEFINE_IDR(name) struct idr name = IDR_INIT(name)
77 * This is what we export.
80 void *idr_find(struct idr *idp, int id);
81 int idr_pre_get(struct idr *idp, gfp_t gfp_mask);
82 int idr_get_new(struct idr *idp, void *ptr, int *id);
83 int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id);
84 int idr_for_each(struct idr *idp,
85 int (*fn)(int id, void *p, void *data), void *data);
86 void *idr_replace(struct idr *idp, void *ptr, int id);
87 void idr_remove(struct idr *idp, int id);
88 void idr_remove_all(struct idr *idp);
89 void idr_destroy(struct idr *idp);
90 void idr_init(struct idr *idp);
94 * IDA - IDR based id allocator, use when translation from id to
95 * pointer isn't necessary.
97 #define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */
98 #define IDA_BITMAP_LONGS (128 / sizeof(long) - 1)
99 #define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8)
103 unsigned long bitmap[IDA_BITMAP_LONGS];
108 struct ida_bitmap *free_bitmap;
111 #define IDA_INIT(name) { .idr = IDR_INIT(name), .free_bitmap = NULL, }
112 #define DEFINE_IDA(name) struct ida name = IDA_INIT(name)
114 int ida_pre_get(struct ida *ida, gfp_t gfp_mask);
115 int ida_get_new_above(struct ida *ida, int starting_id, int *p_id);
116 int ida_get_new(struct ida *ida, int *p_id);
117 void ida_remove(struct ida *ida, int id);
118 void ida_destroy(struct ida *ida);
119 void ida_init(struct ida *ida);
121 void __init idr_init_cache(void);
123 #endif /* __IDR_H__ */