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_IDR_SHIFT (sizeof(int)*8 - 1)
42 #define MAX_IDR_BIT (1U << MAX_IDR_SHIFT)
43 #define MAX_IDR_MASK (MAX_IDR_BIT - 1)
45 /* Leave the possibility of an incomplete final layer */
46 #define MAX_IDR_LEVEL ((MAX_IDR_SHIFT + IDR_BITS - 1) / IDR_BITS)
48 /* Number of id_layer structs to leave in free list */
49 #define MAX_IDR_FREE (MAX_IDR_LEVEL * 2)
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 w/o concurrent changes */
67 #define IDR_INIT(name) \
69 .lock = __SPIN_LOCK_UNLOCKED(name.lock), \
71 #define DEFINE_IDR(name) struct idr name = IDR_INIT(name)
75 * idr synchronization (stolen from radix-tree.h)
77 * idr_find() is able to be called locklessly, using RCU. The caller must
78 * ensure calls to this function are made within rcu_read_lock() regions.
79 * Other readers (lock-free or otherwise) and modifications may be running
82 * It is still required that the caller manage the synchronization and
83 * lifetimes of the items. So if RCU lock-free lookups are used, typically
84 * this would mean that the items have their own locks, or are amenable to
85 * lock-free access; and that the items are freed by RCU (or only freed after
86 * having been deleted from the idr tree *and* a synchronize_rcu() grace
91 * This is what we export.
94 void *idr_find(struct idr *idp, int id);
95 int idr_pre_get(struct idr *idp, gfp_t gfp_mask);
96 int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id);
97 int idr_for_each(struct idr *idp,
98 int (*fn)(int id, void *p, void *data), void *data);
99 void *idr_get_next(struct idr *idp, int *nextid);
100 void *idr_replace(struct idr *idp, void *ptr, int id);
101 void idr_remove(struct idr *idp, int id);
102 void idr_destroy(struct idr *idp);
103 void idr_init(struct idr *idp);
106 * idr_get_new - allocate new idr entry
108 * @ptr: pointer you want associated with the id
109 * @id: pointer to the allocated handle
111 * Simple wrapper around idr_get_new_above() w/ @starting_id of zero.
113 static inline int idr_get_new(struct idr *idp, void *ptr, int *id)
115 return idr_get_new_above(idp, ptr, 0, id);
119 * idr_for_each_entry - iterate over an idr's elements of a given type
121 * @entry: the type * to use as cursor
122 * @id: id entry's key
124 #define idr_for_each_entry(idp, entry, id) \
125 for (id = 0, entry = (typeof(entry))idr_get_next((idp), &(id)); \
127 ++id, entry = (typeof(entry))idr_get_next((idp), &(id)))
129 void __idr_remove_all(struct idr *idp); /* don't use */
132 * idr_remove_all - remove all ids from the given idr tree
135 * If you're trying to destroy @idp, calling idr_destroy() is enough.
136 * This is going away. Don't use.
138 static inline void __deprecated idr_remove_all(struct idr *idp)
140 __idr_remove_all(idp);
144 * IDA - IDR based id allocator, use when translation from id to
145 * pointer isn't necessary.
147 * IDA_BITMAP_LONGS is calculated to be one less to accommodate
148 * ida_bitmap->nr_busy so that the whole struct fits in 128 bytes.
150 #define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */
151 #define IDA_BITMAP_LONGS (IDA_CHUNK_SIZE / sizeof(long) - 1)
152 #define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8)
156 unsigned long bitmap[IDA_BITMAP_LONGS];
161 struct ida_bitmap *free_bitmap;
164 #define IDA_INIT(name) { .idr = IDR_INIT((name).idr), .free_bitmap = NULL, }
165 #define DEFINE_IDA(name) struct ida name = IDA_INIT(name)
167 int ida_pre_get(struct ida *ida, gfp_t gfp_mask);
168 int ida_get_new_above(struct ida *ida, int starting_id, int *p_id);
169 void ida_remove(struct ida *ida, int id);
170 void ida_destroy(struct ida *ida);
171 void ida_init(struct ida *ida);
173 int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end,
175 void ida_simple_remove(struct ida *ida, unsigned int id);
178 * ida_get_new - allocate new ID
180 * @p_id: pointer to the allocated handle
182 * Simple wrapper around ida_get_new_above() w/ @starting_id of zero.
184 static inline int ida_get_new(struct ida *ida, int *p_id)
186 return ida_get_new_above(ida, 0, p_id);
189 void __init idr_init_cache(void);
191 #endif /* __IDR_H__ */