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>
21 * We want shallower trees and thus more bits covered at each layer. 8
22 * bits gives us large enough first layer for most use cases and maximum
23 * tree depth of 4. Each idr_layer is slightly larger than 2k on 64bit and
27 #define IDR_SIZE (1 << IDR_BITS)
28 #define IDR_MASK ((1 << IDR_BITS)-1)
31 int prefix; /* the ID prefix of this idr_layer */
32 DECLARE_BITMAP(bitmap, IDR_SIZE); /* A zero bit means "space here" */
33 struct idr_layer __rcu *ary[1<<IDR_BITS];
34 int count; /* When zero, we can release it */
35 int layer; /* distance from leaf */
36 struct rcu_head rcu_head;
40 struct idr_layer __rcu *top;
41 struct idr_layer *id_free;
42 int layers; /* only valid w/o concurrent changes */
47 #define IDR_INIT(name) \
49 .lock = __SPIN_LOCK_UNLOCKED(name.lock), \
51 #define DEFINE_IDR(name) struct idr name = IDR_INIT(name)
55 * idr synchronization (stolen from radix-tree.h)
57 * idr_find() is able to be called locklessly, using RCU. The caller must
58 * ensure calls to this function are made within rcu_read_lock() regions.
59 * Other readers (lock-free or otherwise) and modifications may be running
62 * It is still required that the caller manage the synchronization and
63 * lifetimes of the items. So if RCU lock-free lookups are used, typically
64 * this would mean that the items have their own locks, or are amenable to
65 * lock-free access; and that the items are freed by RCU (or only freed after
66 * having been deleted from the idr tree *and* a synchronize_rcu() grace
71 * This is what we export.
74 void *idr_find(struct idr *idp, int id);
75 int idr_pre_get(struct idr *idp, gfp_t gfp_mask);
76 int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id);
77 void idr_preload(gfp_t gfp_mask);
78 int idr_alloc(struct idr *idp, void *ptr, int start, int end, gfp_t gfp_mask);
79 int idr_for_each(struct idr *idp,
80 int (*fn)(int id, void *p, void *data), void *data);
81 void *idr_get_next(struct idr *idp, int *nextid);
82 void *idr_replace(struct idr *idp, void *ptr, int id);
83 void idr_remove(struct idr *idp, int id);
84 void idr_free(struct idr *idp, int id);
85 void idr_destroy(struct idr *idp);
86 void idr_init(struct idr *idp);
89 * idr_preload_end - end preload section started with idr_preload()
91 * Each idr_preload() should be matched with an invocation of this
92 * function. See idr_preload() for details.
94 static inline void idr_preload_end(void)
100 * idr_get_new - allocate new idr entry
102 * @ptr: pointer you want associated with the id
103 * @id: pointer to the allocated handle
105 * Simple wrapper around idr_get_new_above() w/ @starting_id of zero.
107 static inline int idr_get_new(struct idr *idp, void *ptr, int *id)
109 return idr_get_new_above(idp, ptr, 0, id);
113 * idr_for_each_entry - iterate over an idr's elements of a given type
115 * @entry: the type * to use as cursor
116 * @id: id entry's key
118 #define idr_for_each_entry(idp, entry, id) \
119 for (id = 0, entry = (typeof(entry))idr_get_next((idp), &(id)); \
121 ++id, entry = (typeof(entry))idr_get_next((idp), &(id)))
123 void __idr_remove_all(struct idr *idp); /* don't use */
126 * idr_remove_all - remove all ids from the given idr tree
129 * If you're trying to destroy @idp, calling idr_destroy() is enough.
130 * This is going away. Don't use.
132 static inline void __deprecated idr_remove_all(struct idr *idp)
134 __idr_remove_all(idp);
138 * IDA - IDR based id allocator, use when translation from id to
139 * pointer isn't necessary.
141 * IDA_BITMAP_LONGS is calculated to be one less to accommodate
142 * ida_bitmap->nr_busy so that the whole struct fits in 128 bytes.
144 #define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */
145 #define IDA_BITMAP_LONGS (IDA_CHUNK_SIZE / sizeof(long) - 1)
146 #define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8)
150 unsigned long bitmap[IDA_BITMAP_LONGS];
155 struct ida_bitmap *free_bitmap;
158 #define IDA_INIT(name) { .idr = IDR_INIT((name).idr), .free_bitmap = NULL, }
159 #define DEFINE_IDA(name) struct ida name = IDA_INIT(name)
161 int ida_pre_get(struct ida *ida, gfp_t gfp_mask);
162 int ida_get_new_above(struct ida *ida, int starting_id, int *p_id);
163 void ida_remove(struct ida *ida, int id);
164 void ida_destroy(struct ida *ida);
165 void ida_init(struct ida *ida);
167 int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end,
169 void ida_simple_remove(struct ida *ida, unsigned int id);
172 * ida_get_new - allocate new ID
174 * @p_id: pointer to the allocated handle
176 * Simple wrapper around ida_get_new_above() w/ @starting_id of zero.
178 static inline int ida_get_new(struct ida *ida, int *p_id)
180 return ida_get_new_above(ida, 0, p_id);
183 void __init idr_init_cache(void);
185 #endif /* __IDR_H__ */