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 *hint; /* the last layer allocated from */
41 struct idr_layer __rcu *top;
42 struct idr_layer *id_free;
43 int layers; /* only valid w/o concurrent changes */
45 int cur; /* current pos for cyclic allocation */
49 #define IDR_INIT(name) \
51 .lock = __SPIN_LOCK_UNLOCKED(name.lock), \
53 #define DEFINE_IDR(name) struct idr name = IDR_INIT(name)
57 * idr synchronization (stolen from radix-tree.h)
59 * idr_find() is able to be called locklessly, using RCU. The caller must
60 * ensure calls to this function are made within rcu_read_lock() regions.
61 * Other readers (lock-free or otherwise) and modifications may be running
64 * It is still required that the caller manage the synchronization and
65 * lifetimes of the items. So if RCU lock-free lookups are used, typically
66 * this would mean that the items have their own locks, or are amenable to
67 * lock-free access; and that the items are freed by RCU (or only freed after
68 * having been deleted from the idr tree *and* a synchronize_rcu() grace
73 * This is what we export.
76 void *idr_find_slowpath(struct idr *idp, 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_alloc_cyclic(struct idr *idr, void *ptr, int start, int end, gfp_t gfp_mask);
80 int idr_for_each(struct idr *idp,
81 int (*fn)(int id, void *p, void *data), void *data);
82 void *idr_get_next(struct idr *idp, int *nextid);
83 void *idr_replace(struct idr *idp, void *ptr, int id);
84 void idr_remove(struct idr *idp, int id);
85 void idr_free(struct idr *idp, int id);
86 void idr_destroy(struct idr *idp);
87 void idr_init(struct idr *idp);
88 bool idr_is_empty(struct idr *idp);
91 * idr_preload_end - end preload section started with idr_preload()
93 * Each idr_preload() should be matched with an invocation of this
94 * function. See idr_preload() for details.
96 static inline void idr_preload_end(void)
102 * idr_find - return pointer for given id
106 * Return the pointer given the id it has been registered with. A %NULL
107 * return indicates that @id is not valid or you passed %NULL in
110 * This function can be called under rcu_read_lock(), given that the leaf
111 * pointers lifetimes are correctly managed.
113 static inline void *idr_find(struct idr *idr, int id)
115 struct idr_layer *hint = rcu_dereference_raw(idr->hint);
117 if (hint && (id & ~IDR_MASK) == hint->prefix)
118 return rcu_dereference_raw(hint->ary[id & IDR_MASK]);
120 return idr_find_slowpath(idr, id);
124 * idr_for_each_entry - iterate over an idr's elements of a given type
126 * @entry: the type * to use as cursor
127 * @id: id entry's key
129 * @entry and @id do not need to be initialized before the loop, and
130 * after normal terminatinon @entry is left with the value NULL. This
131 * is convenient for a "not found" value.
133 #define idr_for_each_entry(idp, entry, id) \
134 for (id = 0; ((entry) = idr_get_next(idp, &(id))) != NULL; ++id)
137 * Don't use the following functions. These exist only to suppress
138 * deprecated warnings on EXPORT_SYMBOL()s.
140 int __idr_pre_get(struct idr *idp, gfp_t gfp_mask);
141 int __idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id);
142 void __idr_remove_all(struct idr *idp);
145 * idr_pre_get - reserve resources for idr allocation
147 * @gfp_mask: memory allocation flags
149 * Part of old alloc interface. This is going away. Use
150 * idr_preload[_end]() and idr_alloc() instead.
152 static inline int __deprecated idr_pre_get(struct idr *idp, gfp_t gfp_mask)
154 return __idr_pre_get(idp, gfp_mask);
158 * idr_get_new_above - allocate new idr entry above or equal to a start id
160 * @ptr: pointer you want associated with the id
161 * @starting_id: id to start search at
162 * @id: pointer to the allocated handle
164 * Part of old alloc interface. This is going away. Use
165 * idr_preload[_end]() and idr_alloc() instead.
167 static inline int __deprecated idr_get_new_above(struct idr *idp, void *ptr,
168 int starting_id, int *id)
170 return __idr_get_new_above(idp, ptr, starting_id, id);
174 * idr_get_new - allocate new idr entry
176 * @ptr: pointer you want associated with the id
177 * @id: pointer to the allocated handle
179 * Part of old alloc interface. This is going away. Use
180 * idr_preload[_end]() and idr_alloc() instead.
182 static inline int __deprecated idr_get_new(struct idr *idp, void *ptr, int *id)
184 return __idr_get_new_above(idp, ptr, 0, id);
188 * idr_remove_all - remove all ids from the given idr tree
191 * If you're trying to destroy @idp, calling idr_destroy() is enough.
192 * This is going away. Don't use.
194 static inline void __deprecated idr_remove_all(struct idr *idp)
196 __idr_remove_all(idp);
200 * IDA - IDR based id allocator, use when translation from id to
201 * pointer isn't necessary.
203 * IDA_BITMAP_LONGS is calculated to be one less to accommodate
204 * ida_bitmap->nr_busy so that the whole struct fits in 128 bytes.
206 #define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */
207 #define IDA_BITMAP_LONGS (IDA_CHUNK_SIZE / sizeof(long) - 1)
208 #define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8)
212 unsigned long bitmap[IDA_BITMAP_LONGS];
217 struct ida_bitmap *free_bitmap;
220 #define IDA_INIT(name) { .idr = IDR_INIT((name).idr), .free_bitmap = NULL, }
221 #define DEFINE_IDA(name) struct ida name = IDA_INIT(name)
223 int ida_pre_get(struct ida *ida, gfp_t gfp_mask);
224 int ida_get_new_above(struct ida *ida, int starting_id, int *p_id);
225 void ida_remove(struct ida *ida, int id);
226 void ida_destroy(struct ida *ida);
227 void ida_init(struct ida *ida);
229 int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end,
231 void ida_simple_remove(struct ida *ida, unsigned int id);
234 * ida_get_new - allocate new ID
236 * @p_id: pointer to the allocated handle
238 * Simple wrapper around ida_get_new_above() w/ @starting_id of zero.
240 static inline int ida_get_new(struct ida *ida, int *p_id)
242 return ida_get_new_above(ida, 0, p_id);
245 void __init idr_init_cache(void);
247 #endif /* __IDR_H__ */