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1da177e4 LT |
1 | /* |
2 | * include/linux/idr.h | |
3 | * | |
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. | |
7 | * | |
8 | * Small id to pointer translation service avoiding fixed sized | |
9 | * tables. | |
10 | */ | |
f668ab1a LT |
11 | |
12 | #ifndef __IDR_H__ | |
13 | #define __IDR_H__ | |
14 | ||
1da177e4 LT |
15 | #include <linux/types.h> |
16 | #include <linux/bitops.h> | |
199f0ca5 | 17 | #include <linux/init.h> |
2027d1ab | 18 | #include <linux/rcupdate.h> |
1da177e4 | 19 | |
050a6b47 TH |
20 | /* |
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 | |
24 | * 1k on 32bit. | |
25 | */ | |
26 | #define IDR_BITS 8 | |
1da177e4 LT |
27 | #define IDR_SIZE (1 << IDR_BITS) |
28 | #define IDR_MASK ((1 << IDR_BITS)-1) | |
29 | ||
1da177e4 | 30 | struct idr_layer { |
54616283 | 31 | int prefix; /* the ID prefix of this idr_layer */ |
1d9b2e1e | 32 | DECLARE_BITMAP(bitmap, IDR_SIZE); /* A zero bit means "space here" */ |
d2c2486b | 33 | struct idr_layer __rcu *ary[1<<IDR_BITS]; |
4106ecaf TH |
34 | int count; /* When zero, we can release it */ |
35 | int layer; /* distance from leaf */ | |
36 | struct rcu_head rcu_head; | |
1da177e4 LT |
37 | }; |
38 | ||
39 | struct idr { | |
0ffc2a9c | 40 | struct idr_layer __rcu *hint; /* the last layer allocated from */ |
4106ecaf TH |
41 | struct idr_layer __rcu *top; |
42 | struct idr_layer *id_free; | |
43 | int layers; /* only valid w/o concurrent changes */ | |
44 | int id_free_cnt; | |
45 | spinlock_t lock; | |
1da177e4 LT |
46 | }; |
47 | ||
4106ecaf TH |
48 | #define IDR_INIT(name) \ |
49 | { \ | |
50 | .lock = __SPIN_LOCK_UNLOCKED(name.lock), \ | |
1da177e4 LT |
51 | } |
52 | #define DEFINE_IDR(name) struct idr name = IDR_INIT(name) | |
53 | ||
f9c46d6e | 54 | /** |
56083ab1 | 55 | * DOC: idr sync |
f9c46d6e ND |
56 | * idr synchronization (stolen from radix-tree.h) |
57 | * | |
58 | * idr_find() is able to be called locklessly, using RCU. The caller must | |
59 | * ensure calls to this function are made within rcu_read_lock() regions. | |
60 | * Other readers (lock-free or otherwise) and modifications may be running | |
61 | * concurrently. | |
62 | * | |
63 | * It is still required that the caller manage the synchronization and | |
64 | * lifetimes of the items. So if RCU lock-free lookups are used, typically | |
65 | * this would mean that the items have their own locks, or are amenable to | |
66 | * lock-free access; and that the items are freed by RCU (or only freed after | |
67 | * having been deleted from the idr tree *and* a synchronize_rcu() grace | |
68 | * period). | |
69 | */ | |
70 | ||
1da177e4 LT |
71 | /* |
72 | * This is what we export. | |
73 | */ | |
74 | ||
0ffc2a9c | 75 | void *idr_find_slowpath(struct idr *idp, int id); |
d5c7409f TH |
76 | void idr_preload(gfp_t gfp_mask); |
77 | int idr_alloc(struct idr *idp, void *ptr, int start, int end, gfp_t gfp_mask); | |
96d7fa42 KH |
78 | int idr_for_each(struct idr *idp, |
79 | int (*fn)(int id, void *p, void *data), void *data); | |
38460b48 | 80 | void *idr_get_next(struct idr *idp, int *nextid); |
5806f07c | 81 | void *idr_replace(struct idr *idp, void *ptr, int id); |
1da177e4 | 82 | void idr_remove(struct idr *idp, int id); |
d5c7409f | 83 | void idr_free(struct idr *idp, int id); |
8d3b3591 | 84 | void idr_destroy(struct idr *idp); |
1da177e4 | 85 | void idr_init(struct idr *idp); |
f668ab1a | 86 | |
d5c7409f TH |
87 | /** |
88 | * idr_preload_end - end preload section started with idr_preload() | |
89 | * | |
90 | * Each idr_preload() should be matched with an invocation of this | |
91 | * function. See idr_preload() for details. | |
92 | */ | |
93 | static inline void idr_preload_end(void) | |
94 | { | |
95 | preempt_enable(); | |
96 | } | |
97 | ||
0ffc2a9c TH |
98 | /** |
99 | * idr_find - return pointer for given id | |
5857f70c | 100 | * @idr: idr handle |
0ffc2a9c TH |
101 | * @id: lookup key |
102 | * | |
103 | * Return the pointer given the id it has been registered with. A %NULL | |
104 | * return indicates that @id is not valid or you passed %NULL in | |
105 | * idr_get_new(). | |
106 | * | |
107 | * This function can be called under rcu_read_lock(), given that the leaf | |
108 | * pointers lifetimes are correctly managed. | |
109 | */ | |
110 | static inline void *idr_find(struct idr *idr, int id) | |
111 | { | |
112 | struct idr_layer *hint = rcu_dereference_raw(idr->hint); | |
113 | ||
114 | if (hint && (id & ~IDR_MASK) == hint->prefix) | |
115 | return rcu_dereference_raw(hint->ary[id & IDR_MASK]); | |
116 | ||
117 | return idr_find_slowpath(idr, id); | |
118 | } | |
119 | ||
49038ef4 TH |
120 | /** |
121 | * idr_for_each_entry - iterate over an idr's elements of a given type | |
122 | * @idp: idr handle | |
123 | * @entry: the type * to use as cursor | |
124 | * @id: id entry's key | |
125 | */ | |
126 | #define idr_for_each_entry(idp, entry, id) \ | |
127 | for (id = 0, entry = (typeof(entry))idr_get_next((idp), &(id)); \ | |
128 | entry != NULL; \ | |
129 | ++id, entry = (typeof(entry))idr_get_next((idp), &(id))) | |
130 | ||
c8615d37 TH |
131 | /* |
132 | * Don't use the following functions. These exist only to suppress | |
133 | * deprecated warnings on EXPORT_SYMBOL()s. | |
134 | */ | |
135 | int __idr_pre_get(struct idr *idp, gfp_t gfp_mask); | |
136 | int __idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id); | |
137 | void __idr_remove_all(struct idr *idp); | |
138 | ||
139 | /** | |
140 | * idr_pre_get - reserve resources for idr allocation | |
141 | * @idp: idr handle | |
142 | * @gfp_mask: memory allocation flags | |
143 | * | |
144 | * Part of old alloc interface. This is going away. Use | |
145 | * idr_preload[_end]() and idr_alloc() instead. | |
146 | */ | |
147 | static inline int __deprecated idr_pre_get(struct idr *idp, gfp_t gfp_mask) | |
148 | { | |
149 | return __idr_pre_get(idp, gfp_mask); | |
150 | } | |
151 | ||
152 | /** | |
153 | * idr_get_new_above - allocate new idr entry above or equal to a start id | |
154 | * @idp: idr handle | |
155 | * @ptr: pointer you want associated with the id | |
156 | * @starting_id: id to start search at | |
157 | * @id: pointer to the allocated handle | |
158 | * | |
159 | * Part of old alloc interface. This is going away. Use | |
160 | * idr_preload[_end]() and idr_alloc() instead. | |
161 | */ | |
162 | static inline int __deprecated idr_get_new_above(struct idr *idp, void *ptr, | |
163 | int starting_id, int *id) | |
164 | { | |
165 | return __idr_get_new_above(idp, ptr, starting_id, id); | |
166 | } | |
167 | ||
168 | /** | |
169 | * idr_get_new - allocate new idr entry | |
170 | * @idp: idr handle | |
171 | * @ptr: pointer you want associated with the id | |
172 | * @id: pointer to the allocated handle | |
173 | * | |
174 | * Part of old alloc interface. This is going away. Use | |
175 | * idr_preload[_end]() and idr_alloc() instead. | |
176 | */ | |
177 | static inline int __deprecated idr_get_new(struct idr *idp, void *ptr, int *id) | |
178 | { | |
179 | return __idr_get_new_above(idp, ptr, 0, id); | |
180 | } | |
fe6e24ec TH |
181 | |
182 | /** | |
183 | * idr_remove_all - remove all ids from the given idr tree | |
184 | * @idp: idr handle | |
185 | * | |
186 | * If you're trying to destroy @idp, calling idr_destroy() is enough. | |
187 | * This is going away. Don't use. | |
188 | */ | |
189 | static inline void __deprecated idr_remove_all(struct idr *idp) | |
190 | { | |
191 | __idr_remove_all(idp); | |
192 | } | |
72dba584 TH |
193 | |
194 | /* | |
195 | * IDA - IDR based id allocator, use when translation from id to | |
196 | * pointer isn't necessary. | |
ed9f524a NK |
197 | * |
198 | * IDA_BITMAP_LONGS is calculated to be one less to accommodate | |
199 | * ida_bitmap->nr_busy so that the whole struct fits in 128 bytes. | |
72dba584 TH |
200 | */ |
201 | #define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */ | |
ed9f524a NK |
202 | #define IDA_BITMAP_LONGS (IDA_CHUNK_SIZE / sizeof(long) - 1) |
203 | #define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8) | |
72dba584 TH |
204 | |
205 | struct ida_bitmap { | |
206 | long nr_busy; | |
207 | unsigned long bitmap[IDA_BITMAP_LONGS]; | |
208 | }; | |
209 | ||
210 | struct ida { | |
211 | struct idr idr; | |
212 | struct ida_bitmap *free_bitmap; | |
213 | }; | |
214 | ||
eece09ec | 215 | #define IDA_INIT(name) { .idr = IDR_INIT((name).idr), .free_bitmap = NULL, } |
72dba584 TH |
216 | #define DEFINE_IDA(name) struct ida name = IDA_INIT(name) |
217 | ||
218 | int ida_pre_get(struct ida *ida, gfp_t gfp_mask); | |
219 | int ida_get_new_above(struct ida *ida, int starting_id, int *p_id); | |
72dba584 TH |
220 | void ida_remove(struct ida *ida, int id); |
221 | void ida_destroy(struct ida *ida); | |
222 | void ida_init(struct ida *ida); | |
223 | ||
88eca020 RR |
224 | int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end, |
225 | gfp_t gfp_mask); | |
226 | void ida_simple_remove(struct ida *ida, unsigned int id); | |
227 | ||
9749f30f | 228 | /** |
49038ef4 TH |
229 | * ida_get_new - allocate new ID |
230 | * @ida: idr handle | |
231 | * @p_id: pointer to the allocated handle | |
232 | * | |
233 | * Simple wrapper around ida_get_new_above() w/ @starting_id of zero. | |
9749f30f | 234 | */ |
49038ef4 TH |
235 | static inline int ida_get_new(struct ida *ida, int *p_id) |
236 | { | |
237 | return ida_get_new_above(ida, 0, p_id); | |
238 | } | |
239 | ||
240 | void __init idr_init_cache(void); | |
9749f30f | 241 | |
f668ab1a | 242 | #endif /* __IDR_H__ */ |