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 */
11
12 #ifndef __IDR_H__
13 #define __IDR_H__
14
15 #include <linux/radix-tree.h>
16 #include <linux/gfp.h>
17 #include <linux/percpu.h>
18
19 struct idr {
20 struct radix_tree_root idr_rt;
21 unsigned int idr_base;
22 unsigned int idr_next;
23 };
24
25 /*
26 * The IDR API does not expose the tagging functionality of the radix tree
27 * to users. Use tag 0 to track whether a node has free space below it.
28 */
29 #define IDR_FREE 0
30
31 /* Set the IDR flag and the IDR_FREE tag */
32 #define IDR_RT_MARKER (ROOT_IS_IDR | (__force gfp_t) \
33 (1 << (ROOT_TAG_SHIFT + IDR_FREE)))
34
35 #define IDR_INIT_BASE(name, base) { \
36 .idr_rt = RADIX_TREE_INIT(name, IDR_RT_MARKER), \
37 .idr_base = (base), \
38 .idr_next = 0, \
39 }
40
41 /**
42 * IDR_INIT() - Initialise an IDR.
43 * @name: Name of IDR.
44 *
45 * A freshly-initialised IDR contains no IDs.
46 */
47 #define IDR_INIT(name) IDR_INIT_BASE(name, 0)
48
49 /**
50 * DEFINE_IDR() - Define a statically-allocated IDR.
51 * @name: Name of IDR.
52 *
53 * An IDR defined using this macro is ready for use with no additional
54 * initialisation required. It contains no IDs.
55 */
56 #define DEFINE_IDR(name) struct idr name = IDR_INIT(name)
57
58 /**
59 * idr_get_cursor - Return the current position of the cyclic allocator
60 * @idr: idr handle
61 *
62 * The value returned is the value that will be next returned from
63 * idr_alloc_cyclic() if it is free (otherwise the search will start from
64 * this position).
65 */
66 static inline unsigned int idr_get_cursor(const struct idr *idr)
67 {
68 return READ_ONCE(idr->idr_next);
69 }
70
71 /**
72 * idr_set_cursor - Set the current position of the cyclic allocator
73 * @idr: idr handle
74 * @val: new position
75 *
76 * The next call to idr_alloc_cyclic() will return @val if it is free
77 * (otherwise the search will start from this position).
78 */
79 static inline void idr_set_cursor(struct idr *idr, unsigned int val)
80 {
81 WRITE_ONCE(idr->idr_next, val);
82 }
83
84 /**
85 * DOC: idr sync
86 * idr synchronization (stolen from radix-tree.h)
87 *
88 * idr_find() is able to be called locklessly, using RCU. The caller must
89 * ensure calls to this function are made within rcu_read_lock() regions.
90 * Other readers (lock-free or otherwise) and modifications may be running
91 * concurrently.
92 *
93 * It is still required that the caller manage the synchronization and
94 * lifetimes of the items. So if RCU lock-free lookups are used, typically
95 * this would mean that the items have their own locks, or are amenable to
96 * lock-free access; and that the items are freed by RCU (or only freed after
97 * having been deleted from the idr tree *and* a synchronize_rcu() grace
98 * period).
99 */
100
101 void idr_preload(gfp_t gfp_mask);
102
103 int idr_alloc(struct idr *, void *ptr, int start, int end, gfp_t);
104 int __must_check idr_alloc_u32(struct idr *, void *ptr, u32 *id,
105 unsigned long max, gfp_t);
106 int idr_alloc_cyclic(struct idr *, void *ptr, int start, int end, gfp_t);
107 void *idr_remove(struct idr *, unsigned long id);
108 void *idr_find(const struct idr *, unsigned long id);
109 int idr_for_each(const struct idr *,
110 int (*fn)(int id, void *p, void *data), void *data);
111 void *idr_get_next(struct idr *, int *nextid);
112 void *idr_get_next_ul(struct idr *, unsigned long *nextid);
113 void *idr_replace(struct idr *, void *, unsigned long id);
114 void idr_destroy(struct idr *);
115
116 /**
117 * idr_init_base() - Initialise an IDR.
118 * @idr: IDR handle.
119 * @base: The base value for the IDR.
120 *
121 * This variation of idr_init() creates an IDR which will allocate IDs
122 * starting at %base.
123 */
124 static inline void idr_init_base(struct idr *idr, int base)
125 {
126 INIT_RADIX_TREE(&idr->idr_rt, IDR_RT_MARKER);
127 idr->idr_base = base;
128 idr->idr_next = 0;
129 }
130
131 /**
132 * idr_init() - Initialise an IDR.
133 * @idr: IDR handle.
134 *
135 * Initialise a dynamically allocated IDR. To initialise a
136 * statically allocated IDR, use DEFINE_IDR().
137 */
138 static inline void idr_init(struct idr *idr)
139 {
140 idr_init_base(idr, 0);
141 }
142
143 /**
144 * idr_is_empty() - Are there any IDs allocated?
145 * @idr: IDR handle.
146 *
147 * Return: %true if any IDs have been allocated from this IDR.
148 */
149 static inline bool idr_is_empty(const struct idr *idr)
150 {
151 return radix_tree_empty(&idr->idr_rt) &&
152 radix_tree_tagged(&idr->idr_rt, IDR_FREE);
153 }
154
155 /**
156 * idr_preload_end - end preload section started with idr_preload()
157 *
158 * Each idr_preload() should be matched with an invocation of this
159 * function. See idr_preload() for details.
160 */
161 static inline void idr_preload_end(void)
162 {
163 preempt_enable();
164 }
165
166 /**
167 * idr_for_each_entry() - Iterate over an IDR's elements of a given type.
168 * @idr: IDR handle.
169 * @entry: The type * to use as cursor
170 * @id: Entry ID.
171 *
172 * @entry and @id do not need to be initialized before the loop, and
173 * after normal termination @entry is left with the value NULL. This
174 * is convenient for a "not found" value.
175 */
176 #define idr_for_each_entry(idr, entry, id) \
177 for (id = 0; ((entry) = idr_get_next(idr, &(id))) != NULL; ++id)
178
179 /**
180 * idr_for_each_entry_ul() - Iterate over an IDR's elements of a given type.
181 * @idr: IDR handle.
182 * @entry: The type * to use as cursor.
183 * @id: Entry ID.
184 *
185 * @entry and @id do not need to be initialized before the loop, and
186 * after normal termination @entry is left with the value NULL. This
187 * is convenient for a "not found" value.
188 */
189 #define idr_for_each_entry_ul(idr, entry, id) \
190 for (id = 0; ((entry) = idr_get_next_ul(idr, &(id))) != NULL; ++id)
191
192 /**
193 * idr_for_each_entry_continue() - Continue iteration over an IDR's elements of a given type
194 * @idr: IDR handle.
195 * @entry: The type * to use as a cursor.
196 * @id: Entry ID.
197 *
198 * Continue to iterate over entries, continuing after the current position.
199 */
200 #define idr_for_each_entry_continue(idr, entry, id) \
201 for ((entry) = idr_get_next((idr), &(id)); \
202 entry; \
203 ++id, (entry) = idr_get_next((idr), &(id)))
204
205 /*
206 * IDA - IDR based id allocator, use when translation from id to
207 * pointer isn't necessary.
208 */
209 #define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */
210 #define IDA_BITMAP_LONGS (IDA_CHUNK_SIZE / sizeof(long))
211 #define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8)
212
213 struct ida_bitmap {
214 unsigned long bitmap[IDA_BITMAP_LONGS];
215 };
216
217 DECLARE_PER_CPU(struct ida_bitmap *, ida_bitmap);
218
219 struct ida {
220 struct radix_tree_root ida_rt;
221 };
222
223 #define IDA_INIT(name) { \
224 .ida_rt = RADIX_TREE_INIT(name, IDR_RT_MARKER | GFP_NOWAIT), \
225 }
226 #define DEFINE_IDA(name) struct ida name = IDA_INIT(name)
227
228 int ida_pre_get(struct ida *ida, gfp_t gfp_mask);
229 int ida_get_new_above(struct ida *ida, int starting_id, int *p_id);
230 void ida_remove(struct ida *ida, int id);
231 void ida_destroy(struct ida *ida);
232
233 int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end,
234 gfp_t gfp_mask);
235 void ida_simple_remove(struct ida *ida, unsigned int id);
236
237 static inline void ida_init(struct ida *ida)
238 {
239 INIT_RADIX_TREE(&ida->ida_rt, IDR_RT_MARKER | GFP_NOWAIT);
240 }
241
242 /**
243 * ida_get_new - allocate new ID
244 * @ida: idr handle
245 * @p_id: pointer to the allocated handle
246 *
247 * Simple wrapper around ida_get_new_above() w/ @starting_id of zero.
248 */
249 static inline int ida_get_new(struct ida *ida, int *p_id)
250 {
251 return ida_get_new_above(ida, 0, p_id);
252 }
253
254 static inline bool ida_is_empty(const struct ida *ida)
255 {
256 return radix_tree_empty(&ida->ida_rt);
257 }
258 #endif /* __IDR_H__ */
259
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