1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3 * include/linux/idr.h
4 *
5 * 2002-10-18 written by Jim Houston jim.houston@ccur.com
6 * Copyright (C) 2002 by Concurrent Computer Corporation
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 */
idr_get_cursor(const struct idr * idr)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 */
idr_set_cursor(struct idr * idr,unsigned int val)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 #define idr_lock(idr) xa_lock(&(idr)->idr_rt)
102 #define idr_unlock(idr) xa_unlock(&(idr)->idr_rt)
103 #define idr_lock_bh(idr) xa_lock_bh(&(idr)->idr_rt)
104 #define idr_unlock_bh(idr) xa_unlock_bh(&(idr)->idr_rt)
105 #define idr_lock_irq(idr) xa_lock_irq(&(idr)->idr_rt)
106 #define idr_unlock_irq(idr) xa_unlock_irq(&(idr)->idr_rt)
107 #define idr_lock_irqsave(idr, flags) \
108 xa_lock_irqsave(&(idr)->idr_rt, flags)
109 #define idr_unlock_irqrestore(idr, flags) \
110 xa_unlock_irqrestore(&(idr)->idr_rt, flags)
111
112 void idr_preload(gfp_t gfp_mask);
113
114 int idr_alloc(struct idr *, void *ptr, int start, int end, gfp_t);
115 int __must_check idr_alloc_u32(struct idr *, void *ptr, u32 *id,
116 unsigned long max, gfp_t);
117 int idr_alloc_cyclic(struct idr *, void *ptr, int start, int end, gfp_t);
118 void *idr_remove(struct idr *, unsigned long id);
119 void *idr_find(const struct idr *, unsigned long id);
120 int idr_for_each(const struct idr *,
121 int (*fn)(int id, void *p, void *data), void *data);
122 void *idr_get_next(struct idr *, int *nextid);
123 void *idr_get_next_ul(struct idr *, unsigned long *nextid);
124 void *idr_replace(struct idr *, void *, unsigned long id);
125 void idr_destroy(struct idr *);
126
127 /**
128 * idr_init_base() - Initialise an IDR.
129 * @idr: IDR handle.
130 * @base: The base value for the IDR.
131 *
132 * This variation of idr_init() creates an IDR which will allocate IDs
133 * starting at %base.
134 */
idr_init_base(struct idr * idr,int base)135 static inline void idr_init_base(struct idr *idr, int base)
136 {
137 INIT_RADIX_TREE(&idr->idr_rt, IDR_RT_MARKER);
138 idr->idr_base = base;
139 idr->idr_next = 0;
140 }
141
142 /**
143 * idr_init() - Initialise an IDR.
144 * @idr: IDR handle.
145 *
146 * Initialise a dynamically allocated IDR. To initialise a
147 * statically allocated IDR, use DEFINE_IDR().
148 */
idr_init(struct idr * idr)149 static inline void idr_init(struct idr *idr)
150 {
151 idr_init_base(idr, 0);
152 }
153
154 /**
155 * idr_is_empty() - Are there any IDs allocated?
156 * @idr: IDR handle.
157 *
158 * Return: %true if any IDs have been allocated from this IDR.
159 */
idr_is_empty(const struct idr * idr)160 static inline bool idr_is_empty(const struct idr *idr)
161 {
162 return radix_tree_empty(&idr->idr_rt) &&
163 radix_tree_tagged(&idr->idr_rt, IDR_FREE);
164 }
165
166 /**
167 * idr_preload_end - end preload section started with idr_preload()
168 *
169 * Each idr_preload() should be matched with an invocation of this
170 * function. See idr_preload() for details.
171 */
idr_preload_end(void)172 static inline void idr_preload_end(void)
173 {
174 preempt_enable();
175 }
176
177 /**
178 * idr_for_each_entry() - Iterate over an IDR's elements of a given type.
179 * @idr: IDR handle.
180 * @entry: The type * to use as cursor
181 * @id: Entry ID.
182 *
183 * @entry and @id do not need to be initialized before the loop, and
184 * after normal termination @entry is left with the value NULL. This
185 * is convenient for a "not found" value.
186 */
187 #define idr_for_each_entry(idr, entry, id) \
188 for (id = 0; ((entry) = idr_get_next(idr, &(id))) != NULL; id += 1U)
189
190 /**
191 * idr_for_each_entry_ul() - Iterate over an IDR's elements of a given type.
192 * @idr: IDR handle.
193 * @entry: The type * to use as cursor.
194 * @tmp: A temporary placeholder for ID.
195 * @id: Entry ID.
196 *
197 * @entry and @id do not need to be initialized before the loop, and
198 * after normal termination @entry is left with the value NULL. This
199 * is convenient for a "not found" value.
200 */
201 #define idr_for_each_entry_ul(idr, entry, tmp, id) \
202 for (tmp = 0, id = 0; \
203 tmp <= id && ((entry) = idr_get_next_ul(idr, &(id))) != NULL; \
204 tmp = id, ++id)
205
206 /**
207 * idr_for_each_entry_continue() - Continue iteration over an IDR's elements of a given type
208 * @idr: IDR handle.
209 * @entry: The type * to use as a cursor.
210 * @id: Entry ID.
211 *
212 * Continue to iterate over entries, continuing after the current position.
213 */
214 #define idr_for_each_entry_continue(idr, entry, id) \
215 for ((entry) = idr_get_next((idr), &(id)); \
216 entry; \
217 ++id, (entry) = idr_get_next((idr), &(id)))
218
219 /**
220 * idr_for_each_entry_continue_ul() - Continue iteration over an IDR's elements of a given type
221 * @idr: IDR handle.
222 * @entry: The type * to use as a cursor.
223 * @tmp: A temporary placeholder for ID.
224 * @id: Entry ID.
225 *
226 * Continue to iterate over entries, continuing after the current position.
227 */
228 #define idr_for_each_entry_continue_ul(idr, entry, tmp, id) \
229 for (tmp = id; \
230 tmp <= id && ((entry) = idr_get_next_ul(idr, &(id))) != NULL; \
231 tmp = id, ++id)
232
233 /*
234 * IDA - ID Allocator, use when translation from id to pointer isn't necessary.
235 */
236 #define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */
237 #define IDA_BITMAP_LONGS (IDA_CHUNK_SIZE / sizeof(long))
238 #define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8)
239
240 struct ida_bitmap {
241 unsigned long bitmap[IDA_BITMAP_LONGS];
242 };
243
244 struct ida {
245 struct xarray xa;
246 };
247
248 #define IDA_INIT_FLAGS (XA_FLAGS_LOCK_IRQ | XA_FLAGS_ALLOC)
249
250 #define IDA_INIT(name) { \
251 .xa = XARRAY_INIT(name, IDA_INIT_FLAGS) \
252 }
253 #define DEFINE_IDA(name) struct ida name = IDA_INIT(name)
254
255 int ida_alloc_range(struct ida *, unsigned int min, unsigned int max, gfp_t);
256 void ida_free(struct ida *, unsigned int id);
257 void ida_destroy(struct ida *ida);
258
259 /**
260 * ida_alloc() - Allocate an unused ID.
261 * @ida: IDA handle.
262 * @gfp: Memory allocation flags.
263 *
264 * Allocate an ID between 0 and %INT_MAX, inclusive.
265 *
266 * Context: Any context.
267 * Return: The allocated ID, or %-ENOMEM if memory could not be allocated,
268 * or %-ENOSPC if there are no free IDs.
269 */
ida_alloc(struct ida * ida,gfp_t gfp)270 static inline int ida_alloc(struct ida *ida, gfp_t gfp)
271 {
272 return ida_alloc_range(ida, 0, ~0, gfp);
273 }
274
275 /**
276 * ida_alloc_min() - Allocate an unused ID.
277 * @ida: IDA handle.
278 * @min: Lowest ID to allocate.
279 * @gfp: Memory allocation flags.
280 *
281 * Allocate an ID between @min and %INT_MAX, inclusive.
282 *
283 * Context: Any context.
284 * Return: The allocated ID, or %-ENOMEM if memory could not be allocated,
285 * or %-ENOSPC if there are no free IDs.
286 */
ida_alloc_min(struct ida * ida,unsigned int min,gfp_t gfp)287 static inline int ida_alloc_min(struct ida *ida, unsigned int min, gfp_t gfp)
288 {
289 return ida_alloc_range(ida, min, ~0, gfp);
290 }
291
292 /**
293 * ida_alloc_max() - Allocate an unused ID.
294 * @ida: IDA handle.
295 * @max: Highest ID to allocate.
296 * @gfp: Memory allocation flags.
297 *
298 * Allocate an ID between 0 and @max, inclusive.
299 *
300 * Context: Any context.
301 * Return: The allocated ID, or %-ENOMEM if memory could not be allocated,
302 * or %-ENOSPC if there are no free IDs.
303 */
ida_alloc_max(struct ida * ida,unsigned int max,gfp_t gfp)304 static inline int ida_alloc_max(struct ida *ida, unsigned int max, gfp_t gfp)
305 {
306 return ida_alloc_range(ida, 0, max, gfp);
307 }
308
ida_init(struct ida * ida)309 static inline void ida_init(struct ida *ida)
310 {
311 xa_init_flags(&ida->xa, IDA_INIT_FLAGS);
312 }
313
314 #define ida_simple_get(ida, start, end, gfp) \
315 ida_alloc_range(ida, start, (end) - 1, gfp)
316 #define ida_simple_remove(ida, id) ida_free(ida, id)
317
ida_is_empty(const struct ida * ida)318 static inline bool ida_is_empty(const struct ida *ida)
319 {
320 return xa_empty(&ida->xa);
321 }
322 #endif /* __IDR_H__ */
323
