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 #include <linux/cleanup.h>
19
20 struct idr {
21 struct radix_tree_root idr_rt;
22 unsigned int idr_base;
23 unsigned int idr_next;
24 };
25
26 /*
27 * The IDR API does not expose the tagging functionality of the radix tree
28 * to users. Use tag 0 to track whether a node has free space below it.
29 */
30 #define IDR_FREE 0
31
32 /* Set the IDR flag and the IDR_FREE tag */
33 #define IDR_RT_MARKER (ROOT_IS_IDR | (__force gfp_t) \
34 (1 << (ROOT_TAG_SHIFT + IDR_FREE)))
35
36 #define IDR_INIT_BASE(name, base) { \
37 .idr_rt = RADIX_TREE_INIT(name, IDR_RT_MARKER), \
38 .idr_base = (base), \
39 .idr_next = 0, \
40 }
41
42 /**
43 * IDR_INIT() - Initialise an IDR.
44 * @name: Name of IDR.
45 *
46 * A freshly-initialised IDR contains no IDs.
47 */
48 #define IDR_INIT(name) IDR_INIT_BASE(name, 0)
49
50 /**
51 * DEFINE_IDR() - Define a statically-allocated IDR.
52 * @name: Name of IDR.
53 *
54 * An IDR defined using this macro is ready for use with no additional
55 * initialisation required. It contains no IDs.
56 */
57 #define DEFINE_IDR(name) struct idr name = IDR_INIT(name)
58
59 /**
60 * idr_get_cursor - Return the current position of the cyclic allocator
61 * @idr: idr handle
62 *
63 * The value returned is the value that will be next returned from
64 * idr_alloc_cyclic() if it is free (otherwise the search will start from
65 * this position).
66 */
idr_get_cursor(const struct idr * idr)67 static inline unsigned int idr_get_cursor(const struct idr *idr)
68 {
69 return READ_ONCE(idr->idr_next);
70 }
71
72 /**
73 * idr_set_cursor - Set the current position of the cyclic allocator
74 * @idr: idr handle
75 * @val: new position
76 *
77 * The next call to idr_alloc_cyclic() will return @val if it is free
78 * (otherwise the search will start from this position).
79 */
idr_set_cursor(struct idr * idr,unsigned int val)80 static inline void idr_set_cursor(struct idr *idr, unsigned int val)
81 {
82 WRITE_ONCE(idr->idr_next, val);
83 }
84
85 /**
86 * DOC: idr sync
87 * idr synchronization (stolen from radix-tree.h)
88 *
89 * idr_find() is able to be called locklessly, using RCU. The caller must
90 * ensure calls to this function are made within rcu_read_lock() regions.
91 * Other readers (lock-free or otherwise) and modifications may be running
92 * concurrently.
93 *
94 * It is still required that the caller manage the synchronization and
95 * lifetimes of the items. So if RCU lock-free lookups are used, typically
96 * this would mean that the items have their own locks, or are amenable to
97 * lock-free access; and that the items are freed by RCU (or only freed after
98 * having been deleted from the idr tree *and* a synchronize_rcu() grace
99 * period).
100 */
101
102 #define idr_lock(idr) xa_lock(&(idr)->idr_rt)
103 #define idr_unlock(idr) xa_unlock(&(idr)->idr_rt)
104 #define idr_lock_bh(idr) xa_lock_bh(&(idr)->idr_rt)
105 #define idr_unlock_bh(idr) xa_unlock_bh(&(idr)->idr_rt)
106 #define idr_lock_irq(idr) xa_lock_irq(&(idr)->idr_rt)
107 #define idr_unlock_irq(idr) xa_unlock_irq(&(idr)->idr_rt)
108 #define idr_lock_irqsave(idr, flags) \
109 xa_lock_irqsave(&(idr)->idr_rt, flags)
110 #define idr_unlock_irqrestore(idr, flags) \
111 xa_unlock_irqrestore(&(idr)->idr_rt, flags)
112
113 void idr_preload(gfp_t gfp_mask);
114
115 int idr_alloc(struct idr *, void *ptr, int start, int end, gfp_t);
116 int __must_check idr_alloc_u32(struct idr *, void *ptr, u32 *id,
117 unsigned long max, gfp_t);
118 int idr_alloc_cyclic(struct idr *, void *ptr, int start, int end, gfp_t);
119 void *idr_remove(struct idr *, unsigned long id);
120 void *idr_find(const struct idr *, unsigned long id);
121 int idr_for_each(const struct idr *,
122 int (*fn)(int id, void *p, void *data), void *data);
123 void *idr_get_next(struct idr *, int *nextid);
124 void *idr_get_next_ul(struct idr *, unsigned long *nextid);
125 void *idr_replace(struct idr *, void *, unsigned long id);
126 void idr_destroy(struct idr *);
127
128 struct __class_idr {
129 struct idr *idr;
130 int id;
131 };
132
133 #define idr_null ((struct __class_idr){ NULL, -1 })
134 #define take_idr_id(id) __get_and_null(id, idr_null)
135
136 DEFINE_CLASS(idr_alloc, struct __class_idr,
137 if (_T.id >= 0) idr_remove(_T.idr, _T.id),
138 ((struct __class_idr){
139 .idr = idr,
140 .id = idr_alloc(idr, ptr, start, end, gfp),
141 }),
142 struct idr *idr, void *ptr, int start, int end, gfp_t gfp);
143
144 /**
145 * idr_init_base() - Initialise an IDR.
146 * @idr: IDR handle.
147 * @base: The base value for the IDR.
148 *
149 * This variation of idr_init() creates an IDR which will allocate IDs
150 * starting at %base.
151 */
idr_init_base(struct idr * idr,int base)152 static inline void idr_init_base(struct idr *idr, int base)
153 {
154 INIT_RADIX_TREE(&idr->idr_rt, IDR_RT_MARKER);
155 idr->idr_base = base;
156 idr->idr_next = 0;
157 }
158
159 /**
160 * idr_init() - Initialise an IDR.
161 * @idr: IDR handle.
162 *
163 * Initialise a dynamically allocated IDR. To initialise a
164 * statically allocated IDR, use DEFINE_IDR().
165 */
idr_init(struct idr * idr)166 static inline void idr_init(struct idr *idr)
167 {
168 idr_init_base(idr, 0);
169 }
170
171 /**
172 * idr_is_empty() - Are there any IDs allocated?
173 * @idr: IDR handle.
174 *
175 * Return: %true if any IDs have been allocated from this IDR.
176 */
idr_is_empty(const struct idr * idr)177 static inline bool idr_is_empty(const struct idr *idr)
178 {
179 return radix_tree_empty(&idr->idr_rt) &&
180 radix_tree_tagged(&idr->idr_rt, IDR_FREE);
181 }
182
183 /**
184 * idr_preload_end - end preload section started with idr_preload()
185 *
186 * Each idr_preload() should be matched with an invocation of this
187 * function. See idr_preload() for details.
188 */
idr_preload_end(void)189 static inline void idr_preload_end(void)
190 {
191 local_unlock(&radix_tree_preloads.lock);
192 }
193
194 /**
195 * idr_for_each_entry() - Iterate over an IDR's elements of a given type.
196 * @idr: IDR handle.
197 * @entry: The type * to use as cursor
198 * @id: Entry ID.
199 *
200 * @entry and @id do not need to be initialized before the loop, and
201 * after normal termination @entry is left with the value NULL. This
202 * is convenient for a "not found" value.
203 */
204 #define idr_for_each_entry(idr, entry, id) \
205 for (id = 0; ((entry) = idr_get_next(idr, &(id))) != NULL; id += 1U)
206
207 /**
208 * idr_for_each_entry_ul() - Iterate over an IDR's elements of a given type.
209 * @idr: IDR handle.
210 * @entry: The type * to use as cursor.
211 * @tmp: A temporary placeholder for ID.
212 * @id: Entry ID.
213 *
214 * @entry and @id do not need to be initialized before the loop, and
215 * after normal termination @entry is left with the value NULL. This
216 * is convenient for a "not found" value.
217 */
218 #define idr_for_each_entry_ul(idr, entry, tmp, id) \
219 for (tmp = 0, id = 0; \
220 ((entry) = tmp <= id ? idr_get_next_ul(idr, &(id)) : NULL) != NULL; \
221 tmp = id, ++id)
222
223 /**
224 * idr_for_each_entry_continue() - Continue iteration over an IDR's elements of a given type
225 * @idr: IDR handle.
226 * @entry: The type * to use as a cursor.
227 * @id: Entry ID.
228 *
229 * Continue to iterate over entries, continuing after the current position.
230 */
231 #define idr_for_each_entry_continue(idr, entry, id) \
232 for ((entry) = idr_get_next((idr), &(id)); \
233 entry; \
234 ++id, (entry) = idr_get_next((idr), &(id)))
235
236 /**
237 * idr_for_each_entry_continue_ul() - Continue iteration over an IDR's elements of a given type
238 * @idr: IDR handle.
239 * @entry: The type * to use as a cursor.
240 * @tmp: A temporary placeholder for ID.
241 * @id: Entry ID.
242 *
243 * Continue to iterate over entries, continuing after the current position.
244 * After normal termination @entry is left with the value NULL. This
245 * is convenient for a "not found" value.
246 */
247 #define idr_for_each_entry_continue_ul(idr, entry, tmp, id) \
248 for (tmp = id; \
249 ((entry) = tmp <= id ? idr_get_next_ul(idr, &(id)) : NULL) != NULL; \
250 tmp = id, ++id)
251
252 /*
253 * IDA - ID Allocator, use when translation from id to pointer isn't necessary.
254 */
255 #define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */
256 #define IDA_BITMAP_LONGS (IDA_CHUNK_SIZE / sizeof(long))
257 #define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8)
258
259 struct ida_bitmap {
260 unsigned long bitmap[IDA_BITMAP_LONGS];
261 };
262
263 struct ida {
264 struct xarray xa;
265 };
266
267 #define IDA_INIT_FLAGS (XA_FLAGS_LOCK_IRQ | XA_FLAGS_ALLOC)
268
269 #define IDA_INIT(name) { \
270 .xa = XARRAY_INIT(name, IDA_INIT_FLAGS) \
271 }
272 #define DEFINE_IDA(name) struct ida name = IDA_INIT(name)
273
274 int ida_alloc_range(struct ida *, unsigned int min, unsigned int max, gfp_t);
275 void ida_free(struct ida *, unsigned int id);
276 void ida_destroy(struct ida *ida);
277 int ida_find_first_range(struct ida *ida, unsigned int min, unsigned int max);
278
279 /**
280 * ida_alloc() - Allocate an unused ID.
281 * @ida: IDA handle.
282 * @gfp: Memory allocation flags.
283 *
284 * Allocate an ID between 0 and %INT_MAX, inclusive.
285 *
286 * Context: Any context. It is safe to call this function without
287 * locking in your code.
288 * Return: The allocated ID, or %-ENOMEM if memory could not be allocated,
289 * or %-ENOSPC if there are no free IDs.
290 */
ida_alloc(struct ida * ida,gfp_t gfp)291 static inline int ida_alloc(struct ida *ida, gfp_t gfp)
292 {
293 return ida_alloc_range(ida, 0, ~0, gfp);
294 }
295
296 /**
297 * ida_alloc_min() - Allocate an unused ID.
298 * @ida: IDA handle.
299 * @min: Lowest ID to allocate.
300 * @gfp: Memory allocation flags.
301 *
302 * Allocate an ID between @min and %INT_MAX, inclusive.
303 *
304 * Context: Any context. It is safe to call this function without
305 * locking in your code.
306 * Return: The allocated ID, or %-ENOMEM if memory could not be allocated,
307 * or %-ENOSPC if there are no free IDs.
308 */
ida_alloc_min(struct ida * ida,unsigned int min,gfp_t gfp)309 static inline int ida_alloc_min(struct ida *ida, unsigned int min, gfp_t gfp)
310 {
311 return ida_alloc_range(ida, min, ~0, gfp);
312 }
313
314 /**
315 * ida_alloc_max() - Allocate an unused ID.
316 * @ida: IDA handle.
317 * @max: Highest ID to allocate.
318 * @gfp: Memory allocation flags.
319 *
320 * Allocate an ID between 0 and @max, inclusive.
321 *
322 * Context: Any context. It is safe to call this function without
323 * locking in your code.
324 * Return: The allocated ID, or %-ENOMEM if memory could not be allocated,
325 * or %-ENOSPC if there are no free IDs.
326 */
ida_alloc_max(struct ida * ida,unsigned int max,gfp_t gfp)327 static inline int ida_alloc_max(struct ida *ida, unsigned int max, gfp_t gfp)
328 {
329 return ida_alloc_range(ida, 0, max, gfp);
330 }
331
ida_init(struct ida * ida)332 static inline void ida_init(struct ida *ida)
333 {
334 xa_init_flags(&ida->xa, IDA_INIT_FLAGS);
335 }
336
337 /*
338 * ida_simple_get() and ida_simple_remove() are deprecated. Use
339 * ida_alloc() and ida_free() instead respectively.
340 */
341 #define ida_simple_get(ida, start, end, gfp) \
342 ida_alloc_range(ida, start, (end) - 1, gfp)
343 #define ida_simple_remove(ida, id) ida_free(ida, id)
344
ida_is_empty(const struct ida * ida)345 static inline bool ida_is_empty(const struct ida *ida)
346 {
347 return xa_empty(&ida->xa);
348 }
349
ida_exists(struct ida * ida,unsigned int id)350 static inline bool ida_exists(struct ida *ida, unsigned int id)
351 {
352 return ida_find_first_range(ida, id, id) == id;
353 }
354
ida_find_first(struct ida * ida)355 static inline int ida_find_first(struct ida *ida)
356 {
357 return ida_find_first_range(ida, 0, ~0);
358 }
359 #endif /* __IDR_H__ */
360