xref: /linux/include/linux/idr.h (revision 0ea5c948cb64bab5bc7a5516774eb8536f05aa0d)
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 	local_unlock(&radix_tree_preloads.lock);
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 	     ((entry) = tmp <= id ? idr_get_next_ul(idr, &(id)) : NULL) != 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  * After normal termination @entry is left with the value NULL.  This
228  * is convenient for a "not found" value.
229  */
230 #define idr_for_each_entry_continue_ul(idr, entry, tmp, id)		\
231 	for (tmp = id;							\
232 	     ((entry) = tmp <= id ? idr_get_next_ul(idr, &(id)) : NULL) != NULL; \
233 	     tmp = id, ++id)
234 
235 /*
236  * IDA - ID Allocator, use when translation from id to pointer isn't necessary.
237  */
238 #define IDA_CHUNK_SIZE		128	/* 128 bytes per chunk */
239 #define IDA_BITMAP_LONGS	(IDA_CHUNK_SIZE / sizeof(long))
240 #define IDA_BITMAP_BITS 	(IDA_BITMAP_LONGS * sizeof(long) * 8)
241 
242 struct ida_bitmap {
243 	unsigned long		bitmap[IDA_BITMAP_LONGS];
244 };
245 
246 struct ida {
247 	struct xarray xa;
248 };
249 
250 #define IDA_INIT_FLAGS	(XA_FLAGS_LOCK_IRQ | XA_FLAGS_ALLOC)
251 
252 #define IDA_INIT(name)	{						\
253 	.xa = XARRAY_INIT(name, IDA_INIT_FLAGS)				\
254 }
255 #define DEFINE_IDA(name)	struct ida name = IDA_INIT(name)
256 
257 int ida_alloc_range(struct ida *, unsigned int min, unsigned int max, gfp_t);
258 void ida_free(struct ida *, unsigned int id);
259 void ida_destroy(struct ida *ida);
260 
261 /**
262  * ida_alloc() - Allocate an unused ID.
263  * @ida: IDA handle.
264  * @gfp: Memory allocation flags.
265  *
266  * Allocate an ID between 0 and %INT_MAX, inclusive.
267  *
268  * Context: Any context. It is safe to call this function without
269  * locking in your code.
270  * Return: The allocated ID, or %-ENOMEM if memory could not be allocated,
271  * or %-ENOSPC if there are no free IDs.
272  */
ida_alloc(struct ida * ida,gfp_t gfp)273 static inline int ida_alloc(struct ida *ida, gfp_t gfp)
274 {
275 	return ida_alloc_range(ida, 0, ~0, gfp);
276 }
277 
278 /**
279  * ida_alloc_min() - Allocate an unused ID.
280  * @ida: IDA handle.
281  * @min: Lowest ID to allocate.
282  * @gfp: Memory allocation flags.
283  *
284  * Allocate an ID between @min 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_min(struct ida * ida,unsigned int min,gfp_t gfp)291 static inline int ida_alloc_min(struct ida *ida, unsigned int min, gfp_t gfp)
292 {
293 	return ida_alloc_range(ida, min, ~0, gfp);
294 }
295 
296 /**
297  * ida_alloc_max() - Allocate an unused ID.
298  * @ida: IDA handle.
299  * @max: Highest ID to allocate.
300  * @gfp: Memory allocation flags.
301  *
302  * Allocate an ID between 0 and @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_max(struct ida * ida,unsigned int max,gfp_t gfp)309 static inline int ida_alloc_max(struct ida *ida, unsigned int max, gfp_t gfp)
310 {
311 	return ida_alloc_range(ida, 0, max, gfp);
312 }
313 
ida_init(struct ida * ida)314 static inline void ida_init(struct ida *ida)
315 {
316 	xa_init_flags(&ida->xa, IDA_INIT_FLAGS);
317 }
318 
319 /*
320  * ida_simple_get() and ida_simple_remove() are deprecated. Use
321  * ida_alloc() and ida_free() instead respectively.
322  */
323 #define ida_simple_get(ida, start, end, gfp)	\
324 			ida_alloc_range(ida, start, (end) - 1, gfp)
325 #define ida_simple_remove(ida, id)	ida_free(ida, id)
326 
ida_is_empty(const struct ida * ida)327 static inline bool ida_is_empty(const struct ida *ida)
328 {
329 	return xa_empty(&ida->xa);
330 }
331 #endif /* __IDR_H__ */
332