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
19struct 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 */
66static 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 */
79static 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
112void idr_preload(gfp_t gfp_mask);
113
114int idr_alloc(struct idr *, void *ptr, int start, int end, gfp_t);
115int __must_check idr_alloc_u32(struct idr *, void *ptr, u32 *id,
116				unsigned long max, gfp_t);
117int idr_alloc_cyclic(struct idr *, void *ptr, int start, int end, gfp_t);
118void *idr_remove(struct idr *, unsigned long id);
119void *idr_find(const struct idr *, unsigned long id);
120int idr_for_each(const struct idr *,
121		 int (*fn)(int id, void *p, void *data), void *data);
122void *idr_get_next(struct idr *, int *nextid);
123void *idr_get_next_ul(struct idr *, unsigned long *nextid);
124void *idr_replace(struct idr *, void *, unsigned long id);
125void 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 */
135static 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 */
149static 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 */
160static 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 */
172static 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
242struct ida_bitmap {
243	unsigned long		bitmap[IDA_BITMAP_LONGS];
244};
245
246struct 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
257int ida_alloc_range(struct ida *, unsigned int min, unsigned int max, gfp_t);
258void ida_free(struct ida *, unsigned int id);
259void 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 */
273static 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 */
291static 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 */
309static 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
314static 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
327static inline bool ida_is_empty(const struct ida *ida)
328{
329	return xa_empty(&ida->xa);
330}
331#endif /* __IDR_H__ */
332