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
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 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)
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 * @id: Entry ID.
195 *
196 * @entry and @id do not need to be initialized before the loop, and
197 * after normal termination @entry is left with the value NULL. This
198 * is convenient for a "not found" value.
199 */
200#define idr_for_each_entry_ul(idr, entry, id) \
201 for (id = 0; ((entry) = idr_get_next_ul(idr, &(id))) != NULL; ++id)
202
203/**
204 * idr_for_each_entry_continue() - Continue iteration over an IDR's elements of a given type
205 * @idr: IDR handle.
206 * @entry: The type * to use as a cursor.
207 * @id: Entry ID.
208 *
209 * Continue to iterate over entries, continuing after the current position.
210 */
211#define idr_for_each_entry_continue(idr, entry, id) \
212 for ((entry) = idr_get_next((idr), &(id)); \
213 entry; \
214 ++id, (entry) = idr_get_next((idr), &(id)))
215
216/*
217 * IDA - ID Allocator, use when translation from id to pointer isn't necessary.
218 */
219#define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */
220#define IDA_BITMAP_LONGS (IDA_CHUNK_SIZE / sizeof(long))
221#define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8)
222
223struct ida_bitmap {
224 unsigned long bitmap[IDA_BITMAP_LONGS];
225};
226
227struct ida {
228 struct xarray xa;
229};
230
231#define IDA_INIT_FLAGS (XA_FLAGS_LOCK_IRQ | XA_FLAGS_ALLOC)
232
233#define IDA_INIT(name) { \
234 .xa = XARRAY_INIT(name, IDA_INIT_FLAGS) \
235}
236#define DEFINE_IDA(name) struct ida name = IDA_INIT(name)
237
238int ida_alloc_range(struct ida *, unsigned int min, unsigned int max, gfp_t);
239void ida_free(struct ida *, unsigned int id);
240void ida_destroy(struct ida *ida);
241
242/**
243 * ida_alloc() - Allocate an unused ID.
244 * @ida: IDA handle.
245 * @gfp: Memory allocation flags.
246 *
247 * Allocate an ID between 0 and %INT_MAX, inclusive.
248 *
249 * Context: Any context.
250 * Return: The allocated ID, or %-ENOMEM if memory could not be allocated,
251 * or %-ENOSPC if there are no free IDs.
252 */
253static inline int ida_alloc(struct ida *ida, gfp_t gfp)
254{
255 return ida_alloc_range(ida, 0, ~0, gfp);
256}
257
258/**
259 * ida_alloc_min() - Allocate an unused ID.
260 * @ida: IDA handle.
261 * @min: Lowest ID to allocate.
262 * @gfp: Memory allocation flags.
263 *
264 * Allocate an ID between @min 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 */
270static inline int ida_alloc_min(struct ida *ida, unsigned int min, gfp_t gfp)
271{
272 return ida_alloc_range(ida, min, ~0, gfp);
273}
274
275/**
276 * ida_alloc_max() - Allocate an unused ID.
277 * @ida: IDA handle.
278 * @max: Highest ID to allocate.
279 * @gfp: Memory allocation flags.
280 *
281 * Allocate an ID between 0 and @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 */
287static inline int ida_alloc_max(struct ida *ida, unsigned int max, gfp_t gfp)
288{
289 return ida_alloc_range(ida, 0, max, gfp);
290}
291
292static inline void ida_init(struct ida *ida)
293{
294 xa_init_flags(&ida->xa, IDA_INIT_FLAGS);
295}
296
297#define ida_simple_get(ida, start, end, gfp) \
298 ida_alloc_range(ida, start, (end) - 1, gfp)
299#define ida_simple_remove(ida, id) ida_free(ida, id)
300
301static inline bool ida_is_empty(const struct ida *ida)
302{
303 return xa_empty(&ida->xa);
304}
305#endif /* __IDR_H__ */
306