aboutsummaryrefslogtreecommitdiff
path: root/include/linux/idr.h
blob: 4ec8986e5dfb61c7f2fd47abd2563893bb4deaa0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * include/linux/idr.h
 * 
 * 2002-10-18  written by Jim Houston jim.houston@ccur.com
 *	Copyright (C) 2002 by Concurrent Computer Corporation
 *
 * Small id to pointer translation service avoiding fixed sized
 * tables.
 */

#ifndef __IDR_H__
#define __IDR_H__

#include <linux/radix-tree.h>
#include <linux/gfp.h>
#include <linux/percpu.h>

struct idr {
	struct radix_tree_root	idr_rt;
	unsigned int		idr_base;
	unsigned int		idr_next;
};

/*
 * The IDR API does not expose the tagging functionality of the radix tree
 * to users.  Use tag 0 to track whether a node has free space below it.
 */
#define IDR_FREE	0

/* Set the IDR flag and the IDR_FREE tag */
#define IDR_RT_MARKER	(ROOT_IS_IDR | (__force gfp_t)			\
					(1 << (ROOT_TAG_SHIFT + IDR_FREE)))

#define IDR_INIT_BASE(name, base) {					\
	.idr_rt = RADIX_TREE_INIT(name, IDR_RT_MARKER),			\
	.idr_base = (base),						\
	.idr_next = 0,							\
}

/**
 * IDR_INIT() - Initialise an IDR.
 * @name: Name of IDR.
 *
 * A freshly-initialised IDR contains no IDs.
 */
#define IDR_INIT(name)	IDR_INIT_BASE(name, 0)

/**
 * DEFINE_IDR() - Define a statically-allocated IDR.
 * @name: Name of IDR.
 *
 * An IDR defined using this macro is ready for use with no additional
 * initialisation required.  It contains no IDs.
 */
#define DEFINE_IDR(name)	struct idr name = IDR_INIT(name)

/**
 * idr_get_cursor - Return the current position of the cyclic allocator
 * @idr: idr handle
 *
 * The value returned is the value that will be next returned from
 * idr_alloc_cyclic() if it is free (otherwise the search will start from
 * this position).
 */
static inline unsigned int idr_get_cursor(const struct idr *idr)
{
	return READ_ONCE(idr->idr_next);
}

/**
 * idr_set_cursor - Set the current position of the cyclic allocator
 * @idr: idr handle
 * @val: new position
 *
 * The next call to idr_alloc_cyclic() will return @val if it is free
 * (otherwise the search will start from this position).
 */
static inline void idr_set_cursor(struct idr *idr, unsigned int val)
{
	WRITE_ONCE(idr->idr_next, val);
}

/**
 * DOC: idr sync
 * idr synchronization (stolen from radix-tree.h)
 *
 * idr_find() is able to be called locklessly, using RCU. The caller must
 * ensure calls to this function are made within rcu_read_lock() regions.
 * Other readers (lock-free or otherwise) and modifications may be running
 * concurrently.
 *
 * It is still required that the caller manage the synchronization and
 * lifetimes of the items. So if RCU lock-free lookups are used, typically
 * this would mean that the items have their own locks, or are amenable to
 * lock-free access; and that the items are freed by RCU (or only freed after
 * having been deleted from the idr tree *and* a synchronize_rcu() grace
 * period).
 */

#define idr_lock(idr)		xa_lock(&(idr)->idr_rt)
#define idr_unlock(idr)		xa_unlock(&(idr)->idr_rt)
#define idr_lock_bh(idr)	xa_lock_bh(&(idr)->idr_rt)
#define idr_unlock_bh(idr)	xa_unlock_bh(&(idr)->idr_rt)
#define idr_lock_irq(idr)	xa_lock_irq(&(idr)->idr_rt)
#define idr_unlock_irq(idr)	xa_unlock_irq(&(idr)->idr_rt)
#define idr_lock_irqsave(idr, flags) \
				xa_lock_irqsave(&(idr)->idr_rt, flags)
#define idr_unlock_irqrestore(idr, flags) \
				xa_unlock_irqrestore(&(idr)->idr_rt, flags)

void idr_preload(gfp_t gfp_mask);

int idr_alloc(struct idr *, void *ptr, int start, int end, gfp_t);
int __must_check idr_alloc_u32(struct idr *, void *ptr, u32 *id,
				unsigned long max, gfp_t);
int idr_alloc_cyclic(struct idr *, void *ptr, int start, int end, gfp_t);
void *idr_remove(struct idr *, unsigned long id);
void *idr_find(const struct idr *, unsigned long id);
int idr_for_each(const struct idr *,
		 int (*fn)(int id, void *p, void *data), void *data);
void *idr_get_next(struct idr *, int *nextid);
void *idr_get_next_ul(struct idr *, unsigned long *nextid);
void *idr_replace(struct idr *, void *, unsigned long id);
void idr_destroy(struct idr *);

/**
 * idr_init_base() - Initialise an IDR.
 * @idr: IDR handle.
 * @base: The base value for the IDR.
 *
 * This variation of idr_init() creates an IDR which will allocate IDs
 * starting at %base.
 */
static inline void idr_init_base(struct idr *idr, int base)
{
	INIT_RADIX_TREE(&idr->idr_rt, IDR_RT_MARKER);
	idr->idr_base = base;
	idr->idr_next = 0;
}

/**
 * idr_init() - Initialise an IDR.
 * @idr: IDR handle.
 *
 * Initialise a dynamically allocated IDR.  To initialise a
 * statically allocated IDR, use DEFINE_IDR().
 */
static inline void idr_init(struct idr *idr)
{
	idr_init_base(idr, 0);
}

/**
 * idr_is_empty() - Are there any IDs allocated?
 * @idr: IDR handle.
 *
 * Return: %true if any IDs have been allocated from this IDR.
 */
static inline bool idr_is_empty(const struct idr *idr)
{
	return radix_tree_empty(&idr->idr_rt) &&
		radix_tree_tagged(&idr->idr_rt, IDR_FREE);
}

/**
 * idr_preload_end - end preload section started with idr_preload()
 *
 * Each idr_preload() should be matched with an invocation of this
 * function.  See idr_preload() for details.
 */
static inline void idr_preload_end(void)
{
	preempt_enable();
}

/**
 * idr_for_each_entry() - Iterate over an IDR's elements of a given type.
 * @idr: IDR handle.
 * @entry: The type * to use as cursor
 * @id: Entry ID.
 *
 * @entry and @id do not need to be initialized before the loop, and
 * after normal termination @entry is left with the value NULL.  This
 * is convenient for a "not found" value.
 */
#define idr_for_each_entry(idr, entry, id)			\
	for (id = 0; ((entry) = idr_get_next(idr, &(id))) != NULL; ++id)

/**
 * idr_for_each_entry_ul() - Iterate over an IDR's elements of a given type.
 * @idr: IDR handle.
 * @entry: The type * to use as cursor.
 * @tmp: A temporary placeholder for ID.
 * @id: Entry ID.
 *
 * @entry and @id do not need to be initialized before the loop, and
 * after normal termination @entry is left with the value NULL.  This
 * is convenient for a "not found" value.
 */
#define idr_for_each_entry_ul(idr, entry, tmp, id)			\
	for (tmp = 0, id = 0;						\
	     tmp <= id && ((entry) = idr_get_next_ul(idr, &(id))) != NULL; \
	     tmp = id, ++id)

/**
 * idr_for_each_entry_continue() - Continue iteration over an IDR's elements of a given type
 * @idr: IDR handle.
 * @entry: The type * to use as a cursor.
 * @id: Entry ID.
 *
 * Continue to iterate over entries, continuing after the current position.
 */
#define idr_for_each_entry_continue(idr, entry, id)			\
	for ((entry) = idr_get_next((idr), &(id));			\
	     entry;							\
	     ++id, (entry) = idr_get_next((idr), &(id)))

/**
 * idr_for_each_entry_continue_ul() - Continue iteration over an IDR's elements of a given type
 * @idr: IDR handle.
 * @entry: The type * to use as a cursor.
 * @tmp: A temporary placeholder for ID.
 * @id: Entry ID.
 *
 * Continue to iterate over entries, continuing after the current position.
 */
#define idr_for_each_entry_continue_ul(idr, entry, tmp, id)		\
	for (tmp = id;							\
	     tmp <= id && ((entry) = idr_get_next_ul(idr, &(id))) != NULL; \
	     tmp = id, ++id)

/*
 * IDA - ID Allocator, use when translation from id to pointer isn't necessary.
 */
#define IDA_CHUNK_SIZE		128	/* 128 bytes per chunk */
#define IDA_BITMAP_LONGS	(IDA_CHUNK_SIZE / sizeof(long))
#define IDA_BITMAP_BITS 	(IDA_BITMAP_LONGS * sizeof(long) * 8)

struct ida_bitmap {
	unsigned long		bitmap[IDA_BITMAP_LONGS];
};

struct ida {
	struct xarray xa;
};

#define IDA_INIT_FLAGS	(XA_FLAGS_LOCK_IRQ | XA_FLAGS_ALLOC)

#define IDA_INIT(name)	{						\
	.xa = XARRAY_INIT(name, IDA_INIT_FLAGS)				\
}
#define DEFINE_IDA(name)	struct ida name = IDA_INIT(name)

int ida_alloc_range(struct ida *, unsigned int min, unsigned int max, gfp_t);
void ida_free(struct ida *, unsigned int id);
void ida_destroy(struct ida *ida);

/**
 * ida_alloc() - Allocate an unused ID.
 * @ida: IDA handle.
 * @gfp: Memory allocation flags.
 *
 * Allocate an ID between 0 and %INT_MAX, inclusive.
 *
 * Context: Any context.
 * Return: The allocated ID, or %-ENOMEM if memory could not be allocated,
 * or %-ENOSPC if there are no free IDs.
 */
static inline int ida_alloc(struct ida *ida, gfp_t gfp)
{
	return ida_alloc_range(ida, 0, ~0, gfp);
}

/**
 * ida_alloc_min() - Allocate an unused ID.
 * @ida: IDA handle.
 * @min: Lowest ID to allocate.
 * @gfp: Memory allocation flags.
 *
 * Allocate an ID between @min and %INT_MAX, inclusive.
 *
 * Context: Any context.
 * Return: The allocated ID, or %-ENOMEM if memory could not be allocated,
 * or %-ENOSPC if there are no free IDs.
 */
static inline int ida_alloc_min(struct ida *ida, unsigned int min, gfp_t gfp)
{
	return ida_alloc_range(ida, min, ~0, gfp);
}

/**
 * ida_alloc_max() - Allocate an unused ID.
 * @ida: IDA handle.
 * @max: Highest ID to allocate.
 * @gfp: Memory allocation flags.
 *
 * Allocate an ID between 0 and @max, inclusive.
 *
 * Context: Any context.
 * Return: The allocated ID, or %-ENOMEM if memory could not be allocated,
 * or %-ENOSPC if there are no free IDs.
 */
static inline int ida_alloc_max(struct ida *ida, unsigned int max, gfp_t gfp)
{
	return ida_alloc_range(ida, 0, max, gfp);
}

static inline void ida_init(struct ida *ida)
{
	xa_init_flags(&ida->xa, IDA_INIT_FLAGS);
}

#define ida_simple_get(ida, start, end, gfp)	\
			ida_alloc_range(ida, start, (end) - 1, gfp)
#define ida_simple_remove(ida, id)	ida_free(ida, id)

static inline bool ida_is_empty(const struct ida *ida)
{
	return xa_empty(&ida->xa);
}
#endif /* __IDR_H__ */