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 
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 	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 += 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  * @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 - IDR based id allocator, use when translation from id to
218  * pointer isn't necessary.
219  */
220 #define IDA_CHUNK_SIZE		128	/* 128 bytes per chunk */
221 #define IDA_BITMAP_LONGS	(IDA_CHUNK_SIZE / sizeof(long))
222 #define IDA_BITMAP_BITS 	(IDA_BITMAP_LONGS * sizeof(long) * 8)
223 
224 struct ida_bitmap {
225 	unsigned long		bitmap[IDA_BITMAP_LONGS];
226 };
227 
228 DECLARE_PER_CPU(struct ida_bitmap *, ida_bitmap);
229 
230 struct ida {
231 	struct radix_tree_root	ida_rt;
232 };
233 
234 #define IDA_INIT(name)	{						\
235 	.ida_rt = RADIX_TREE_INIT(name, IDR_RT_MARKER | GFP_NOWAIT),	\
236 }
237 #define DEFINE_IDA(name)	struct ida name = IDA_INIT(name)
238 
239 int ida_alloc_range(struct ida *, unsigned int min, unsigned int max, gfp_t);
240 void ida_free(struct ida *, unsigned int id);
241 void ida_destroy(struct ida *ida);
242 
243 /**
244  * ida_alloc() - Allocate an unused ID.
245  * @ida: IDA handle.
246  * @gfp: Memory allocation flags.
247  *
248  * Allocate an ID between 0 and %INT_MAX, inclusive.
249  *
250  * Context: Any context.
251  * Return: The allocated ID, or %-ENOMEM if memory could not be allocated,
252  * or %-ENOSPC if there are no free IDs.
253  */
ida_alloc(struct ida * ida,gfp_t gfp)254 static inline int ida_alloc(struct ida *ida, gfp_t gfp)
255 {
256 	return ida_alloc_range(ida, 0, ~0, gfp);
257 }
258 
259 /**
260  * ida_alloc_min() - Allocate an unused ID.
261  * @ida: IDA handle.
262  * @min: Lowest ID to allocate.
263  * @gfp: Memory allocation flags.
264  *
265  * Allocate an ID between @min and %INT_MAX, inclusive.
266  *
267  * Context: Any context.
268  * Return: The allocated ID, or %-ENOMEM if memory could not be allocated,
269  * or %-ENOSPC if there are no free IDs.
270  */
ida_alloc_min(struct ida * ida,unsigned int min,gfp_t gfp)271 static inline int ida_alloc_min(struct ida *ida, unsigned int min, gfp_t gfp)
272 {
273 	return ida_alloc_range(ida, min, ~0, gfp);
274 }
275 
276 /**
277  * ida_alloc_max() - Allocate an unused ID.
278  * @ida: IDA handle.
279  * @max: Highest ID to allocate.
280  * @gfp: Memory allocation flags.
281  *
282  * Allocate an ID between 0 and @max, inclusive.
283  *
284  * Context: Any context.
285  * Return: The allocated ID, or %-ENOMEM if memory could not be allocated,
286  * or %-ENOSPC if there are no free IDs.
287  */
ida_alloc_max(struct ida * ida,unsigned int max,gfp_t gfp)288 static inline int ida_alloc_max(struct ida *ida, unsigned int max, gfp_t gfp)
289 {
290 	return ida_alloc_range(ida, 0, max, gfp);
291 }
292 
ida_init(struct ida * ida)293 static inline void ida_init(struct ida *ida)
294 {
295 	INIT_RADIX_TREE(&ida->ida_rt, IDR_RT_MARKER | GFP_NOWAIT);
296 }
297 
298 #define ida_simple_get(ida, start, end, gfp)	\
299 			ida_alloc_range(ida, start, (end) - 1, gfp)
300 #define ida_simple_remove(ida, id)	ida_free(ida, id)
301 
ida_is_empty(const struct ida * ida)302 static inline bool ida_is_empty(const struct ida *ida)
303 {
304 	return radix_tree_empty(&ida->ida_rt);
305 }
306 
307 /* in lib/radix-tree.c */
308 int ida_pre_get(struct ida *ida, gfp_t gfp_mask);
309 #endif /* __IDR_H__ */
310