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Linux/include/linux/idr.h

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  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  */
 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  */
 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  */
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  */
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  */
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  */
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  * @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              tmp <= id && ((entry) = idr_get_next_ul(idr, &(id))) != 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  */
228 #define idr_for_each_entry_continue_ul(idr, entry, tmp, id)             \
229         for (tmp = id;                                                  \
230              tmp <= id && ((entry) = idr_get_next_ul(idr, &(id))) != NULL; \
231              tmp = id, ++id)
232 
233 /*
234  * IDA - ID Allocator, use when translation from id to pointer isn't necessary.
235  */
236 #define IDA_CHUNK_SIZE          128     /* 128 bytes per chunk */
237 #define IDA_BITMAP_LONGS        (IDA_CHUNK_SIZE / sizeof(long))
238 #define IDA_BITMAP_BITS         (IDA_BITMAP_LONGS * sizeof(long) * 8)
239 
240 struct ida_bitmap {
241         unsigned long           bitmap[IDA_BITMAP_LONGS];
242 };
243 
244 struct ida {
245         struct xarray xa;
246 };
247 
248 #define IDA_INIT_FLAGS  (XA_FLAGS_LOCK_IRQ | XA_FLAGS_ALLOC)
249 
250 #define IDA_INIT(name)  {                                               \
251         .xa = XARRAY_INIT(name, IDA_INIT_FLAGS)                         \
252 }
253 #define DEFINE_IDA(name)        struct ida name = IDA_INIT(name)
254 
255 int ida_alloc_range(struct ida *, unsigned int min, unsigned int max, gfp_t);
256 void ida_free(struct ida *, unsigned int id);
257 void ida_destroy(struct ida *ida);
258 
259 /**
260  * ida_alloc() - Allocate an unused ID.
261  * @ida: IDA handle.
262  * @gfp: Memory allocation flags.
263  *
264  * Allocate an ID between 0 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  */
270 static inline int ida_alloc(struct ida *ida, gfp_t gfp)
271 {
272         return ida_alloc_range(ida, 0, ~0, gfp);
273 }
274 
275 /**
276  * ida_alloc_min() - Allocate an unused ID.
277  * @ida: IDA handle.
278  * @min: Lowest ID to allocate.
279  * @gfp: Memory allocation flags.
280  *
281  * Allocate an ID between @min and %INT_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  */
287 static inline int ida_alloc_min(struct ida *ida, unsigned int min, gfp_t gfp)
288 {
289         return ida_alloc_range(ida, min, ~0, gfp);
290 }
291 
292 /**
293  * ida_alloc_max() - Allocate an unused ID.
294  * @ida: IDA handle.
295  * @max: Highest ID to allocate.
296  * @gfp: Memory allocation flags.
297  *
298  * Allocate an ID between 0 and @max, inclusive.
299  *
300  * Context: Any context.
301  * Return: The allocated ID, or %-ENOMEM if memory could not be allocated,
302  * or %-ENOSPC if there are no free IDs.
303  */
304 static inline int ida_alloc_max(struct ida *ida, unsigned int max, gfp_t gfp)
305 {
306         return ida_alloc_range(ida, 0, max, gfp);
307 }
308 
309 static inline void ida_init(struct ida *ida)
310 {
311         xa_init_flags(&ida->xa, IDA_INIT_FLAGS);
312 }
313 
314 #define ida_simple_get(ida, start, end, gfp)    \
315                         ida_alloc_range(ida, start, (end) - 1, gfp)
316 #define ida_simple_remove(ida, id)      ida_free(ida, id)
317 
318 static inline bool ida_is_empty(const struct ida *ida)
319 {
320         return xa_empty(&ida->xa);
321 }
322 #endif /* __IDR_H__ */
323 

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