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1 : /* SPDX-License-Identifier: GPL-2.0+ */
2 : #ifndef _LINUX_XARRAY_H
3 : #define _LINUX_XARRAY_H
4 : /*
5 : * eXtensible Arrays
6 : * Copyright (c) 2017 Microsoft Corporation
7 : * Author: Matthew Wilcox <willy@infradead.org>
8 : *
9 : * See Documentation/core-api/xarray.rst for how to use the XArray.
10 : */
11 :
12 : #include <linux/bug.h>
13 : #include <linux/compiler.h>
14 : #include <linux/gfp.h>
15 : #include <linux/kconfig.h>
16 : #include <linux/kernel.h>
17 : #include <linux/rcupdate.h>
18 : #include <linux/spinlock.h>
19 : #include <linux/types.h>
20 :
21 : /*
22 : * The bottom two bits of the entry determine how the XArray interprets
23 : * the contents:
24 : *
25 : * 00: Pointer entry
26 : * 10: Internal entry
27 : * x1: Value entry or tagged pointer
28 : *
29 : * Attempting to store internal entries in the XArray is a bug.
30 : *
31 : * Most internal entries are pointers to the next node in the tree.
32 : * The following internal entries have a special meaning:
33 : *
34 : * 0-62: Sibling entries
35 : * 256: Retry entry
36 : * 257: Zero entry
37 : *
38 : * Errors are also represented as internal entries, but use the negative
39 : * space (-4094 to -2). They're never stored in the slots array; only
40 : * returned by the normal API.
41 : */
42 :
43 : #define BITS_PER_XA_VALUE (BITS_PER_LONG - 1)
44 :
45 : /**
46 : * xa_mk_value() - Create an XArray entry from an integer.
47 : * @v: Value to store in XArray.
48 : *
49 : * Context: Any context.
50 : * Return: An entry suitable for storing in the XArray.
51 : */
52 457 : static inline void *xa_mk_value(unsigned long v)
53 : {
54 457 : WARN_ON((long)v < 0);
55 457 : return (void *)((v << 1) | 1);
56 : }
57 :
58 : /**
59 : * xa_to_value() - Get value stored in an XArray entry.
60 : * @entry: XArray entry.
61 : *
62 : * Context: Any context.
63 : * Return: The value stored in the XArray entry.
64 : */
65 442 : static inline unsigned long xa_to_value(const void *entry)
66 : {
67 442 : return (unsigned long)entry >> 1;
68 : }
69 :
70 : /**
71 : * xa_is_value() - Determine if an entry is a value.
72 : * @entry: XArray entry.
73 : *
74 : * Context: Any context.
75 : * Return: True if the entry is a value, false if it is a pointer.
76 : */
77 94391 : static inline bool xa_is_value(const void *entry)
78 : {
79 94391 : return (unsigned long)entry & 1;
80 : }
81 :
82 : /**
83 : * xa_tag_pointer() - Create an XArray entry for a tagged pointer.
84 : * @p: Plain pointer.
85 : * @tag: Tag value (0, 1 or 3).
86 : *
87 : * If the user of the XArray prefers, they can tag their pointers instead
88 : * of storing value entries. Three tags are available (0, 1 and 3).
89 : * These are distinct from the xa_mark_t as they are not replicated up
90 : * through the array and cannot be searched for.
91 : *
92 : * Context: Any context.
93 : * Return: An XArray entry.
94 : */
95 : static inline void *xa_tag_pointer(void *p, unsigned long tag)
96 : {
97 : return (void *)((unsigned long)p | tag);
98 : }
99 :
100 : /**
101 : * xa_untag_pointer() - Turn an XArray entry into a plain pointer.
102 : * @entry: XArray entry.
103 : *
104 : * If you have stored a tagged pointer in the XArray, call this function
105 : * to get the untagged version of the pointer.
106 : *
107 : * Context: Any context.
108 : * Return: A pointer.
109 : */
110 : static inline void *xa_untag_pointer(void *entry)
111 : {
112 : return (void *)((unsigned long)entry & ~3UL);
113 : }
114 :
115 : /**
116 : * xa_pointer_tag() - Get the tag stored in an XArray entry.
117 : * @entry: XArray entry.
118 : *
119 : * If you have stored a tagged pointer in the XArray, call this function
120 : * to get the tag of that pointer.
121 : *
122 : * Context: Any context.
123 : * Return: A tag.
124 : */
125 : static inline unsigned int xa_pointer_tag(void *entry)
126 : {
127 : return (unsigned long)entry & 3UL;
128 : }
129 :
130 : /*
131 : * xa_mk_internal() - Create an internal entry.
132 : * @v: Value to turn into an internal entry.
133 : *
134 : * Internal entries are used for a number of purposes. Entries 0-255 are
135 : * used for sibling entries (only 0-62 are used by the current code). 256
136 : * is used for the retry entry. 257 is used for the reserved / zero entry.
137 : * Negative internal entries are used to represent errnos. Node pointers
138 : * are also tagged as internal entries in some situations.
139 : *
140 : * Context: Any context.
141 : * Return: An XArray internal entry corresponding to this value.
142 : */
143 489059 : static inline void *xa_mk_internal(unsigned long v)
144 : {
145 20412 : return (void *)((v << 2) | 2);
146 : }
147 :
148 : /*
149 : * xa_to_internal() - Extract the value from an internal entry.
150 : * @entry: XArray entry.
151 : *
152 : * Context: Any context.
153 : * Return: The value which was stored in the internal entry.
154 : */
155 0 : static inline unsigned long xa_to_internal(const void *entry)
156 : {
157 0 : return (unsigned long)entry >> 2;
158 : }
159 :
160 : /*
161 : * xa_is_internal() - Is the entry an internal entry?
162 : * @entry: XArray entry.
163 : *
164 : * Context: Any context.
165 : * Return: %true if the entry is an internal entry.
166 : */
167 2378067 : static inline bool xa_is_internal(const void *entry)
168 : {
169 4004 : return ((unsigned long)entry & 3) == 2;
170 : }
171 :
172 : #define XA_ZERO_ENTRY xa_mk_internal(257)
173 :
174 : /**
175 : * xa_is_zero() - Is the entry a zero entry?
176 : * @entry: Entry retrieved from the XArray
177 : *
178 : * The normal API will return NULL as the contents of a slot containing
179 : * a zero entry. You can only see zero entries by using the advanced API.
180 : *
181 : * Return: %true if the entry is a zero entry.
182 : */
183 127593 : static inline bool xa_is_zero(const void *entry)
184 : {
185 79161 : return unlikely(entry == XA_ZERO_ENTRY);
186 : }
187 :
188 : /**
189 : * xa_is_err() - Report whether an XArray operation returned an error
190 : * @entry: Result from calling an XArray function
191 : *
192 : * If an XArray operation cannot complete an operation, it will return
193 : * a special value indicating an error. This function tells you
194 : * whether an error occurred; xa_err() tells you which error occurred.
195 : *
196 : * Context: Any context.
197 : * Return: %true if the entry indicates an error.
198 : */
199 671640 : static inline bool xa_is_err(const void *entry)
200 : {
201 0 : return unlikely(xa_is_internal(entry) &&
202 : entry >= xa_mk_internal(-MAX_ERRNO));
203 : }
204 :
205 : /**
206 : * xa_err() - Turn an XArray result into an errno.
207 : * @entry: Result from calling an XArray function.
208 : *
209 : * If an XArray operation cannot complete an operation, it will return
210 : * a special pointer value which encodes an errno. This function extracts
211 : * the errno from the pointer value, or returns 0 if the pointer does not
212 : * represent an errno.
213 : *
214 : * Context: Any context.
215 : * Return: A negative errno or 0.
216 : */
217 671640 : static inline int xa_err(void *entry)
218 : {
219 : /* xa_to_internal() would not do sign extension. */
220 671640 : if (xa_is_err(entry))
221 0 : return (long)entry >> 2;
222 : return 0;
223 : }
224 :
225 : /**
226 : * struct xa_limit - Represents a range of IDs.
227 : * @min: The lowest ID to allocate (inclusive).
228 : * @max: The maximum ID to allocate (inclusive).
229 : *
230 : * This structure is used either directly or via the XA_LIMIT() macro
231 : * to communicate the range of IDs that are valid for allocation.
232 : * Two common ranges are predefined for you:
233 : * * xa_limit_32b - [0 - UINT_MAX]
234 : * * xa_limit_31b - [0 - INT_MAX]
235 : */
236 : struct xa_limit {
237 : u32 max;
238 : u32 min;
239 : };
240 :
241 : #define XA_LIMIT(_min, _max) (struct xa_limit) { .min = _min, .max = _max }
242 :
243 : #define xa_limit_32b XA_LIMIT(0, UINT_MAX)
244 : #define xa_limit_31b XA_LIMIT(0, INT_MAX)
245 :
246 : typedef unsigned __bitwise xa_mark_t;
247 : #define XA_MARK_0 ((__force xa_mark_t)0U)
248 : #define XA_MARK_1 ((__force xa_mark_t)1U)
249 : #define XA_MARK_2 ((__force xa_mark_t)2U)
250 : #define XA_PRESENT ((__force xa_mark_t)8U)
251 : #define XA_MARK_MAX XA_MARK_2
252 : #define XA_FREE_MARK XA_MARK_0
253 :
254 : enum xa_lock_type {
255 : XA_LOCK_IRQ = 1,
256 : XA_LOCK_BH = 2,
257 : };
258 :
259 : /*
260 : * Values for xa_flags. The radix tree stores its GFP flags in the xa_flags,
261 : * and we remain compatible with that.
262 : */
263 : #define XA_FLAGS_LOCK_IRQ ((__force gfp_t)XA_LOCK_IRQ)
264 : #define XA_FLAGS_LOCK_BH ((__force gfp_t)XA_LOCK_BH)
265 : #define XA_FLAGS_TRACK_FREE ((__force gfp_t)4U)
266 : #define XA_FLAGS_ZERO_BUSY ((__force gfp_t)8U)
267 : #define XA_FLAGS_ALLOC_WRAPPED ((__force gfp_t)16U)
268 : #define XA_FLAGS_ACCOUNT ((__force gfp_t)32U)
269 : #define XA_FLAGS_MARK(mark) ((__force gfp_t)((1U << __GFP_BITS_SHIFT) << \
270 : (__force unsigned)(mark)))
271 :
272 : /* ALLOC is for a normal 0-based alloc. ALLOC1 is for an 1-based alloc */
273 : #define XA_FLAGS_ALLOC (XA_FLAGS_TRACK_FREE | XA_FLAGS_MARK(XA_FREE_MARK))
274 : #define XA_FLAGS_ALLOC1 (XA_FLAGS_TRACK_FREE | XA_FLAGS_ZERO_BUSY)
275 :
276 : /**
277 : * struct xarray - The anchor of the XArray.
278 : * @xa_lock: Lock that protects the contents of the XArray.
279 : *
280 : * To use the xarray, define it statically or embed it in your data structure.
281 : * It is a very small data structure, so it does not usually make sense to
282 : * allocate it separately and keep a pointer to it in your data structure.
283 : *
284 : * You may use the xa_lock to protect your own data structures as well.
285 : */
286 : /*
287 : * If all of the entries in the array are NULL, @xa_head is a NULL pointer.
288 : * If the only non-NULL entry in the array is at index 0, @xa_head is that
289 : * entry. If any other entry in the array is non-NULL, @xa_head points
290 : * to an @xa_node.
291 : */
292 : struct xarray {
293 : spinlock_t xa_lock;
294 : /* private: The rest of the data structure is not to be used directly. */
295 : gfp_t xa_flags;
296 : void __rcu * xa_head;
297 : };
298 :
299 : #define XARRAY_INIT(name, flags) { \
300 : .xa_lock = __SPIN_LOCK_UNLOCKED(name.xa_lock), \
301 : .xa_flags = flags, \
302 : .xa_head = NULL, \
303 : }
304 :
305 : /**
306 : * DEFINE_XARRAY_FLAGS() - Define an XArray with custom flags.
307 : * @name: A string that names your XArray.
308 : * @flags: XA_FLAG values.
309 : *
310 : * This is intended for file scope definitions of XArrays. It declares
311 : * and initialises an empty XArray with the chosen name and flags. It is
312 : * equivalent to calling xa_init_flags() on the array, but it does the
313 : * initialisation at compiletime instead of runtime.
314 : */
315 : #define DEFINE_XARRAY_FLAGS(name, flags) \
316 : struct xarray name = XARRAY_INIT(name, flags)
317 :
318 : /**
319 : * DEFINE_XARRAY() - Define an XArray.
320 : * @name: A string that names your XArray.
321 : *
322 : * This is intended for file scope definitions of XArrays. It declares
323 : * and initialises an empty XArray with the chosen name. It is equivalent
324 : * to calling xa_init() on the array, but it does the initialisation at
325 : * compiletime instead of runtime.
326 : */
327 : #define DEFINE_XARRAY(name) DEFINE_XARRAY_FLAGS(name, 0)
328 :
329 : /**
330 : * DEFINE_XARRAY_ALLOC() - Define an XArray which allocates IDs starting at 0.
331 : * @name: A string that names your XArray.
332 : *
333 : * This is intended for file scope definitions of allocating XArrays.
334 : * See also DEFINE_XARRAY().
335 : */
336 : #define DEFINE_XARRAY_ALLOC(name) DEFINE_XARRAY_FLAGS(name, XA_FLAGS_ALLOC)
337 :
338 : /**
339 : * DEFINE_XARRAY_ALLOC1() - Define an XArray which allocates IDs starting at 1.
340 : * @name: A string that names your XArray.
341 : *
342 : * This is intended for file scope definitions of allocating XArrays.
343 : * See also DEFINE_XARRAY().
344 : */
345 : #define DEFINE_XARRAY_ALLOC1(name) DEFINE_XARRAY_FLAGS(name, XA_FLAGS_ALLOC1)
346 :
347 : void *xa_load(struct xarray *, unsigned long index);
348 : void *xa_store(struct xarray *, unsigned long index, void *entry, gfp_t);
349 : void *xa_erase(struct xarray *, unsigned long index);
350 : void *xa_store_range(struct xarray *, unsigned long first, unsigned long last,
351 : void *entry, gfp_t);
352 : bool xa_get_mark(struct xarray *, unsigned long index, xa_mark_t);
353 : void xa_set_mark(struct xarray *, unsigned long index, xa_mark_t);
354 : void xa_clear_mark(struct xarray *, unsigned long index, xa_mark_t);
355 : void *xa_find(struct xarray *xa, unsigned long *index,
356 : unsigned long max, xa_mark_t) __attribute__((nonnull(2)));
357 : void *xa_find_after(struct xarray *xa, unsigned long *index,
358 : unsigned long max, xa_mark_t) __attribute__((nonnull(2)));
359 : unsigned int xa_extract(struct xarray *, void **dst, unsigned long start,
360 : unsigned long max, unsigned int n, xa_mark_t);
361 : void xa_destroy(struct xarray *);
362 :
363 : /**
364 : * xa_init_flags() - Initialise an empty XArray with flags.
365 : * @xa: XArray.
366 : * @flags: XA_FLAG values.
367 : *
368 : * If you need to initialise an XArray with special flags (eg you need
369 : * to take the lock from interrupt context), use this function instead
370 : * of xa_init().
371 : *
372 : * Context: Any context.
373 : */
374 15020 : static inline void xa_init_flags(struct xarray *xa, gfp_t flags)
375 : {
376 15029 : spin_lock_init(&xa->xa_lock);
377 15020 : xa->xa_flags = flags;
378 15020 : xa->xa_head = NULL;
379 : }
380 :
381 : /**
382 : * xa_init() - Initialise an empty XArray.
383 : * @xa: XArray.
384 : *
385 : * An empty XArray is full of NULL entries.
386 : *
387 : * Context: Any context.
388 : */
389 9 : static inline void xa_init(struct xarray *xa)
390 : {
391 9 : xa_init_flags(xa, 0);
392 9 : }
393 :
394 : /**
395 : * xa_empty() - Determine if an array has any present entries.
396 : * @xa: XArray.
397 : *
398 : * Context: Any context.
399 : * Return: %true if the array contains only NULL pointers.
400 : */
401 : static inline bool xa_empty(const struct xarray *xa)
402 : {
403 : return xa->xa_head == NULL;
404 : }
405 :
406 : /**
407 : * xa_marked() - Inquire whether any entry in this array has a mark set
408 : * @xa: Array
409 : * @mark: Mark value
410 : *
411 : * Context: Any context.
412 : * Return: %true if any entry has this mark set.
413 : */
414 18680 : static inline bool xa_marked(const struct xarray *xa, xa_mark_t mark)
415 : {
416 18680 : return xa->xa_flags & XA_FLAGS_MARK(mark);
417 : }
418 :
419 : /**
420 : * xa_for_each_range() - Iterate over a portion of an XArray.
421 : * @xa: XArray.
422 : * @index: Index of @entry.
423 : * @entry: Entry retrieved from array.
424 : * @start: First index to retrieve from array.
425 : * @last: Last index to retrieve from array.
426 : *
427 : * During the iteration, @entry will have the value of the entry stored
428 : * in @xa at @index. You may modify @index during the iteration if you
429 : * want to skip or reprocess indices. It is safe to modify the array
430 : * during the iteration. At the end of the iteration, @entry will be set
431 : * to NULL and @index will have a value less than or equal to max.
432 : *
433 : * xa_for_each_range() is O(n.log(n)) while xas_for_each() is O(n). You have
434 : * to handle your own locking with xas_for_each(), and if you have to unlock
435 : * after each iteration, it will also end up being O(n.log(n)).
436 : * xa_for_each_range() will spin if it hits a retry entry; if you intend to
437 : * see retry entries, you should use the xas_for_each() iterator instead.
438 : * The xas_for_each() iterator will expand into more inline code than
439 : * xa_for_each_range().
440 : *
441 : * Context: Any context. Takes and releases the RCU lock.
442 : */
443 : #define xa_for_each_range(xa, index, entry, start, last) \
444 : for (index = start, \
445 : entry = xa_find(xa, &index, last, XA_PRESENT); \
446 : entry; \
447 : entry = xa_find_after(xa, &index, last, XA_PRESENT))
448 :
449 : /**
450 : * xa_for_each_start() - Iterate over a portion of an XArray.
451 : * @xa: XArray.
452 : * @index: Index of @entry.
453 : * @entry: Entry retrieved from array.
454 : * @start: First index to retrieve from array.
455 : *
456 : * During the iteration, @entry will have the value of the entry stored
457 : * in @xa at @index. You may modify @index during the iteration if you
458 : * want to skip or reprocess indices. It is safe to modify the array
459 : * during the iteration. At the end of the iteration, @entry will be set
460 : * to NULL and @index will have a value less than or equal to max.
461 : *
462 : * xa_for_each_start() is O(n.log(n)) while xas_for_each() is O(n). You have
463 : * to handle your own locking with xas_for_each(), and if you have to unlock
464 : * after each iteration, it will also end up being O(n.log(n)).
465 : * xa_for_each_start() will spin if it hits a retry entry; if you intend to
466 : * see retry entries, you should use the xas_for_each() iterator instead.
467 : * The xas_for_each() iterator will expand into more inline code than
468 : * xa_for_each_start().
469 : *
470 : * Context: Any context. Takes and releases the RCU lock.
471 : */
472 : #define xa_for_each_start(xa, index, entry, start) \
473 : xa_for_each_range(xa, index, entry, start, ULONG_MAX)
474 :
475 : /**
476 : * xa_for_each() - Iterate over present entries in an XArray.
477 : * @xa: XArray.
478 : * @index: Index of @entry.
479 : * @entry: Entry retrieved from array.
480 : *
481 : * During the iteration, @entry will have the value of the entry stored
482 : * in @xa at @index. You may modify @index during the iteration if you want
483 : * to skip or reprocess indices. It is safe to modify the array during the
484 : * iteration. At the end of the iteration, @entry will be set to NULL and
485 : * @index will have a value less than or equal to max.
486 : *
487 : * xa_for_each() is O(n.log(n)) while xas_for_each() is O(n). You have
488 : * to handle your own locking with xas_for_each(), and if you have to unlock
489 : * after each iteration, it will also end up being O(n.log(n)). xa_for_each()
490 : * will spin if it hits a retry entry; if you intend to see retry entries,
491 : * you should use the xas_for_each() iterator instead. The xas_for_each()
492 : * iterator will expand into more inline code than xa_for_each().
493 : *
494 : * Context: Any context. Takes and releases the RCU lock.
495 : */
496 : #define xa_for_each(xa, index, entry) \
497 : xa_for_each_start(xa, index, entry, 0)
498 :
499 : /**
500 : * xa_for_each_marked() - Iterate over marked entries in an XArray.
501 : * @xa: XArray.
502 : * @index: Index of @entry.
503 : * @entry: Entry retrieved from array.
504 : * @filter: Selection criterion.
505 : *
506 : * During the iteration, @entry will have the value of the entry stored
507 : * in @xa at @index. The iteration will skip all entries in the array
508 : * which do not match @filter. You may modify @index during the iteration
509 : * if you want to skip or reprocess indices. It is safe to modify the array
510 : * during the iteration. At the end of the iteration, @entry will be set to
511 : * NULL and @index will have a value less than or equal to max.
512 : *
513 : * xa_for_each_marked() is O(n.log(n)) while xas_for_each_marked() is O(n).
514 : * You have to handle your own locking with xas_for_each(), and if you have
515 : * to unlock after each iteration, it will also end up being O(n.log(n)).
516 : * xa_for_each_marked() will spin if it hits a retry entry; if you intend to
517 : * see retry entries, you should use the xas_for_each_marked() iterator
518 : * instead. The xas_for_each_marked() iterator will expand into more inline
519 : * code than xa_for_each_marked().
520 : *
521 : * Context: Any context. Takes and releases the RCU lock.
522 : */
523 : #define xa_for_each_marked(xa, index, entry, filter) \
524 : for (index = 0, entry = xa_find(xa, &index, ULONG_MAX, filter); \
525 : entry; entry = xa_find_after(xa, &index, ULONG_MAX, filter))
526 :
527 : #define xa_trylock(xa) spin_trylock(&(xa)->xa_lock)
528 : #define xa_lock(xa) spin_lock(&(xa)->xa_lock)
529 : #define xa_unlock(xa) spin_unlock(&(xa)->xa_lock)
530 : #define xa_lock_bh(xa) spin_lock_bh(&(xa)->xa_lock)
531 : #define xa_unlock_bh(xa) spin_unlock_bh(&(xa)->xa_lock)
532 : #define xa_lock_irq(xa) spin_lock_irq(&(xa)->xa_lock)
533 : #define xa_unlock_irq(xa) spin_unlock_irq(&(xa)->xa_lock)
534 : #define xa_lock_irqsave(xa, flags) \
535 : spin_lock_irqsave(&(xa)->xa_lock, flags)
536 : #define xa_unlock_irqrestore(xa, flags) \
537 : spin_unlock_irqrestore(&(xa)->xa_lock, flags)
538 : #define xa_lock_nested(xa, subclass) \
539 : spin_lock_nested(&(xa)->xa_lock, subclass)
540 : #define xa_lock_bh_nested(xa, subclass) \
541 : spin_lock_bh_nested(&(xa)->xa_lock, subclass)
542 : #define xa_lock_irq_nested(xa, subclass) \
543 : spin_lock_irq_nested(&(xa)->xa_lock, subclass)
544 : #define xa_lock_irqsave_nested(xa, flags, subclass) \
545 : spin_lock_irqsave_nested(&(xa)->xa_lock, flags, subclass)
546 :
547 : /*
548 : * Versions of the normal API which require the caller to hold the
549 : * xa_lock. If the GFP flags allow it, they will drop the lock to
550 : * allocate memory, then reacquire it afterwards. These functions
551 : * may also re-enable interrupts if the XArray flags indicate the
552 : * locking should be interrupt safe.
553 : */
554 : void *__xa_erase(struct xarray *, unsigned long index);
555 : void *__xa_store(struct xarray *, unsigned long index, void *entry, gfp_t);
556 : void *__xa_cmpxchg(struct xarray *, unsigned long index, void *old,
557 : void *entry, gfp_t);
558 : int __must_check __xa_insert(struct xarray *, unsigned long index,
559 : void *entry, gfp_t);
560 : int __must_check __xa_alloc(struct xarray *, u32 *id, void *entry,
561 : struct xa_limit, gfp_t);
562 : int __must_check __xa_alloc_cyclic(struct xarray *, u32 *id, void *entry,
563 : struct xa_limit, u32 *next, gfp_t);
564 : void __xa_set_mark(struct xarray *, unsigned long index, xa_mark_t);
565 : void __xa_clear_mark(struct xarray *, unsigned long index, xa_mark_t);
566 :
567 : /**
568 : * xa_store_bh() - Store this entry in the XArray.
569 : * @xa: XArray.
570 : * @index: Index into array.
571 : * @entry: New entry.
572 : * @gfp: Memory allocation flags.
573 : *
574 : * This function is like calling xa_store() except it disables softirqs
575 : * while holding the array lock.
576 : *
577 : * Context: Any context. Takes and releases the xa_lock while
578 : * disabling softirqs.
579 : * Return: The old entry at this index or xa_err() if an error happened.
580 : */
581 : static inline void *xa_store_bh(struct xarray *xa, unsigned long index,
582 : void *entry, gfp_t gfp)
583 : {
584 : void *curr;
585 :
586 : xa_lock_bh(xa);
587 : curr = __xa_store(xa, index, entry, gfp);
588 : xa_unlock_bh(xa);
589 :
590 : return curr;
591 : }
592 :
593 : /**
594 : * xa_store_irq() - Store this entry in the XArray.
595 : * @xa: XArray.
596 : * @index: Index into array.
597 : * @entry: New entry.
598 : * @gfp: Memory allocation flags.
599 : *
600 : * This function is like calling xa_store() except it disables interrupts
601 : * while holding the array lock.
602 : *
603 : * Context: Process context. Takes and releases the xa_lock while
604 : * disabling interrupts.
605 : * Return: The old entry at this index or xa_err() if an error happened.
606 : */
607 : static inline void *xa_store_irq(struct xarray *xa, unsigned long index,
608 : void *entry, gfp_t gfp)
609 : {
610 : void *curr;
611 :
612 : xa_lock_irq(xa);
613 : curr = __xa_store(xa, index, entry, gfp);
614 : xa_unlock_irq(xa);
615 :
616 : return curr;
617 : }
618 :
619 : /**
620 : * xa_erase_bh() - Erase this entry from the XArray.
621 : * @xa: XArray.
622 : * @index: Index of entry.
623 : *
624 : * After this function returns, loading from @index will return %NULL.
625 : * If the index is part of a multi-index entry, all indices will be erased
626 : * and none of the entries will be part of a multi-index entry.
627 : *
628 : * Context: Any context. Takes and releases the xa_lock while
629 : * disabling softirqs.
630 : * Return: The entry which used to be at this index.
631 : */
632 : static inline void *xa_erase_bh(struct xarray *xa, unsigned long index)
633 : {
634 : void *entry;
635 :
636 : xa_lock_bh(xa);
637 : entry = __xa_erase(xa, index);
638 : xa_unlock_bh(xa);
639 :
640 : return entry;
641 : }
642 :
643 : /**
644 : * xa_erase_irq() - Erase this entry from the XArray.
645 : * @xa: XArray.
646 : * @index: Index of entry.
647 : *
648 : * After this function returns, loading from @index will return %NULL.
649 : * If the index is part of a multi-index entry, all indices will be erased
650 : * and none of the entries will be part of a multi-index entry.
651 : *
652 : * Context: Process context. Takes and releases the xa_lock while
653 : * disabling interrupts.
654 : * Return: The entry which used to be at this index.
655 : */
656 : static inline void *xa_erase_irq(struct xarray *xa, unsigned long index)
657 : {
658 : void *entry;
659 :
660 : xa_lock_irq(xa);
661 : entry = __xa_erase(xa, index);
662 : xa_unlock_irq(xa);
663 :
664 : return entry;
665 : }
666 :
667 : /**
668 : * xa_cmpxchg() - Conditionally replace an entry in the XArray.
669 : * @xa: XArray.
670 : * @index: Index into array.
671 : * @old: Old value to test against.
672 : * @entry: New value to place in array.
673 : * @gfp: Memory allocation flags.
674 : *
675 : * If the entry at @index is the same as @old, replace it with @entry.
676 : * If the return value is equal to @old, then the exchange was successful.
677 : *
678 : * Context: Any context. Takes and releases the xa_lock. May sleep
679 : * if the @gfp flags permit.
680 : * Return: The old value at this index or xa_err() if an error happened.
681 : */
682 : static inline void *xa_cmpxchg(struct xarray *xa, unsigned long index,
683 : void *old, void *entry, gfp_t gfp)
684 : {
685 : void *curr;
686 :
687 : xa_lock(xa);
688 : curr = __xa_cmpxchg(xa, index, old, entry, gfp);
689 : xa_unlock(xa);
690 :
691 : return curr;
692 : }
693 :
694 : /**
695 : * xa_cmpxchg_bh() - Conditionally replace an entry in the XArray.
696 : * @xa: XArray.
697 : * @index: Index into array.
698 : * @old: Old value to test against.
699 : * @entry: New value to place in array.
700 : * @gfp: Memory allocation flags.
701 : *
702 : * This function is like calling xa_cmpxchg() except it disables softirqs
703 : * while holding the array lock.
704 : *
705 : * Context: Any context. Takes and releases the xa_lock while
706 : * disabling softirqs. May sleep if the @gfp flags permit.
707 : * Return: The old value at this index or xa_err() if an error happened.
708 : */
709 : static inline void *xa_cmpxchg_bh(struct xarray *xa, unsigned long index,
710 : void *old, void *entry, gfp_t gfp)
711 : {
712 : void *curr;
713 :
714 : xa_lock_bh(xa);
715 : curr = __xa_cmpxchg(xa, index, old, entry, gfp);
716 : xa_unlock_bh(xa);
717 :
718 : return curr;
719 : }
720 :
721 : /**
722 : * xa_cmpxchg_irq() - Conditionally replace an entry in the XArray.
723 : * @xa: XArray.
724 : * @index: Index into array.
725 : * @old: Old value to test against.
726 : * @entry: New value to place in array.
727 : * @gfp: Memory allocation flags.
728 : *
729 : * This function is like calling xa_cmpxchg() except it disables interrupts
730 : * while holding the array lock.
731 : *
732 : * Context: Process context. Takes and releases the xa_lock while
733 : * disabling interrupts. May sleep if the @gfp flags permit.
734 : * Return: The old value at this index or xa_err() if an error happened.
735 : */
736 0 : static inline void *xa_cmpxchg_irq(struct xarray *xa, unsigned long index,
737 : void *old, void *entry, gfp_t gfp)
738 : {
739 0 : void *curr;
740 :
741 0 : xa_lock_irq(xa);
742 0 : curr = __xa_cmpxchg(xa, index, old, entry, gfp);
743 0 : xa_unlock_irq(xa);
744 :
745 0 : return curr;
746 : }
747 :
748 : /**
749 : * xa_insert() - Store this entry in the XArray unless another entry is
750 : * already present.
751 : * @xa: XArray.
752 : * @index: Index into array.
753 : * @entry: New entry.
754 : * @gfp: Memory allocation flags.
755 : *
756 : * Inserting a NULL entry will store a reserved entry (like xa_reserve())
757 : * if no entry is present. Inserting will fail if a reserved entry is
758 : * present, even though loading from this index will return NULL.
759 : *
760 : * Context: Any context. Takes and releases the xa_lock. May sleep if
761 : * the @gfp flags permit.
762 : * Return: 0 if the store succeeded. -EBUSY if another entry was present.
763 : * -ENOMEM if memory could not be allocated.
764 : */
765 10 : static inline int __must_check xa_insert(struct xarray *xa,
766 : unsigned long index, void *entry, gfp_t gfp)
767 : {
768 10 : int err;
769 :
770 10 : xa_lock(xa);
771 10 : err = __xa_insert(xa, index, entry, gfp);
772 10 : xa_unlock(xa);
773 :
774 10 : return err;
775 : }
776 :
777 : /**
778 : * xa_insert_bh() - Store this entry in the XArray unless another entry is
779 : * already present.
780 : * @xa: XArray.
781 : * @index: Index into array.
782 : * @entry: New entry.
783 : * @gfp: Memory allocation flags.
784 : *
785 : * Inserting a NULL entry will store a reserved entry (like xa_reserve())
786 : * if no entry is present. Inserting will fail if a reserved entry is
787 : * present, even though loading from this index will return NULL.
788 : *
789 : * Context: Any context. Takes and releases the xa_lock while
790 : * disabling softirqs. May sleep if the @gfp flags permit.
791 : * Return: 0 if the store succeeded. -EBUSY if another entry was present.
792 : * -ENOMEM if memory could not be allocated.
793 : */
794 : static inline int __must_check xa_insert_bh(struct xarray *xa,
795 : unsigned long index, void *entry, gfp_t gfp)
796 : {
797 : int err;
798 :
799 : xa_lock_bh(xa);
800 : err = __xa_insert(xa, index, entry, gfp);
801 : xa_unlock_bh(xa);
802 :
803 : return err;
804 : }
805 :
806 : /**
807 : * xa_insert_irq() - Store this entry in the XArray unless another entry is
808 : * already present.
809 : * @xa: XArray.
810 : * @index: Index into array.
811 : * @entry: New entry.
812 : * @gfp: Memory allocation flags.
813 : *
814 : * Inserting a NULL entry will store a reserved entry (like xa_reserve())
815 : * if no entry is present. Inserting will fail if a reserved entry is
816 : * present, even though loading from this index will return NULL.
817 : *
818 : * Context: Process context. Takes and releases the xa_lock while
819 : * disabling interrupts. May sleep if the @gfp flags permit.
820 : * Return: 0 if the store succeeded. -EBUSY if another entry was present.
821 : * -ENOMEM if memory could not be allocated.
822 : */
823 : static inline int __must_check xa_insert_irq(struct xarray *xa,
824 : unsigned long index, void *entry, gfp_t gfp)
825 : {
826 : int err;
827 :
828 : xa_lock_irq(xa);
829 : err = __xa_insert(xa, index, entry, gfp);
830 : xa_unlock_irq(xa);
831 :
832 : return err;
833 : }
834 :
835 : /**
836 : * xa_alloc() - Find somewhere to store this entry in the XArray.
837 : * @xa: XArray.
838 : * @id: Pointer to ID.
839 : * @entry: New entry.
840 : * @limit: Range of ID to allocate.
841 : * @gfp: Memory allocation flags.
842 : *
843 : * Finds an empty entry in @xa between @limit.min and @limit.max,
844 : * stores the index into the @id pointer, then stores the entry at
845 : * that index. A concurrent lookup will not see an uninitialised @id.
846 : *
847 : * Context: Any context. Takes and releases the xa_lock. May sleep if
848 : * the @gfp flags permit.
849 : * Return: 0 on success, -ENOMEM if memory could not be allocated or
850 : * -EBUSY if there are no free entries in @limit.
851 : */
852 : static inline __must_check int xa_alloc(struct xarray *xa, u32 *id,
853 : void *entry, struct xa_limit limit, gfp_t gfp)
854 : {
855 : int err;
856 :
857 : xa_lock(xa);
858 : err = __xa_alloc(xa, id, entry, limit, gfp);
859 : xa_unlock(xa);
860 :
861 : return err;
862 : }
863 :
864 : /**
865 : * xa_alloc_bh() - Find somewhere to store this entry in the XArray.
866 : * @xa: XArray.
867 : * @id: Pointer to ID.
868 : * @entry: New entry.
869 : * @limit: Range of ID to allocate.
870 : * @gfp: Memory allocation flags.
871 : *
872 : * Finds an empty entry in @xa between @limit.min and @limit.max,
873 : * stores the index into the @id pointer, then stores the entry at
874 : * that index. A concurrent lookup will not see an uninitialised @id.
875 : *
876 : * Context: Any context. Takes and releases the xa_lock while
877 : * disabling softirqs. May sleep if the @gfp flags permit.
878 : * Return: 0 on success, -ENOMEM if memory could not be allocated or
879 : * -EBUSY if there are no free entries in @limit.
880 : */
881 : static inline int __must_check xa_alloc_bh(struct xarray *xa, u32 *id,
882 : void *entry, struct xa_limit limit, gfp_t gfp)
883 : {
884 : int err;
885 :
886 : xa_lock_bh(xa);
887 : err = __xa_alloc(xa, id, entry, limit, gfp);
888 : xa_unlock_bh(xa);
889 :
890 : return err;
891 : }
892 :
893 : /**
894 : * xa_alloc_irq() - Find somewhere to store this entry in the XArray.
895 : * @xa: XArray.
896 : * @id: Pointer to ID.
897 : * @entry: New entry.
898 : * @limit: Range of ID to allocate.
899 : * @gfp: Memory allocation flags.
900 : *
901 : * Finds an empty entry in @xa between @limit.min and @limit.max,
902 : * stores the index into the @id pointer, then stores the entry at
903 : * that index. A concurrent lookup will not see an uninitialised @id.
904 : *
905 : * Context: Process context. Takes and releases the xa_lock while
906 : * disabling interrupts. May sleep if the @gfp flags permit.
907 : * Return: 0 on success, -ENOMEM if memory could not be allocated or
908 : * -EBUSY if there are no free entries in @limit.
909 : */
910 : static inline int __must_check xa_alloc_irq(struct xarray *xa, u32 *id,
911 : void *entry, struct xa_limit limit, gfp_t gfp)
912 : {
913 : int err;
914 :
915 : xa_lock_irq(xa);
916 : err = __xa_alloc(xa, id, entry, limit, gfp);
917 : xa_unlock_irq(xa);
918 :
919 : return err;
920 : }
921 :
922 : /**
923 : * xa_alloc_cyclic() - Find somewhere to store this entry in the XArray.
924 : * @xa: XArray.
925 : * @id: Pointer to ID.
926 : * @entry: New entry.
927 : * @limit: Range of allocated ID.
928 : * @next: Pointer to next ID to allocate.
929 : * @gfp: Memory allocation flags.
930 : *
931 : * Finds an empty entry in @xa between @limit.min and @limit.max,
932 : * stores the index into the @id pointer, then stores the entry at
933 : * that index. A concurrent lookup will not see an uninitialised @id.
934 : * The search for an empty entry will start at @next and will wrap
935 : * around if necessary.
936 : *
937 : * Context: Any context. Takes and releases the xa_lock. May sleep if
938 : * the @gfp flags permit.
939 : * Return: 0 if the allocation succeeded without wrapping. 1 if the
940 : * allocation succeeded after wrapping, -ENOMEM if memory could not be
941 : * allocated or -EBUSY if there are no free entries in @limit.
942 : */
943 : static inline int xa_alloc_cyclic(struct xarray *xa, u32 *id, void *entry,
944 : struct xa_limit limit, u32 *next, gfp_t gfp)
945 : {
946 : int err;
947 :
948 : xa_lock(xa);
949 : err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
950 : xa_unlock(xa);
951 :
952 : return err;
953 : }
954 :
955 : /**
956 : * xa_alloc_cyclic_bh() - Find somewhere to store this entry in the XArray.
957 : * @xa: XArray.
958 : * @id: Pointer to ID.
959 : * @entry: New entry.
960 : * @limit: Range of allocated ID.
961 : * @next: Pointer to next ID to allocate.
962 : * @gfp: Memory allocation flags.
963 : *
964 : * Finds an empty entry in @xa between @limit.min and @limit.max,
965 : * stores the index into the @id pointer, then stores the entry at
966 : * that index. A concurrent lookup will not see an uninitialised @id.
967 : * The search for an empty entry will start at @next and will wrap
968 : * around if necessary.
969 : *
970 : * Context: Any context. Takes and releases the xa_lock while
971 : * disabling softirqs. May sleep if the @gfp flags permit.
972 : * Return: 0 if the allocation succeeded without wrapping. 1 if the
973 : * allocation succeeded after wrapping, -ENOMEM if memory could not be
974 : * allocated or -EBUSY if there are no free entries in @limit.
975 : */
976 : static inline int xa_alloc_cyclic_bh(struct xarray *xa, u32 *id, void *entry,
977 : struct xa_limit limit, u32 *next, gfp_t gfp)
978 : {
979 : int err;
980 :
981 : xa_lock_bh(xa);
982 : err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
983 : xa_unlock_bh(xa);
984 :
985 : return err;
986 : }
987 :
988 : /**
989 : * xa_alloc_cyclic_irq() - Find somewhere to store this entry in the XArray.
990 : * @xa: XArray.
991 : * @id: Pointer to ID.
992 : * @entry: New entry.
993 : * @limit: Range of allocated ID.
994 : * @next: Pointer to next ID to allocate.
995 : * @gfp: Memory allocation flags.
996 : *
997 : * Finds an empty entry in @xa between @limit.min and @limit.max,
998 : * stores the index into the @id pointer, then stores the entry at
999 : * that index. A concurrent lookup will not see an uninitialised @id.
1000 : * The search for an empty entry will start at @next and will wrap
1001 : * around if necessary.
1002 : *
1003 : * Context: Process context. Takes and releases the xa_lock while
1004 : * disabling interrupts. May sleep if the @gfp flags permit.
1005 : * Return: 0 if the allocation succeeded without wrapping. 1 if the
1006 : * allocation succeeded after wrapping, -ENOMEM if memory could not be
1007 : * allocated or -EBUSY if there are no free entries in @limit.
1008 : */
1009 : static inline int xa_alloc_cyclic_irq(struct xarray *xa, u32 *id, void *entry,
1010 : struct xa_limit limit, u32 *next, gfp_t gfp)
1011 : {
1012 : int err;
1013 :
1014 : xa_lock_irq(xa);
1015 : err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
1016 : xa_unlock_irq(xa);
1017 :
1018 : return err;
1019 : }
1020 :
1021 : /**
1022 : * xa_reserve() - Reserve this index in the XArray.
1023 : * @xa: XArray.
1024 : * @index: Index into array.
1025 : * @gfp: Memory allocation flags.
1026 : *
1027 : * Ensures there is somewhere to store an entry at @index in the array.
1028 : * If there is already something stored at @index, this function does
1029 : * nothing. If there was nothing there, the entry is marked as reserved.
1030 : * Loading from a reserved entry returns a %NULL pointer.
1031 : *
1032 : * If you do not use the entry that you have reserved, call xa_release()
1033 : * or xa_erase() to free any unnecessary memory.
1034 : *
1035 : * Context: Any context. Takes and releases the xa_lock.
1036 : * May sleep if the @gfp flags permit.
1037 : * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
1038 : */
1039 : static inline __must_check
1040 : int xa_reserve(struct xarray *xa, unsigned long index, gfp_t gfp)
1041 : {
1042 : return xa_err(xa_cmpxchg(xa, index, NULL, XA_ZERO_ENTRY, gfp));
1043 : }
1044 :
1045 : /**
1046 : * xa_reserve_bh() - Reserve this index in the XArray.
1047 : * @xa: XArray.
1048 : * @index: Index into array.
1049 : * @gfp: Memory allocation flags.
1050 : *
1051 : * A softirq-disabling version of xa_reserve().
1052 : *
1053 : * Context: Any context. Takes and releases the xa_lock while
1054 : * disabling softirqs.
1055 : * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
1056 : */
1057 : static inline __must_check
1058 : int xa_reserve_bh(struct xarray *xa, unsigned long index, gfp_t gfp)
1059 : {
1060 : return xa_err(xa_cmpxchg_bh(xa, index, NULL, XA_ZERO_ENTRY, gfp));
1061 : }
1062 :
1063 : /**
1064 : * xa_reserve_irq() - Reserve this index in the XArray.
1065 : * @xa: XArray.
1066 : * @index: Index into array.
1067 : * @gfp: Memory allocation flags.
1068 : *
1069 : * An interrupt-disabling version of xa_reserve().
1070 : *
1071 : * Context: Process context. Takes and releases the xa_lock while
1072 : * disabling interrupts.
1073 : * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
1074 : */
1075 : static inline __must_check
1076 : int xa_reserve_irq(struct xarray *xa, unsigned long index, gfp_t gfp)
1077 : {
1078 : return xa_err(xa_cmpxchg_irq(xa, index, NULL, XA_ZERO_ENTRY, gfp));
1079 : }
1080 :
1081 : /**
1082 : * xa_release() - Release a reserved entry.
1083 : * @xa: XArray.
1084 : * @index: Index of entry.
1085 : *
1086 : * After calling xa_reserve(), you can call this function to release the
1087 : * reservation. If the entry at @index has been stored to, this function
1088 : * will do nothing.
1089 : */
1090 : static inline void xa_release(struct xarray *xa, unsigned long index)
1091 : {
1092 : xa_cmpxchg(xa, index, XA_ZERO_ENTRY, NULL, 0);
1093 : }
1094 :
1095 : /* Everything below here is the Advanced API. Proceed with caution. */
1096 :
1097 : /*
1098 : * The xarray is constructed out of a set of 'chunks' of pointers. Choosing
1099 : * the best chunk size requires some tradeoffs. A power of two recommends
1100 : * itself so that we can walk the tree based purely on shifts and masks.
1101 : * Generally, the larger the better; as the number of slots per level of the
1102 : * tree increases, the less tall the tree needs to be. But that needs to be
1103 : * balanced against the memory consumption of each node. On a 64-bit system,
1104 : * xa_node is currently 576 bytes, and we get 7 of them per 4kB page. If we
1105 : * doubled the number of slots per node, we'd get only 3 nodes per 4kB page.
1106 : */
1107 : #ifndef XA_CHUNK_SHIFT
1108 : #define XA_CHUNK_SHIFT (CONFIG_BASE_SMALL ? 4 : 6)
1109 : #endif
1110 : #define XA_CHUNK_SIZE (1UL << XA_CHUNK_SHIFT)
1111 : #define XA_CHUNK_MASK (XA_CHUNK_SIZE - 1)
1112 : #define XA_MAX_MARKS 3
1113 : #define XA_MARK_LONGS DIV_ROUND_UP(XA_CHUNK_SIZE, BITS_PER_LONG)
1114 :
1115 : /*
1116 : * @count is the count of every non-NULL element in the ->slots array
1117 : * whether that is a value entry, a retry entry, a user pointer,
1118 : * a sibling entry or a pointer to the next level of the tree.
1119 : * @nr_values is the count of every element in ->slots which is
1120 : * either a value entry or a sibling of a value entry.
1121 : */
1122 : struct xa_node {
1123 : unsigned char shift; /* Bits remaining in each slot */
1124 : unsigned char offset; /* Slot offset in parent */
1125 : unsigned char count; /* Total entry count */
1126 : unsigned char nr_values; /* Value entry count */
1127 : struct xa_node __rcu *parent; /* NULL at top of tree */
1128 : struct xarray *array; /* The array we belong to */
1129 : union {
1130 : struct list_head private_list; /* For tree user */
1131 : struct rcu_head rcu_head; /* Used when freeing node */
1132 : };
1133 : void __rcu *slots[XA_CHUNK_SIZE];
1134 : union {
1135 : unsigned long tags[XA_MAX_MARKS][XA_MARK_LONGS];
1136 : unsigned long marks[XA_MAX_MARKS][XA_MARK_LONGS];
1137 : };
1138 : };
1139 :
1140 : void xa_dump(const struct xarray *);
1141 : void xa_dump_node(const struct xa_node *);
1142 :
1143 : #ifdef XA_DEBUG
1144 : #define XA_BUG_ON(xa, x) do { \
1145 : if (x) { \
1146 : xa_dump(xa); \
1147 : BUG(); \
1148 : } \
1149 : } while (0)
1150 : #define XA_NODE_BUG_ON(node, x) do { \
1151 : if (x) { \
1152 : if (node) xa_dump_node(node); \
1153 : BUG(); \
1154 : } \
1155 : } while (0)
1156 : #else
1157 : #define XA_BUG_ON(xa, x) do { } while (0)
1158 : #define XA_NODE_BUG_ON(node, x) do { } while (0)
1159 : #endif
1160 :
1161 : /* Private */
1162 321060 : static inline void *xa_head(const struct xarray *xa)
1163 : {
1164 321060 : return rcu_dereference_check(xa->xa_head,
1165 : lockdep_is_held(&xa->xa_lock));
1166 : }
1167 :
1168 : /* Private */
1169 5816 : static inline void *xa_head_locked(const struct xarray *xa)
1170 : {
1171 5816 : return rcu_dereference_protected(xa->xa_head,
1172 : lockdep_is_held(&xa->xa_lock));
1173 : }
1174 :
1175 : /* Private */
1176 651557 : static inline void *xa_entry(const struct xarray *xa,
1177 : const struct xa_node *node, unsigned int offset)
1178 : {
1179 651557 : XA_NODE_BUG_ON(node, offset >= XA_CHUNK_SIZE);
1180 651557 : return rcu_dereference_check(node->slots[offset],
1181 : lockdep_is_held(&xa->xa_lock));
1182 : }
1183 :
1184 : /* Private */
1185 31759 : static inline void *xa_entry_locked(const struct xarray *xa,
1186 : const struct xa_node *node, unsigned int offset)
1187 : {
1188 31759 : XA_NODE_BUG_ON(node, offset >= XA_CHUNK_SIZE);
1189 31759 : return rcu_dereference_protected(node->slots[offset],
1190 : lockdep_is_held(&xa->xa_lock));
1191 : }
1192 :
1193 : /* Private */
1194 20593 : static inline struct xa_node *xa_parent(const struct xarray *xa,
1195 : const struct xa_node *node)
1196 : {
1197 20593 : return rcu_dereference_check(node->parent,
1198 : lockdep_is_held(&xa->xa_lock));
1199 : }
1200 :
1201 : /* Private */
1202 6512 : static inline struct xa_node *xa_parent_locked(const struct xarray *xa,
1203 : const struct xa_node *node)
1204 : {
1205 6512 : return rcu_dereference_protected(node->parent,
1206 : lockdep_is_held(&xa->xa_lock));
1207 : }
1208 :
1209 : /* Private */
1210 1206 : static inline void *xa_mk_node(const struct xa_node *node)
1211 : {
1212 1206 : return (void *)((unsigned long)node | 2);
1213 : }
1214 :
1215 : /* Private */
1216 912982 : static inline struct xa_node *xa_to_node(const void *entry)
1217 : {
1218 912914 : return (struct xa_node *)((unsigned long)entry - 2);
1219 : }
1220 :
1221 : /* Private */
1222 1088159 : static inline bool xa_is_node(const void *entry)
1223 : {
1224 1263403 : return xa_is_internal(entry) && (unsigned long)entry > 4096;
1225 : }
1226 :
1227 : /* Private */
1228 292622 : static inline void *xa_mk_sibling(unsigned int offset)
1229 : {
1230 0 : return xa_mk_internal(offset);
1231 : }
1232 :
1233 : /* Private */
1234 0 : static inline unsigned long xa_to_sibling(const void *entry)
1235 : {
1236 0 : return xa_to_internal(entry);
1237 : }
1238 :
1239 : /**
1240 : * xa_is_sibling() - Is the entry a sibling entry?
1241 : * @entry: Entry retrieved from the XArray
1242 : *
1243 : * Return: %true if the entry is a sibling entry.
1244 : */
1245 618224 : static inline bool xa_is_sibling(const void *entry)
1246 : {
1247 909546 : return IS_ENABLED(CONFIG_XARRAY_MULTI) && xa_is_internal(entry) &&
1248 292622 : (entry < xa_mk_sibling(XA_CHUNK_SIZE - 1));
1249 : }
1250 :
1251 : #define XA_RETRY_ENTRY xa_mk_internal(256)
1252 :
1253 : /**
1254 : * xa_is_retry() - Is the entry a retry entry?
1255 : * @entry: Entry retrieved from the XArray
1256 : *
1257 : * Return: %true if the entry is a retry entry.
1258 : */
1259 48432 : static inline bool xa_is_retry(const void *entry)
1260 : {
1261 48432 : return unlikely(entry == XA_RETRY_ENTRY);
1262 : }
1263 :
1264 : /**
1265 : * xa_is_advanced() - Is the entry only permitted for the advanced API?
1266 : * @entry: Entry to be stored in the XArray.
1267 : *
1268 : * Return: %true if the entry cannot be stored by the normal API.
1269 : */
1270 14 : static inline bool xa_is_advanced(const void *entry)
1271 : {
1272 14 : return xa_is_internal(entry) && (entry <= XA_RETRY_ENTRY);
1273 : }
1274 :
1275 : /**
1276 : * typedef xa_update_node_t - A callback function from the XArray.
1277 : * @node: The node which is being processed
1278 : *
1279 : * This function is called every time the XArray updates the count of
1280 : * present and value entries in a node. It allows advanced users to
1281 : * maintain the private_list in the node.
1282 : *
1283 : * Context: The xa_lock is held and interrupts may be disabled.
1284 : * Implementations should not drop the xa_lock, nor re-enable
1285 : * interrupts.
1286 : */
1287 : typedef void (*xa_update_node_t)(struct xa_node *node);
1288 :
1289 : void xa_delete_node(struct xa_node *, xa_update_node_t);
1290 :
1291 : /*
1292 : * The xa_state is opaque to its users. It contains various different pieces
1293 : * of state involved in the current operation on the XArray. It should be
1294 : * declared on the stack and passed between the various internal routines.
1295 : * The various elements in it should not be accessed directly, but only
1296 : * through the provided accessor functions. The below documentation is for
1297 : * the benefit of those working on the code, not for users of the XArray.
1298 : *
1299 : * @xa_node usually points to the xa_node containing the slot we're operating
1300 : * on (and @xa_offset is the offset in the slots array). If there is a
1301 : * single entry in the array at index 0, there are no allocated xa_nodes to
1302 : * point to, and so we store %NULL in @xa_node. @xa_node is set to
1303 : * the value %XAS_RESTART if the xa_state is not walked to the correct
1304 : * position in the tree of nodes for this operation. If an error occurs
1305 : * during an operation, it is set to an %XAS_ERROR value. If we run off the
1306 : * end of the allocated nodes, it is set to %XAS_BOUNDS.
1307 : */
1308 : struct xa_state {
1309 : struct xarray *xa;
1310 : unsigned long xa_index;
1311 : unsigned char xa_shift;
1312 : unsigned char xa_sibs;
1313 : unsigned char xa_offset;
1314 : unsigned char xa_pad; /* Helps gcc generate better code */
1315 : struct xa_node *xa_node;
1316 : struct xa_node *xa_alloc;
1317 : xa_update_node_t xa_update;
1318 : };
1319 :
1320 : /*
1321 : * We encode errnos in the xas->xa_node. If an error has happened, we need to
1322 : * drop the lock to fix it, and once we've done so the xa_state is invalid.
1323 : */
1324 : #define XA_ERROR(errno) ((struct xa_node *)(((unsigned long)errno << 2) | 2UL))
1325 : #define XAS_BOUNDS ((struct xa_node *)1UL)
1326 : #define XAS_RESTART ((struct xa_node *)3UL)
1327 :
1328 : #define __XA_STATE(array, index, shift, sibs) { \
1329 : .xa = array, \
1330 : .xa_index = index, \
1331 : .xa_shift = shift, \
1332 : .xa_sibs = sibs, \
1333 : .xa_offset = 0, \
1334 : .xa_pad = 0, \
1335 : .xa_node = XAS_RESTART, \
1336 : .xa_alloc = NULL, \
1337 : .xa_update = NULL \
1338 : }
1339 :
1340 : /**
1341 : * XA_STATE() - Declare an XArray operation state.
1342 : * @name: Name of this operation state (usually xas).
1343 : * @array: Array to operate on.
1344 : * @index: Initial index of interest.
1345 : *
1346 : * Declare and initialise an xa_state on the stack.
1347 : */
1348 : #define XA_STATE(name, array, index) \
1349 : struct xa_state name = __XA_STATE(array, index, 0, 0)
1350 :
1351 : /**
1352 : * XA_STATE_ORDER() - Declare an XArray operation state.
1353 : * @name: Name of this operation state (usually xas).
1354 : * @array: Array to operate on.
1355 : * @index: Initial index of interest.
1356 : * @order: Order of entry.
1357 : *
1358 : * Declare and initialise an xa_state on the stack. This variant of
1359 : * XA_STATE() allows you to specify the 'order' of the element you
1360 : * want to operate on.`
1361 : */
1362 : #define XA_STATE_ORDER(name, array, index, order) \
1363 : struct xa_state name = __XA_STATE(array, \
1364 : (index >> order) << order, \
1365 : order - (order % XA_CHUNK_SHIFT), \
1366 : (1U << (order % XA_CHUNK_SHIFT)) - 1)
1367 :
1368 : #define xas_marked(xas, mark) xa_marked((xas)->xa, (mark))
1369 : #define xas_trylock(xas) xa_trylock((xas)->xa)
1370 : #define xas_lock(xas) xa_lock((xas)->xa)
1371 : #define xas_unlock(xas) xa_unlock((xas)->xa)
1372 : #define xas_lock_bh(xas) xa_lock_bh((xas)->xa)
1373 : #define xas_unlock_bh(xas) xa_unlock_bh((xas)->xa)
1374 : #define xas_lock_irq(xas) xa_lock_irq((xas)->xa)
1375 : #define xas_unlock_irq(xas) xa_unlock_irq((xas)->xa)
1376 : #define xas_lock_irqsave(xas, flags) \
1377 : xa_lock_irqsave((xas)->xa, flags)
1378 : #define xas_unlock_irqrestore(xas, flags) \
1379 : xa_unlock_irqrestore((xas)->xa, flags)
1380 :
1381 : /**
1382 : * xas_error() - Return an errno stored in the xa_state.
1383 : * @xas: XArray operation state.
1384 : *
1385 : * Return: 0 if no error has been noted. A negative errno if one has.
1386 : */
1387 671636 : static inline int xas_error(const struct xa_state *xas)
1388 : {
1389 1341273 : return xa_err(xas->xa_node);
1390 : }
1391 :
1392 : /**
1393 : * xas_set_err() - Note an error in the xa_state.
1394 : * @xas: XArray operation state.
1395 : * @err: Negative error number.
1396 : *
1397 : * Only call this function with a negative @err; zero or positive errors
1398 : * will probably not behave the way you think they should. If you want
1399 : * to clear the error from an xa_state, use xas_reset().
1400 : */
1401 0 : static inline void xas_set_err(struct xa_state *xas, long err)
1402 : {
1403 0 : xas->xa_node = XA_ERROR(err);
1404 0 : }
1405 :
1406 : /**
1407 : * xas_invalid() - Is the xas in a retry or error state?
1408 : * @xas: XArray operation state.
1409 : *
1410 : * Return: %true if the xas cannot be used for operations.
1411 : */
1412 378124 : static inline bool xas_invalid(const struct xa_state *xas)
1413 : {
1414 56787 : return (unsigned long)xas->xa_node & 3;
1415 : }
1416 :
1417 : /**
1418 : * xas_valid() - Is the xas a valid cursor into the array?
1419 : * @xas: XArray operation state.
1420 : *
1421 : * Return: %true if the xas can be used for operations.
1422 : */
1423 321337 : static inline bool xas_valid(const struct xa_state *xas)
1424 : {
1425 319351 : return !xas_invalid(xas);
1426 : }
1427 :
1428 : /**
1429 : * xas_is_node() - Does the xas point to a node?
1430 : * @xas: XArray operation state.
1431 : *
1432 : * Return: %true if the xas currently references a node.
1433 : */
1434 1986 : static inline bool xas_is_node(const struct xa_state *xas)
1435 : {
1436 2135 : return xas_valid(xas) && xas->xa_node;
1437 : }
1438 :
1439 : /* True if the pointer is something other than a node */
1440 4920 : static inline bool xas_not_node(struct xa_node *node)
1441 : {
1442 5435 : return ((unsigned long)node & 3) || !node;
1443 : }
1444 :
1445 : /* True if the node represents RESTART or an error */
1446 5277 : static inline bool xas_frozen(struct xa_node *node)
1447 : {
1448 5277 : return (unsigned long)node & 2;
1449 : }
1450 :
1451 : /* True if the node represents head-of-tree, RESTART or BOUNDS */
1452 69603 : static inline bool xas_top(struct xa_node *node)
1453 : {
1454 69603 : return node <= XAS_RESTART;
1455 : }
1456 :
1457 : /**
1458 : * xas_reset() - Reset an XArray operation state.
1459 : * @xas: XArray operation state.
1460 : *
1461 : * Resets the error or walk state of the @xas so future walks of the
1462 : * array will start from the root. Use this if you have dropped the
1463 : * xarray lock and want to reuse the xa_state.
1464 : *
1465 : * Context: Any context.
1466 : */
1467 0 : static inline void xas_reset(struct xa_state *xas)
1468 : {
1469 0 : xas->xa_node = XAS_RESTART;
1470 0 : }
1471 :
1472 : /**
1473 : * xas_retry() - Retry the operation if appropriate.
1474 : * @xas: XArray operation state.
1475 : * @entry: Entry from xarray.
1476 : *
1477 : * The advanced functions may sometimes return an internal entry, such as
1478 : * a retry entry or a zero entry. This function sets up the @xas to restart
1479 : * the walk from the head of the array if needed.
1480 : *
1481 : * Context: Any context.
1482 : * Return: true if the operation needs to be retried.
1483 : */
1484 48432 : static inline bool xas_retry(struct xa_state *xas, const void *entry)
1485 : {
1486 48432 : if (xa_is_zero(entry))
1487 : return true;
1488 48432 : if (!xa_is_retry(entry))
1489 : return false;
1490 0 : xas_reset(xas);
1491 0 : return true;
1492 : }
1493 :
1494 : void *xas_load(struct xa_state *);
1495 : void *xas_store(struct xa_state *, void *entry);
1496 : void *xas_find(struct xa_state *, unsigned long max);
1497 : void *xas_find_conflict(struct xa_state *);
1498 :
1499 : bool xas_get_mark(const struct xa_state *, xa_mark_t);
1500 : void xas_set_mark(const struct xa_state *, xa_mark_t);
1501 : void xas_clear_mark(const struct xa_state *, xa_mark_t);
1502 : void *xas_find_marked(struct xa_state *, unsigned long max, xa_mark_t);
1503 : void xas_init_marks(const struct xa_state *);
1504 :
1505 : bool xas_nomem(struct xa_state *, gfp_t);
1506 : void xas_pause(struct xa_state *);
1507 :
1508 : void xas_create_range(struct xa_state *);
1509 :
1510 : #ifdef CONFIG_XARRAY_MULTI
1511 : int xa_get_order(struct xarray *, unsigned long index);
1512 : void xas_split(struct xa_state *, void *entry, unsigned int order);
1513 : void xas_split_alloc(struct xa_state *, void *entry, unsigned int order, gfp_t);
1514 : #else
1515 : static inline int xa_get_order(struct xarray *xa, unsigned long index)
1516 : {
1517 : return 0;
1518 : }
1519 :
1520 : static inline void xas_split(struct xa_state *xas, void *entry,
1521 : unsigned int order)
1522 : {
1523 : xas_store(xas, entry);
1524 : }
1525 :
1526 : static inline void xas_split_alloc(struct xa_state *xas, void *entry,
1527 : unsigned int order, gfp_t gfp)
1528 : {
1529 : }
1530 : #endif
1531 :
1532 : /**
1533 : * xas_reload() - Refetch an entry from the xarray.
1534 : * @xas: XArray operation state.
1535 : *
1536 : * Use this function to check that a previously loaded entry still has
1537 : * the same value. This is useful for the lockless pagecache lookup where
1538 : * we walk the array with only the RCU lock to protect us, lock the page,
1539 : * then check that the page hasn't moved since we looked it up.
1540 : *
1541 : * The caller guarantees that @xas is still valid. If it may be in an
1542 : * error or restart state, call xas_load() instead.
1543 : *
1544 : * Return: The entry at this location in the xarray.
1545 : */
1546 1312 : static inline void *xas_reload(struct xa_state *xas)
1547 : {
1548 1312 : struct xa_node *node = xas->xa_node;
1549 1312 : void *entry;
1550 1312 : char offset;
1551 :
1552 1312 : if (!node)
1553 12 : return xa_head(xas->xa);
1554 1300 : if (IS_ENABLED(CONFIG_XARRAY_MULTI)) {
1555 1300 : offset = (xas->xa_index >> node->shift) & XA_CHUNK_MASK;
1556 1300 : entry = xa_entry(xas->xa, node, offset);
1557 1300 : if (!xa_is_sibling(entry))
1558 : return entry;
1559 0 : offset = xa_to_sibling(entry);
1560 : } else {
1561 : offset = xas->xa_offset;
1562 : }
1563 0 : return xa_entry(xas->xa, node, offset);
1564 : }
1565 :
1566 : /**
1567 : * xas_set() - Set up XArray operation state for a different index.
1568 : * @xas: XArray operation state.
1569 : * @index: New index into the XArray.
1570 : *
1571 : * Move the operation state to refer to a different index. This will
1572 : * have the effect of starting a walk from the top; see xas_next()
1573 : * to move to an adjacent index.
1574 : */
1575 0 : static inline void xas_set(struct xa_state *xas, unsigned long index)
1576 : {
1577 0 : xas->xa_index = index;
1578 0 : xas->xa_node = XAS_RESTART;
1579 0 : }
1580 :
1581 : /**
1582 : * xas_set_order() - Set up XArray operation state for a multislot entry.
1583 : * @xas: XArray operation state.
1584 : * @index: Target of the operation.
1585 : * @order: Entry occupies 2^@order indices.
1586 : */
1587 0 : static inline void xas_set_order(struct xa_state *xas, unsigned long index,
1588 : unsigned int order)
1589 : {
1590 : #ifdef CONFIG_XARRAY_MULTI
1591 0 : xas->xa_index = order < BITS_PER_LONG ? (index >> order) << order : 0;
1592 0 : xas->xa_shift = order - (order % XA_CHUNK_SHIFT);
1593 0 : xas->xa_sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1;
1594 0 : xas->xa_node = XAS_RESTART;
1595 : #else
1596 : BUG_ON(order > 0);
1597 : xas_set(xas, index);
1598 : #endif
1599 : }
1600 :
1601 : /**
1602 : * xas_set_update() - Set up XArray operation state for a callback.
1603 : * @xas: XArray operation state.
1604 : * @update: Function to call when updating a node.
1605 : *
1606 : * The XArray can notify a caller after it has updated an xa_node.
1607 : * This is advanced functionality and is only needed by the page cache.
1608 : */
1609 0 : static inline void xas_set_update(struct xa_state *xas, xa_update_node_t update)
1610 : {
1611 0 : xas->xa_update = update;
1612 0 : }
1613 :
1614 : /**
1615 : * xas_next_entry() - Advance iterator to next present entry.
1616 : * @xas: XArray operation state.
1617 : * @max: Highest index to return.
1618 : *
1619 : * xas_next_entry() is an inline function to optimise xarray traversal for
1620 : * speed. It is equivalent to calling xas_find(), and will call xas_find()
1621 : * for all the hard cases.
1622 : *
1623 : * Return: The next present entry after the one currently referred to by @xas.
1624 : */
1625 0 : static inline void *xas_next_entry(struct xa_state *xas, unsigned long max)
1626 : {
1627 0 : struct xa_node *node = xas->xa_node;
1628 0 : void *entry;
1629 :
1630 0 : if (unlikely(xas_not_node(node) || node->shift ||
1631 : xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)))
1632 0 : return xas_find(xas, max);
1633 :
1634 0 : do {
1635 0 : if (unlikely(xas->xa_index >= max))
1636 0 : return xas_find(xas, max);
1637 0 : if (unlikely(xas->xa_offset == XA_CHUNK_MASK))
1638 0 : return xas_find(xas, max);
1639 0 : entry = xa_entry(xas->xa, node, xas->xa_offset + 1);
1640 0 : if (unlikely(xa_is_internal(entry)))
1641 0 : return xas_find(xas, max);
1642 0 : xas->xa_offset++;
1643 0 : xas->xa_index++;
1644 0 : } while (!entry);
1645 :
1646 : return entry;
1647 : }
1648 :
1649 : /* Private */
1650 5169 : static inline unsigned int xas_find_chunk(struct xa_state *xas, bool advance,
1651 : xa_mark_t mark)
1652 : {
1653 5169 : unsigned long *addr = xas->xa_node->marks[(__force unsigned)mark];
1654 5169 : unsigned int offset = xas->xa_offset;
1655 :
1656 5169 : if (advance)
1657 3911 : offset++;
1658 5169 : if (XA_CHUNK_SIZE == BITS_PER_LONG) {
1659 5169 : if (offset < XA_CHUNK_SIZE) {
1660 5134 : unsigned long data = *addr & (~0UL << offset);
1661 5134 : if (data)
1662 4492 : return __ffs(data);
1663 : }
1664 : return XA_CHUNK_SIZE;
1665 : }
1666 :
1667 : return find_next_bit(addr, XA_CHUNK_SIZE, offset);
1668 : }
1669 :
1670 : /**
1671 : * xas_next_marked() - Advance iterator to next marked entry.
1672 : * @xas: XArray operation state.
1673 : * @max: Highest index to return.
1674 : * @mark: Mark to search for.
1675 : *
1676 : * xas_next_marked() is an inline function to optimise xarray traversal for
1677 : * speed. It is equivalent to calling xas_find_marked(), and will call
1678 : * xas_find_marked() for all the hard cases.
1679 : *
1680 : * Return: The next marked entry after the one currently referred to by @xas.
1681 : */
1682 364 : static inline void *xas_next_marked(struct xa_state *xas, unsigned long max,
1683 : xa_mark_t mark)
1684 : {
1685 364 : struct xa_node *node = xas->xa_node;
1686 364 : void *entry;
1687 364 : unsigned int offset;
1688 :
1689 728 : if (unlikely(xas_not_node(node) || node->shift))
1690 9 : return xas_find_marked(xas, max, mark);
1691 355 : offset = xas_find_chunk(xas, true, mark);
1692 355 : xas->xa_offset = offset;
1693 355 : xas->xa_index = (xas->xa_index & ~XA_CHUNK_MASK) + offset;
1694 355 : if (xas->xa_index > max)
1695 : return NULL;
1696 327 : if (offset == XA_CHUNK_SIZE)
1697 33 : return xas_find_marked(xas, max, mark);
1698 294 : entry = xa_entry(xas->xa, node, offset);
1699 294 : if (!entry)
1700 0 : return xas_find_marked(xas, max, mark);
1701 : return entry;
1702 : }
1703 :
1704 : /*
1705 : * If iterating while holding a lock, drop the lock and reschedule
1706 : * every %XA_CHECK_SCHED loops.
1707 : */
1708 : enum {
1709 : XA_CHECK_SCHED = 4096,
1710 : };
1711 :
1712 : /**
1713 : * xas_for_each() - Iterate over a range of an XArray.
1714 : * @xas: XArray operation state.
1715 : * @entry: Entry retrieved from the array.
1716 : * @max: Maximum index to retrieve from array.
1717 : *
1718 : * The loop body will be executed for each entry present in the xarray
1719 : * between the current xas position and @max. @entry will be set to
1720 : * the entry retrieved from the xarray. It is safe to delete entries
1721 : * from the array in the loop body. You should hold either the RCU lock
1722 : * or the xa_lock while iterating. If you need to drop the lock, call
1723 : * xas_pause() first.
1724 : */
1725 : #define xas_for_each(xas, entry, max) \
1726 : for (entry = xas_find(xas, max); entry; \
1727 : entry = xas_next_entry(xas, max))
1728 :
1729 : /**
1730 : * xas_for_each_marked() - Iterate over a range of an XArray.
1731 : * @xas: XArray operation state.
1732 : * @entry: Entry retrieved from the array.
1733 : * @max: Maximum index to retrieve from array.
1734 : * @mark: Mark to search for.
1735 : *
1736 : * The loop body will be executed for each marked entry in the xarray
1737 : * between the current xas position and @max. @entry will be set to
1738 : * the entry retrieved from the xarray. It is safe to delete entries
1739 : * from the array in the loop body. You should hold either the RCU lock
1740 : * or the xa_lock while iterating. If you need to drop the lock, call
1741 : * xas_pause() first.
1742 : */
1743 : #define xas_for_each_marked(xas, entry, max, mark) \
1744 : for (entry = xas_find_marked(xas, max, mark); entry; \
1745 : entry = xas_next_marked(xas, max, mark))
1746 :
1747 : /**
1748 : * xas_for_each_conflict() - Iterate over a range of an XArray.
1749 : * @xas: XArray operation state.
1750 : * @entry: Entry retrieved from the array.
1751 : *
1752 : * The loop body will be executed for each entry in the XArray that
1753 : * lies within the range specified by @xas. If the loop terminates
1754 : * normally, @entry will be %NULL. The user may break out of the loop,
1755 : * which will leave @entry set to the conflicting entry. The caller
1756 : * may also call xa_set_err() to exit the loop while setting an error
1757 : * to record the reason.
1758 : */
1759 : #define xas_for_each_conflict(xas, entry) \
1760 : while ((entry = xas_find_conflict(xas)))
1761 :
1762 : void *__xas_next(struct xa_state *);
1763 : void *__xas_prev(struct xa_state *);
1764 :
1765 : /**
1766 : * xas_prev() - Move iterator to previous index.
1767 : * @xas: XArray operation state.
1768 : *
1769 : * If the @xas was in an error state, it will remain in an error state
1770 : * and this function will return %NULL. If the @xas has never been walked,
1771 : * it will have the effect of calling xas_load(). Otherwise one will be
1772 : * subtracted from the index and the state will be walked to the correct
1773 : * location in the array for the next operation.
1774 : *
1775 : * If the iterator was referencing index 0, this function wraps
1776 : * around to %ULONG_MAX.
1777 : *
1778 : * Return: The entry at the new index. This may be %NULL or an internal
1779 : * entry.
1780 : */
1781 0 : static inline void *xas_prev(struct xa_state *xas)
1782 : {
1783 0 : struct xa_node *node = xas->xa_node;
1784 :
1785 0 : if (unlikely(xas_not_node(node) || node->shift ||
1786 : xas->xa_offset == 0))
1787 0 : return __xas_prev(xas);
1788 :
1789 0 : xas->xa_index--;
1790 0 : xas->xa_offset--;
1791 0 : return xa_entry(xas->xa, node, xas->xa_offset);
1792 : }
1793 :
1794 : /**
1795 : * xas_next() - Move state to next index.
1796 : * @xas: XArray operation state.
1797 : *
1798 : * If the @xas was in an error state, it will remain in an error state
1799 : * and this function will return %NULL. If the @xas has never been walked,
1800 : * it will have the effect of calling xas_load(). Otherwise one will be
1801 : * added to the index and the state will be walked to the correct
1802 : * location in the array for the next operation.
1803 : *
1804 : * If the iterator was referencing index %ULONG_MAX, this function wraps
1805 : * around to 0.
1806 : *
1807 : * Return: The entry at the new index. This may be %NULL or an internal
1808 : * entry.
1809 : */
1810 0 : static inline void *xas_next(struct xa_state *xas)
1811 : {
1812 0 : struct xa_node *node = xas->xa_node;
1813 :
1814 0 : if (unlikely(xas_not_node(node) || node->shift ||
1815 : xas->xa_offset == XA_CHUNK_MASK))
1816 0 : return __xas_next(xas);
1817 :
1818 0 : xas->xa_index++;
1819 0 : xas->xa_offset++;
1820 0 : return xa_entry(xas->xa, node, xas->xa_offset);
1821 : }
1822 :
1823 : #endif /* _LINUX_XARRAY_H */
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