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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/bitmap.h>
13 : #include <linux/bug.h>
14 : #include <linux/compiler.h>
15 : #include <linux/gfp.h>
16 : #include <linux/kconfig.h>
17 : #include <linux/kernel.h>
18 : #include <linux/rcupdate.h>
19 : #include <linux/spinlock.h>
20 : #include <linux/types.h>
21 :
22 : /*
23 : * The bottom two bits of the entry determine how the XArray interprets
24 : * the contents:
25 : *
26 : * 00: Pointer entry
27 : * 10: Internal entry
28 : * x1: Value entry or tagged pointer
29 : *
30 : * Attempting to store internal entries in the XArray is a bug.
31 : *
32 : * Most internal entries are pointers to the next node in the tree.
33 : * The following internal entries have a special meaning:
34 : *
35 : * 0-62: Sibling entries
36 : * 256: Retry entry
37 : * 257: Zero entry
38 : *
39 : * Errors are also represented as internal entries, but use the negative
40 : * space (-4094 to -2). They're never stored in the slots array; only
41 : * returned by the normal API.
42 : */
43 :
44 : #define BITS_PER_XA_VALUE (BITS_PER_LONG - 1)
45 :
46 : /**
47 : * xa_mk_value() - Create an XArray entry from an integer.
48 : * @v: Value to store in XArray.
49 : *
50 : * Context: Any context.
51 : * Return: An entry suitable for storing in the XArray.
52 : */
53 : static inline void *xa_mk_value(unsigned long v)
54 : {
55 88 : WARN_ON((long)v < 0);
56 88 : return (void *)((v << 1) | 1);
57 : }
58 :
59 : /**
60 : * xa_to_value() - Get value stored in an XArray entry.
61 : * @entry: XArray entry.
62 : *
63 : * Context: Any context.
64 : * Return: The value stored in the XArray entry.
65 : */
66 : static inline unsigned long xa_to_value(const void *entry)
67 : {
68 83 : return (unsigned long)entry >> 1;
69 : }
70 :
71 : /**
72 : * xa_is_value() - Determine if an entry is a value.
73 : * @entry: XArray entry.
74 : *
75 : * Context: Any context.
76 : * Return: True if the entry is a value, false if it is a pointer.
77 : */
78 : static inline bool xa_is_value(const void *entry)
79 : {
80 25252 : return (unsigned long)entry & 1;
81 : }
82 :
83 : /**
84 : * xa_tag_pointer() - Create an XArray entry for a tagged pointer.
85 : * @p: Plain pointer.
86 : * @tag: Tag value (0, 1 or 3).
87 : *
88 : * If the user of the XArray prefers, they can tag their pointers instead
89 : * of storing value entries. Three tags are available (0, 1 and 3).
90 : * These are distinct from the xa_mark_t as they are not replicated up
91 : * through the array and cannot be searched for.
92 : *
93 : * Context: Any context.
94 : * Return: An XArray entry.
95 : */
96 : static inline void *xa_tag_pointer(void *p, unsigned long tag)
97 : {
98 : return (void *)((unsigned long)p | tag);
99 : }
100 :
101 : /**
102 : * xa_untag_pointer() - Turn an XArray entry into a plain pointer.
103 : * @entry: XArray entry.
104 : *
105 : * If you have stored a tagged pointer in the XArray, call this function
106 : * to get the untagged version of the pointer.
107 : *
108 : * Context: Any context.
109 : * Return: A pointer.
110 : */
111 : static inline void *xa_untag_pointer(void *entry)
112 : {
113 : return (void *)((unsigned long)entry & ~3UL);
114 : }
115 :
116 : /**
117 : * xa_pointer_tag() - Get the tag stored in an XArray entry.
118 : * @entry: XArray entry.
119 : *
120 : * If you have stored a tagged pointer in the XArray, call this function
121 : * to get the tag of that pointer.
122 : *
123 : * Context: Any context.
124 : * Return: A tag.
125 : */
126 : static inline unsigned int xa_pointer_tag(void *entry)
127 : {
128 : return (unsigned long)entry & 3UL;
129 : }
130 :
131 : /*
132 : * xa_mk_internal() - Create an internal entry.
133 : * @v: Value to turn into an internal entry.
134 : *
135 : * Internal entries are used for a number of purposes. Entries 0-255 are
136 : * used for sibling entries (only 0-62 are used by the current code). 256
137 : * is used for the retry entry. 257 is used for the reserved / zero entry.
138 : * Negative internal entries are used to represent errnos. Node pointers
139 : * are also tagged as internal entries in some situations.
140 : *
141 : * Context: Any context.
142 : * Return: An XArray internal entry corresponding to this value.
143 : */
144 : static inline void *xa_mk_internal(unsigned long v)
145 : {
146 0 : return (void *)((v << 2) | 2);
147 : }
148 :
149 : /*
150 : * xa_to_internal() - Extract the value from an internal entry.
151 : * @entry: XArray entry.
152 : *
153 : * Context: Any context.
154 : * Return: The value which was stored in the internal entry.
155 : */
156 : static inline unsigned long xa_to_internal(const void *entry)
157 : {
158 : return (unsigned long)entry >> 2;
159 : }
160 :
161 : /*
162 : * xa_is_internal() - Is the entry an internal entry?
163 : * @entry: XArray entry.
164 : *
165 : * Context: Any context.
166 : * Return: %true if the entry is an internal entry.
167 : */
168 : static inline bool xa_is_internal(const void *entry)
169 : {
170 987 : return ((unsigned long)entry & 3) == 2;
171 : }
172 :
173 : #define XA_ZERO_ENTRY xa_mk_internal(257)
174 :
175 : /**
176 : * xa_is_zero() - Is the entry a zero entry?
177 : * @entry: Entry retrieved from the XArray
178 : *
179 : * The normal API will return NULL as the contents of a slot containing
180 : * a zero entry. You can only see zero entries by using the advanced API.
181 : *
182 : * Return: %true if the entry is a zero entry.
183 : */
184 : static inline bool xa_is_zero(const void *entry)
185 : {
186 97 : return unlikely(entry == XA_ZERO_ENTRY);
187 : }
188 :
189 : /**
190 : * xa_is_err() - Report whether an XArray operation returned an error
191 : * @entry: Result from calling an XArray function
192 : *
193 : * If an XArray operation cannot complete an operation, it will return
194 : * a special value indicating an error. This function tells you
195 : * whether an error occurred; xa_err() tells you which error occurred.
196 : *
197 : * Context: Any context.
198 : * Return: %true if the entry indicates an error.
199 : */
200 : static inline bool xa_is_err(const void *entry)
201 : {
202 421 : return unlikely(xa_is_internal(entry) &&
203 : entry >= xa_mk_internal(-MAX_ERRNO));
204 : }
205 :
206 : /**
207 : * xa_err() - Turn an XArray result into an errno.
208 : * @entry: Result from calling an XArray function.
209 : *
210 : * If an XArray operation cannot complete an operation, it will return
211 : * a special pointer value which encodes an errno. This function extracts
212 : * the errno from the pointer value, or returns 0 if the pointer does not
213 : * represent an errno.
214 : *
215 : * Context: Any context.
216 : * Return: A negative errno or 0.
217 : */
218 : static inline int xa_err(void *entry)
219 : {
220 : /* xa_to_internal() would not do sign extension. */
221 421 : if (xa_is_err(entry))
222 0 : return (long)entry >> 2;
223 : return 0;
224 : }
225 :
226 : /**
227 : * struct xa_limit - Represents a range of IDs.
228 : * @min: The lowest ID to allocate (inclusive).
229 : * @max: The maximum ID to allocate (inclusive).
230 : *
231 : * This structure is used either directly or via the XA_LIMIT() macro
232 : * to communicate the range of IDs that are valid for allocation.
233 : * Three common ranges are predefined for you:
234 : * * xa_limit_32b - [0 - UINT_MAX]
235 : * * xa_limit_31b - [0 - INT_MAX]
236 : * * xa_limit_16b - [0 - USHRT_MAX]
237 : */
238 : struct xa_limit {
239 : u32 max;
240 : u32 min;
241 : };
242 :
243 : #define XA_LIMIT(_min, _max) (struct xa_limit) { .min = _min, .max = _max }
244 :
245 : #define xa_limit_32b XA_LIMIT(0, UINT_MAX)
246 : #define xa_limit_31b XA_LIMIT(0, INT_MAX)
247 : #define xa_limit_16b XA_LIMIT(0, USHRT_MAX)
248 :
249 : typedef unsigned __bitwise xa_mark_t;
250 : #define XA_MARK_0 ((__force xa_mark_t)0U)
251 : #define XA_MARK_1 ((__force xa_mark_t)1U)
252 : #define XA_MARK_2 ((__force xa_mark_t)2U)
253 : #define XA_PRESENT ((__force xa_mark_t)8U)
254 : #define XA_MARK_MAX XA_MARK_2
255 : #define XA_FREE_MARK XA_MARK_0
256 :
257 : enum xa_lock_type {
258 : XA_LOCK_IRQ = 1,
259 : XA_LOCK_BH = 2,
260 : };
261 :
262 : /*
263 : * Values for xa_flags. The radix tree stores its GFP flags in the xa_flags,
264 : * and we remain compatible with that.
265 : */
266 : #define XA_FLAGS_LOCK_IRQ ((__force gfp_t)XA_LOCK_IRQ)
267 : #define XA_FLAGS_LOCK_BH ((__force gfp_t)XA_LOCK_BH)
268 : #define XA_FLAGS_TRACK_FREE ((__force gfp_t)4U)
269 : #define XA_FLAGS_ZERO_BUSY ((__force gfp_t)8U)
270 : #define XA_FLAGS_ALLOC_WRAPPED ((__force gfp_t)16U)
271 : #define XA_FLAGS_ACCOUNT ((__force gfp_t)32U)
272 : #define XA_FLAGS_MARK(mark) ((__force gfp_t)((1U << __GFP_BITS_SHIFT) << \
273 : (__force unsigned)(mark)))
274 :
275 : /* ALLOC is for a normal 0-based alloc. ALLOC1 is for an 1-based alloc */
276 : #define XA_FLAGS_ALLOC (XA_FLAGS_TRACK_FREE | XA_FLAGS_MARK(XA_FREE_MARK))
277 : #define XA_FLAGS_ALLOC1 (XA_FLAGS_TRACK_FREE | XA_FLAGS_ZERO_BUSY)
278 :
279 : /**
280 : * struct xarray - The anchor of the XArray.
281 : * @xa_lock: Lock that protects the contents of the XArray.
282 : *
283 : * To use the xarray, define it statically or embed it in your data structure.
284 : * It is a very small data structure, so it does not usually make sense to
285 : * allocate it separately and keep a pointer to it in your data structure.
286 : *
287 : * You may use the xa_lock to protect your own data structures as well.
288 : */
289 : /*
290 : * If all of the entries in the array are NULL, @xa_head is a NULL pointer.
291 : * If the only non-NULL entry in the array is at index 0, @xa_head is that
292 : * entry. If any other entry in the array is non-NULL, @xa_head points
293 : * to an @xa_node.
294 : */
295 : struct xarray {
296 : spinlock_t xa_lock;
297 : /* private: The rest of the data structure is not to be used directly. */
298 : gfp_t xa_flags;
299 : void __rcu * xa_head;
300 : };
301 :
302 : #define XARRAY_INIT(name, flags) { \
303 : .xa_lock = __SPIN_LOCK_UNLOCKED(name.xa_lock), \
304 : .xa_flags = flags, \
305 : .xa_head = NULL, \
306 : }
307 :
308 : /**
309 : * DEFINE_XARRAY_FLAGS() - Define an XArray with custom flags.
310 : * @name: A string that names your XArray.
311 : * @flags: XA_FLAG values.
312 : *
313 : * This is intended for file scope definitions of XArrays. It declares
314 : * and initialises an empty XArray with the chosen name and flags. It is
315 : * equivalent to calling xa_init_flags() on the array, but it does the
316 : * initialisation at compiletime instead of runtime.
317 : */
318 : #define DEFINE_XARRAY_FLAGS(name, flags) \
319 : struct xarray name = XARRAY_INIT(name, flags)
320 :
321 : /**
322 : * DEFINE_XARRAY() - Define an XArray.
323 : * @name: A string that names your XArray.
324 : *
325 : * This is intended for file scope definitions of XArrays. It declares
326 : * and initialises an empty XArray with the chosen name. It is equivalent
327 : * to calling xa_init() on the array, but it does the initialisation at
328 : * compiletime instead of runtime.
329 : */
330 : #define DEFINE_XARRAY(name) DEFINE_XARRAY_FLAGS(name, 0)
331 :
332 : /**
333 : * DEFINE_XARRAY_ALLOC() - Define an XArray which allocates IDs starting at 0.
334 : * @name: A string that names your XArray.
335 : *
336 : * This is intended for file scope definitions of allocating XArrays.
337 : * See also DEFINE_XARRAY().
338 : */
339 : #define DEFINE_XARRAY_ALLOC(name) DEFINE_XARRAY_FLAGS(name, XA_FLAGS_ALLOC)
340 :
341 : /**
342 : * DEFINE_XARRAY_ALLOC1() - Define an XArray which allocates IDs starting at 1.
343 : * @name: A string that names your XArray.
344 : *
345 : * This is intended for file scope definitions of allocating XArrays.
346 : * See also DEFINE_XARRAY().
347 : */
348 : #define DEFINE_XARRAY_ALLOC1(name) DEFINE_XARRAY_FLAGS(name, XA_FLAGS_ALLOC1)
349 :
350 : void *xa_load(struct xarray *, unsigned long index);
351 : void *xa_store(struct xarray *, unsigned long index, void *entry, gfp_t);
352 : void *xa_erase(struct xarray *, unsigned long index);
353 : void *xa_store_range(struct xarray *, unsigned long first, unsigned long last,
354 : void *entry, gfp_t);
355 : bool xa_get_mark(struct xarray *, unsigned long index, xa_mark_t);
356 : void xa_set_mark(struct xarray *, unsigned long index, xa_mark_t);
357 : void xa_clear_mark(struct xarray *, unsigned long index, xa_mark_t);
358 : void *xa_find(struct xarray *xa, unsigned long *index,
359 : unsigned long max, xa_mark_t) __attribute__((nonnull(2)));
360 : void *xa_find_after(struct xarray *xa, unsigned long *index,
361 : unsigned long max, xa_mark_t) __attribute__((nonnull(2)));
362 : unsigned int xa_extract(struct xarray *, void **dst, unsigned long start,
363 : unsigned long max, unsigned int n, xa_mark_t);
364 : void xa_destroy(struct xarray *);
365 :
366 : /**
367 : * xa_init_flags() - Initialise an empty XArray with flags.
368 : * @xa: XArray.
369 : * @flags: XA_FLAG values.
370 : *
371 : * If you need to initialise an XArray with special flags (eg you need
372 : * to take the lock from interrupt context), use this function instead
373 : * of xa_init().
374 : *
375 : * Context: Any context.
376 : */
377 : static inline void xa_init_flags(struct xarray *xa, gfp_t flags)
378 : {
379 89 : spin_lock_init(&xa->xa_lock);
380 89 : xa->xa_flags = flags;
381 89 : xa->xa_head = NULL;
382 : }
383 :
384 : /**
385 : * xa_init() - Initialise an empty XArray.
386 : * @xa: XArray.
387 : *
388 : * An empty XArray is full of NULL entries.
389 : *
390 : * Context: Any context.
391 : */
392 : static inline void xa_init(struct xarray *xa)
393 : {
394 0 : xa_init_flags(xa, 0);
395 : }
396 :
397 : /**
398 : * xa_empty() - Determine if an array has any present entries.
399 : * @xa: XArray.
400 : *
401 : * Context: Any context.
402 : * Return: %true if the array contains only NULL pointers.
403 : */
404 : static inline bool xa_empty(const struct xarray *xa)
405 : {
406 : return xa->xa_head == NULL;
407 : }
408 :
409 : /**
410 : * xa_marked() - Inquire whether any entry in this array has a mark set
411 : * @xa: Array
412 : * @mark: Mark value
413 : *
414 : * Context: Any context.
415 : * Return: %true if any entry has this mark set.
416 : */
417 : static inline bool xa_marked(const struct xarray *xa, xa_mark_t mark)
418 : {
419 207 : return xa->xa_flags & XA_FLAGS_MARK(mark);
420 : }
421 :
422 : /**
423 : * xa_for_each_range() - Iterate over a portion of an XArray.
424 : * @xa: XArray.
425 : * @index: Index of @entry.
426 : * @entry: Entry retrieved from array.
427 : * @start: First index to retrieve from array.
428 : * @last: Last index to retrieve from array.
429 : *
430 : * During the iteration, @entry will have the value of the entry stored
431 : * in @xa at @index. You may modify @index during the iteration if you
432 : * want to skip or reprocess indices. It is safe to modify the array
433 : * during the iteration. At the end of the iteration, @entry will be set
434 : * to NULL and @index will have a value less than or equal to max.
435 : *
436 : * xa_for_each_range() is O(n.log(n)) while xas_for_each() is O(n). You have
437 : * to handle your own locking with xas_for_each(), and if you have to unlock
438 : * after each iteration, it will also end up being O(n.log(n)).
439 : * xa_for_each_range() will spin if it hits a retry entry; if you intend to
440 : * see retry entries, you should use the xas_for_each() iterator instead.
441 : * The xas_for_each() iterator will expand into more inline code than
442 : * xa_for_each_range().
443 : *
444 : * Context: Any context. Takes and releases the RCU lock.
445 : */
446 : #define xa_for_each_range(xa, index, entry, start, last) \
447 : for (index = start, \
448 : entry = xa_find(xa, &index, last, XA_PRESENT); \
449 : entry; \
450 : entry = xa_find_after(xa, &index, last, XA_PRESENT))
451 :
452 : /**
453 : * xa_for_each_start() - Iterate over a portion of an XArray.
454 : * @xa: XArray.
455 : * @index: Index of @entry.
456 : * @entry: Entry retrieved from array.
457 : * @start: First index to retrieve from array.
458 : *
459 : * During the iteration, @entry will have the value of the entry stored
460 : * in @xa at @index. You may modify @index during the iteration if you
461 : * want to skip or reprocess indices. It is safe to modify the array
462 : * during the iteration. At the end of the iteration, @entry will be set
463 : * to NULL and @index will have a value less than or equal to max.
464 : *
465 : * xa_for_each_start() is O(n.log(n)) while xas_for_each() is O(n). You have
466 : * to handle your own locking with xas_for_each(), and if you have to unlock
467 : * after each iteration, it will also end up being O(n.log(n)).
468 : * xa_for_each_start() will spin if it hits a retry entry; if you intend to
469 : * see retry entries, you should use the xas_for_each() iterator instead.
470 : * The xas_for_each() iterator will expand into more inline code than
471 : * xa_for_each_start().
472 : *
473 : * Context: Any context. Takes and releases the RCU lock.
474 : */
475 : #define xa_for_each_start(xa, index, entry, start) \
476 : xa_for_each_range(xa, index, entry, start, ULONG_MAX)
477 :
478 : /**
479 : * xa_for_each() - Iterate over present entries in an XArray.
480 : * @xa: XArray.
481 : * @index: Index of @entry.
482 : * @entry: Entry retrieved from array.
483 : *
484 : * During the iteration, @entry will have the value of the entry stored
485 : * in @xa at @index. You may modify @index during the iteration if you want
486 : * to skip or reprocess indices. It is safe to modify the array during the
487 : * iteration. At the end of the iteration, @entry will be set to NULL and
488 : * @index will have a value less than or equal to max.
489 : *
490 : * xa_for_each() is O(n.log(n)) while xas_for_each() is O(n). You have
491 : * to handle your own locking with xas_for_each(), and if you have to unlock
492 : * after each iteration, it will also end up being O(n.log(n)). xa_for_each()
493 : * will spin if it hits a retry entry; if you intend to see retry entries,
494 : * you should use the xas_for_each() iterator instead. The xas_for_each()
495 : * iterator will expand into more inline code than xa_for_each().
496 : *
497 : * Context: Any context. Takes and releases the RCU lock.
498 : */
499 : #define xa_for_each(xa, index, entry) \
500 : xa_for_each_start(xa, index, entry, 0)
501 :
502 : /**
503 : * xa_for_each_marked() - Iterate over marked entries in an XArray.
504 : * @xa: XArray.
505 : * @index: Index of @entry.
506 : * @entry: Entry retrieved from array.
507 : * @filter: Selection criterion.
508 : *
509 : * During the iteration, @entry will have the value of the entry stored
510 : * in @xa at @index. The iteration will skip all entries in the array
511 : * which do not match @filter. You may modify @index during the iteration
512 : * if you want to skip or reprocess indices. It is safe to modify the array
513 : * during the iteration. At the end of the iteration, @entry will be set to
514 : * NULL and @index will have a value less than or equal to max.
515 : *
516 : * xa_for_each_marked() is O(n.log(n)) while xas_for_each_marked() is O(n).
517 : * You have to handle your own locking with xas_for_each(), and if you have
518 : * to unlock after each iteration, it will also end up being O(n.log(n)).
519 : * xa_for_each_marked() will spin if it hits a retry entry; if you intend to
520 : * see retry entries, you should use the xas_for_each_marked() iterator
521 : * instead. The xas_for_each_marked() iterator will expand into more inline
522 : * code than xa_for_each_marked().
523 : *
524 : * Context: Any context. Takes and releases the RCU lock.
525 : */
526 : #define xa_for_each_marked(xa, index, entry, filter) \
527 : for (index = 0, entry = xa_find(xa, &index, ULONG_MAX, filter); \
528 : entry; entry = xa_find_after(xa, &index, ULONG_MAX, filter))
529 :
530 : #define xa_trylock(xa) spin_trylock(&(xa)->xa_lock)
531 : #define xa_lock(xa) spin_lock(&(xa)->xa_lock)
532 : #define xa_unlock(xa) spin_unlock(&(xa)->xa_lock)
533 : #define xa_lock_bh(xa) spin_lock_bh(&(xa)->xa_lock)
534 : #define xa_unlock_bh(xa) spin_unlock_bh(&(xa)->xa_lock)
535 : #define xa_lock_irq(xa) spin_lock_irq(&(xa)->xa_lock)
536 : #define xa_unlock_irq(xa) spin_unlock_irq(&(xa)->xa_lock)
537 : #define xa_lock_irqsave(xa, flags) \
538 : spin_lock_irqsave(&(xa)->xa_lock, flags)
539 : #define xa_unlock_irqrestore(xa, flags) \
540 : spin_unlock_irqrestore(&(xa)->xa_lock, flags)
541 : #define xa_lock_nested(xa, subclass) \
542 : spin_lock_nested(&(xa)->xa_lock, subclass)
543 : #define xa_lock_bh_nested(xa, subclass) \
544 : spin_lock_bh_nested(&(xa)->xa_lock, subclass)
545 : #define xa_lock_irq_nested(xa, subclass) \
546 : spin_lock_irq_nested(&(xa)->xa_lock, subclass)
547 : #define xa_lock_irqsave_nested(xa, flags, subclass) \
548 : spin_lock_irqsave_nested(&(xa)->xa_lock, flags, subclass)
549 :
550 : /*
551 : * Versions of the normal API which require the caller to hold the
552 : * xa_lock. If the GFP flags allow it, they will drop the lock to
553 : * allocate memory, then reacquire it afterwards. These functions
554 : * may also re-enable interrupts if the XArray flags indicate the
555 : * locking should be interrupt safe.
556 : */
557 : void *__xa_erase(struct xarray *, unsigned long index);
558 : void *__xa_store(struct xarray *, unsigned long index, void *entry, gfp_t);
559 : void *__xa_cmpxchg(struct xarray *, unsigned long index, void *old,
560 : void *entry, gfp_t);
561 : int __must_check __xa_insert(struct xarray *, unsigned long index,
562 : void *entry, gfp_t);
563 : int __must_check __xa_alloc(struct xarray *, u32 *id, void *entry,
564 : struct xa_limit, gfp_t);
565 : int __must_check __xa_alloc_cyclic(struct xarray *, u32 *id, void *entry,
566 : struct xa_limit, u32 *next, gfp_t);
567 : void __xa_set_mark(struct xarray *, unsigned long index, xa_mark_t);
568 : void __xa_clear_mark(struct xarray *, unsigned long index, xa_mark_t);
569 :
570 : /**
571 : * xa_store_bh() - Store this entry in the XArray.
572 : * @xa: XArray.
573 : * @index: Index into array.
574 : * @entry: New entry.
575 : * @gfp: Memory allocation flags.
576 : *
577 : * This function is like calling xa_store() except it disables softirqs
578 : * while holding the array lock.
579 : *
580 : * Context: Any context. Takes and releases the xa_lock while
581 : * disabling softirqs.
582 : * Return: The old entry at this index or xa_err() if an error happened.
583 : */
584 : static inline void *xa_store_bh(struct xarray *xa, unsigned long index,
585 : void *entry, gfp_t gfp)
586 : {
587 : void *curr;
588 :
589 : xa_lock_bh(xa);
590 : curr = __xa_store(xa, index, entry, gfp);
591 : xa_unlock_bh(xa);
592 :
593 : return curr;
594 : }
595 :
596 : /**
597 : * xa_store_irq() - Store this entry in the XArray.
598 : * @xa: XArray.
599 : * @index: Index into array.
600 : * @entry: New entry.
601 : * @gfp: Memory allocation flags.
602 : *
603 : * This function is like calling xa_store() except it disables interrupts
604 : * while holding the array lock.
605 : *
606 : * Context: Process context. Takes and releases the xa_lock while
607 : * disabling interrupts.
608 : * Return: The old entry at this index or xa_err() if an error happened.
609 : */
610 : static inline void *xa_store_irq(struct xarray *xa, unsigned long index,
611 : void *entry, gfp_t gfp)
612 : {
613 : void *curr;
614 :
615 0 : xa_lock_irq(xa);
616 0 : curr = __xa_store(xa, index, entry, gfp);
617 0 : xa_unlock_irq(xa);
618 :
619 : return curr;
620 : }
621 :
622 : /**
623 : * xa_erase_bh() - Erase this entry from the XArray.
624 : * @xa: XArray.
625 : * @index: Index of entry.
626 : *
627 : * After this function returns, loading from @index will return %NULL.
628 : * If the index is part of a multi-index entry, all indices will be erased
629 : * and none of the entries will be part of a multi-index entry.
630 : *
631 : * Context: Any context. Takes and releases the xa_lock while
632 : * disabling softirqs.
633 : * Return: The entry which used to be at this index.
634 : */
635 : static inline void *xa_erase_bh(struct xarray *xa, unsigned long index)
636 : {
637 : void *entry;
638 :
639 : xa_lock_bh(xa);
640 : entry = __xa_erase(xa, index);
641 : xa_unlock_bh(xa);
642 :
643 : return entry;
644 : }
645 :
646 : /**
647 : * xa_erase_irq() - Erase this entry from the XArray.
648 : * @xa: XArray.
649 : * @index: Index of entry.
650 : *
651 : * After this function returns, loading from @index will return %NULL.
652 : * If the index is part of a multi-index entry, all indices will be erased
653 : * and none of the entries will be part of a multi-index entry.
654 : *
655 : * Context: Process context. Takes and releases the xa_lock while
656 : * disabling interrupts.
657 : * Return: The entry which used to be at this index.
658 : */
659 : static inline void *xa_erase_irq(struct xarray *xa, unsigned long index)
660 : {
661 : void *entry;
662 :
663 0 : xa_lock_irq(xa);
664 0 : entry = __xa_erase(xa, index);
665 0 : xa_unlock_irq(xa);
666 :
667 : return entry;
668 : }
669 :
670 : /**
671 : * xa_cmpxchg() - Conditionally replace an entry in the XArray.
672 : * @xa: XArray.
673 : * @index: Index into array.
674 : * @old: Old value to test against.
675 : * @entry: New value to place in array.
676 : * @gfp: Memory allocation flags.
677 : *
678 : * If the entry at @index is the same as @old, replace it with @entry.
679 : * If the return value is equal to @old, then the exchange was successful.
680 : *
681 : * Context: Any context. Takes and releases the xa_lock. May sleep
682 : * if the @gfp flags permit.
683 : * Return: The old value at this index or xa_err() if an error happened.
684 : */
685 : static inline void *xa_cmpxchg(struct xarray *xa, unsigned long index,
686 : void *old, void *entry, gfp_t gfp)
687 : {
688 : void *curr;
689 :
690 : xa_lock(xa);
691 : curr = __xa_cmpxchg(xa, index, old, entry, gfp);
692 : xa_unlock(xa);
693 :
694 : return curr;
695 : }
696 :
697 : /**
698 : * xa_cmpxchg_bh() - Conditionally replace an entry in the XArray.
699 : * @xa: XArray.
700 : * @index: Index into array.
701 : * @old: Old value to test against.
702 : * @entry: New value to place in array.
703 : * @gfp: Memory allocation flags.
704 : *
705 : * This function is like calling xa_cmpxchg() except it disables softirqs
706 : * while holding the array lock.
707 : *
708 : * Context: Any context. Takes and releases the xa_lock while
709 : * disabling softirqs. May sleep if the @gfp flags permit.
710 : * Return: The old value at this index or xa_err() if an error happened.
711 : */
712 : static inline void *xa_cmpxchg_bh(struct xarray *xa, unsigned long index,
713 : void *old, void *entry, gfp_t gfp)
714 : {
715 : void *curr;
716 :
717 : xa_lock_bh(xa);
718 : curr = __xa_cmpxchg(xa, index, old, entry, gfp);
719 : xa_unlock_bh(xa);
720 :
721 : return curr;
722 : }
723 :
724 : /**
725 : * xa_cmpxchg_irq() - Conditionally replace an entry in the XArray.
726 : * @xa: XArray.
727 : * @index: Index into array.
728 : * @old: Old value to test against.
729 : * @entry: New value to place in array.
730 : * @gfp: Memory allocation flags.
731 : *
732 : * This function is like calling xa_cmpxchg() except it disables interrupts
733 : * while holding the array lock.
734 : *
735 : * Context: Process context. Takes and releases the xa_lock while
736 : * disabling interrupts. May sleep if the @gfp flags permit.
737 : * Return: The old value at this index or xa_err() if an error happened.
738 : */
739 : static inline void *xa_cmpxchg_irq(struct xarray *xa, unsigned long index,
740 : void *old, void *entry, gfp_t gfp)
741 : {
742 : void *curr;
743 :
744 0 : xa_lock_irq(xa);
745 0 : curr = __xa_cmpxchg(xa, index, old, entry, gfp);
746 0 : xa_unlock_irq(xa);
747 :
748 : return curr;
749 : }
750 :
751 : /**
752 : * xa_insert() - Store this entry in the XArray unless another entry is
753 : * already present.
754 : * @xa: XArray.
755 : * @index: Index into array.
756 : * @entry: New entry.
757 : * @gfp: Memory allocation flags.
758 : *
759 : * Inserting a NULL entry will store a reserved entry (like xa_reserve())
760 : * if no entry is present. Inserting will fail if a reserved entry is
761 : * present, even though loading from this index will return NULL.
762 : *
763 : * Context: Any context. Takes and releases the xa_lock. May sleep if
764 : * the @gfp flags permit.
765 : * Return: 0 if the store succeeded. -EBUSY if another entry was present.
766 : * -ENOMEM if memory could not be allocated.
767 : */
768 : static inline int __must_check xa_insert(struct xarray *xa,
769 : unsigned long index, void *entry, gfp_t gfp)
770 : {
771 : int err;
772 :
773 0 : xa_lock(xa);
774 0 : err = __xa_insert(xa, index, entry, gfp);
775 0 : xa_unlock(xa);
776 :
777 : return err;
778 : }
779 :
780 : /**
781 : * xa_insert_bh() - Store this entry in the XArray unless another entry is
782 : * already present.
783 : * @xa: XArray.
784 : * @index: Index into array.
785 : * @entry: New entry.
786 : * @gfp: Memory allocation flags.
787 : *
788 : * Inserting a NULL entry will store a reserved entry (like xa_reserve())
789 : * if no entry is present. Inserting will fail if a reserved entry is
790 : * present, even though loading from this index will return NULL.
791 : *
792 : * Context: Any context. Takes and releases the xa_lock while
793 : * disabling softirqs. May sleep if the @gfp flags permit.
794 : * Return: 0 if the store succeeded. -EBUSY if another entry was present.
795 : * -ENOMEM if memory could not be allocated.
796 : */
797 : static inline int __must_check xa_insert_bh(struct xarray *xa,
798 : unsigned long index, void *entry, gfp_t gfp)
799 : {
800 : int err;
801 :
802 : xa_lock_bh(xa);
803 : err = __xa_insert(xa, index, entry, gfp);
804 : xa_unlock_bh(xa);
805 :
806 : return err;
807 : }
808 :
809 : /**
810 : * xa_insert_irq() - Store this entry in the XArray unless another entry is
811 : * already present.
812 : * @xa: XArray.
813 : * @index: Index into array.
814 : * @entry: New entry.
815 : * @gfp: Memory allocation flags.
816 : *
817 : * Inserting a NULL entry will store a reserved entry (like xa_reserve())
818 : * if no entry is present. Inserting will fail if a reserved entry is
819 : * present, even though loading from this index will return NULL.
820 : *
821 : * Context: Process context. Takes and releases the xa_lock while
822 : * disabling interrupts. May sleep if the @gfp flags permit.
823 : * Return: 0 if the store succeeded. -EBUSY if another entry was present.
824 : * -ENOMEM if memory could not be allocated.
825 : */
826 : static inline int __must_check xa_insert_irq(struct xarray *xa,
827 : unsigned long index, void *entry, gfp_t gfp)
828 : {
829 : int err;
830 :
831 : xa_lock_irq(xa);
832 : err = __xa_insert(xa, index, entry, gfp);
833 : xa_unlock_irq(xa);
834 :
835 : return err;
836 : }
837 :
838 : /**
839 : * xa_alloc() - Find somewhere to store this entry in the XArray.
840 : * @xa: XArray.
841 : * @id: Pointer to ID.
842 : * @entry: New entry.
843 : * @limit: Range of ID to allocate.
844 : * @gfp: Memory allocation flags.
845 : *
846 : * Finds an empty entry in @xa between @limit.min and @limit.max,
847 : * stores the index into the @id pointer, then stores the entry at
848 : * that index. A concurrent lookup will not see an uninitialised @id.
849 : *
850 : * Context: Any context. Takes and releases the xa_lock. May sleep if
851 : * the @gfp flags permit.
852 : * Return: 0 on success, -ENOMEM if memory could not be allocated or
853 : * -EBUSY if there are no free entries in @limit.
854 : */
855 : static inline __must_check int xa_alloc(struct xarray *xa, u32 *id,
856 : void *entry, struct xa_limit limit, gfp_t gfp)
857 : {
858 : int err;
859 :
860 0 : xa_lock(xa);
861 0 : err = __xa_alloc(xa, id, entry, limit, gfp);
862 0 : xa_unlock(xa);
863 :
864 : return err;
865 : }
866 :
867 : /**
868 : * xa_alloc_bh() - Find somewhere to store this entry in the XArray.
869 : * @xa: XArray.
870 : * @id: Pointer to ID.
871 : * @entry: New entry.
872 : * @limit: Range of ID to allocate.
873 : * @gfp: Memory allocation flags.
874 : *
875 : * Finds an empty entry in @xa between @limit.min and @limit.max,
876 : * stores the index into the @id pointer, then stores the entry at
877 : * that index. A concurrent lookup will not see an uninitialised @id.
878 : *
879 : * Context: Any context. Takes and releases the xa_lock while
880 : * disabling softirqs. May sleep if the @gfp flags permit.
881 : * Return: 0 on success, -ENOMEM if memory could not be allocated or
882 : * -EBUSY if there are no free entries in @limit.
883 : */
884 : static inline int __must_check xa_alloc_bh(struct xarray *xa, u32 *id,
885 : void *entry, struct xa_limit limit, gfp_t gfp)
886 : {
887 : int err;
888 :
889 : xa_lock_bh(xa);
890 : err = __xa_alloc(xa, id, entry, limit, gfp);
891 : xa_unlock_bh(xa);
892 :
893 : return err;
894 : }
895 :
896 : /**
897 : * xa_alloc_irq() - Find somewhere to store this entry in the XArray.
898 : * @xa: XArray.
899 : * @id: Pointer to ID.
900 : * @entry: New entry.
901 : * @limit: Range of ID to allocate.
902 : * @gfp: Memory allocation flags.
903 : *
904 : * Finds an empty entry in @xa between @limit.min and @limit.max,
905 : * stores the index into the @id pointer, then stores the entry at
906 : * that index. A concurrent lookup will not see an uninitialised @id.
907 : *
908 : * Context: Process context. Takes and releases the xa_lock while
909 : * disabling interrupts. May sleep if the @gfp flags permit.
910 : * Return: 0 on success, -ENOMEM if memory could not be allocated or
911 : * -EBUSY if there are no free entries in @limit.
912 : */
913 : static inline int __must_check xa_alloc_irq(struct xarray *xa, u32 *id,
914 : void *entry, struct xa_limit limit, gfp_t gfp)
915 : {
916 : int err;
917 :
918 : xa_lock_irq(xa);
919 : err = __xa_alloc(xa, id, entry, limit, gfp);
920 : xa_unlock_irq(xa);
921 :
922 : return err;
923 : }
924 :
925 : /**
926 : * xa_alloc_cyclic() - Find somewhere to store this entry in the XArray.
927 : * @xa: XArray.
928 : * @id: Pointer to ID.
929 : * @entry: New entry.
930 : * @limit: Range of allocated ID.
931 : * @next: Pointer to next ID to allocate.
932 : * @gfp: Memory allocation flags.
933 : *
934 : * Finds an empty entry in @xa between @limit.min and @limit.max,
935 : * stores the index into the @id pointer, then stores the entry at
936 : * that index. A concurrent lookup will not see an uninitialised @id.
937 : * The search for an empty entry will start at @next and will wrap
938 : * around if necessary.
939 : *
940 : * Context: Any context. Takes and releases the xa_lock. May sleep if
941 : * the @gfp flags permit.
942 : * Return: 0 if the allocation succeeded without wrapping. 1 if the
943 : * allocation succeeded after wrapping, -ENOMEM if memory could not be
944 : * allocated or -EBUSY if there are no free entries in @limit.
945 : */
946 : static inline int xa_alloc_cyclic(struct xarray *xa, u32 *id, void *entry,
947 : struct xa_limit limit, u32 *next, gfp_t gfp)
948 : {
949 : int err;
950 :
951 0 : xa_lock(xa);
952 0 : err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
953 0 : xa_unlock(xa);
954 :
955 : return err;
956 : }
957 :
958 : /**
959 : * xa_alloc_cyclic_bh() - Find somewhere to store this entry in the XArray.
960 : * @xa: XArray.
961 : * @id: Pointer to ID.
962 : * @entry: New entry.
963 : * @limit: Range of allocated ID.
964 : * @next: Pointer to next ID to allocate.
965 : * @gfp: Memory allocation flags.
966 : *
967 : * Finds an empty entry in @xa between @limit.min and @limit.max,
968 : * stores the index into the @id pointer, then stores the entry at
969 : * that index. A concurrent lookup will not see an uninitialised @id.
970 : * The search for an empty entry will start at @next and will wrap
971 : * around if necessary.
972 : *
973 : * Context: Any context. Takes and releases the xa_lock while
974 : * disabling softirqs. May sleep if the @gfp flags permit.
975 : * Return: 0 if the allocation succeeded without wrapping. 1 if the
976 : * allocation succeeded after wrapping, -ENOMEM if memory could not be
977 : * allocated or -EBUSY if there are no free entries in @limit.
978 : */
979 : static inline int xa_alloc_cyclic_bh(struct xarray *xa, u32 *id, void *entry,
980 : struct xa_limit limit, u32 *next, gfp_t gfp)
981 : {
982 : int err;
983 :
984 : xa_lock_bh(xa);
985 : err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
986 : xa_unlock_bh(xa);
987 :
988 : return err;
989 : }
990 :
991 : /**
992 : * xa_alloc_cyclic_irq() - Find somewhere to store this entry in the XArray.
993 : * @xa: XArray.
994 : * @id: Pointer to ID.
995 : * @entry: New entry.
996 : * @limit: Range of allocated ID.
997 : * @next: Pointer to next ID to allocate.
998 : * @gfp: Memory allocation flags.
999 : *
1000 : * Finds an empty entry in @xa between @limit.min and @limit.max,
1001 : * stores the index into the @id pointer, then stores the entry at
1002 : * that index. A concurrent lookup will not see an uninitialised @id.
1003 : * The search for an empty entry will start at @next and will wrap
1004 : * around if necessary.
1005 : *
1006 : * Context: Process context. Takes and releases the xa_lock while
1007 : * disabling interrupts. May sleep if the @gfp flags permit.
1008 : * Return: 0 if the allocation succeeded without wrapping. 1 if the
1009 : * allocation succeeded after wrapping, -ENOMEM if memory could not be
1010 : * allocated or -EBUSY if there are no free entries in @limit.
1011 : */
1012 : static inline int xa_alloc_cyclic_irq(struct xarray *xa, u32 *id, void *entry,
1013 : struct xa_limit limit, u32 *next, gfp_t gfp)
1014 : {
1015 : int err;
1016 :
1017 : xa_lock_irq(xa);
1018 : err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
1019 : xa_unlock_irq(xa);
1020 :
1021 : return err;
1022 : }
1023 :
1024 : /**
1025 : * xa_reserve() - Reserve this index in the XArray.
1026 : * @xa: XArray.
1027 : * @index: Index into array.
1028 : * @gfp: Memory allocation flags.
1029 : *
1030 : * Ensures there is somewhere to store an entry at @index in the array.
1031 : * If there is already something stored at @index, this function does
1032 : * nothing. If there was nothing there, the entry is marked as reserved.
1033 : * Loading from a reserved entry returns a %NULL pointer.
1034 : *
1035 : * If you do not use the entry that you have reserved, call xa_release()
1036 : * or xa_erase() to free any unnecessary memory.
1037 : *
1038 : * Context: Any context. Takes and releases the xa_lock.
1039 : * May sleep if the @gfp flags permit.
1040 : * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
1041 : */
1042 : static inline __must_check
1043 : int xa_reserve(struct xarray *xa, unsigned long index, gfp_t gfp)
1044 : {
1045 : return xa_err(xa_cmpxchg(xa, index, NULL, XA_ZERO_ENTRY, gfp));
1046 : }
1047 :
1048 : /**
1049 : * xa_reserve_bh() - Reserve this index in the XArray.
1050 : * @xa: XArray.
1051 : * @index: Index into array.
1052 : * @gfp: Memory allocation flags.
1053 : *
1054 : * A softirq-disabling version of xa_reserve().
1055 : *
1056 : * Context: Any context. Takes and releases the xa_lock while
1057 : * disabling softirqs.
1058 : * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
1059 : */
1060 : static inline __must_check
1061 : int xa_reserve_bh(struct xarray *xa, unsigned long index, gfp_t gfp)
1062 : {
1063 : return xa_err(xa_cmpxchg_bh(xa, index, NULL, XA_ZERO_ENTRY, gfp));
1064 : }
1065 :
1066 : /**
1067 : * xa_reserve_irq() - Reserve this index in the XArray.
1068 : * @xa: XArray.
1069 : * @index: Index into array.
1070 : * @gfp: Memory allocation flags.
1071 : *
1072 : * An interrupt-disabling version of xa_reserve().
1073 : *
1074 : * Context: Process context. Takes and releases the xa_lock while
1075 : * disabling interrupts.
1076 : * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
1077 : */
1078 : static inline __must_check
1079 : int xa_reserve_irq(struct xarray *xa, unsigned long index, gfp_t gfp)
1080 : {
1081 : return xa_err(xa_cmpxchg_irq(xa, index, NULL, XA_ZERO_ENTRY, gfp));
1082 : }
1083 :
1084 : /**
1085 : * xa_release() - Release a reserved entry.
1086 : * @xa: XArray.
1087 : * @index: Index of entry.
1088 : *
1089 : * After calling xa_reserve(), you can call this function to release the
1090 : * reservation. If the entry at @index has been stored to, this function
1091 : * will do nothing.
1092 : */
1093 : static inline void xa_release(struct xarray *xa, unsigned long index)
1094 : {
1095 : xa_cmpxchg(xa, index, XA_ZERO_ENTRY, NULL, 0);
1096 : }
1097 :
1098 : /* Everything below here is the Advanced API. Proceed with caution. */
1099 :
1100 : /*
1101 : * The xarray is constructed out of a set of 'chunks' of pointers. Choosing
1102 : * the best chunk size requires some tradeoffs. A power of two recommends
1103 : * itself so that we can walk the tree based purely on shifts and masks.
1104 : * Generally, the larger the better; as the number of slots per level of the
1105 : * tree increases, the less tall the tree needs to be. But that needs to be
1106 : * balanced against the memory consumption of each node. On a 64-bit system,
1107 : * xa_node is currently 576 bytes, and we get 7 of them per 4kB page. If we
1108 : * doubled the number of slots per node, we'd get only 3 nodes per 4kB page.
1109 : */
1110 : #ifndef XA_CHUNK_SHIFT
1111 : #define XA_CHUNK_SHIFT (CONFIG_BASE_SMALL ? 4 : 6)
1112 : #endif
1113 : #define XA_CHUNK_SIZE (1UL << XA_CHUNK_SHIFT)
1114 : #define XA_CHUNK_MASK (XA_CHUNK_SIZE - 1)
1115 : #define XA_MAX_MARKS 3
1116 : #define XA_MARK_LONGS DIV_ROUND_UP(XA_CHUNK_SIZE, BITS_PER_LONG)
1117 :
1118 : /*
1119 : * @count is the count of every non-NULL element in the ->slots array
1120 : * whether that is a value entry, a retry entry, a user pointer,
1121 : * a sibling entry or a pointer to the next level of the tree.
1122 : * @nr_values is the count of every element in ->slots which is
1123 : * either a value entry or a sibling of a value entry.
1124 : */
1125 : struct xa_node {
1126 : unsigned char shift; /* Bits remaining in each slot */
1127 : unsigned char offset; /* Slot offset in parent */
1128 : unsigned char count; /* Total entry count */
1129 : unsigned char nr_values; /* Value entry count */
1130 : struct xa_node __rcu *parent; /* NULL at top of tree */
1131 : struct xarray *array; /* The array we belong to */
1132 : union {
1133 : struct list_head private_list; /* For tree user */
1134 : struct rcu_head rcu_head; /* Used when freeing node */
1135 : };
1136 : void __rcu *slots[XA_CHUNK_SIZE];
1137 : union {
1138 : unsigned long tags[XA_MAX_MARKS][XA_MARK_LONGS];
1139 : unsigned long marks[XA_MAX_MARKS][XA_MARK_LONGS];
1140 : };
1141 : };
1142 :
1143 : void xa_dump(const struct xarray *);
1144 : void xa_dump_node(const struct xa_node *);
1145 :
1146 : #ifdef XA_DEBUG
1147 : #define XA_BUG_ON(xa, x) do { \
1148 : if (x) { \
1149 : xa_dump(xa); \
1150 : BUG(); \
1151 : } \
1152 : } while (0)
1153 : #define XA_NODE_BUG_ON(node, x) do { \
1154 : if (x) { \
1155 : if (node) xa_dump_node(node); \
1156 : BUG(); \
1157 : } \
1158 : } while (0)
1159 : #else
1160 : #define XA_BUG_ON(xa, x) do { } while (0)
1161 : #define XA_NODE_BUG_ON(node, x) do { } while (0)
1162 : #endif
1163 :
1164 : /* Private */
1165 : static inline void *xa_head(const struct xarray *xa)
1166 : {
1167 209 : return rcu_dereference_check(xa->xa_head,
1168 : lockdep_is_held(&xa->xa_lock));
1169 : }
1170 :
1171 : /* Private */
1172 : static inline void *xa_head_locked(const struct xarray *xa)
1173 : {
1174 : return rcu_dereference_protected(xa->xa_head,
1175 : lockdep_is_held(&xa->xa_lock));
1176 : }
1177 :
1178 : /* Private */
1179 : static inline void *xa_entry(const struct xarray *xa,
1180 : const struct xa_node *node, unsigned int offset)
1181 : {
1182 : XA_NODE_BUG_ON(node, offset >= XA_CHUNK_SIZE);
1183 6 : return rcu_dereference_check(node->slots[offset],
1184 : lockdep_is_held(&xa->xa_lock));
1185 : }
1186 :
1187 : /* Private */
1188 : static inline void *xa_entry_locked(const struct xarray *xa,
1189 : const struct xa_node *node, unsigned int offset)
1190 : {
1191 : XA_NODE_BUG_ON(node, offset >= XA_CHUNK_SIZE);
1192 0 : return rcu_dereference_protected(node->slots[offset],
1193 : lockdep_is_held(&xa->xa_lock));
1194 : }
1195 :
1196 : /* Private */
1197 : static inline struct xa_node *xa_parent(const struct xarray *xa,
1198 : const struct xa_node *node)
1199 : {
1200 0 : return rcu_dereference_check(node->parent,
1201 : lockdep_is_held(&xa->xa_lock));
1202 : }
1203 :
1204 : /* Private */
1205 : static inline struct xa_node *xa_parent_locked(const struct xarray *xa,
1206 : const struct xa_node *node)
1207 : {
1208 : return rcu_dereference_protected(node->parent,
1209 : lockdep_is_held(&xa->xa_lock));
1210 : }
1211 :
1212 : /* Private */
1213 : static inline void *xa_mk_node(const struct xa_node *node)
1214 : {
1215 2 : return (void *)((unsigned long)node | 2);
1216 : }
1217 :
1218 : /* Private */
1219 : static inline struct xa_node *xa_to_node(const void *entry)
1220 : {
1221 7 : return (struct xa_node *)((unsigned long)entry - 2);
1222 : }
1223 :
1224 : /* Private */
1225 : static inline bool xa_is_node(const void *entry)
1226 : {
1227 771 : return xa_is_internal(entry) && (unsigned long)entry > 4096;
1228 : }
1229 :
1230 : /* Private */
1231 : static inline void *xa_mk_sibling(unsigned int offset)
1232 : {
1233 0 : return xa_mk_internal(offset);
1234 : }
1235 :
1236 : /* Private */
1237 : static inline unsigned long xa_to_sibling(const void *entry)
1238 : {
1239 : return xa_to_internal(entry);
1240 : }
1241 :
1242 : /**
1243 : * xa_is_sibling() - Is the entry a sibling entry?
1244 : * @entry: Entry retrieved from the XArray
1245 : *
1246 : * Return: %true if the entry is a sibling entry.
1247 : */
1248 : static inline bool xa_is_sibling(const void *entry)
1249 : {
1250 : return IS_ENABLED(CONFIG_XARRAY_MULTI) && xa_is_internal(entry) &&
1251 : (entry < xa_mk_sibling(XA_CHUNK_SIZE - 1));
1252 : }
1253 :
1254 : #define XA_RETRY_ENTRY xa_mk_internal(256)
1255 :
1256 : /**
1257 : * xa_is_retry() - Is the entry a retry entry?
1258 : * @entry: Entry retrieved from the XArray
1259 : *
1260 : * Return: %true if the entry is a retry entry.
1261 : */
1262 : static inline bool xa_is_retry(const void *entry)
1263 : {
1264 2 : return unlikely(entry == XA_RETRY_ENTRY);
1265 : }
1266 :
1267 : /**
1268 : * xa_is_advanced() - Is the entry only permitted for the advanced API?
1269 : * @entry: Entry to be stored in the XArray.
1270 : *
1271 : * Return: %true if the entry cannot be stored by the normal API.
1272 : */
1273 : static inline bool xa_is_advanced(const void *entry)
1274 : {
1275 2 : return xa_is_internal(entry) && (entry <= XA_RETRY_ENTRY);
1276 : }
1277 :
1278 : /**
1279 : * typedef xa_update_node_t - A callback function from the XArray.
1280 : * @node: The node which is being processed
1281 : *
1282 : * This function is called every time the XArray updates the count of
1283 : * present and value entries in a node. It allows advanced users to
1284 : * maintain the private_list in the node.
1285 : *
1286 : * Context: The xa_lock is held and interrupts may be disabled.
1287 : * Implementations should not drop the xa_lock, nor re-enable
1288 : * interrupts.
1289 : */
1290 : typedef void (*xa_update_node_t)(struct xa_node *node);
1291 :
1292 : void xa_delete_node(struct xa_node *, xa_update_node_t);
1293 :
1294 : /*
1295 : * The xa_state is opaque to its users. It contains various different pieces
1296 : * of state involved in the current operation on the XArray. It should be
1297 : * declared on the stack and passed between the various internal routines.
1298 : * The various elements in it should not be accessed directly, but only
1299 : * through the provided accessor functions. The below documentation is for
1300 : * the benefit of those working on the code, not for users of the XArray.
1301 : *
1302 : * @xa_node usually points to the xa_node containing the slot we're operating
1303 : * on (and @xa_offset is the offset in the slots array). If there is a
1304 : * single entry in the array at index 0, there are no allocated xa_nodes to
1305 : * point to, and so we store %NULL in @xa_node. @xa_node is set to
1306 : * the value %XAS_RESTART if the xa_state is not walked to the correct
1307 : * position in the tree of nodes for this operation. If an error occurs
1308 : * during an operation, it is set to an %XAS_ERROR value. If we run off the
1309 : * end of the allocated nodes, it is set to %XAS_BOUNDS.
1310 : */
1311 : struct xa_state {
1312 : struct xarray *xa;
1313 : unsigned long xa_index;
1314 : unsigned char xa_shift;
1315 : unsigned char xa_sibs;
1316 : unsigned char xa_offset;
1317 : unsigned char xa_pad; /* Helps gcc generate better code */
1318 : struct xa_node *xa_node;
1319 : struct xa_node *xa_alloc;
1320 : xa_update_node_t xa_update;
1321 : struct list_lru *xa_lru;
1322 : };
1323 :
1324 : /*
1325 : * We encode errnos in the xas->xa_node. If an error has happened, we need to
1326 : * drop the lock to fix it, and once we've done so the xa_state is invalid.
1327 : */
1328 : #define XA_ERROR(errno) ((struct xa_node *)(((unsigned long)errno << 2) | 2UL))
1329 : #define XAS_BOUNDS ((struct xa_node *)1UL)
1330 : #define XAS_RESTART ((struct xa_node *)3UL)
1331 :
1332 : #define __XA_STATE(array, index, shift, sibs) { \
1333 : .xa = array, \
1334 : .xa_index = index, \
1335 : .xa_shift = shift, \
1336 : .xa_sibs = sibs, \
1337 : .xa_offset = 0, \
1338 : .xa_pad = 0, \
1339 : .xa_node = XAS_RESTART, \
1340 : .xa_alloc = NULL, \
1341 : .xa_update = NULL, \
1342 : .xa_lru = NULL, \
1343 : }
1344 :
1345 : /**
1346 : * XA_STATE() - Declare an XArray operation state.
1347 : * @name: Name of this operation state (usually xas).
1348 : * @array: Array to operate on.
1349 : * @index: Initial index of interest.
1350 : *
1351 : * Declare and initialise an xa_state on the stack.
1352 : */
1353 : #define XA_STATE(name, array, index) \
1354 : struct xa_state name = __XA_STATE(array, index, 0, 0)
1355 :
1356 : /**
1357 : * XA_STATE_ORDER() - Declare an XArray operation state.
1358 : * @name: Name of this operation state (usually xas).
1359 : * @array: Array to operate on.
1360 : * @index: Initial index of interest.
1361 : * @order: Order of entry.
1362 : *
1363 : * Declare and initialise an xa_state on the stack. This variant of
1364 : * XA_STATE() allows you to specify the 'order' of the element you
1365 : * want to operate on.`
1366 : */
1367 : #define XA_STATE_ORDER(name, array, index, order) \
1368 : struct xa_state name = __XA_STATE(array, \
1369 : (index >> order) << order, \
1370 : order - (order % XA_CHUNK_SHIFT), \
1371 : (1U << (order % XA_CHUNK_SHIFT)) - 1)
1372 :
1373 : #define xas_marked(xas, mark) xa_marked((xas)->xa, (mark))
1374 : #define xas_trylock(xas) xa_trylock((xas)->xa)
1375 : #define xas_lock(xas) xa_lock((xas)->xa)
1376 : #define xas_unlock(xas) xa_unlock((xas)->xa)
1377 : #define xas_lock_bh(xas) xa_lock_bh((xas)->xa)
1378 : #define xas_unlock_bh(xas) xa_unlock_bh((xas)->xa)
1379 : #define xas_lock_irq(xas) xa_lock_irq((xas)->xa)
1380 : #define xas_unlock_irq(xas) xa_unlock_irq((xas)->xa)
1381 : #define xas_lock_irqsave(xas, flags) \
1382 : xa_lock_irqsave((xas)->xa, flags)
1383 : #define xas_unlock_irqrestore(xas, flags) \
1384 : xa_unlock_irqrestore((xas)->xa, flags)
1385 :
1386 : /**
1387 : * xas_error() - Return an errno stored in the xa_state.
1388 : * @xas: XArray operation state.
1389 : *
1390 : * Return: 0 if no error has been noted. A negative errno if one has.
1391 : */
1392 : static inline int xas_error(const struct xa_state *xas)
1393 : {
1394 838 : return xa_err(xas->xa_node);
1395 : }
1396 :
1397 : /**
1398 : * xas_set_err() - Note an error in the xa_state.
1399 : * @xas: XArray operation state.
1400 : * @err: Negative error number.
1401 : *
1402 : * Only call this function with a negative @err; zero or positive errors
1403 : * will probably not behave the way you think they should. If you want
1404 : * to clear the error from an xa_state, use xas_reset().
1405 : */
1406 : static inline void xas_set_err(struct xa_state *xas, long err)
1407 : {
1408 0 : xas->xa_node = XA_ERROR(err);
1409 : }
1410 :
1411 : /**
1412 : * xas_invalid() - Is the xas in a retry or error state?
1413 : * @xas: XArray operation state.
1414 : *
1415 : * Return: %true if the xas cannot be used for operations.
1416 : */
1417 : static inline bool xas_invalid(const struct xa_state *xas)
1418 : {
1419 95 : return (unsigned long)xas->xa_node & 3;
1420 : }
1421 :
1422 : /**
1423 : * xas_valid() - Is the xas a valid cursor into the array?
1424 : * @xas: XArray operation state.
1425 : *
1426 : * Return: %true if the xas can be used for operations.
1427 : */
1428 : static inline bool xas_valid(const struct xa_state *xas)
1429 : {
1430 2 : return !xas_invalid(xas);
1431 : }
1432 :
1433 : /**
1434 : * xas_is_node() - Does the xas point to a node?
1435 : * @xas: XArray operation state.
1436 : *
1437 : * Return: %true if the xas currently references a node.
1438 : */
1439 : static inline bool xas_is_node(const struct xa_state *xas)
1440 : {
1441 0 : return xas_valid(xas) && xas->xa_node;
1442 : }
1443 :
1444 : /* True if the pointer is something other than a node */
1445 : static inline bool xas_not_node(struct xa_node *node)
1446 : {
1447 0 : return ((unsigned long)node & 3) || !node;
1448 : }
1449 :
1450 : /* True if the node represents RESTART or an error */
1451 : static inline bool xas_frozen(struct xa_node *node)
1452 : {
1453 0 : return (unsigned long)node & 2;
1454 : }
1455 :
1456 : /* True if the node represents head-of-tree, RESTART or BOUNDS */
1457 : static inline bool xas_top(struct xa_node *node)
1458 : {
1459 : return node <= XAS_RESTART;
1460 : }
1461 :
1462 : /**
1463 : * xas_reset() - Reset an XArray operation state.
1464 : * @xas: XArray operation state.
1465 : *
1466 : * Resets the error or walk state of the @xas so future walks of the
1467 : * array will start from the root. Use this if you have dropped the
1468 : * xarray lock and want to reuse the xa_state.
1469 : *
1470 : * Context: Any context.
1471 : */
1472 : static inline void xas_reset(struct xa_state *xas)
1473 : {
1474 0 : xas->xa_node = XAS_RESTART;
1475 : }
1476 :
1477 : /**
1478 : * xas_retry() - Retry the operation if appropriate.
1479 : * @xas: XArray operation state.
1480 : * @entry: Entry from xarray.
1481 : *
1482 : * The advanced functions may sometimes return an internal entry, such as
1483 : * a retry entry or a zero entry. This function sets up the @xas to restart
1484 : * the walk from the head of the array if needed.
1485 : *
1486 : * Context: Any context.
1487 : * Return: true if the operation needs to be retried.
1488 : */
1489 : static inline bool xas_retry(struct xa_state *xas, const void *entry)
1490 : {
1491 2 : if (xa_is_zero(entry))
1492 : return true;
1493 2 : if (!xa_is_retry(entry))
1494 : return false;
1495 0 : xas_reset(xas);
1496 : return true;
1497 : }
1498 :
1499 : void *xas_load(struct xa_state *);
1500 : void *xas_store(struct xa_state *, void *entry);
1501 : void *xas_find(struct xa_state *, unsigned long max);
1502 : void *xas_find_conflict(struct xa_state *);
1503 :
1504 : bool xas_get_mark(const struct xa_state *, xa_mark_t);
1505 : void xas_set_mark(const struct xa_state *, xa_mark_t);
1506 : void xas_clear_mark(const struct xa_state *, xa_mark_t);
1507 : void *xas_find_marked(struct xa_state *, unsigned long max, xa_mark_t);
1508 : void xas_init_marks(const struct xa_state *);
1509 :
1510 : bool xas_nomem(struct xa_state *, gfp_t);
1511 : void xas_pause(struct xa_state *);
1512 :
1513 : void xas_create_range(struct xa_state *);
1514 :
1515 : #ifdef CONFIG_XARRAY_MULTI
1516 : int xa_get_order(struct xarray *, unsigned long index);
1517 : void xas_split(struct xa_state *, void *entry, unsigned int order);
1518 : void xas_split_alloc(struct xa_state *, void *entry, unsigned int order, gfp_t);
1519 : #else
1520 : static inline int xa_get_order(struct xarray *xa, unsigned long index)
1521 : {
1522 : return 0;
1523 : }
1524 :
1525 : static inline void xas_split(struct xa_state *xas, void *entry,
1526 : unsigned int order)
1527 : {
1528 : xas_store(xas, entry);
1529 : }
1530 :
1531 : static inline void xas_split_alloc(struct xa_state *xas, void *entry,
1532 : unsigned int order, gfp_t gfp)
1533 : {
1534 : }
1535 : #endif
1536 :
1537 : /**
1538 : * xas_reload() - Refetch an entry from the xarray.
1539 : * @xas: XArray operation state.
1540 : *
1541 : * Use this function to check that a previously loaded entry still has
1542 : * the same value. This is useful for the lockless pagecache lookup where
1543 : * we walk the array with only the RCU lock to protect us, lock the page,
1544 : * then check that the page hasn't moved since we looked it up.
1545 : *
1546 : * The caller guarantees that @xas is still valid. If it may be in an
1547 : * error or restart state, call xas_load() instead.
1548 : *
1549 : * Return: The entry at this location in the xarray.
1550 : */
1551 : static inline void *xas_reload(struct xa_state *xas)
1552 : {
1553 0 : struct xa_node *node = xas->xa_node;
1554 : void *entry;
1555 : char offset;
1556 :
1557 0 : if (!node)
1558 0 : return xa_head(xas->xa);
1559 : if (IS_ENABLED(CONFIG_XARRAY_MULTI)) {
1560 : offset = (xas->xa_index >> node->shift) & XA_CHUNK_MASK;
1561 : entry = xa_entry(xas->xa, node, offset);
1562 : if (!xa_is_sibling(entry))
1563 : return entry;
1564 : offset = xa_to_sibling(entry);
1565 : } else {
1566 0 : offset = xas->xa_offset;
1567 : }
1568 0 : return xa_entry(xas->xa, node, offset);
1569 : }
1570 :
1571 : /**
1572 : * xas_set() - Set up XArray operation state for a different index.
1573 : * @xas: XArray operation state.
1574 : * @index: New index into the XArray.
1575 : *
1576 : * Move the operation state to refer to a different index. This will
1577 : * have the effect of starting a walk from the top; see xas_next()
1578 : * to move to an adjacent index.
1579 : */
1580 : static inline void xas_set(struct xa_state *xas, unsigned long index)
1581 : {
1582 0 : xas->xa_index = index;
1583 0 : xas->xa_node = XAS_RESTART;
1584 : }
1585 :
1586 : /**
1587 : * xas_advance() - Skip over sibling entries.
1588 : * @xas: XArray operation state.
1589 : * @index: Index of last sibling entry.
1590 : *
1591 : * Move the operation state to refer to the last sibling entry.
1592 : * This is useful for loops that normally want to see sibling
1593 : * entries but sometimes want to skip them. Use xas_set() if you
1594 : * want to move to an index which is not part of this entry.
1595 : */
1596 : static inline void xas_advance(struct xa_state *xas, unsigned long index)
1597 : {
1598 0 : unsigned char shift = xas_is_node(xas) ? xas->xa_node->shift : 0;
1599 :
1600 0 : xas->xa_index = index;
1601 0 : xas->xa_offset = (index >> shift) & XA_CHUNK_MASK;
1602 : }
1603 :
1604 : /**
1605 : * xas_set_order() - Set up XArray operation state for a multislot entry.
1606 : * @xas: XArray operation state.
1607 : * @index: Target of the operation.
1608 : * @order: Entry occupies 2^@order indices.
1609 : */
1610 0 : static inline void xas_set_order(struct xa_state *xas, unsigned long index,
1611 : unsigned int order)
1612 : {
1613 : #ifdef CONFIG_XARRAY_MULTI
1614 : xas->xa_index = order < BITS_PER_LONG ? (index >> order) << order : 0;
1615 : xas->xa_shift = order - (order % XA_CHUNK_SHIFT);
1616 : xas->xa_sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1;
1617 : xas->xa_node = XAS_RESTART;
1618 : #else
1619 0 : BUG_ON(order > 0);
1620 0 : xas_set(xas, index);
1621 : #endif
1622 0 : }
1623 :
1624 : /**
1625 : * xas_set_update() - Set up XArray operation state for a callback.
1626 : * @xas: XArray operation state.
1627 : * @update: Function to call when updating a node.
1628 : *
1629 : * The XArray can notify a caller after it has updated an xa_node.
1630 : * This is advanced functionality and is only needed by the page cache.
1631 : */
1632 : static inline void xas_set_update(struct xa_state *xas, xa_update_node_t update)
1633 : {
1634 0 : xas->xa_update = update;
1635 : }
1636 :
1637 : static inline void xas_set_lru(struct xa_state *xas, struct list_lru *lru)
1638 : {
1639 0 : xas->xa_lru = lru;
1640 : }
1641 :
1642 : /**
1643 : * xas_next_entry() - Advance iterator to next present entry.
1644 : * @xas: XArray operation state.
1645 : * @max: Highest index to return.
1646 : *
1647 : * xas_next_entry() is an inline function to optimise xarray traversal for
1648 : * speed. It is equivalent to calling xas_find(), and will call xas_find()
1649 : * for all the hard cases.
1650 : *
1651 : * Return: The next present entry after the one currently referred to by @xas.
1652 : */
1653 0 : static inline void *xas_next_entry(struct xa_state *xas, unsigned long max)
1654 : {
1655 0 : struct xa_node *node = xas->xa_node;
1656 : void *entry;
1657 :
1658 0 : if (unlikely(xas_not_node(node) || node->shift ||
1659 : xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)))
1660 0 : return xas_find(xas, max);
1661 :
1662 : do {
1663 0 : if (unlikely(xas->xa_index >= max))
1664 0 : return xas_find(xas, max);
1665 0 : if (unlikely(xas->xa_offset == XA_CHUNK_MASK))
1666 0 : return xas_find(xas, max);
1667 0 : entry = xa_entry(xas->xa, node, xas->xa_offset + 1);
1668 0 : if (unlikely(xa_is_internal(entry)))
1669 0 : return xas_find(xas, max);
1670 0 : xas->xa_offset++;
1671 0 : xas->xa_index++;
1672 0 : } while (!entry);
1673 :
1674 : return entry;
1675 : }
1676 :
1677 : /* Private */
1678 : static inline unsigned int xas_find_chunk(struct xa_state *xas, bool advance,
1679 : xa_mark_t mark)
1680 : {
1681 0 : unsigned long *addr = xas->xa_node->marks[(__force unsigned)mark];
1682 0 : unsigned int offset = xas->xa_offset;
1683 :
1684 0 : if (advance)
1685 0 : offset++;
1686 : if (XA_CHUNK_SIZE == BITS_PER_LONG) {
1687 0 : if (offset < XA_CHUNK_SIZE) {
1688 0 : unsigned long data = *addr & (~0UL << offset);
1689 0 : if (data)
1690 0 : return __ffs(data);
1691 : }
1692 : return XA_CHUNK_SIZE;
1693 : }
1694 :
1695 : return find_next_bit(addr, XA_CHUNK_SIZE, offset);
1696 : }
1697 :
1698 : /**
1699 : * xas_next_marked() - Advance iterator to next marked entry.
1700 : * @xas: XArray operation state.
1701 : * @max: Highest index to return.
1702 : * @mark: Mark to search for.
1703 : *
1704 : * xas_next_marked() is an inline function to optimise xarray traversal for
1705 : * speed. It is equivalent to calling xas_find_marked(), and will call
1706 : * xas_find_marked() for all the hard cases.
1707 : *
1708 : * Return: The next marked entry after the one currently referred to by @xas.
1709 : */
1710 0 : static inline void *xas_next_marked(struct xa_state *xas, unsigned long max,
1711 : xa_mark_t mark)
1712 : {
1713 0 : struct xa_node *node = xas->xa_node;
1714 : void *entry;
1715 : unsigned int offset;
1716 :
1717 0 : if (unlikely(xas_not_node(node) || node->shift))
1718 0 : return xas_find_marked(xas, max, mark);
1719 0 : offset = xas_find_chunk(xas, true, mark);
1720 0 : xas->xa_offset = offset;
1721 0 : xas->xa_index = (xas->xa_index & ~XA_CHUNK_MASK) + offset;
1722 0 : if (xas->xa_index > max)
1723 : return NULL;
1724 0 : if (offset == XA_CHUNK_SIZE)
1725 0 : return xas_find_marked(xas, max, mark);
1726 0 : entry = xa_entry(xas->xa, node, offset);
1727 0 : if (!entry)
1728 0 : return xas_find_marked(xas, max, mark);
1729 : return entry;
1730 : }
1731 :
1732 : /*
1733 : * If iterating while holding a lock, drop the lock and reschedule
1734 : * every %XA_CHECK_SCHED loops.
1735 : */
1736 : enum {
1737 : XA_CHECK_SCHED = 4096,
1738 : };
1739 :
1740 : /**
1741 : * xas_for_each() - Iterate over a range of an XArray.
1742 : * @xas: XArray operation state.
1743 : * @entry: Entry retrieved from the array.
1744 : * @max: Maximum index to retrieve from array.
1745 : *
1746 : * The loop body will be executed for each entry present in the xarray
1747 : * between the current xas position and @max. @entry will be set to
1748 : * the entry retrieved from the xarray. It is safe to delete entries
1749 : * from the array in the loop body. You should hold either the RCU lock
1750 : * or the xa_lock while iterating. If you need to drop the lock, call
1751 : * xas_pause() first.
1752 : */
1753 : #define xas_for_each(xas, entry, max) \
1754 : for (entry = xas_find(xas, max); entry; \
1755 : entry = xas_next_entry(xas, max))
1756 :
1757 : /**
1758 : * xas_for_each_marked() - Iterate over a range of an XArray.
1759 : * @xas: XArray operation state.
1760 : * @entry: Entry retrieved from the array.
1761 : * @max: Maximum index to retrieve from array.
1762 : * @mark: Mark to search for.
1763 : *
1764 : * The loop body will be executed for each marked entry in the xarray
1765 : * between the current xas position and @max. @entry will be set to
1766 : * the entry retrieved from the xarray. It is safe to delete entries
1767 : * from the array in the loop body. You should hold either the RCU lock
1768 : * or the xa_lock while iterating. If you need to drop the lock, call
1769 : * xas_pause() first.
1770 : */
1771 : #define xas_for_each_marked(xas, entry, max, mark) \
1772 : for (entry = xas_find_marked(xas, max, mark); entry; \
1773 : entry = xas_next_marked(xas, max, mark))
1774 :
1775 : /**
1776 : * xas_for_each_conflict() - Iterate over a range of an XArray.
1777 : * @xas: XArray operation state.
1778 : * @entry: Entry retrieved from the array.
1779 : *
1780 : * The loop body will be executed for each entry in the XArray that
1781 : * lies within the range specified by @xas. If the loop terminates
1782 : * normally, @entry will be %NULL. The user may break out of the loop,
1783 : * which will leave @entry set to the conflicting entry. The caller
1784 : * may also call xa_set_err() to exit the loop while setting an error
1785 : * to record the reason.
1786 : */
1787 : #define xas_for_each_conflict(xas, entry) \
1788 : while ((entry = xas_find_conflict(xas)))
1789 :
1790 : void *__xas_next(struct xa_state *);
1791 : void *__xas_prev(struct xa_state *);
1792 :
1793 : /**
1794 : * xas_prev() - Move iterator to previous index.
1795 : * @xas: XArray operation state.
1796 : *
1797 : * If the @xas was in an error state, it will remain in an error state
1798 : * and this function will return %NULL. If the @xas has never been walked,
1799 : * it will have the effect of calling xas_load(). Otherwise one will be
1800 : * subtracted from the index and the state will be walked to the correct
1801 : * location in the array for the next operation.
1802 : *
1803 : * If the iterator was referencing index 0, this function wraps
1804 : * around to %ULONG_MAX.
1805 : *
1806 : * Return: The entry at the new index. This may be %NULL or an internal
1807 : * entry.
1808 : */
1809 0 : static inline void *xas_prev(struct xa_state *xas)
1810 : {
1811 0 : struct xa_node *node = xas->xa_node;
1812 :
1813 0 : if (unlikely(xas_not_node(node) || node->shift ||
1814 : xas->xa_offset == 0))
1815 0 : return __xas_prev(xas);
1816 :
1817 0 : xas->xa_index--;
1818 0 : xas->xa_offset--;
1819 0 : return xa_entry(xas->xa, node, xas->xa_offset);
1820 : }
1821 :
1822 : /**
1823 : * xas_next() - Move state to next index.
1824 : * @xas: XArray operation state.
1825 : *
1826 : * If the @xas was in an error state, it will remain in an error state
1827 : * and this function will return %NULL. If the @xas has never been walked,
1828 : * it will have the effect of calling xas_load(). Otherwise one will be
1829 : * added to the index and the state will be walked to the correct
1830 : * location in the array for the next operation.
1831 : *
1832 : * If the iterator was referencing index %ULONG_MAX, this function wraps
1833 : * around to 0.
1834 : *
1835 : * Return: The entry at the new index. This may be %NULL or an internal
1836 : * entry.
1837 : */
1838 0 : static inline void *xas_next(struct xa_state *xas)
1839 : {
1840 0 : struct xa_node *node = xas->xa_node;
1841 :
1842 0 : if (unlikely(xas_not_node(node) || node->shift ||
1843 : xas->xa_offset == XA_CHUNK_MASK))
1844 0 : return __xas_next(xas);
1845 :
1846 0 : xas->xa_index++;
1847 0 : xas->xa_offset++;
1848 0 : return xa_entry(xas->xa, node, xas->xa_offset);
1849 : }
1850 :
1851 : #endif /* _LINUX_XARRAY_H */
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