1 /* SPDX-License-Identifier: GPL-2.0+ */
2 #ifndef _LINUX_XARRAY_H
3 #define _LINUX_XARRAY_H
6 * Copyright (c) 2017 Microsoft Corporation
7 * Author: Matthew Wilcox <willy@infradead.org>
9 * See Documentation/core-api/xarray.rst for how to use the XArray.
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>
23 * The bottom two bits of the entry determine how the XArray interprets
28 * x1: Value entry or tagged pointer
30 * Attempting to store internal entries in the XArray is a bug.
32 * Most internal entries are pointers to the next node in the tree.
33 * The following internal entries have a special meaning:
35 * 0-62: Sibling entries
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.
44 #define BITS_PER_XA_VALUE (BITS_PER_LONG - 1)
47 * xa_mk_value() - Create an XArray entry from an integer.
48 * @v: Value to store in XArray.
50 * Context: Any context.
51 * Return: An entry suitable for storing in the XArray.
53 static inline void *xa_mk_value(unsigned long v)
56 return (void *)((v << 1) | 1);
60 * xa_to_value() - Get value stored in an XArray entry.
61 * @entry: XArray entry.
63 * Context: Any context.
64 * Return: The value stored in the XArray entry.
66 static inline unsigned long xa_to_value(const void *entry)
68 return (unsigned long)entry >> 1;
72 * xa_is_value() - Determine if an entry is a value.
73 * @entry: XArray entry.
75 * Context: Any context.
76 * Return: True if the entry is a value, false if it is a pointer.
78 static inline bool xa_is_value(const void *entry)
80 return (unsigned long)entry & 1;
84 * xa_tag_pointer() - Create an XArray entry for a tagged pointer.
86 * @tag: Tag value (0, 1 or 3).
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.
93 * Context: Any context.
94 * Return: An XArray entry.
96 static inline void *xa_tag_pointer(void *p, unsigned long tag)
98 return (void *)((unsigned long)p | tag);
102 * xa_untag_pointer() - Turn an XArray entry into a plain pointer.
103 * @entry: XArray entry.
105 * If you have stored a tagged pointer in the XArray, call this function
106 * to get the untagged version of the pointer.
108 * Context: Any context.
111 static inline void *xa_untag_pointer(void *entry)
113 return (void *)((unsigned long)entry & ~3UL);
117 * xa_pointer_tag() - Get the tag stored in an XArray entry.
118 * @entry: XArray entry.
120 * If you have stored a tagged pointer in the XArray, call this function
121 * to get the tag of that pointer.
123 * Context: Any context.
126 static inline unsigned int xa_pointer_tag(void *entry)
128 return (unsigned long)entry & 3UL;
132 * xa_mk_internal() - Create an internal entry.
133 * @v: Value to turn into an internal entry.
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.
141 * Context: Any context.
142 * Return: An XArray internal entry corresponding to this value.
144 static inline void *xa_mk_internal(unsigned long v)
146 return (void *)((v << 2) | 2);
150 * xa_to_internal() - Extract the value from an internal entry.
151 * @entry: XArray entry.
153 * Context: Any context.
154 * Return: The value which was stored in the internal entry.
156 static inline unsigned long xa_to_internal(const void *entry)
158 return (unsigned long)entry >> 2;
162 * xa_is_internal() - Is the entry an internal entry?
163 * @entry: XArray entry.
165 * Context: Any context.
166 * Return: %true if the entry is an internal entry.
168 static inline bool xa_is_internal(const void *entry)
170 return ((unsigned long)entry & 3) == 2;
173 #define XA_ZERO_ENTRY xa_mk_internal(257)
176 * xa_is_zero() - Is the entry a zero entry?
177 * @entry: Entry retrieved from the XArray
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.
182 * Return: %true if the entry is a zero entry.
184 static inline bool xa_is_zero(const void *entry)
186 return unlikely(entry == XA_ZERO_ENTRY);
190 * xa_is_err() - Report whether an XArray operation returned an error
191 * @entry: Result from calling an XArray function
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.
197 * Context: Any context.
198 * Return: %true if the entry indicates an error.
200 static inline bool xa_is_err(const void *entry)
202 return unlikely(xa_is_internal(entry) &&
203 entry >= xa_mk_internal(-MAX_ERRNO));
207 * xa_err() - Turn an XArray result into an errno.
208 * @entry: Result from calling an XArray function.
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.
215 * Context: Any context.
216 * Return: A negative errno or 0.
218 static inline int xa_err(void *entry)
220 /* xa_to_internal() would not do sign extension. */
221 if (xa_is_err(entry))
222 return (long)entry >> 2;
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).
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]
243 #define XA_LIMIT(_min, _max) (struct xa_limit) { .min = _min, .max = _max }
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)
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
263 * Values for xa_flags. The radix tree stores its GFP flags in the xa_flags,
264 * and we remain compatible with that.
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)))
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)
280 * struct xarray - The anchor of the XArray.
281 * @xa_lock: Lock that protects the contents of the XArray.
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.
287 * You may use the xa_lock to protect your own data structures as well.
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
297 /* private: The rest of the data structure is not to be used directly. */
299 void __rcu * xa_head;
302 #define XARRAY_INIT(name, flags) { \
303 .xa_lock = __SPIN_LOCK_UNLOCKED(name.xa_lock), \
309 * DEFINE_XARRAY_FLAGS() - Define an XArray with custom flags.
310 * @name: A string that names your XArray.
311 * @flags: XA_FLAG values.
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.
318 #define DEFINE_XARRAY_FLAGS(name, flags) \
319 struct xarray name = XARRAY_INIT(name, flags)
322 * DEFINE_XARRAY() - Define an XArray.
323 * @name: A string that names your XArray.
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.
330 #define DEFINE_XARRAY(name) DEFINE_XARRAY_FLAGS(name, 0)
333 * DEFINE_XARRAY_ALLOC() - Define an XArray which allocates IDs starting at 0.
334 * @name: A string that names your XArray.
336 * This is intended for file scope definitions of allocating XArrays.
337 * See also DEFINE_XARRAY().
339 #define DEFINE_XARRAY_ALLOC(name) DEFINE_XARRAY_FLAGS(name, XA_FLAGS_ALLOC)
342 * DEFINE_XARRAY_ALLOC1() - Define an XArray which allocates IDs starting at 1.
343 * @name: A string that names your XArray.
345 * This is intended for file scope definitions of allocating XArrays.
346 * See also DEFINE_XARRAY().
348 #define DEFINE_XARRAY_ALLOC1(name) DEFINE_XARRAY_FLAGS(name, XA_FLAGS_ALLOC1)
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,
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 *);
367 * xa_init_flags() - Initialise an empty XArray with flags.
369 * @flags: XA_FLAG values.
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
375 * Context: Any context.
377 static inline void xa_init_flags(struct xarray *xa, gfp_t flags)
379 spin_lock_init(&xa->xa_lock);
380 xa->xa_flags = flags;
385 * xa_init() - Initialise an empty XArray.
388 * An empty XArray is full of NULL entries.
390 * Context: Any context.
392 static inline void xa_init(struct xarray *xa)
394 xa_init_flags(xa, 0);
398 * xa_empty() - Determine if an array has any present entries.
401 * Context: Any context.
402 * Return: %true if the array contains only NULL pointers.
404 static inline bool xa_empty(const struct xarray *xa)
406 return xa->xa_head == NULL;
410 * xa_marked() - Inquire whether any entry in this array has a mark set
414 * Context: Any context.
415 * Return: %true if any entry has this mark set.
417 static inline bool xa_marked(const struct xarray *xa, xa_mark_t mark)
419 return xa->xa_flags & XA_FLAGS_MARK(mark);
423 * xa_for_each_range() - Iterate over a portion of an 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.
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.
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().
444 * Context: Any context. Takes and releases the RCU lock.
446 #define xa_for_each_range(xa, index, entry, start, last) \
447 for (index = start, \
448 entry = xa_find(xa, &index, last, XA_PRESENT); \
450 entry = xa_find_after(xa, &index, last, XA_PRESENT))
453 * xa_for_each_start() - Iterate over a portion of an XArray.
455 * @index: Index of @entry.
456 * @entry: Entry retrieved from array.
457 * @start: First index to retrieve from array.
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.
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().
473 * Context: Any context. Takes and releases the RCU lock.
475 #define xa_for_each_start(xa, index, entry, start) \
476 xa_for_each_range(xa, index, entry, start, ULONG_MAX)
479 * xa_for_each() - Iterate over present entries in an XArray.
481 * @index: Index of @entry.
482 * @entry: Entry retrieved from array.
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.
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().
497 * Context: Any context. Takes and releases the RCU lock.
499 #define xa_for_each(xa, index, entry) \
500 xa_for_each_start(xa, index, entry, 0)
503 * xa_for_each_marked() - Iterate over marked entries in an XArray.
505 * @index: Index of @entry.
506 * @entry: Entry retrieved from array.
507 * @filter: Selection criterion.
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.
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().
524 * Context: Any context. Takes and releases the RCU lock.
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))
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)
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.
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,
561 int __must_check __xa_insert(struct xarray *, unsigned long index,
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);
571 * xa_store_bh() - Store this entry in the XArray.
573 * @index: Index into array.
575 * @gfp: Memory allocation flags.
577 * This function is like calling xa_store() except it disables softirqs
578 * while holding the array lock.
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.
584 static inline void *xa_store_bh(struct xarray *xa, unsigned long index,
585 void *entry, gfp_t gfp)
590 curr = __xa_store(xa, index, entry, gfp);
597 * xa_store_irq() - Store this entry in the XArray.
599 * @index: Index into array.
601 * @gfp: Memory allocation flags.
603 * This function is like calling xa_store() except it disables interrupts
604 * while holding the array lock.
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.
610 static inline void *xa_store_irq(struct xarray *xa, unsigned long index,
611 void *entry, gfp_t gfp)
616 curr = __xa_store(xa, index, entry, gfp);
623 * xa_erase_bh() - Erase this entry from the XArray.
625 * @index: Index of entry.
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.
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.
635 static inline void *xa_erase_bh(struct xarray *xa, unsigned long index)
640 entry = __xa_erase(xa, index);
647 * xa_erase_irq() - Erase this entry from the XArray.
649 * @index: Index of entry.
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.
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.
659 static inline void *xa_erase_irq(struct xarray *xa, unsigned long index)
664 entry = __xa_erase(xa, index);
671 * xa_cmpxchg() - Conditionally replace an entry in the 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.
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.
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.
685 static inline void *xa_cmpxchg(struct xarray *xa, unsigned long index,
686 void *old, void *entry, gfp_t gfp)
691 curr = __xa_cmpxchg(xa, index, old, entry, gfp);
698 * xa_cmpxchg_bh() - Conditionally replace an entry in the 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.
705 * This function is like calling xa_cmpxchg() except it disables softirqs
706 * while holding the array lock.
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.
712 static inline void *xa_cmpxchg_bh(struct xarray *xa, unsigned long index,
713 void *old, void *entry, gfp_t gfp)
718 curr = __xa_cmpxchg(xa, index, old, entry, gfp);
725 * xa_cmpxchg_irq() - Conditionally replace an entry in the 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.
732 * This function is like calling xa_cmpxchg() except it disables interrupts
733 * while holding the array lock.
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.
739 static inline void *xa_cmpxchg_irq(struct xarray *xa, unsigned long index,
740 void *old, void *entry, gfp_t gfp)
745 curr = __xa_cmpxchg(xa, index, old, entry, gfp);
752 * xa_insert() - Store this entry in the XArray unless another entry is
755 * @index: Index into array.
757 * @gfp: Memory allocation flags.
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.
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.
768 static inline int __must_check xa_insert(struct xarray *xa,
769 unsigned long index, void *entry, gfp_t gfp)
774 err = __xa_insert(xa, index, entry, gfp);
781 * xa_insert_bh() - Store this entry in the XArray unless another entry is
784 * @index: Index into array.
786 * @gfp: Memory allocation flags.
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.
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.
797 static inline int __must_check xa_insert_bh(struct xarray *xa,
798 unsigned long index, void *entry, gfp_t gfp)
803 err = __xa_insert(xa, index, entry, gfp);
810 * xa_insert_irq() - Store this entry in the XArray unless another entry is
813 * @index: Index into array.
815 * @gfp: Memory allocation flags.
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.
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.
826 static inline int __must_check xa_insert_irq(struct xarray *xa,
827 unsigned long index, void *entry, gfp_t gfp)
832 err = __xa_insert(xa, index, entry, gfp);
839 * xa_alloc() - Find somewhere to store this entry in the XArray.
841 * @id: Pointer to ID.
843 * @limit: Range of ID to allocate.
844 * @gfp: Memory allocation flags.
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.
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.
855 static inline __must_check int xa_alloc(struct xarray *xa, u32 *id,
856 void *entry, struct xa_limit limit, gfp_t gfp)
861 err = __xa_alloc(xa, id, entry, limit, gfp);
868 * xa_alloc_bh() - Find somewhere to store this entry in the XArray.
870 * @id: Pointer to ID.
872 * @limit: Range of ID to allocate.
873 * @gfp: Memory allocation flags.
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.
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.
884 static inline int __must_check xa_alloc_bh(struct xarray *xa, u32 *id,
885 void *entry, struct xa_limit limit, gfp_t gfp)
890 err = __xa_alloc(xa, id, entry, limit, gfp);
897 * xa_alloc_irq() - Find somewhere to store this entry in the XArray.
899 * @id: Pointer to ID.
901 * @limit: Range of ID to allocate.
902 * @gfp: Memory allocation flags.
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.
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.
913 static inline int __must_check xa_alloc_irq(struct xarray *xa, u32 *id,
914 void *entry, struct xa_limit limit, gfp_t gfp)
919 err = __xa_alloc(xa, id, entry, limit, gfp);
926 * xa_alloc_cyclic() - Find somewhere to store this entry in the XArray.
928 * @id: Pointer to ID.
930 * @limit: Range of allocated ID.
931 * @next: Pointer to next ID to allocate.
932 * @gfp: Memory allocation flags.
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.
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.
946 static inline int xa_alloc_cyclic(struct xarray *xa, u32 *id, void *entry,
947 struct xa_limit limit, u32 *next, gfp_t gfp)
952 err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
959 * xa_alloc_cyclic_bh() - Find somewhere to store this entry in the XArray.
961 * @id: Pointer to ID.
963 * @limit: Range of allocated ID.
964 * @next: Pointer to next ID to allocate.
965 * @gfp: Memory allocation flags.
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.
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.
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)
985 err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
992 * xa_alloc_cyclic_irq() - Find somewhere to store this entry in the XArray.
994 * @id: Pointer to ID.
996 * @limit: Range of allocated ID.
997 * @next: Pointer to next ID to allocate.
998 * @gfp: Memory allocation flags.
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.
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.
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)
1018 err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
1025 * xa_reserve() - Reserve this index in the XArray.
1027 * @index: Index into array.
1028 * @gfp: Memory allocation flags.
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.
1035 * If you do not use the entry that you have reserved, call xa_release()
1036 * or xa_erase() to free any unnecessary memory.
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.
1042 static inline __must_check
1043 int xa_reserve(struct xarray *xa, unsigned long index, gfp_t gfp)
1045 return xa_err(xa_cmpxchg(xa, index, NULL, XA_ZERO_ENTRY, gfp));
1049 * xa_reserve_bh() - Reserve this index in the XArray.
1051 * @index: Index into array.
1052 * @gfp: Memory allocation flags.
1054 * A softirq-disabling version of xa_reserve().
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.
1060 static inline __must_check
1061 int xa_reserve_bh(struct xarray *xa, unsigned long index, gfp_t gfp)
1063 return xa_err(xa_cmpxchg_bh(xa, index, NULL, XA_ZERO_ENTRY, gfp));
1067 * xa_reserve_irq() - Reserve this index in the XArray.
1069 * @index: Index into array.
1070 * @gfp: Memory allocation flags.
1072 * An interrupt-disabling version of xa_reserve().
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.
1078 static inline __must_check
1079 int xa_reserve_irq(struct xarray *xa, unsigned long index, gfp_t gfp)
1081 return xa_err(xa_cmpxchg_irq(xa, index, NULL, XA_ZERO_ENTRY, gfp));
1085 * xa_release() - Release a reserved entry.
1087 * @index: Index of entry.
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
1093 static inline void xa_release(struct xarray *xa, unsigned long index)
1095 xa_cmpxchg(xa, index, XA_ZERO_ENTRY, NULL, 0);
1098 /* Everything below here is the Advanced API. Proceed with caution. */
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.
1110 #ifndef XA_CHUNK_SHIFT
1111 #define XA_CHUNK_SHIFT (CONFIG_BASE_SMALL ? 4 : 6)
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)
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.
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 */
1133 struct list_head private_list; /* For tree user */
1134 struct rcu_head rcu_head; /* Used when freeing node */
1136 void __rcu *slots[XA_CHUNK_SIZE];
1138 unsigned long tags[XA_MAX_MARKS][XA_MARK_LONGS];
1139 unsigned long marks[XA_MAX_MARKS][XA_MARK_LONGS];
1143 void xa_dump(const struct xarray *);
1144 void xa_dump_node(const struct xa_node *);
1147 #define XA_BUG_ON(xa, x) do { \
1153 #define XA_NODE_BUG_ON(node, x) do { \
1155 if (node) xa_dump_node(node); \
1160 #define XA_BUG_ON(xa, x) do { } while (0)
1161 #define XA_NODE_BUG_ON(node, x) do { } while (0)
1165 static inline void *xa_head(const struct xarray *xa)
1167 return rcu_dereference_check(xa->xa_head,
1168 lockdep_is_held(&xa->xa_lock));
1172 static inline void *xa_head_locked(const struct xarray *xa)
1174 return rcu_dereference_protected(xa->xa_head,
1175 lockdep_is_held(&xa->xa_lock));
1179 static inline void *xa_entry(const struct xarray *xa,
1180 const struct xa_node *node, unsigned int offset)
1182 XA_NODE_BUG_ON(node, offset >= XA_CHUNK_SIZE);
1183 return rcu_dereference_check(node->slots[offset],
1184 lockdep_is_held(&xa->xa_lock));
1188 static inline void *xa_entry_locked(const struct xarray *xa,
1189 const struct xa_node *node, unsigned int offset)
1191 XA_NODE_BUG_ON(node, offset >= XA_CHUNK_SIZE);
1192 return rcu_dereference_protected(node->slots[offset],
1193 lockdep_is_held(&xa->xa_lock));
1197 static inline struct xa_node *xa_parent(const struct xarray *xa,
1198 const struct xa_node *node)
1200 return rcu_dereference_check(node->parent,
1201 lockdep_is_held(&xa->xa_lock));
1205 static inline struct xa_node *xa_parent_locked(const struct xarray *xa,
1206 const struct xa_node *node)
1208 return rcu_dereference_protected(node->parent,
1209 lockdep_is_held(&xa->xa_lock));
1213 static inline void *xa_mk_node(const struct xa_node *node)
1215 return (void *)((unsigned long)node | 2);
1219 static inline struct xa_node *xa_to_node(const void *entry)
1221 return (struct xa_node *)((unsigned long)entry - 2);
1225 static inline bool xa_is_node(const void *entry)
1227 return xa_is_internal(entry) && (unsigned long)entry > 4096;
1231 static inline void *xa_mk_sibling(unsigned int offset)
1233 return xa_mk_internal(offset);
1237 static inline unsigned long xa_to_sibling(const void *entry)
1239 return xa_to_internal(entry);
1243 * xa_is_sibling() - Is the entry a sibling entry?
1244 * @entry: Entry retrieved from the XArray
1246 * Return: %true if the entry is a sibling entry.
1248 static inline bool xa_is_sibling(const void *entry)
1250 return IS_ENABLED(CONFIG_XARRAY_MULTI) && xa_is_internal(entry) &&
1251 (entry < xa_mk_sibling(XA_CHUNK_SIZE - 1));
1254 #define XA_RETRY_ENTRY xa_mk_internal(256)
1257 * xa_is_retry() - Is the entry a retry entry?
1258 * @entry: Entry retrieved from the XArray
1260 * Return: %true if the entry is a retry entry.
1262 static inline bool xa_is_retry(const void *entry)
1264 return unlikely(entry == XA_RETRY_ENTRY);
1268 * xa_is_advanced() - Is the entry only permitted for the advanced API?
1269 * @entry: Entry to be stored in the XArray.
1271 * Return: %true if the entry cannot be stored by the normal API.
1273 static inline bool xa_is_advanced(const void *entry)
1275 return xa_is_internal(entry) && (entry <= XA_RETRY_ENTRY);
1279 * typedef xa_update_node_t - A callback function from the XArray.
1280 * @node: The node which is being processed
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.
1286 * Context: The xa_lock is held and interrupts may be disabled.
1287 * Implementations should not drop the xa_lock, nor re-enable
1290 typedef void (*xa_update_node_t)(struct xa_node *node);
1292 void xa_delete_node(struct xa_node *, xa_update_node_t);
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.
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.
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;
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.
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)
1332 #define __XA_STATE(array, index, shift, sibs) { \
1334 .xa_index = index, \
1335 .xa_shift = shift, \
1339 .xa_node = XAS_RESTART, \
1341 .xa_update = NULL, \
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.
1351 * Declare and initialise an xa_state on the stack.
1353 #define XA_STATE(name, array, index) \
1354 struct xa_state name = __XA_STATE(array, index, 0, 0)
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.
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.`
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)
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)
1387 * xas_error() - Return an errno stored in the xa_state.
1388 * @xas: XArray operation state.
1390 * Return: 0 if no error has been noted. A negative errno if one has.
1392 static inline int xas_error(const struct xa_state *xas)
1394 return xa_err(xas->xa_node);
1398 * xas_set_err() - Note an error in the xa_state.
1399 * @xas: XArray operation state.
1400 * @err: Negative error number.
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().
1406 static inline void xas_set_err(struct xa_state *xas, long err)
1408 xas->xa_node = XA_ERROR(err);
1412 * xas_invalid() - Is the xas in a retry or error state?
1413 * @xas: XArray operation state.
1415 * Return: %true if the xas cannot be used for operations.
1417 static inline bool xas_invalid(const struct xa_state *xas)
1419 return (unsigned long)xas->xa_node & 3;
1423 * xas_valid() - Is the xas a valid cursor into the array?
1424 * @xas: XArray operation state.
1426 * Return: %true if the xas can be used for operations.
1428 static inline bool xas_valid(const struct xa_state *xas)
1430 return !xas_invalid(xas);
1434 * xas_is_node() - Does the xas point to a node?
1435 * @xas: XArray operation state.
1437 * Return: %true if the xas currently references a node.
1439 static inline bool xas_is_node(const struct xa_state *xas)
1441 return xas_valid(xas) && xas->xa_node;
1444 /* True if the pointer is something other than a node */
1445 static inline bool xas_not_node(struct xa_node *node)
1447 return ((unsigned long)node & 3) || !node;
1450 /* True if the node represents RESTART or an error */
1451 static inline bool xas_frozen(struct xa_node *node)
1453 return (unsigned long)node & 2;
1456 /* True if the node represents head-of-tree, RESTART or BOUNDS */
1457 static inline bool xas_top(struct xa_node *node)
1459 return node <= XAS_RESTART;
1463 * xas_reset() - Reset an XArray operation state.
1464 * @xas: XArray operation state.
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.
1470 * Context: Any context.
1472 static inline void xas_reset(struct xa_state *xas)
1474 xas->xa_node = XAS_RESTART;
1478 * xas_retry() - Retry the operation if appropriate.
1479 * @xas: XArray operation state.
1480 * @entry: Entry from xarray.
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.
1486 * Context: Any context.
1487 * Return: true if the operation needs to be retried.
1489 static inline bool xas_retry(struct xa_state *xas, const void *entry)
1491 if (xa_is_zero(entry))
1493 if (!xa_is_retry(entry))
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 *);
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 *);
1510 bool xas_nomem(struct xa_state *, gfp_t);
1511 void xas_pause(struct xa_state *);
1513 void xas_create_range(struct xa_state *);
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);
1520 static inline int xa_get_order(struct xarray *xa, unsigned long index)
1525 static inline void xas_split(struct xa_state *xas, void *entry,
1528 xas_store(xas, entry);
1531 static inline void xas_split_alloc(struct xa_state *xas, void *entry,
1532 unsigned int order, gfp_t gfp)
1538 * xas_reload() - Refetch an entry from the xarray.
1539 * @xas: XArray operation state.
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.
1546 * The caller guarantees that @xas is still valid. If it may be in an
1547 * error or restart state, call xas_load() instead.
1549 * Return: The entry at this location in the xarray.
1551 static inline void *xas_reload(struct xa_state *xas)
1553 struct xa_node *node = xas->xa_node;
1558 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))
1564 offset = xa_to_sibling(entry);
1566 offset = xas->xa_offset;
1568 return xa_entry(xas->xa, node, offset);
1572 * xas_set() - Set up XArray operation state for a different index.
1573 * @xas: XArray operation state.
1574 * @index: New index into the XArray.
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.
1580 static inline void xas_set(struct xa_state *xas, unsigned long index)
1582 xas->xa_index = index;
1583 xas->xa_node = XAS_RESTART;
1587 * xas_advance() - Skip over sibling entries.
1588 * @xas: XArray operation state.
1589 * @index: Index of last sibling entry.
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.
1596 static inline void xas_advance(struct xa_state *xas, unsigned long index)
1598 unsigned char shift = xas_is_node(xas) ? xas->xa_node->shift : 0;
1600 xas->xa_index = index;
1601 xas->xa_offset = (index >> shift) & XA_CHUNK_MASK;
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.
1610 static inline void xas_set_order(struct xa_state *xas, unsigned long index,
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;
1620 xas_set(xas, index);
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.
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.
1632 static inline void xas_set_update(struct xa_state *xas, xa_update_node_t update)
1634 xas->xa_update = update;
1637 static inline void xas_set_lru(struct xa_state *xas, struct list_lru *lru)
1643 * xas_next_entry() - Advance iterator to next present entry.
1644 * @xas: XArray operation state.
1645 * @max: Highest index to return.
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.
1651 * Return: The next present entry after the one currently referred to by @xas.
1653 static inline void *xas_next_entry(struct xa_state *xas, unsigned long max)
1655 struct xa_node *node = xas->xa_node;
1658 if (unlikely(xas_not_node(node) || node->shift ||
1659 xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)))
1660 return xas_find(xas, max);
1663 if (unlikely(xas->xa_index >= max))
1664 return xas_find(xas, max);
1665 if (unlikely(xas->xa_offset == XA_CHUNK_MASK))
1666 return xas_find(xas, max);
1667 entry = xa_entry(xas->xa, node, xas->xa_offset + 1);
1668 if (unlikely(xa_is_internal(entry)))
1669 return xas_find(xas, max);
1678 static inline unsigned int xas_find_chunk(struct xa_state *xas, bool advance,
1681 unsigned long *addr = xas->xa_node->marks[(__force unsigned)mark];
1682 unsigned int offset = xas->xa_offset;
1686 if (XA_CHUNK_SIZE == BITS_PER_LONG) {
1687 if (offset < XA_CHUNK_SIZE) {
1688 unsigned long data = *addr & (~0UL << offset);
1692 return XA_CHUNK_SIZE;
1695 return find_next_bit(addr, XA_CHUNK_SIZE, offset);
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.
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.
1708 * Return: The next marked entry after the one currently referred to by @xas.
1710 static inline void *xas_next_marked(struct xa_state *xas, unsigned long max,
1713 struct xa_node *node = xas->xa_node;
1715 unsigned int offset;
1717 if (unlikely(xas_not_node(node) || node->shift))
1718 return xas_find_marked(xas, max, mark);
1719 offset = xas_find_chunk(xas, true, mark);
1720 xas->xa_offset = offset;
1721 xas->xa_index = (xas->xa_index & ~XA_CHUNK_MASK) + offset;
1722 if (xas->xa_index > max)
1724 if (offset == XA_CHUNK_SIZE)
1725 return xas_find_marked(xas, max, mark);
1726 entry = xa_entry(xas->xa, node, offset);
1728 return xas_find_marked(xas, max, mark);
1733 * If iterating while holding a lock, drop the lock and reschedule
1734 * every %XA_CHECK_SCHED loops.
1737 XA_CHECK_SCHED = 4096,
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.
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.
1753 #define xas_for_each(xas, entry, max) \
1754 for (entry = xas_find(xas, max); entry; \
1755 entry = xas_next_entry(xas, max))
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.
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.
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))
1776 * xas_for_each_conflict() - Iterate over a range of an XArray.
1777 * @xas: XArray operation state.
1778 * @entry: Entry retrieved from the array.
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.
1787 #define xas_for_each_conflict(xas, entry) \
1788 while ((entry = xas_find_conflict(xas)))
1790 void *__xas_next(struct xa_state *);
1791 void *__xas_prev(struct xa_state *);
1794 * xas_prev() - Move iterator to previous index.
1795 * @xas: XArray operation state.
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.
1803 * If the iterator was referencing index 0, this function wraps
1804 * around to %ULONG_MAX.
1806 * Return: The entry at the new index. This may be %NULL or an internal
1809 static inline void *xas_prev(struct xa_state *xas)
1811 struct xa_node *node = xas->xa_node;
1813 if (unlikely(xas_not_node(node) || node->shift ||
1814 xas->xa_offset == 0))
1815 return __xas_prev(xas);
1819 return xa_entry(xas->xa, node, xas->xa_offset);
1823 * xas_next() - Move state to next index.
1824 * @xas: XArray operation state.
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.
1832 * If the iterator was referencing index %ULONG_MAX, this function wraps
1835 * Return: The entry at the new index. This may be %NULL or an internal
1838 static inline void *xas_next(struct xa_state *xas)
1840 struct xa_node *node = xas->xa_node;
1842 if (unlikely(xas_not_node(node) || node->shift ||
1843 xas->xa_offset == XA_CHUNK_MASK))
1844 return __xas_next(xas);
1848 return xa_entry(xas->xa, node, xas->xa_offset);
1851 #endif /* _LINUX_XARRAY_H */