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 * This is taken from kernel commit:
11 * 7b785645e ("mm: fix page cache convergence regression")
13 * at kernel verison 5.2-rc2
15 * See Documentation/core-api/xarray.rst for how to use the XArray.
17 #ifdef HAVE_RADIX_TREE_EXCEPTIONAL_ENTRY
18 #include <linux/bug.h>
19 #include <linux/compiler.h>
20 #include <linux/gfp.h>
21 #include <linux/kconfig.h>
22 #include <linux/kernel.h>
23 #include <linux/rcupdate.h>
24 #include <linux/spinlock.h>
25 #include <linux/types.h>
28 * The bottom two bits of the entry determine how the XArray interprets
33 * x1: Value entry or tagged pointer
35 * Attempting to store internal entries in the XArray is a bug.
37 * Most internal entries are pointers to the next node in the tree.
38 * The following internal entries have a special meaning:
40 * 0-62: Sibling entries
44 * Errors are also represented as internal entries, but use the negative
45 * space (-4094 to -2). They're never stored in the slots array; only
46 * returned by the normal API.
49 #define BITS_PER_XA_VALUE (BITS_PER_LONG - 1)
52 * xa_mk_value() - Create an XArray entry from an integer.
53 * @v: Value to store in XArray.
55 * Context: Any context.
56 * Return: An entry suitable for storing in the XArray.
58 static inline void *xa_mk_value(unsigned long v)
61 return (void *)((v << 1) | 1);
65 * xa_to_value() - Get value stored in an XArray entry.
66 * @entry: XArray entry.
68 * Context: Any context.
69 * Return: The value stored in the XArray entry.
71 static inline unsigned long xa_to_value(const void *entry)
73 return (unsigned long)entry >> 1;
77 * xa_is_value() - Determine if an entry is a value.
78 * @entry: XArray entry.
80 * Context: Any context.
81 * Return: True if the entry is a value, false if it is a pointer.
83 static inline bool xa_is_value(const void *entry)
85 return (unsigned long)entry & 1;
89 * xa_tag_pointer() - Create an XArray entry for a tagged pointer.
91 * @tag: Tag value (0, 1 or 3).
93 * If the user of the XArray prefers, they can tag their pointers instead
94 * of storing value entries. Three tags are available (0, 1 and 3).
95 * These are distinct from the xa_mark_t as they are not replicated up
96 * through the array and cannot be searched for.
98 * Context: Any context.
99 * Return: An XArray entry.
101 static inline void *xa_tag_pointer(void *p, unsigned long tag)
103 return (void *)((unsigned long)p | tag);
107 * xa_untag_pointer() - Turn an XArray entry into a plain pointer.
108 * @entry: XArray entry.
110 * If you have stored a tagged pointer in the XArray, call this function
111 * to get the untagged version of the pointer.
113 * Context: Any context.
116 static inline void *xa_untag_pointer(void *entry)
118 return (void *)((unsigned long)entry & ~3UL);
122 * xa_pointer_tag() - Get the tag stored in an XArray entry.
123 * @entry: XArray entry.
125 * If you have stored a tagged pointer in the XArray, call this function
126 * to get the tag of that pointer.
128 * Context: Any context.
131 static inline unsigned int xa_pointer_tag(void *entry)
133 return (unsigned long)entry & 3UL;
137 * xa_mk_internal() - Create an internal entry.
138 * @v: Value to turn into an internal entry.
140 * Internal entries are used for a number of purposes. Entries 0-255 are
141 * used for sibling entries (only 0-62 are used by the current code). 256
142 * is used for the retry entry. 257 is used for the reserved / zero entry.
143 * Negative internal entries are used to represent errnos. Node pointers
144 * are also tagged as internal entries in some situations.
146 * Context: Any context.
147 * Return: An XArray internal entry corresponding to this value.
149 static inline void *xa_mk_internal(unsigned long v)
151 return (void *)((v << 2) | 2);
155 * xa_to_internal() - Extract the value from an internal entry.
156 * @entry: XArray entry.
158 * Context: Any context.
159 * Return: The value which was stored in the internal entry.
161 static inline unsigned long xa_to_internal(const void *entry)
163 return (unsigned long)entry >> 2;
167 * xa_is_internal() - Is the entry an internal entry?
168 * @entry: XArray entry.
170 * Context: Any context.
171 * Return: %true if the entry is an internal entry.
173 static inline bool xa_is_internal(const void *entry)
175 return ((unsigned long)entry & 3) == 2;
178 #define XA_ZERO_ENTRY xa_mk_internal(257)
181 * xa_is_zero() - Is the entry a zero entry?
182 * @entry: Entry retrieved from the XArray
184 * The normal API will return NULL as the contents of a slot containing
185 * a zero entry. You can only see zero entries by using the advanced API.
187 * Return: %true if the entry is a zero entry.
189 static inline bool xa_is_zero(const void *entry)
191 return unlikely(entry == XA_ZERO_ENTRY);
195 * xa_is_err() - Report whether an XArray operation returned an error
196 * @entry: Result from calling an XArray function
198 * If an XArray operation cannot complete an operation, it will return
199 * a special value indicating an error. This function tells you
200 * whether an error occurred; xa_err() tells you which error occurred.
202 * Context: Any context.
203 * Return: %true if the entry indicates an error.
205 static inline bool xa_is_err(const void *entry)
207 return unlikely(xa_is_internal(entry) &&
208 entry >= xa_mk_internal(-MAX_ERRNO));
212 * xa_err() - Turn an XArray result into an errno.
213 * @entry: Result from calling an XArray function.
215 * If an XArray operation cannot complete an operation, it will return
216 * a special pointer value which encodes an errno. This function extracts
217 * the errno from the pointer value, or returns 0 if the pointer does not
218 * represent an errno.
220 * Context: Any context.
221 * Return: A negative errno or 0.
223 static inline int xa_err(void *entry)
225 /* xa_to_internal() would not do sign extension. */
226 if (xa_is_err(entry))
227 return (long)entry >> 2;
232 * struct xa_limit - Represents a range of IDs.
233 * @min: The lowest ID to allocate (inclusive).
234 * @max: The maximum ID to allocate (inclusive).
236 * This structure is used either directly or via the XA_LIMIT() macro
237 * to communicate the range of IDs that are valid for allocation.
238 * Two common ranges are predefined for you:
239 * * xa_limit_32b - [0 - UINT_MAX]
240 * * xa_limit_31b - [0 - INT_MAX]
247 #define XA_LIMIT(_min, _max) (struct xa_limit) { .min = _min, .max = _max }
249 #define xa_limit_32b XA_LIMIT(0, UINT_MAX)
250 #define xa_limit_31b XA_LIMIT(0, INT_MAX)
252 typedef unsigned __bitwise xa_mark_t;
253 #define XA_MARK_0 ((__force xa_mark_t)0U)
254 #define XA_MARK_1 ((__force xa_mark_t)1U)
255 #define XA_MARK_2 ((__force xa_mark_t)2U)
256 #define XA_PRESENT ((__force xa_mark_t)8U)
257 #define XA_MARK_MAX XA_MARK_2
258 #define XA_FREE_MARK XA_MARK_0
266 * Values for xa_flags. The radix tree stores its GFP flags in the xa_flags,
267 * and we remain compatible with that.
269 #define XA_FLAGS_LOCK_IRQ ((__force gfp_t)XA_LOCK_IRQ)
270 #define XA_FLAGS_LOCK_BH ((__force gfp_t)XA_LOCK_BH)
271 #define XA_FLAGS_TRACK_FREE ((__force gfp_t)4U)
272 #define XA_FLAGS_ZERO_BUSY ((__force gfp_t)8U)
273 #define XA_FLAGS_ALLOC_WRAPPED ((__force gfp_t)16U)
274 #define XA_FLAGS_ACCOUNT ((__force gfp_t)32U)
275 #define XA_FLAGS_MARK(mark) ((__force gfp_t)((1U << __GFP_BITS_SHIFT) << \
276 (__force unsigned)(mark)))
278 /* ALLOC is for a normal 0-based alloc. ALLOC1 is for an 1-based alloc */
279 #define XA_FLAGS_ALLOC (XA_FLAGS_TRACK_FREE | XA_FLAGS_MARK(XA_FREE_MARK))
280 #define XA_FLAGS_ALLOC1 (XA_FLAGS_TRACK_FREE | XA_FLAGS_ZERO_BUSY)
283 * struct xarray - The anchor of the XArray.
284 * @xa_lock: Lock that protects the contents of the XArray.
286 * To use the xarray, define it statically or embed it in your data structure.
287 * It is a very small data structure, so it does not usually make sense to
288 * allocate it separately and keep a pointer to it in your data structure.
290 * You may use the xa_lock to protect your own data structures as well.
293 * If all of the entries in the array are NULL, @xa_head is a NULL pointer.
294 * If the only non-NULL entry in the array is at index 0, @xa_head is that
295 * entry. If any other entry in the array is non-NULL, @xa_head points
300 /* private: The rest of the data structure is not to be used directly. */
305 #define XARRAY_INIT(name, flags) { \
306 .xa_lock = __SPIN_LOCK_UNLOCKED(name.xa_lock), \
312 * DEFINE_XARRAY_FLAGS() - Define an XArray with custom flags.
313 * @name: A string that names your XArray.
314 * @flags: XA_FLAG values.
316 * This is intended for file scope definitions of XArrays. It declares
317 * and initialises an empty XArray with the chosen name and flags. It is
318 * equivalent to calling xa_init_flags() on the array, but it does the
319 * initialisation at compiletime instead of runtime.
321 #define DEFINE_XARRAY_FLAGS(name, flags) \
322 struct xarray name = XARRAY_INIT(name, flags)
325 * DEFINE_XARRAY() - Define an XArray.
326 * @name: A string that names your XArray.
328 * This is intended for file scope definitions of XArrays. It declares
329 * and initialises an empty XArray with the chosen name. It is equivalent
330 * to calling xa_init() on the array, but it does the initialisation at
331 * compiletime instead of runtime.
333 #define DEFINE_XARRAY(name) DEFINE_XARRAY_FLAGS(name, 0)
336 * DEFINE_XARRAY_ALLOC() - Define an XArray which allocates IDs starting at 0.
337 * @name: A string that names your XArray.
339 * This is intended for file scope definitions of allocating XArrays.
340 * See also DEFINE_XARRAY().
342 #define DEFINE_XARRAY_ALLOC(name) DEFINE_XARRAY_FLAGS(name, XA_FLAGS_ALLOC)
345 * DEFINE_XARRAY_ALLOC1() - Define an XArray which allocates IDs starting at 1.
346 * @name: A string that names your XArray.
348 * This is intended for file scope definitions of allocating XArrays.
349 * See also DEFINE_XARRAY().
351 #define DEFINE_XARRAY_ALLOC1(name) DEFINE_XARRAY_FLAGS(name, XA_FLAGS_ALLOC1)
353 void *xa_load(struct xarray *, unsigned long index);
354 void *xa_store(struct xarray *, unsigned long index, void *entry, gfp_t);
355 void *xa_erase(struct xarray *, unsigned long index);
356 void *xa_store_range(struct xarray *, unsigned long first, unsigned long last,
358 bool xa_get_mark(struct xarray *, unsigned long index, xa_mark_t);
359 void xa_set_mark(struct xarray *, unsigned long index, xa_mark_t);
360 void xa_clear_mark(struct xarray *, unsigned long index, xa_mark_t);
361 void *xa_find(struct xarray *xa, unsigned long *index,
362 unsigned long max, xa_mark_t) __attribute__((nonnull(2)));
363 void *xa_find_after(struct xarray *xa, unsigned long *index,
364 unsigned long max, xa_mark_t) __attribute__((nonnull(2)));
365 unsigned int xa_extract(struct xarray *, void **dst, unsigned long start,
366 unsigned long max, unsigned int n, xa_mark_t);
367 void xa_destroy(struct xarray *);
370 * xa_init_flags() - Initialise an empty XArray with flags.
372 * @flags: XA_FLAG values.
374 * If you need to initialise an XArray with special flags (eg you need
375 * to take the lock from interrupt context), use this function instead
378 * Context: Any context.
380 static inline void xa_init_flags(struct xarray *xa, gfp_t flags)
382 spin_lock_init(&xa->xa_lock);
383 xa->xa_flags = flags;
388 * xa_init() - Initialise an empty XArray.
391 * An empty XArray is full of NULL entries.
393 * Context: Any context.
395 static inline void xa_init(struct xarray *xa)
397 xa_init_flags(xa, 0);
401 * xa_empty() - Determine if an array has any present entries.
404 * Context: Any context.
405 * Return: %true if the array contains only NULL pointers.
407 static inline bool xa_empty(const struct xarray *xa)
409 return xa->xa_head == NULL;
413 * xa_marked() - Inquire whether any entry in this array has a mark set
417 * Context: Any context.
418 * Return: %true if any entry has this mark set.
420 static inline bool xa_marked(const struct xarray *xa, xa_mark_t mark)
422 return xa->xa_flags & XA_FLAGS_MARK(mark);
426 * xa_for_each_start() - Iterate over a portion of an XArray.
428 * @index: Index of @entry.
429 * @entry: Entry retrieved from array.
430 * @start: First index to retrieve from array.
432 * During the iteration, @entry will have the value of the entry stored
433 * in @xa at @index. You may modify @index during the iteration if you
434 * want to skip or reprocess indices. It is safe to modify the array
435 * during the iteration. At the end of the iteration, @entry will be set
436 * to NULL and @index will have a value less than or equal to max.
438 * xa_for_each_start() is O(n.log(n)) while xas_for_each() is O(n). You have
439 * to handle your own locking with xas_for_each(), and if you have to unlock
440 * after each iteration, it will also end up being O(n.log(n)).
441 * xa_for_each_start() will spin if it hits a retry entry; if you intend to
442 * see retry entries, you should use the xas_for_each() iterator instead.
443 * The xas_for_each() iterator will expand into more inline code than
444 * xa_for_each_start().
446 * Context: Any context. Takes and releases the RCU lock.
448 #define xa_for_each_start(xa, index, entry, start) \
449 for (index = start, \
450 entry = xa_find(xa, &index, ULONG_MAX, XA_PRESENT); \
452 entry = xa_find_after(xa, &index, ULONG_MAX, XA_PRESENT))
455 * xa_for_each() - Iterate over present entries in an XArray.
457 * @index: Index of @entry.
458 * @entry: Entry retrieved from array.
460 * During the iteration, @entry will have the value of the entry stored
461 * in @xa at @index. You may modify @index during the iteration if you want
462 * to skip or reprocess indices. It is safe to modify the array during the
463 * iteration. At the end of the iteration, @entry will be set to NULL and
464 * @index will have a value less than or equal to max.
466 * xa_for_each() is O(n.log(n)) while xas_for_each() is O(n). You have
467 * to handle your own locking with xas_for_each(), and if you have to unlock
468 * after each iteration, it will also end up being O(n.log(n)). xa_for_each()
469 * will spin if it hits a retry entry; if you intend to see retry entries,
470 * you should use the xas_for_each() iterator instead. The xas_for_each()
471 * iterator will expand into more inline code than xa_for_each().
473 * Context: Any context. Takes and releases the RCU lock.
475 #define xa_for_each(xa, index, entry) \
476 xa_for_each_start(xa, index, entry, 0)
479 * xa_for_each_marked() - Iterate over marked entries in an XArray.
481 * @index: Index of @entry.
482 * @entry: Entry retrieved from array.
483 * @filter: Selection criterion.
485 * During the iteration, @entry will have the value of the entry stored
486 * in @xa at @index. The iteration will skip all entries in the array
487 * which do not match @filter. You may modify @index during the iteration
488 * if you want to skip or reprocess indices. It is safe to modify the array
489 * during the iteration. At the end of the iteration, @entry will be set to
490 * NULL and @index will have a value less than or equal to max.
492 * xa_for_each_marked() is O(n.log(n)) while xas_for_each_marked() is O(n).
493 * You have to handle your own locking with xas_for_each(), and if you have
494 * to unlock after each iteration, it will also end up being O(n.log(n)).
495 * xa_for_each_marked() will spin if it hits a retry entry; if you intend to
496 * see retry entries, you should use the xas_for_each_marked() iterator
497 * instead. The xas_for_each_marked() iterator will expand into more inline
498 * code than xa_for_each_marked().
500 * Context: Any context. Takes and releases the RCU lock.
502 #define xa_for_each_marked(xa, index, entry, filter) \
503 for (index = 0, entry = xa_find(xa, &index, ULONG_MAX, filter); \
504 entry; entry = xa_find_after(xa, &index, ULONG_MAX, filter))
506 #define xa_trylock(xa) spin_trylock(&(xa)->xa_lock)
507 #define xa_lock(xa) spin_lock(&(xa)->xa_lock)
508 #define xa_unlock(xa) spin_unlock(&(xa)->xa_lock)
509 #define xa_lock_bh(xa) spin_lock_bh(&(xa)->xa_lock)
510 #define xa_unlock_bh(xa) spin_unlock_bh(&(xa)->xa_lock)
511 #define xa_lock_irq(xa) spin_lock_irq(&(xa)->xa_lock)
512 #define xa_unlock_irq(xa) spin_unlock_irq(&(xa)->xa_lock)
513 #define xa_lock_irqsave(xa, flags) \
514 spin_lock_irqsave(&(xa)->xa_lock, flags)
515 #define xa_unlock_irqrestore(xa, flags) \
516 spin_unlock_irqrestore(&(xa)->xa_lock, flags)
519 * Versions of the normal API which require the caller to hold the
520 * xa_lock. If the GFP flags allow it, they will drop the lock to
521 * allocate memory, then reacquire it afterwards. These functions
522 * may also re-enable interrupts if the XArray flags indicate the
523 * locking should be interrupt safe.
525 void *__xa_erase(struct xarray *, unsigned long index);
526 void *__xa_store(struct xarray *, unsigned long index, void *entry, gfp_t);
527 void *__xa_cmpxchg(struct xarray *, unsigned long index, void *old,
529 int __must_check __xa_insert(struct xarray *, unsigned long index,
531 int __must_check __xa_alloc(struct xarray *, u32 *id, void *entry,
532 struct xa_limit, gfp_t);
533 int __must_check __xa_alloc_cyclic(struct xarray *, u32 *id, void *entry,
534 struct xa_limit, u32 *next, gfp_t);
535 void __xa_set_mark(struct xarray *, unsigned long index, xa_mark_t);
536 void __xa_clear_mark(struct xarray *, unsigned long index, xa_mark_t);
539 * xa_store_bh() - Store this entry in the XArray.
541 * @index: Index into array.
543 * @gfp: Memory allocation flags.
545 * This function is like calling xa_store() except it disables softirqs
546 * while holding the array lock.
548 * Context: Any context. Takes and releases the xa_lock while
549 * disabling softirqs.
550 * Return: The entry which used to be at this index.
552 static inline void *xa_store_bh(struct xarray *xa, unsigned long index,
553 void *entry, gfp_t gfp)
558 curr = __xa_store(xa, index, entry, gfp);
565 * xa_store_irq() - Store this entry in the XArray.
567 * @index: Index into array.
569 * @gfp: Memory allocation flags.
571 * This function is like calling xa_store() except it disables interrupts
572 * while holding the array lock.
574 * Context: Process context. Takes and releases the xa_lock while
575 * disabling interrupts.
576 * Return: The entry which used to be at this index.
578 static inline void *xa_store_irq(struct xarray *xa, unsigned long index,
579 void *entry, gfp_t gfp)
584 curr = __xa_store(xa, index, entry, gfp);
591 * xa_erase_bh() - Erase this entry from the XArray.
593 * @index: Index of entry.
595 * After this function returns, loading from @index will return %NULL.
596 * If the index is part of a multi-index entry, all indices will be erased
597 * and none of the entries will be part of a multi-index entry.
599 * Context: Any context. Takes and releases the xa_lock while
600 * disabling softirqs.
601 * Return: The entry which used to be at this index.
603 static inline void *xa_erase_bh(struct xarray *xa, unsigned long index)
608 entry = __xa_erase(xa, index);
615 * xa_erase_irq() - Erase this entry from the XArray.
617 * @index: Index of entry.
619 * After this function returns, loading from @index will return %NULL.
620 * If the index is part of a multi-index entry, all indices will be erased
621 * and none of the entries will be part of a multi-index entry.
623 * Context: Process context. Takes and releases the xa_lock while
624 * disabling interrupts.
625 * Return: The entry which used to be at this index.
627 static inline void *xa_erase_irq(struct xarray *xa, unsigned long index)
632 entry = __xa_erase(xa, index);
639 * xa_cmpxchg() - Conditionally replace an entry in the XArray.
641 * @index: Index into array.
642 * @old: Old value to test against.
643 * @entry: New value to place in array.
644 * @gfp: Memory allocation flags.
646 * If the entry at @index is the same as @old, replace it with @entry.
647 * If the return value is equal to @old, then the exchange was successful.
649 * Context: Any context. Takes and releases the xa_lock. May sleep
650 * if the @gfp flags permit.
651 * Return: The old value at this index or xa_err() if an error happened.
653 static inline void *xa_cmpxchg(struct xarray *xa, unsigned long index,
654 void *old, void *entry, gfp_t gfp)
659 curr = __xa_cmpxchg(xa, index, old, entry, gfp);
666 * xa_cmpxchg_bh() - Conditionally replace an entry in the XArray.
668 * @index: Index into array.
669 * @old: Old value to test against.
670 * @entry: New value to place in array.
671 * @gfp: Memory allocation flags.
673 * This function is like calling xa_cmpxchg() except it disables softirqs
674 * while holding the array lock.
676 * Context: Any context. Takes and releases the xa_lock while
677 * disabling softirqs. May sleep if the @gfp flags permit.
678 * Return: The old value at this index or xa_err() if an error happened.
680 static inline void *xa_cmpxchg_bh(struct xarray *xa, unsigned long index,
681 void *old, void *entry, gfp_t gfp)
686 curr = __xa_cmpxchg(xa, index, old, entry, gfp);
693 * xa_cmpxchg_irq() - Conditionally replace an entry in the XArray.
695 * @index: Index into array.
696 * @old: Old value to test against.
697 * @entry: New value to place in array.
698 * @gfp: Memory allocation flags.
700 * This function is like calling xa_cmpxchg() except it disables interrupts
701 * while holding the array lock.
703 * Context: Process context. Takes and releases the xa_lock while
704 * disabling interrupts. May sleep if the @gfp flags permit.
705 * Return: The old value at this index or xa_err() if an error happened.
707 static inline void *xa_cmpxchg_irq(struct xarray *xa, unsigned long index,
708 void *old, void *entry, gfp_t gfp)
713 curr = __xa_cmpxchg(xa, index, old, entry, gfp);
720 * xa_insert() - Store this entry in the XArray unless another entry is
723 * @index: Index into array.
725 * @gfp: Memory allocation flags.
727 * Inserting a NULL entry will store a reserved entry (like xa_reserve())
728 * if no entry is present. Inserting will fail if a reserved entry is
729 * present, even though loading from this index will return NULL.
731 * Context: Any context. Takes and releases the xa_lock. May sleep if
732 * the @gfp flags permit.
733 * Return: 0 if the store succeeded. -EBUSY if another entry was present.
734 * -ENOMEM if memory could not be allocated.
736 static inline int __must_check xa_insert(struct xarray *xa,
737 unsigned long index, void *entry, gfp_t gfp)
742 err = __xa_insert(xa, index, entry, gfp);
749 * xa_insert_bh() - Store this entry in the XArray unless another entry is
752 * @index: Index into array.
754 * @gfp: Memory allocation flags.
756 * Inserting a NULL entry will store a reserved entry (like xa_reserve())
757 * if no entry is present. Inserting will fail if a reserved entry is
758 * present, even though loading from this index will return NULL.
760 * Context: Any context. Takes and releases the xa_lock while
761 * disabling softirqs. May sleep if the @gfp flags permit.
762 * Return: 0 if the store succeeded. -EBUSY if another entry was present.
763 * -ENOMEM if memory could not be allocated.
765 static inline int __must_check xa_insert_bh(struct xarray *xa,
766 unsigned long index, void *entry, gfp_t gfp)
771 err = __xa_insert(xa, index, entry, gfp);
778 * xa_insert_irq() - Store this entry in the XArray unless another entry is
781 * @index: Index into array.
783 * @gfp: Memory allocation flags.
785 * Inserting a NULL entry will store a reserved entry (like xa_reserve())
786 * if no entry is present. Inserting will fail if a reserved entry is
787 * present, even though loading from this index will return NULL.
789 * Context: Process context. Takes and releases the xa_lock while
790 * disabling interrupts. May sleep if the @gfp flags permit.
791 * Return: 0 if the store succeeded. -EBUSY if another entry was present.
792 * -ENOMEM if memory could not be allocated.
794 static inline int __must_check xa_insert_irq(struct xarray *xa,
795 unsigned long index, void *entry, gfp_t gfp)
800 err = __xa_insert(xa, index, entry, gfp);
807 * xa_alloc() - Find somewhere to store this entry in the XArray.
809 * @id: Pointer to ID.
811 * @limit: Range of ID to allocate.
812 * @gfp: Memory allocation flags.
814 * Finds an empty entry in @xa between @limit.min and @limit.max,
815 * stores the index into the @id pointer, then stores the entry at
816 * that index. A concurrent lookup will not see an uninitialised @id.
818 * Context: Any context. Takes and releases the xa_lock. May sleep if
819 * the @gfp flags permit.
820 * Return: 0 on success, -ENOMEM if memory could not be allocated or
821 * -EBUSY if there are no free entries in @limit.
823 static inline __must_check int xa_alloc(struct xarray *xa, u32 *id,
824 void *entry, struct xa_limit limit, gfp_t gfp)
829 err = __xa_alloc(xa, id, entry, limit, gfp);
836 * xa_alloc_bh() - Find somewhere to store this entry in the XArray.
838 * @id: Pointer to ID.
840 * @limit: Range of ID to allocate.
841 * @gfp: Memory allocation flags.
843 * Finds an empty entry in @xa between @limit.min and @limit.max,
844 * stores the index into the @id pointer, then stores the entry at
845 * that index. A concurrent lookup will not see an uninitialised @id.
847 * Context: Any context. Takes and releases the xa_lock while
848 * disabling softirqs. May sleep if the @gfp flags permit.
849 * Return: 0 on success, -ENOMEM if memory could not be allocated or
850 * -EBUSY if there are no free entries in @limit.
852 static inline int __must_check xa_alloc_bh(struct xarray *xa, u32 *id,
853 void *entry, struct xa_limit limit, gfp_t gfp)
858 err = __xa_alloc(xa, id, entry, limit, gfp);
865 * xa_alloc_irq() - Find somewhere to store this entry in the XArray.
867 * @id: Pointer to ID.
869 * @limit: Range of ID to allocate.
870 * @gfp: Memory allocation flags.
872 * Finds an empty entry in @xa between @limit.min and @limit.max,
873 * stores the index into the @id pointer, then stores the entry at
874 * that index. A concurrent lookup will not see an uninitialised @id.
876 * Context: Process context. Takes and releases the xa_lock while
877 * disabling interrupts. May sleep if the @gfp flags permit.
878 * Return: 0 on success, -ENOMEM if memory could not be allocated or
879 * -EBUSY if there are no free entries in @limit.
881 static inline int __must_check xa_alloc_irq(struct xarray *xa, u32 *id,
882 void *entry, struct xa_limit limit, gfp_t gfp)
887 err = __xa_alloc(xa, id, entry, limit, gfp);
894 * xa_alloc_cyclic() - Find somewhere to store this entry in the XArray.
896 * @id: Pointer to ID.
898 * @limit: Range of allocated ID.
899 * @next: Pointer to next ID to allocate.
900 * @gfp: Memory allocation flags.
902 * Finds an empty entry in @xa between @limit.min and @limit.max,
903 * stores the index into the @id pointer, then stores the entry at
904 * that index. A concurrent lookup will not see an uninitialised @id.
905 * The search for an empty entry will start at @next and will wrap
906 * around if necessary.
908 * Context: Any context. Takes and releases the xa_lock. May sleep if
909 * the @gfp flags permit.
910 * Return: 0 if the allocation succeeded without wrapping. 1 if the
911 * allocation succeeded after wrapping, -ENOMEM if memory could not be
912 * allocated or -EBUSY if there are no free entries in @limit.
914 static inline int xa_alloc_cyclic(struct xarray *xa, u32 *id, void *entry,
915 struct xa_limit limit, u32 *next, gfp_t gfp)
920 err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
927 * xa_alloc_cyclic_bh() - Find somewhere to store this entry in the XArray.
929 * @id: Pointer to ID.
931 * @limit: Range of allocated ID.
932 * @next: Pointer to next ID to allocate.
933 * @gfp: Memory allocation flags.
935 * Finds an empty entry in @xa between @limit.min and @limit.max,
936 * stores the index into the @id pointer, then stores the entry at
937 * that index. A concurrent lookup will not see an uninitialised @id.
938 * The search for an empty entry will start at @next and will wrap
939 * around if necessary.
941 * Context: Any context. Takes and releases the xa_lock while
942 * disabling softirqs. May sleep if the @gfp flags permit.
943 * Return: 0 if the allocation succeeded without wrapping. 1 if the
944 * allocation succeeded after wrapping, -ENOMEM if memory could not be
945 * allocated or -EBUSY if there are no free entries in @limit.
947 static inline int xa_alloc_cyclic_bh(struct xarray *xa, u32 *id, void *entry,
948 struct xa_limit limit, u32 *next, gfp_t gfp)
953 err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
960 * xa_alloc_cyclic_irq() - Find somewhere to store this entry in the XArray.
962 * @id: Pointer to ID.
964 * @limit: Range of allocated ID.
965 * @next: Pointer to next ID to allocate.
966 * @gfp: Memory allocation flags.
968 * Finds an empty entry in @xa between @limit.min and @limit.max,
969 * stores the index into the @id pointer, then stores the entry at
970 * that index. A concurrent lookup will not see an uninitialised @id.
971 * The search for an empty entry will start at @next and will wrap
972 * around if necessary.
974 * Context: Process context. Takes and releases the xa_lock while
975 * disabling interrupts. May sleep if the @gfp flags permit.
976 * Return: 0 if the allocation succeeded without wrapping. 1 if the
977 * allocation succeeded after wrapping, -ENOMEM if memory could not be
978 * allocated or -EBUSY if there are no free entries in @limit.
980 static inline int xa_alloc_cyclic_irq(struct xarray *xa, u32 *id, void *entry,
981 struct xa_limit limit, u32 *next, gfp_t gfp)
986 err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
993 * xa_reserve() - Reserve this index in the XArray.
995 * @index: Index into array.
996 * @gfp: Memory allocation flags.
998 * Ensures there is somewhere to store an entry at @index in the array.
999 * If there is already something stored at @index, this function does
1000 * nothing. If there was nothing there, the entry is marked as reserved.
1001 * Loading from a reserved entry returns a %NULL pointer.
1003 * If you do not use the entry that you have reserved, call xa_release()
1004 * or xa_erase() to free any unnecessary memory.
1006 * Context: Any context. Takes and releases the xa_lock.
1007 * May sleep if the @gfp flags permit.
1008 * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
1010 static inline __must_check
1011 int xa_reserve(struct xarray *xa, unsigned long index, gfp_t gfp)
1013 return xa_err(xa_cmpxchg(xa, index, NULL, XA_ZERO_ENTRY, gfp));
1017 * xa_reserve_bh() - Reserve this index in the XArray.
1019 * @index: Index into array.
1020 * @gfp: Memory allocation flags.
1022 * A softirq-disabling version of xa_reserve().
1024 * Context: Any context. Takes and releases the xa_lock while
1025 * disabling softirqs.
1026 * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
1028 static inline __must_check
1029 int xa_reserve_bh(struct xarray *xa, unsigned long index, gfp_t gfp)
1031 return xa_err(xa_cmpxchg_bh(xa, index, NULL, XA_ZERO_ENTRY, gfp));
1035 * xa_reserve_irq() - Reserve this index in the XArray.
1037 * @index: Index into array.
1038 * @gfp: Memory allocation flags.
1040 * An interrupt-disabling version of xa_reserve().
1042 * Context: Process context. Takes and releases the xa_lock while
1043 * disabling interrupts.
1044 * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
1046 static inline __must_check
1047 int xa_reserve_irq(struct xarray *xa, unsigned long index, gfp_t gfp)
1049 return xa_err(xa_cmpxchg_irq(xa, index, NULL, XA_ZERO_ENTRY, gfp));
1053 * xa_release() - Release a reserved entry.
1055 * @index: Index of entry.
1057 * After calling xa_reserve(), you can call this function to release the
1058 * reservation. If the entry at @index has been stored to, this function
1061 static inline void xa_release(struct xarray *xa, unsigned long index)
1063 xa_cmpxchg(xa, index, XA_ZERO_ENTRY, NULL, 0);
1066 /* Everything below here is the Advanced API. Proceed with caution. */
1069 * The xarray is constructed out of a set of 'chunks' of pointers. Choosing
1070 * the best chunk size requires some tradeoffs. A power of two recommends
1071 * itself so that we can walk the tree based purely on shifts and masks.
1072 * Generally, the larger the better; as the number of slots per level of the
1073 * tree increases, the less tall the tree needs to be. But that needs to be
1074 * balanced against the memory consumption of each node. On a 64-bit system,
1075 * xa_node is currently 576 bytes, and we get 7 of them per 4kB page. If we
1076 * doubled the number of slots per node, we'd get only 3 nodes per 4kB page.
1078 #ifndef XA_CHUNK_SHIFT
1079 #define XA_CHUNK_SHIFT (CONFIG_BASE_SMALL ? 4 : 6)
1081 #define XA_CHUNK_SIZE (1UL << XA_CHUNK_SHIFT)
1082 #define XA_CHUNK_MASK (XA_CHUNK_SIZE - 1)
1083 #define XA_MAX_MARKS 3
1084 #define XA_MARK_LONGS DIV_ROUND_UP(XA_CHUNK_SIZE, BITS_PER_LONG)
1087 * @count is the count of every non-NULL element in the ->slots array
1088 * whether that is a value entry, a retry entry, a user pointer,
1089 * a sibling entry or a pointer to the next level of the tree.
1090 * @nr_values is the count of every element in ->slots which is
1091 * either a value entry or a sibling of a value entry.
1094 unsigned char shift; /* Bits remaining in each slot */
1095 unsigned char offset; /* Slot offset in parent */
1096 unsigned char count; /* Total entry count */
1097 unsigned char nr_values; /* Value entry count */
1098 struct xa_node __rcu *parent; /* NULL at top of tree */
1099 struct xarray *array; /* The array we belong to */
1101 struct list_head private_list; /* For tree user */
1102 struct rcu_head rcu_head; /* Used when freeing node */
1104 void __rcu *slots[XA_CHUNK_SIZE];
1106 unsigned long tags[XA_MAX_MARKS][XA_MARK_LONGS];
1107 unsigned long marks[XA_MAX_MARKS][XA_MARK_LONGS];
1111 void xa_dump(const struct xarray *);
1112 void xa_dump_node(const struct xa_node *);
1115 #define XA_BUG_ON(xa, x) do { \
1121 #define XA_NODE_BUG_ON(node, x) do { \
1123 if (node) xa_dump_node(node); \
1128 #define XA_BUG_ON(xa, x) do { } while (0)
1129 #define XA_NODE_BUG_ON(node, x) do { } while (0)
1133 static inline void *xa_head(const struct xarray *xa)
1135 return rcu_dereference_check(xa->xa_head,
1136 lockdep_is_held(&xa->xa_lock));
1140 static inline void *xa_head_locked(const struct xarray *xa)
1142 return rcu_dereference_protected(xa->xa_head,
1143 lockdep_is_held(&xa->xa_lock));
1147 static inline void *xa_entry(const struct xarray *xa,
1148 const struct xa_node *node, unsigned int offset)
1150 XA_NODE_BUG_ON(node, offset >= XA_CHUNK_SIZE);
1151 return rcu_dereference_check(node->slots[offset],
1152 lockdep_is_held(&xa->xa_lock));
1156 static inline void *xa_entry_locked(const struct xarray *xa,
1157 const struct xa_node *node, unsigned int offset)
1159 XA_NODE_BUG_ON(node, offset >= XA_CHUNK_SIZE);
1160 return rcu_dereference_protected(node->slots[offset],
1161 lockdep_is_held(&xa->xa_lock));
1165 static inline struct xa_node *xa_parent(const struct xarray *xa,
1166 const struct xa_node *node)
1168 return rcu_dereference_check(node->parent,
1169 lockdep_is_held(&xa->xa_lock));
1173 static inline struct xa_node *xa_parent_locked(const struct xarray *xa,
1174 const struct xa_node *node)
1176 return rcu_dereference_protected(node->parent,
1177 lockdep_is_held(&xa->xa_lock));
1181 static inline void *xa_mk_node(const struct xa_node *node)
1183 return (void *)((unsigned long)node | 2);
1187 static inline struct xa_node *xa_to_node(const void *entry)
1189 return (struct xa_node *)((unsigned long)entry - 2);
1193 static inline bool xa_is_node(const void *entry)
1195 return xa_is_internal(entry) && (unsigned long)entry > 4096;
1199 static inline void *xa_mk_sibling(unsigned int offset)
1201 return xa_mk_internal(offset);
1205 static inline unsigned long xa_to_sibling(const void *entry)
1207 return xa_to_internal(entry);
1211 * xa_is_sibling() - Is the entry a sibling entry?
1212 * @entry: Entry retrieved from the XArray
1214 * Return: %true if the entry is a sibling entry.
1216 static inline bool xa_is_sibling(const void *entry)
1218 return IS_ENABLED(CONFIG_XARRAY_MULTI) && xa_is_internal(entry) &&
1219 (entry < xa_mk_sibling(XA_CHUNK_SIZE - 1));
1222 #define XA_RETRY_ENTRY xa_mk_internal(256)
1225 * xa_is_retry() - Is the entry a retry entry?
1226 * @entry: Entry retrieved from the XArray
1228 * Return: %true if the entry is a retry entry.
1230 static inline bool xa_is_retry(const void *entry)
1232 return unlikely(entry == XA_RETRY_ENTRY);
1236 * xa_is_advanced() - Is the entry only permitted for the advanced API?
1237 * @entry: Entry to be stored in the XArray.
1239 * Return: %true if the entry cannot be stored by the normal API.
1241 static inline bool xa_is_advanced(const void *entry)
1243 return xa_is_internal(entry) && (entry <= XA_RETRY_ENTRY);
1247 * typedef xa_update_node_t - A callback function from the XArray.
1248 * @node: The node which is being processed
1250 * This function is called every time the XArray updates the count of
1251 * present and value entries in a node. It allows advanced users to
1252 * maintain the private_list in the node.
1254 * Context: The xa_lock is held and interrupts may be disabled.
1255 * Implementations should not drop the xa_lock, nor re-enable
1258 typedef void (*xa_update_node_t)(struct xa_node *node);
1261 * The xa_state is opaque to its users. It contains various different pieces
1262 * of state involved in the current operation on the XArray. It should be
1263 * declared on the stack and passed between the various internal routines.
1264 * The various elements in it should not be accessed directly, but only
1265 * through the provided accessor functions. The below documentation is for
1266 * the benefit of those working on the code, not for users of the XArray.
1268 * @xa_node usually points to the xa_node containing the slot we're operating
1269 * on (and @xa_offset is the offset in the slots array). If there is a
1270 * single entry in the array at index 0, there are no allocated xa_nodes to
1271 * point to, and so we store %NULL in @xa_node. @xa_node is set to
1272 * the value %XAS_RESTART if the xa_state is not walked to the correct
1273 * position in the tree of nodes for this operation. If an error occurs
1274 * during an operation, it is set to an %XAS_ERROR value. If we run off the
1275 * end of the allocated nodes, it is set to %XAS_BOUNDS.
1279 unsigned long xa_index;
1280 unsigned char xa_shift;
1281 unsigned char xa_sibs;
1282 unsigned char xa_offset;
1283 unsigned char xa_pad; /* Helps gcc generate better code */
1284 struct xa_node *xa_node;
1285 struct xa_node *xa_alloc;
1286 xa_update_node_t xa_update;
1290 * We encode errnos in the xas->xa_node. If an error has happened, we need to
1291 * drop the lock to fix it, and once we've done so the xa_state is invalid.
1293 #define XA_ERROR(errno) ((struct xa_node *)(((unsigned long)errno << 2) | 2UL))
1294 #define XAS_BOUNDS ((struct xa_node *)1UL)
1295 #define XAS_RESTART ((struct xa_node *)3UL)
1297 #define __XA_STATE(array, index, shift, sibs) { \
1299 .xa_index = index, \
1300 .xa_shift = shift, \
1304 .xa_node = XAS_RESTART, \
1310 * XA_STATE() - Declare an XArray operation state.
1311 * @name: Name of this operation state (usually xas).
1312 * @array: Array to operate on.
1313 * @index: Initial index of interest.
1315 * Declare and initialise an xa_state on the stack.
1317 #define XA_STATE(name, array, index) \
1318 struct xa_state name = __XA_STATE(array, index, 0, 0)
1321 * XA_STATE_ORDER() - Declare an XArray operation state.
1322 * @name: Name of this operation state (usually xas).
1323 * @array: Array to operate on.
1324 * @index: Initial index of interest.
1325 * @order: Order of entry.
1327 * Declare and initialise an xa_state on the stack. This variant of
1328 * XA_STATE() allows you to specify the 'order' of the element you
1329 * want to operate on.`
1331 #define XA_STATE_ORDER(name, array, index, order) \
1332 struct xa_state name = __XA_STATE(array, \
1333 (index >> order) << order, \
1334 order - (order % XA_CHUNK_SHIFT), \
1335 (1U << (order % XA_CHUNK_SHIFT)) - 1)
1337 #define xas_marked(xas, mark) xa_marked((xas)->xa, (mark))
1338 #define xas_trylock(xas) xa_trylock((xas)->xa)
1339 #define xas_lock(xas) xa_lock((xas)->xa)
1340 #define xas_unlock(xas) xa_unlock((xas)->xa)
1341 #define xas_lock_bh(xas) xa_lock_bh((xas)->xa)
1342 #define xas_unlock_bh(xas) xa_unlock_bh((xas)->xa)
1343 #define xas_lock_irq(xas) xa_lock_irq((xas)->xa)
1344 #define xas_unlock_irq(xas) xa_unlock_irq((xas)->xa)
1345 #define xas_lock_irqsave(xas, flags) \
1346 xa_lock_irqsave((xas)->xa, flags)
1347 #define xas_unlock_irqrestore(xas, flags) \
1348 xa_unlock_irqrestore((xas)->xa, flags)
1351 * xas_error() - Return an errno stored in the xa_state.
1352 * @xas: XArray operation state.
1354 * Return: 0 if no error has been noted. A negative errno if one has.
1356 static inline int xas_error(const struct xa_state *xas)
1358 return xa_err(xas->xa_node);
1362 * xas_set_err() - Note an error in the xa_state.
1363 * @xas: XArray operation state.
1364 * @err: Negative error number.
1366 * Only call this function with a negative @err; zero or positive errors
1367 * will probably not behave the way you think they should. If you want
1368 * to clear the error from an xa_state, use xas_reset().
1370 static inline void xas_set_err(struct xa_state *xas, long err)
1372 xas->xa_node = XA_ERROR(err);
1376 * xas_invalid() - Is the xas in a retry or error state?
1377 * @xas: XArray operation state.
1379 * Return: %true if the xas cannot be used for operations.
1381 static inline bool xas_invalid(const struct xa_state *xas)
1383 return (unsigned long)xas->xa_node & 3;
1387 * xas_valid() - Is the xas a valid cursor into the array?
1388 * @xas: XArray operation state.
1390 * Return: %true if the xas can be used for operations.
1392 static inline bool xas_valid(const struct xa_state *xas)
1394 return !xas_invalid(xas);
1398 * xas_is_node() - Does the xas point to a node?
1399 * @xas: XArray operation state.
1401 * Return: %true if the xas currently references a node.
1403 static inline bool xas_is_node(const struct xa_state *xas)
1405 return xas_valid(xas) && xas->xa_node;
1408 /* True if the pointer is something other than a node */
1409 static inline bool xas_not_node(struct xa_node *node)
1411 return ((unsigned long)node & 3) || !node;
1414 /* True if the node represents RESTART or an error */
1415 static inline bool xas_frozen(struct xa_node *node)
1417 return (unsigned long)node & 2;
1420 /* True if the node represents head-of-tree, RESTART or BOUNDS */
1421 static inline bool xas_top(struct xa_node *node)
1423 return node <= XAS_RESTART;
1427 * xas_reset() - Reset an XArray operation state.
1428 * @xas: XArray operation state.
1430 * Resets the error or walk state of the @xas so future walks of the
1431 * array will start from the root. Use this if you have dropped the
1432 * xarray lock and want to reuse the xa_state.
1434 * Context: Any context.
1436 static inline void xas_reset(struct xa_state *xas)
1438 xas->xa_node = XAS_RESTART;
1442 * xas_retry() - Retry the operation if appropriate.
1443 * @xas: XArray operation state.
1444 * @entry: Entry from xarray.
1446 * The advanced functions may sometimes return an internal entry, such as
1447 * a retry entry or a zero entry. This function sets up the @xas to restart
1448 * the walk from the head of the array if needed.
1450 * Context: Any context.
1451 * Return: true if the operation needs to be retried.
1453 static inline bool xas_retry(struct xa_state *xas, const void *entry)
1455 if (xa_is_zero(entry))
1457 if (!xa_is_retry(entry))
1463 void *xas_load(struct xa_state *);
1464 void *xas_store(struct xa_state *, void *entry);
1465 void *xas_find(struct xa_state *, unsigned long max);
1466 void *xas_find_conflict(struct xa_state *);
1468 bool xas_get_mark(const struct xa_state *, xa_mark_t);
1469 void xas_set_mark(const struct xa_state *, xa_mark_t);
1470 void xas_clear_mark(const struct xa_state *, xa_mark_t);
1471 void *xas_find_marked(struct xa_state *, unsigned long max, xa_mark_t);
1472 void xas_init_marks(const struct xa_state *);
1474 bool xas_nomem(struct xa_state *, gfp_t);
1475 void xas_pause(struct xa_state *);
1477 void xas_create_range(struct xa_state *);
1480 * xas_reload() - Refetch an entry from the xarray.
1481 * @xas: XArray operation state.
1483 * Use this function to check that a previously loaded entry still has
1484 * the same value. This is useful for the lockless pagecache lookup where
1485 * we walk the array with only the RCU lock to protect us, lock the page,
1486 * then check that the page hasn't moved since we looked it up.
1488 * The caller guarantees that @xas is still valid. If it may be in an
1489 * error or restart state, call xas_load() instead.
1491 * Return: The entry at this location in the xarray.
1493 static inline void *xas_reload(struct xa_state *xas)
1495 struct xa_node *node = xas->xa_node;
1498 return xa_entry(xas->xa, node, xas->xa_offset);
1499 return xa_head(xas->xa);
1503 * xas_set() - Set up XArray operation state for a different index.
1504 * @xas: XArray operation state.
1505 * @index: New index into the XArray.
1507 * Move the operation state to refer to a different index. This will
1508 * have the effect of starting a walk from the top; see xas_next()
1509 * to move to an adjacent index.
1511 static inline void xas_set(struct xa_state *xas, unsigned long index)
1513 xas->xa_index = index;
1514 xas->xa_node = XAS_RESTART;
1518 * xas_set_order() - Set up XArray operation state for a multislot entry.
1519 * @xas: XArray operation state.
1520 * @index: Target of the operation.
1521 * @order: Entry occupies 2^@order indices.
1523 static inline void xas_set_order(struct xa_state *xas, unsigned long index,
1526 #ifdef CONFIG_XARRAY_MULTI
1527 xas->xa_index = order < BITS_PER_LONG ? (index >> order) << order : 0;
1528 xas->xa_shift = order - (order % XA_CHUNK_SHIFT);
1529 xas->xa_sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1;
1530 xas->xa_node = XAS_RESTART;
1533 xas_set(xas, index);
1538 * xas_set_update() - Set up XArray operation state for a callback.
1539 * @xas: XArray operation state.
1540 * @update: Function to call when updating a node.
1542 * The XArray can notify a caller after it has updated an xa_node.
1543 * This is advanced functionality and is only needed by the page cache.
1545 static inline void xas_set_update(struct xa_state *xas, xa_update_node_t update)
1547 xas->xa_update = update;
1551 * xas_next_entry() - Advance iterator to next present entry.
1552 * @xas: XArray operation state.
1553 * @max: Highest index to return.
1555 * xas_next_entry() is an inline function to optimise xarray traversal for
1556 * speed. It is equivalent to calling xas_find(), and will call xas_find()
1557 * for all the hard cases.
1559 * Return: The next present entry after the one currently referred to by @xas.
1561 static inline void *xas_next_entry(struct xa_state *xas, unsigned long max)
1563 struct xa_node *node = xas->xa_node;
1566 if (unlikely(xas_not_node(node) || node->shift ||
1567 xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)))
1568 return xas_find(xas, max);
1571 if (unlikely(xas->xa_index >= max))
1572 return xas_find(xas, max);
1573 if (unlikely(xas->xa_offset == XA_CHUNK_MASK))
1574 return xas_find(xas, max);
1575 entry = xa_entry(xas->xa, node, xas->xa_offset + 1);
1576 if (unlikely(xa_is_internal(entry)))
1577 return xas_find(xas, max);
1586 static inline unsigned int xas_find_chunk(struct xa_state *xas, bool advance,
1589 unsigned long *addr = xas->xa_node->marks[(__force unsigned)mark];
1590 unsigned int offset = xas->xa_offset;
1594 if (XA_CHUNK_SIZE == BITS_PER_LONG) {
1595 if (offset < XA_CHUNK_SIZE) {
1596 unsigned long data = *addr & (~0UL << offset);
1600 return XA_CHUNK_SIZE;
1603 return find_next_bit(addr, XA_CHUNK_SIZE, offset);
1607 * xas_next_marked() - Advance iterator to next marked entry.
1608 * @xas: XArray operation state.
1609 * @max: Highest index to return.
1610 * @mark: Mark to search for.
1612 * xas_next_marked() is an inline function to optimise xarray traversal for
1613 * speed. It is equivalent to calling xas_find_marked(), and will call
1614 * xas_find_marked() for all the hard cases.
1616 * Return: The next marked entry after the one currently referred to by @xas.
1618 static inline void *xas_next_marked(struct xa_state *xas, unsigned long max,
1621 struct xa_node *node = xas->xa_node;
1622 unsigned int offset;
1624 if (unlikely(xas_not_node(node) || node->shift))
1625 return xas_find_marked(xas, max, mark);
1626 offset = xas_find_chunk(xas, true, mark);
1627 xas->xa_offset = offset;
1628 xas->xa_index = (xas->xa_index & ~XA_CHUNK_MASK) + offset;
1629 if (xas->xa_index > max)
1631 if (offset == XA_CHUNK_SIZE)
1632 return xas_find_marked(xas, max, mark);
1633 return xa_entry(xas->xa, node, offset);
1637 * If iterating while holding a lock, drop the lock and reschedule
1638 * every %XA_CHECK_SCHED loops.
1641 XA_CHECK_SCHED = 4096,
1645 * xas_for_each() - Iterate over a range of an XArray.
1646 * @xas: XArray operation state.
1647 * @entry: Entry retrieved from the array.
1648 * @max: Maximum index to retrieve from array.
1650 * The loop body will be executed for each entry present in the xarray
1651 * between the current xas position and @max. @entry will be set to
1652 * the entry retrieved from the xarray. It is safe to delete entries
1653 * from the array in the loop body. You should hold either the RCU lock
1654 * or the xa_lock while iterating. If you need to drop the lock, call
1655 * xas_pause() first.
1657 #define xas_for_each(xas, entry, max) \
1658 for (entry = xas_find(xas, max); entry; \
1659 entry = xas_next_entry(xas, max))
1662 * xas_for_each_marked() - Iterate over a range of an XArray.
1663 * @xas: XArray operation state.
1664 * @entry: Entry retrieved from the array.
1665 * @max: Maximum index to retrieve from array.
1666 * @mark: Mark to search for.
1668 * The loop body will be executed for each marked entry in the xarray
1669 * between the current xas position and @max. @entry will be set to
1670 * the entry retrieved from the xarray. It is safe to delete entries
1671 * from the array in the loop body. You should hold either the RCU lock
1672 * or the xa_lock while iterating. If you need to drop the lock, call
1673 * xas_pause() first.
1675 #define xas_for_each_marked(xas, entry, max, mark) \
1676 for (entry = xas_find_marked(xas, max, mark); entry; \
1677 entry = xas_next_marked(xas, max, mark))
1680 * xas_for_each_conflict() - Iterate over a range of an XArray.
1681 * @xas: XArray operation state.
1682 * @entry: Entry retrieved from the array.
1684 * The loop body will be executed for each entry in the XArray that lies
1685 * within the range specified by @xas. If the loop completes successfully,
1686 * any entries that lie in this range will be replaced by @entry. The caller
1687 * may break out of the loop; if they do so, the contents of the XArray will
1688 * be unchanged. The operation may fail due to an out of memory condition.
1689 * The caller may also call xa_set_err() to exit the loop while setting an
1690 * error to record the reason.
1692 #define xas_for_each_conflict(xas, entry) \
1693 while ((entry = xas_find_conflict(xas)))
1695 void *__xas_next(struct xa_state *);
1696 void *__xas_prev(struct xa_state *);
1699 * xas_prev() - Move iterator to previous index.
1700 * @xas: XArray operation state.
1702 * If the @xas was in an error state, it will remain in an error state
1703 * and this function will return %NULL. If the @xas has never been walked,
1704 * it will have the effect of calling xas_load(). Otherwise one will be
1705 * subtracted from the index and the state will be walked to the correct
1706 * location in the array for the next operation.
1708 * If the iterator was referencing index 0, this function wraps
1709 * around to %ULONG_MAX.
1711 * Return: The entry at the new index. This may be %NULL or an internal
1714 static inline void *xas_prev(struct xa_state *xas)
1716 struct xa_node *node = xas->xa_node;
1718 if (unlikely(xas_not_node(node) || node->shift ||
1719 xas->xa_offset == 0))
1720 return __xas_prev(xas);
1724 return xa_entry(xas->xa, node, xas->xa_offset);
1728 * xas_next() - Move state to next index.
1729 * @xas: XArray operation state.
1731 * If the @xas was in an error state, it will remain in an error state
1732 * and this function will return %NULL. If the @xas has never been walked,
1733 * it will have the effect of calling xas_load(). Otherwise one will be
1734 * added to the index and the state will be walked to the correct
1735 * location in the array for the next operation.
1737 * If the iterator was referencing index %ULONG_MAX, this function wraps
1740 * Return: The entry at the new index. This may be %NULL or an internal
1743 static inline void *xas_next(struct xa_state *xas)
1745 struct xa_node *node = xas->xa_node;
1747 if (unlikely(xas_not_node(node) || node->shift ||
1748 xas->xa_offset == XA_CHUNK_MASK))
1749 return __xas_next(xas);
1753 return xa_entry(xas->xa, node, xas->xa_offset);
1755 #endif /* HAVE_RADIX_TREE_EXCEPTIONAL_ENTRY */
1757 #endif /* _LINUX_XARRAY_H */