1 /* SPDX-License-Identifier: GPL-2.0+ */
2 #ifndef _LINUX_XARRAY_H
3 #define _LINUX_XARRAY_H
4 /*
5  * eXtensible Arrays
6  * Copyright (c) 2017 Microsoft Corporation
7  * Author: Matthew Wilcox <willy@infradead.org>
8  *
9  * See Documentation/core-api/xarray.rst for how to use the XArray.
10  */
11 
12 #include <linux/bitmap.h>
13 #include <linux/bug.h>
14 #include <linux/compiler.h>
15 #include <linux/gfp.h>
16 #include <linux/kconfig.h>
17 #include <linux/kernel.h>
18 #include <linux/rcupdate.h>
19 #include <linux/sched/mm.h>
20 #include <linux/spinlock.h>
21 #include <linux/types.h>
22 
23 /*
24  * The bottom two bits of the entry determine how the XArray interprets
25  * the contents:
26  *
27  * 00: Pointer entry
28  * 10: Internal entry
29  * x1: Value entry or tagged pointer
30  *
31  * Attempting to store internal entries in the XArray is a bug.
32  *
33  * Most internal entries are pointers to the next node in the tree.
34  * The following internal entries have a special meaning:
35  *
36  * 0-62: Sibling entries
37  * 256: Retry entry
38  * 257: Zero entry
39  *
40  * Errors are also represented as internal entries, but use the negative
41  * space (-4094 to -2).  They're never stored in the slots array; only
42  * returned by the normal API.
43  */
44 
45 #define BITS_PER_XA_VALUE	(BITS_PER_LONG - 1)
46 
47 /**
48  * xa_mk_value() - Create an XArray entry from an integer.
49  * @v: Value to store in XArray.
50  *
51  * Context: Any context.
52  * Return: An entry suitable for storing in the XArray.
53  */
xa_mk_value(unsigned long v)54 static inline void *xa_mk_value(unsigned long v)
55 {
56 	WARN_ON((long)v < 0);
57 	return (void *)((v << 1) | 1);
58 }
59 
60 /**
61  * xa_to_value() - Get value stored in an XArray entry.
62  * @entry: XArray entry.
63  *
64  * Context: Any context.
65  * Return: The value stored in the XArray entry.
66  */
xa_to_value(const void * entry)67 static inline unsigned long xa_to_value(const void *entry)
68 {
69 	return (unsigned long)entry >> 1;
70 }
71 
72 /**
73  * xa_is_value() - Determine if an entry is a value.
74  * @entry: XArray entry.
75  *
76  * Context: Any context.
77  * Return: True if the entry is a value, false if it is a pointer.
78  */
xa_is_value(const void * entry)79 static inline bool xa_is_value(const void *entry)
80 {
81 	return (unsigned long)entry & 1;
82 }
83 
84 /**
85  * xa_tag_pointer() - Create an XArray entry for a tagged pointer.
86  * @p: Plain pointer.
87  * @tag: Tag value (0, 1 or 3).
88  *
89  * If the user of the XArray prefers, they can tag their pointers instead
90  * of storing value entries.  Three tags are available (0, 1 and 3).
91  * These are distinct from the xa_mark_t as they are not replicated up
92  * through the array and cannot be searched for.
93  *
94  * Context: Any context.
95  * Return: An XArray entry.
96  */
xa_tag_pointer(void * p,unsigned long tag)97 static inline void *xa_tag_pointer(void *p, unsigned long tag)
98 {
99 	return (void *)((unsigned long)p | tag);
100 }
101 
102 /**
103  * xa_untag_pointer() - Turn an XArray entry into a plain pointer.
104  * @entry: XArray entry.
105  *
106  * If you have stored a tagged pointer in the XArray, call this function
107  * to get the untagged version of the pointer.
108  *
109  * Context: Any context.
110  * Return: A pointer.
111  */
xa_untag_pointer(void * entry)112 static inline void *xa_untag_pointer(void *entry)
113 {
114 	return (void *)((unsigned long)entry & ~3UL);
115 }
116 
117 /**
118  * xa_pointer_tag() - Get the tag stored in an XArray entry.
119  * @entry: XArray entry.
120  *
121  * If you have stored a tagged pointer in the XArray, call this function
122  * to get the tag of that pointer.
123  *
124  * Context: Any context.
125  * Return: A tag.
126  */
xa_pointer_tag(void * entry)127 static inline unsigned int xa_pointer_tag(void *entry)
128 {
129 	return (unsigned long)entry & 3UL;
130 }
131 
132 /*
133  * xa_mk_internal() - Create an internal entry.
134  * @v: Value to turn into an internal entry.
135  *
136  * Internal entries are used for a number of purposes.  Entries 0-255 are
137  * used for sibling entries (only 0-62 are used by the current code).  256
138  * is used for the retry entry.  257 is used for the reserved / zero entry.
139  * Negative internal entries are used to represent errnos.  Node pointers
140  * are also tagged as internal entries in some situations.
141  *
142  * Context: Any context.
143  * Return: An XArray internal entry corresponding to this value.
144  */
xa_mk_internal(unsigned long v)145 static inline void *xa_mk_internal(unsigned long v)
146 {
147 	return (void *)((v << 2) | 2);
148 }
149 
150 /*
151  * xa_to_internal() - Extract the value from an internal entry.
152  * @entry: XArray entry.
153  *
154  * Context: Any context.
155  * Return: The value which was stored in the internal entry.
156  */
xa_to_internal(const void * entry)157 static inline unsigned long xa_to_internal(const void *entry)
158 {
159 	return (unsigned long)entry >> 2;
160 }
161 
162 /*
163  * xa_is_internal() - Is the entry an internal entry?
164  * @entry: XArray entry.
165  *
166  * Context: Any context.
167  * Return: %true if the entry is an internal entry.
168  */
xa_is_internal(const void * entry)169 static inline bool xa_is_internal(const void *entry)
170 {
171 	return ((unsigned long)entry & 3) == 2;
172 }
173 
174 #define XA_ZERO_ENTRY		xa_mk_internal(257)
175 
176 /**
177  * xa_is_zero() - Is the entry a zero entry?
178  * @entry: Entry retrieved from the XArray
179  *
180  * The normal API will return NULL as the contents of a slot containing
181  * a zero entry.  You can only see zero entries by using the advanced API.
182  *
183  * Return: %true if the entry is a zero entry.
184  */
xa_is_zero(const void * entry)185 static inline bool xa_is_zero(const void *entry)
186 {
187 	return unlikely(entry == XA_ZERO_ENTRY);
188 }
189 
190 /**
191  * xa_is_err() - Report whether an XArray operation returned an error
192  * @entry: Result from calling an XArray function
193  *
194  * If an XArray operation cannot complete an operation, it will return
195  * a special value indicating an error.  This function tells you
196  * whether an error occurred; xa_err() tells you which error occurred.
197  *
198  * Context: Any context.
199  * Return: %true if the entry indicates an error.
200  */
xa_is_err(const void * entry)201 static inline bool xa_is_err(const void *entry)
202 {
203 	return unlikely(xa_is_internal(entry) &&
204 			entry >= xa_mk_internal(-MAX_ERRNO));
205 }
206 
207 /**
208  * xa_err() - Turn an XArray result into an errno.
209  * @entry: Result from calling an XArray function.
210  *
211  * If an XArray operation cannot complete an operation, it will return
212  * a special pointer value which encodes an errno.  This function extracts
213  * the errno from the pointer value, or returns 0 if the pointer does not
214  * represent an errno.
215  *
216  * Context: Any context.
217  * Return: A negative errno or 0.
218  */
xa_err(void * entry)219 static inline int xa_err(void *entry)
220 {
221 	/* xa_to_internal() would not do sign extension. */
222 	if (xa_is_err(entry))
223 		return (long)entry >> 2;
224 	return 0;
225 }
226 
227 /**
228  * struct xa_limit - Represents a range of IDs.
229  * @min: The lowest ID to allocate (inclusive).
230  * @max: The maximum ID to allocate (inclusive).
231  *
232  * This structure is used either directly or via the XA_LIMIT() macro
233  * to communicate the range of IDs that are valid for allocation.
234  * Three common ranges are predefined for you:
235  * * xa_limit_32b	- [0 - UINT_MAX]
236  * * xa_limit_31b	- [0 - INT_MAX]
237  * * xa_limit_16b	- [0 - USHRT_MAX]
238  */
239 struct xa_limit {
240 	u32 max;
241 	u32 min;
242 };
243 
244 #define XA_LIMIT(_min, _max) (struct xa_limit) { .min = _min, .max = _max }
245 
246 #define xa_limit_32b	XA_LIMIT(0, UINT_MAX)
247 #define xa_limit_31b	XA_LIMIT(0, INT_MAX)
248 #define xa_limit_16b	XA_LIMIT(0, USHRT_MAX)
249 
250 typedef unsigned __bitwise xa_mark_t;
251 #define XA_MARK_0		((__force xa_mark_t)0U)
252 #define XA_MARK_1		((__force xa_mark_t)1U)
253 #define XA_MARK_2		((__force xa_mark_t)2U)
254 #define XA_PRESENT		((__force xa_mark_t)8U)
255 #define XA_MARK_MAX		XA_MARK_2
256 #define XA_FREE_MARK		XA_MARK_0
257 
258 enum xa_lock_type {
259 	XA_LOCK_IRQ = 1,
260 	XA_LOCK_BH = 2,
261 };
262 
263 /*
264  * Values for xa_flags.  The radix tree stores its GFP flags in the xa_flags,
265  * and we remain compatible with that.
266  */
267 #define XA_FLAGS_LOCK_IRQ	((__force gfp_t)XA_LOCK_IRQ)
268 #define XA_FLAGS_LOCK_BH	((__force gfp_t)XA_LOCK_BH)
269 #define XA_FLAGS_TRACK_FREE	((__force gfp_t)4U)
270 #define XA_FLAGS_ZERO_BUSY	((__force gfp_t)8U)
271 #define XA_FLAGS_ALLOC_WRAPPED	((__force gfp_t)16U)
272 #define XA_FLAGS_ACCOUNT	((__force gfp_t)32U)
273 #define XA_FLAGS_MARK(mark)	((__force gfp_t)((1U << __GFP_BITS_SHIFT) << \
274 						(__force unsigned)(mark)))
275 
276 /* ALLOC is for a normal 0-based alloc.  ALLOC1 is for an 1-based alloc */
277 #define XA_FLAGS_ALLOC	(XA_FLAGS_TRACK_FREE | XA_FLAGS_MARK(XA_FREE_MARK))
278 #define XA_FLAGS_ALLOC1	(XA_FLAGS_TRACK_FREE | XA_FLAGS_ZERO_BUSY)
279 
280 /**
281  * struct xarray - The anchor of the XArray.
282  * @xa_lock: Lock that protects the contents of the XArray.
283  *
284  * To use the xarray, define it statically or embed it in your data structure.
285  * It is a very small data structure, so it does not usually make sense to
286  * allocate it separately and keep a pointer to it in your data structure.
287  *
288  * You may use the xa_lock to protect your own data structures as well.
289  */
290 /*
291  * If all of the entries in the array are NULL, @xa_head is a NULL pointer.
292  * If the only non-NULL entry in the array is at index 0, @xa_head is that
293  * entry.  If any other entry in the array is non-NULL, @xa_head points
294  * to an @xa_node.
295  */
296 struct xarray {
297 	spinlock_t	xa_lock;
298 /* private: The rest of the data structure is not to be used directly. */
299 	gfp_t		xa_flags;
300 	void __rcu *	xa_head;
301 };
302 
303 #define XARRAY_INIT(name, flags) {				\
304 	.xa_lock = __SPIN_LOCK_UNLOCKED(name.xa_lock),		\
305 	.xa_flags = flags,					\
306 	.xa_head = NULL,					\
307 }
308 
309 /**
310  * DEFINE_XARRAY_FLAGS() - Define an XArray with custom flags.
311  * @name: A string that names your XArray.
312  * @flags: XA_FLAG values.
313  *
314  * This is intended for file scope definitions of XArrays.  It declares
315  * and initialises an empty XArray with the chosen name and flags.  It is
316  * equivalent to calling xa_init_flags() on the array, but it does the
317  * initialisation at compiletime instead of runtime.
318  */
319 #define DEFINE_XARRAY_FLAGS(name, flags)				\
320 	struct xarray name = XARRAY_INIT(name, flags)
321 
322 /**
323  * DEFINE_XARRAY() - Define an XArray.
324  * @name: A string that names your XArray.
325  *
326  * This is intended for file scope definitions of XArrays.  It declares
327  * and initialises an empty XArray with the chosen name.  It is equivalent
328  * to calling xa_init() on the array, but it does the initialisation at
329  * compiletime instead of runtime.
330  */
331 #define DEFINE_XARRAY(name) DEFINE_XARRAY_FLAGS(name, 0)
332 
333 /**
334  * DEFINE_XARRAY_ALLOC() - Define an XArray which allocates IDs starting at 0.
335  * @name: A string that names your XArray.
336  *
337  * This is intended for file scope definitions of allocating XArrays.
338  * See also DEFINE_XARRAY().
339  */
340 #define DEFINE_XARRAY_ALLOC(name) DEFINE_XARRAY_FLAGS(name, XA_FLAGS_ALLOC)
341 
342 /**
343  * DEFINE_XARRAY_ALLOC1() - Define an XArray which allocates IDs starting at 1.
344  * @name: A string that names your XArray.
345  *
346  * This is intended for file scope definitions of allocating XArrays.
347  * See also DEFINE_XARRAY().
348  */
349 #define DEFINE_XARRAY_ALLOC1(name) DEFINE_XARRAY_FLAGS(name, XA_FLAGS_ALLOC1)
350 
351 void *xa_load(struct xarray *, unsigned long index);
352 void *xa_store(struct xarray *, unsigned long index, void *entry, gfp_t);
353 void *xa_erase(struct xarray *, unsigned long index);
354 void *xa_store_range(struct xarray *, unsigned long first, unsigned long last,
355 			void *entry, gfp_t);
356 bool xa_get_mark(struct xarray *, unsigned long index, xa_mark_t);
357 void xa_set_mark(struct xarray *, unsigned long index, xa_mark_t);
358 void xa_clear_mark(struct xarray *, unsigned long index, xa_mark_t);
359 void *xa_find(struct xarray *xa, unsigned long *index,
360 		unsigned long max, xa_mark_t) __attribute__((nonnull(2)));
361 void *xa_find_after(struct xarray *xa, unsigned long *index,
362 		unsigned long max, xa_mark_t) __attribute__((nonnull(2)));
363 unsigned int xa_extract(struct xarray *, void **dst, unsigned long start,
364 		unsigned long max, unsigned int n, xa_mark_t);
365 void xa_destroy(struct xarray *);
366 
367 /**
368  * xa_init_flags() - Initialise an empty XArray with flags.
369  * @xa: XArray.
370  * @flags: XA_FLAG values.
371  *
372  * If you need to initialise an XArray with special flags (eg you need
373  * to take the lock from interrupt context), use this function instead
374  * of xa_init().
375  *
376  * Context: Any context.
377  */
xa_init_flags(struct xarray * xa,gfp_t flags)378 static inline void xa_init_flags(struct xarray *xa, gfp_t flags)
379 {
380 	spin_lock_init(&xa->xa_lock);
381 	xa->xa_flags = flags;
382 	xa->xa_head = NULL;
383 }
384 
385 /**
386  * xa_init() - Initialise an empty XArray.
387  * @xa: XArray.
388  *
389  * An empty XArray is full of NULL entries.
390  *
391  * Context: Any context.
392  */
xa_init(struct xarray * xa)393 static inline void xa_init(struct xarray *xa)
394 {
395 	xa_init_flags(xa, 0);
396 }
397 
398 /**
399  * xa_empty() - Determine if an array has any present entries.
400  * @xa: XArray.
401  *
402  * Context: Any context.
403  * Return: %true if the array contains only NULL pointers.
404  */
xa_empty(const struct xarray * xa)405 static inline bool xa_empty(const struct xarray *xa)
406 {
407 	return xa->xa_head == NULL;
408 }
409 
410 /**
411  * xa_marked() - Inquire whether any entry in this array has a mark set
412  * @xa: Array
413  * @mark: Mark value
414  *
415  * Context: Any context.
416  * Return: %true if any entry has this mark set.
417  */
xa_marked(const struct xarray * xa,xa_mark_t mark)418 static inline bool xa_marked(const struct xarray *xa, xa_mark_t mark)
419 {
420 	return xa->xa_flags & XA_FLAGS_MARK(mark);
421 }
422 
423 /**
424  * xa_for_each_range() - Iterate over a portion of an XArray.
425  * @xa: XArray.
426  * @index: Index of @entry.
427  * @entry: Entry retrieved from array.
428  * @start: First index to retrieve from array.
429  * @last: Last index to retrieve from array.
430  *
431  * During the iteration, @entry will have the value of the entry stored
432  * in @xa at @index.  You may modify @index during the iteration if you
433  * want to skip or reprocess indices.  It is safe to modify the array
434  * during the iteration.  At the end of the iteration, @entry will be set
435  * to NULL and @index will have a value less than or equal to max.
436  *
437  * xa_for_each_range() is O(n.log(n)) while xas_for_each() is O(n).  You have
438  * to handle your own locking with xas_for_each(), and if you have to unlock
439  * after each iteration, it will also end up being O(n.log(n)).
440  * xa_for_each_range() will spin if it hits a retry entry; if you intend to
441  * see retry entries, you should use the xas_for_each() iterator instead.
442  * The xas_for_each() iterator will expand into more inline code than
443  * xa_for_each_range().
444  *
445  * Context: Any context.  Takes and releases the RCU lock.
446  */
447 #define xa_for_each_range(xa, index, entry, start, last)		\
448 	for (index = start,						\
449 	     entry = xa_find(xa, &index, last, XA_PRESENT);		\
450 	     entry;							\
451 	     entry = xa_find_after(xa, &index, last, XA_PRESENT))
452 
453 /**
454  * xa_for_each_start() - Iterate over a portion of an XArray.
455  * @xa: XArray.
456  * @index: Index of @entry.
457  * @entry: Entry retrieved from array.
458  * @start: First index to retrieve from array.
459  *
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
462  * want to skip or reprocess indices.  It is safe to modify the array
463  * during the iteration.  At the end of the iteration, @entry will be set
464  * to NULL and @index will have a value less than or equal to max.
465  *
466  * xa_for_each_start() 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)).
469  * xa_for_each_start() will spin if it hits a retry entry; if you intend to
470  * see retry entries, you should use the xas_for_each() iterator instead.
471  * The xas_for_each() iterator will expand into more inline code than
472  * xa_for_each_start().
473  *
474  * Context: Any context.  Takes and releases the RCU lock.
475  */
476 #define xa_for_each_start(xa, index, entry, start) \
477 	xa_for_each_range(xa, index, entry, start, ULONG_MAX)
478 
479 /**
480  * xa_for_each() - Iterate over present entries in an XArray.
481  * @xa: XArray.
482  * @index: Index of @entry.
483  * @entry: Entry retrieved from array.
484  *
485  * During the iteration, @entry will have the value of the entry stored
486  * in @xa at @index.  You may modify @index during the iteration if you want
487  * to skip or reprocess indices.  It is safe to modify the array during the
488  * iteration.  At the end of the iteration, @entry will be set to NULL and
489  * @index will have a value less than or equal to max.
490  *
491  * xa_for_each() is O(n.log(n)) while xas_for_each() is O(n).  You have
492  * to handle your own locking with xas_for_each(), and if you have to unlock
493  * after each iteration, it will also end up being O(n.log(n)).  xa_for_each()
494  * will spin if it hits a retry entry; if you intend to see retry entries,
495  * you should use the xas_for_each() iterator instead.  The xas_for_each()
496  * iterator will expand into more inline code than xa_for_each().
497  *
498  * Context: Any context.  Takes and releases the RCU lock.
499  */
500 #define xa_for_each(xa, index, entry) \
501 	xa_for_each_start(xa, index, entry, 0)
502 
503 /**
504  * xa_for_each_marked() - Iterate over marked entries in an XArray.
505  * @xa: XArray.
506  * @index: Index of @entry.
507  * @entry: Entry retrieved from array.
508  * @filter: Selection criterion.
509  *
510  * During the iteration, @entry will have the value of the entry stored
511  * in @xa at @index.  The iteration will skip all entries in the array
512  * which do not match @filter.  You may modify @index during the iteration
513  * if you want to skip or reprocess indices.  It is safe to modify the array
514  * during the iteration.  At the end of the iteration, @entry will be set to
515  * NULL and @index will have a value less than or equal to max.
516  *
517  * xa_for_each_marked() is O(n.log(n)) while xas_for_each_marked() is O(n).
518  * You have to handle your own locking with xas_for_each(), and if you have
519  * to unlock after each iteration, it will also end up being O(n.log(n)).
520  * xa_for_each_marked() will spin if it hits a retry entry; if you intend to
521  * see retry entries, you should use the xas_for_each_marked() iterator
522  * instead.  The xas_for_each_marked() iterator will expand into more inline
523  * code than xa_for_each_marked().
524  *
525  * Context: Any context.  Takes and releases the RCU lock.
526  */
527 #define xa_for_each_marked(xa, index, entry, filter) \
528 	for (index = 0, entry = xa_find(xa, &index, ULONG_MAX, filter); \
529 	     entry; entry = xa_find_after(xa, &index, ULONG_MAX, filter))
530 
531 #define xa_trylock(xa)		spin_trylock(&(xa)->xa_lock)
532 #define xa_lock(xa)		spin_lock(&(xa)->xa_lock)
533 #define xa_unlock(xa)		spin_unlock(&(xa)->xa_lock)
534 #define xa_lock_bh(xa)		spin_lock_bh(&(xa)->xa_lock)
535 #define xa_unlock_bh(xa)	spin_unlock_bh(&(xa)->xa_lock)
536 #define xa_lock_irq(xa)		spin_lock_irq(&(xa)->xa_lock)
537 #define xa_unlock_irq(xa)	spin_unlock_irq(&(xa)->xa_lock)
538 #define xa_lock_irqsave(xa, flags) \
539 				spin_lock_irqsave(&(xa)->xa_lock, flags)
540 #define xa_unlock_irqrestore(xa, flags) \
541 				spin_unlock_irqrestore(&(xa)->xa_lock, flags)
542 #define xa_lock_nested(xa, subclass) \
543 				spin_lock_nested(&(xa)->xa_lock, subclass)
544 #define xa_lock_bh_nested(xa, subclass) \
545 				spin_lock_bh_nested(&(xa)->xa_lock, subclass)
546 #define xa_lock_irq_nested(xa, subclass) \
547 				spin_lock_irq_nested(&(xa)->xa_lock, subclass)
548 #define xa_lock_irqsave_nested(xa, flags, subclass) \
549 		spin_lock_irqsave_nested(&(xa)->xa_lock, flags, subclass)
550 
551 /*
552  * Versions of the normal API which require the caller to hold the
553  * xa_lock.  If the GFP flags allow it, they will drop the lock to
554  * allocate memory, then reacquire it afterwards.  These functions
555  * may also re-enable interrupts if the XArray flags indicate the
556  * locking should be interrupt safe.
557  */
558 void *__xa_erase(struct xarray *, unsigned long index);
559 void *__xa_store(struct xarray *, unsigned long index, void *entry, gfp_t);
560 void *__xa_cmpxchg(struct xarray *, unsigned long index, void *old,
561 		void *entry, gfp_t);
562 int __must_check __xa_insert(struct xarray *, unsigned long index,
563 		void *entry, gfp_t);
564 int __must_check __xa_alloc(struct xarray *, u32 *id, void *entry,
565 		struct xa_limit, gfp_t);
566 int __must_check __xa_alloc_cyclic(struct xarray *, u32 *id, void *entry,
567 		struct xa_limit, u32 *next, gfp_t);
568 void __xa_set_mark(struct xarray *, unsigned long index, xa_mark_t);
569 void __xa_clear_mark(struct xarray *, unsigned long index, xa_mark_t);
570 
571 /**
572  * xa_store_bh() - Store this entry in the XArray.
573  * @xa: XArray.
574  * @index: Index into array.
575  * @entry: New entry.
576  * @gfp: Memory allocation flags.
577  *
578  * This function is like calling xa_store() except it disables softirqs
579  * while holding the array lock.
580  *
581  * Context: Any context.  Takes and releases the xa_lock while
582  * disabling softirqs.
583  * Return: The old entry at this index or xa_err() if an error happened.
584  */
xa_store_bh(struct xarray * xa,unsigned long index,void * entry,gfp_t gfp)585 static inline void *xa_store_bh(struct xarray *xa, unsigned long index,
586 		void *entry, gfp_t gfp)
587 {
588 	void *curr;
589 
590 	might_alloc(gfp);
591 	xa_lock_bh(xa);
592 	curr = __xa_store(xa, index, entry, gfp);
593 	xa_unlock_bh(xa);
594 
595 	return curr;
596 }
597 
598 /**
599  * xa_store_irq() - Store this entry in the XArray.
600  * @xa: XArray.
601  * @index: Index into array.
602  * @entry: New entry.
603  * @gfp: Memory allocation flags.
604  *
605  * This function is like calling xa_store() except it disables interrupts
606  * while holding the array lock.
607  *
608  * Context: Process context.  Takes and releases the xa_lock while
609  * disabling interrupts.
610  * Return: The old entry at this index or xa_err() if an error happened.
611  */
xa_store_irq(struct xarray * xa,unsigned long index,void * entry,gfp_t gfp)612 static inline void *xa_store_irq(struct xarray *xa, unsigned long index,
613 		void *entry, gfp_t gfp)
614 {
615 	void *curr;
616 
617 	might_alloc(gfp);
618 	xa_lock_irq(xa);
619 	curr = __xa_store(xa, index, entry, gfp);
620 	xa_unlock_irq(xa);
621 
622 	return curr;
623 }
624 
625 /**
626  * xa_erase_bh() - Erase this entry from the XArray.
627  * @xa: XArray.
628  * @index: Index of entry.
629  *
630  * After this function returns, loading from @index will return %NULL.
631  * If the index is part of a multi-index entry, all indices will be erased
632  * and none of the entries will be part of a multi-index entry.
633  *
634  * Context: Any context.  Takes and releases the xa_lock while
635  * disabling softirqs.
636  * Return: The entry which used to be at this index.
637  */
xa_erase_bh(struct xarray * xa,unsigned long index)638 static inline void *xa_erase_bh(struct xarray *xa, unsigned long index)
639 {
640 	void *entry;
641 
642 	xa_lock_bh(xa);
643 	entry = __xa_erase(xa, index);
644 	xa_unlock_bh(xa);
645 
646 	return entry;
647 }
648 
649 /**
650  * xa_erase_irq() - Erase this entry from the XArray.
651  * @xa: XArray.
652  * @index: Index of entry.
653  *
654  * After this function returns, loading from @index will return %NULL.
655  * If the index is part of a multi-index entry, all indices will be erased
656  * and none of the entries will be part of a multi-index entry.
657  *
658  * Context: Process context.  Takes and releases the xa_lock while
659  * disabling interrupts.
660  * Return: The entry which used to be at this index.
661  */
xa_erase_irq(struct xarray * xa,unsigned long index)662 static inline void *xa_erase_irq(struct xarray *xa, unsigned long index)
663 {
664 	void *entry;
665 
666 	xa_lock_irq(xa);
667 	entry = __xa_erase(xa, index);
668 	xa_unlock_irq(xa);
669 
670 	return entry;
671 }
672 
673 /**
674  * xa_cmpxchg() - Conditionally replace an entry in the XArray.
675  * @xa: XArray.
676  * @index: Index into array.
677  * @old: Old value to test against.
678  * @entry: New value to place in array.
679  * @gfp: Memory allocation flags.
680  *
681  * If the entry at @index is the same as @old, replace it with @entry.
682  * If the return value is equal to @old, then the exchange was successful.
683  *
684  * Context: Any context.  Takes and releases the xa_lock.  May sleep
685  * if the @gfp flags permit.
686  * Return: The old value at this index or xa_err() if an error happened.
687  */
xa_cmpxchg(struct xarray * xa,unsigned long index,void * old,void * entry,gfp_t gfp)688 static inline void *xa_cmpxchg(struct xarray *xa, unsigned long index,
689 			void *old, void *entry, gfp_t gfp)
690 {
691 	void *curr;
692 
693 	might_alloc(gfp);
694 	xa_lock(xa);
695 	curr = __xa_cmpxchg(xa, index, old, entry, gfp);
696 	xa_unlock(xa);
697 
698 	return curr;
699 }
700 
701 /**
702  * xa_cmpxchg_bh() - Conditionally replace an entry in the XArray.
703  * @xa: XArray.
704  * @index: Index into array.
705  * @old: Old value to test against.
706  * @entry: New value to place in array.
707  * @gfp: Memory allocation flags.
708  *
709  * This function is like calling xa_cmpxchg() except it disables softirqs
710  * while holding the array lock.
711  *
712  * Context: Any context.  Takes and releases the xa_lock while
713  * disabling softirqs.  May sleep if the @gfp flags permit.
714  * Return: The old value at this index or xa_err() if an error happened.
715  */
xa_cmpxchg_bh(struct xarray * xa,unsigned long index,void * old,void * entry,gfp_t gfp)716 static inline void *xa_cmpxchg_bh(struct xarray *xa, unsigned long index,
717 			void *old, void *entry, gfp_t gfp)
718 {
719 	void *curr;
720 
721 	might_alloc(gfp);
722 	xa_lock_bh(xa);
723 	curr = __xa_cmpxchg(xa, index, old, entry, gfp);
724 	xa_unlock_bh(xa);
725 
726 	return curr;
727 }
728 
729 /**
730  * xa_cmpxchg_irq() - Conditionally replace an entry in the XArray.
731  * @xa: XArray.
732  * @index: Index into array.
733  * @old: Old value to test against.
734  * @entry: New value to place in array.
735  * @gfp: Memory allocation flags.
736  *
737  * This function is like calling xa_cmpxchg() except it disables interrupts
738  * while holding the array lock.
739  *
740  * Context: Process context.  Takes and releases the xa_lock while
741  * disabling interrupts.  May sleep if the @gfp flags permit.
742  * Return: The old value at this index or xa_err() if an error happened.
743  */
xa_cmpxchg_irq(struct xarray * xa,unsigned long index,void * old,void * entry,gfp_t gfp)744 static inline void *xa_cmpxchg_irq(struct xarray *xa, unsigned long index,
745 			void *old, void *entry, gfp_t gfp)
746 {
747 	void *curr;
748 
749 	might_alloc(gfp);
750 	xa_lock_irq(xa);
751 	curr = __xa_cmpxchg(xa, index, old, entry, gfp);
752 	xa_unlock_irq(xa);
753 
754 	return curr;
755 }
756 
757 /**
758  * xa_insert() - Store this entry in the XArray unless another entry is
759  *			already present.
760  * @xa: XArray.
761  * @index: Index into array.
762  * @entry: New entry.
763  * @gfp: Memory allocation flags.
764  *
765  * Inserting a NULL entry will store a reserved entry (like xa_reserve())
766  * if no entry is present.  Inserting will fail if a reserved entry is
767  * present, even though loading from this index will return NULL.
768  *
769  * Context: Any context.  Takes and releases the xa_lock.  May sleep if
770  * the @gfp flags permit.
771  * Return: 0 if the store succeeded.  -EBUSY if another entry was present.
772  * -ENOMEM if memory could not be allocated.
773  */
xa_insert(struct xarray * xa,unsigned long index,void * entry,gfp_t gfp)774 static inline int __must_check xa_insert(struct xarray *xa,
775 		unsigned long index, void *entry, gfp_t gfp)
776 {
777 	int err;
778 
779 	might_alloc(gfp);
780 	xa_lock(xa);
781 	err = __xa_insert(xa, index, entry, gfp);
782 	xa_unlock(xa);
783 
784 	return err;
785 }
786 
787 /**
788  * xa_insert_bh() - Store this entry in the XArray unless another entry is
789  *			already present.
790  * @xa: XArray.
791  * @index: Index into array.
792  * @entry: New entry.
793  * @gfp: Memory allocation flags.
794  *
795  * Inserting a NULL entry will store a reserved entry (like xa_reserve())
796  * if no entry is present.  Inserting will fail if a reserved entry is
797  * present, even though loading from this index will return NULL.
798  *
799  * Context: Any context.  Takes and releases the xa_lock while
800  * disabling softirqs.  May sleep if the @gfp flags permit.
801  * Return: 0 if the store succeeded.  -EBUSY if another entry was present.
802  * -ENOMEM if memory could not be allocated.
803  */
xa_insert_bh(struct xarray * xa,unsigned long index,void * entry,gfp_t gfp)804 static inline int __must_check xa_insert_bh(struct xarray *xa,
805 		unsigned long index, void *entry, gfp_t gfp)
806 {
807 	int err;
808 
809 	might_alloc(gfp);
810 	xa_lock_bh(xa);
811 	err = __xa_insert(xa, index, entry, gfp);
812 	xa_unlock_bh(xa);
813 
814 	return err;
815 }
816 
817 /**
818  * xa_insert_irq() - Store this entry in the XArray unless another entry is
819  *			already present.
820  * @xa: XArray.
821  * @index: Index into array.
822  * @entry: New entry.
823  * @gfp: Memory allocation flags.
824  *
825  * Inserting a NULL entry will store a reserved entry (like xa_reserve())
826  * if no entry is present.  Inserting will fail if a reserved entry is
827  * present, even though loading from this index will return NULL.
828  *
829  * Context: Process context.  Takes and releases the xa_lock while
830  * disabling interrupts.  May sleep if the @gfp flags permit.
831  * Return: 0 if the store succeeded.  -EBUSY if another entry was present.
832  * -ENOMEM if memory could not be allocated.
833  */
xa_insert_irq(struct xarray * xa,unsigned long index,void * entry,gfp_t gfp)834 static inline int __must_check xa_insert_irq(struct xarray *xa,
835 		unsigned long index, void *entry, gfp_t gfp)
836 {
837 	int err;
838 
839 	might_alloc(gfp);
840 	xa_lock_irq(xa);
841 	err = __xa_insert(xa, index, entry, gfp);
842 	xa_unlock_irq(xa);
843 
844 	return err;
845 }
846 
847 /**
848  * xa_alloc() - Find somewhere to store this entry in the XArray.
849  * @xa: XArray.
850  * @id: Pointer to ID.
851  * @entry: New entry.
852  * @limit: Range of ID to allocate.
853  * @gfp: Memory allocation flags.
854  *
855  * Finds an empty entry in @xa between @limit.min and @limit.max,
856  * stores the index into the @id pointer, then stores the entry at
857  * that index.  A concurrent lookup will not see an uninitialised @id.
858  *
859  * Context: Any context.  Takes and releases the xa_lock.  May sleep if
860  * the @gfp flags permit.
861  * Return: 0 on success, -ENOMEM if memory could not be allocated or
862  * -EBUSY if there are no free entries in @limit.
863  */
xa_alloc(struct xarray * xa,u32 * id,void * entry,struct xa_limit limit,gfp_t gfp)864 static inline __must_check int xa_alloc(struct xarray *xa, u32 *id,
865 		void *entry, struct xa_limit limit, gfp_t gfp)
866 {
867 	int err;
868 
869 	might_alloc(gfp);
870 	xa_lock(xa);
871 	err = __xa_alloc(xa, id, entry, limit, gfp);
872 	xa_unlock(xa);
873 
874 	return err;
875 }
876 
877 /**
878  * xa_alloc_bh() - Find somewhere to store this entry in the XArray.
879  * @xa: XArray.
880  * @id: Pointer to ID.
881  * @entry: New entry.
882  * @limit: Range of ID to allocate.
883  * @gfp: Memory allocation flags.
884  *
885  * Finds an empty entry in @xa between @limit.min and @limit.max,
886  * stores the index into the @id pointer, then stores the entry at
887  * that index.  A concurrent lookup will not see an uninitialised @id.
888  *
889  * Context: Any context.  Takes and releases the xa_lock while
890  * disabling softirqs.  May sleep if the @gfp flags permit.
891  * Return: 0 on success, -ENOMEM if memory could not be allocated or
892  * -EBUSY if there are no free entries in @limit.
893  */
xa_alloc_bh(struct xarray * xa,u32 * id,void * entry,struct xa_limit limit,gfp_t gfp)894 static inline int __must_check xa_alloc_bh(struct xarray *xa, u32 *id,
895 		void *entry, struct xa_limit limit, gfp_t gfp)
896 {
897 	int err;
898 
899 	might_alloc(gfp);
900 	xa_lock_bh(xa);
901 	err = __xa_alloc(xa, id, entry, limit, gfp);
902 	xa_unlock_bh(xa);
903 
904 	return err;
905 }
906 
907 /**
908  * xa_alloc_irq() - Find somewhere to store this entry in the XArray.
909  * @xa: XArray.
910  * @id: Pointer to ID.
911  * @entry: New entry.
912  * @limit: Range of ID to allocate.
913  * @gfp: Memory allocation flags.
914  *
915  * Finds an empty entry in @xa between @limit.min and @limit.max,
916  * stores the index into the @id pointer, then stores the entry at
917  * that index.  A concurrent lookup will not see an uninitialised @id.
918  *
919  * Context: Process context.  Takes and releases the xa_lock while
920  * disabling interrupts.  May sleep if the @gfp flags permit.
921  * Return: 0 on success, -ENOMEM if memory could not be allocated or
922  * -EBUSY if there are no free entries in @limit.
923  */
xa_alloc_irq(struct xarray * xa,u32 * id,void * entry,struct xa_limit limit,gfp_t gfp)924 static inline int __must_check xa_alloc_irq(struct xarray *xa, u32 *id,
925 		void *entry, struct xa_limit limit, gfp_t gfp)
926 {
927 	int err;
928 
929 	might_alloc(gfp);
930 	xa_lock_irq(xa);
931 	err = __xa_alloc(xa, id, entry, limit, gfp);
932 	xa_unlock_irq(xa);
933 
934 	return err;
935 }
936 
937 /**
938  * xa_alloc_cyclic() - Find somewhere to store this entry in the XArray.
939  * @xa: XArray.
940  * @id: Pointer to ID.
941  * @entry: New entry.
942  * @limit: Range of allocated ID.
943  * @next: Pointer to next ID to allocate.
944  * @gfp: Memory allocation flags.
945  *
946  * Finds an empty entry in @xa between @limit.min and @limit.max,
947  * stores the index into the @id pointer, then stores the entry at
948  * that index.  A concurrent lookup will not see an uninitialised @id.
949  * The search for an empty entry will start at @next and will wrap
950  * around if necessary.
951  *
952  * Context: Any context.  Takes and releases the xa_lock.  May sleep if
953  * the @gfp flags permit.
954  * Return: 0 if the allocation succeeded without wrapping.  1 if the
955  * allocation succeeded after wrapping, -ENOMEM if memory could not be
956  * allocated or -EBUSY if there are no free entries in @limit.
957  */
xa_alloc_cyclic(struct xarray * xa,u32 * id,void * entry,struct xa_limit limit,u32 * next,gfp_t gfp)958 static inline int xa_alloc_cyclic(struct xarray *xa, u32 *id, void *entry,
959 		struct xa_limit limit, u32 *next, gfp_t gfp)
960 {
961 	int err;
962 
963 	might_alloc(gfp);
964 	xa_lock(xa);
965 	err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
966 	xa_unlock(xa);
967 
968 	return err;
969 }
970 
971 /**
972  * xa_alloc_cyclic_bh() - Find somewhere to store this entry in the XArray.
973  * @xa: XArray.
974  * @id: Pointer to ID.
975  * @entry: New entry.
976  * @limit: Range of allocated ID.
977  * @next: Pointer to next ID to allocate.
978  * @gfp: Memory allocation flags.
979  *
980  * Finds an empty entry in @xa between @limit.min and @limit.max,
981  * stores the index into the @id pointer, then stores the entry at
982  * that index.  A concurrent lookup will not see an uninitialised @id.
983  * The search for an empty entry will start at @next and will wrap
984  * around if necessary.
985  *
986  * Context: Any context.  Takes and releases the xa_lock while
987  * disabling softirqs.  May sleep if the @gfp flags permit.
988  * Return: 0 if the allocation succeeded without wrapping.  1 if the
989  * allocation succeeded after wrapping, -ENOMEM if memory could not be
990  * allocated or -EBUSY if there are no free entries in @limit.
991  */
xa_alloc_cyclic_bh(struct xarray * xa,u32 * id,void * entry,struct xa_limit limit,u32 * next,gfp_t gfp)992 static inline int xa_alloc_cyclic_bh(struct xarray *xa, u32 *id, void *entry,
993 		struct xa_limit limit, u32 *next, gfp_t gfp)
994 {
995 	int err;
996 
997 	might_alloc(gfp);
998 	xa_lock_bh(xa);
999 	err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
1000 	xa_unlock_bh(xa);
1001 
1002 	return err;
1003 }
1004 
1005 /**
1006  * xa_alloc_cyclic_irq() - Find somewhere to store this entry in the XArray.
1007  * @xa: XArray.
1008  * @id: Pointer to ID.
1009  * @entry: New entry.
1010  * @limit: Range of allocated ID.
1011  * @next: Pointer to next ID to allocate.
1012  * @gfp: Memory allocation flags.
1013  *
1014  * Finds an empty entry in @xa between @limit.min and @limit.max,
1015  * stores the index into the @id pointer, then stores the entry at
1016  * that index.  A concurrent lookup will not see an uninitialised @id.
1017  * The search for an empty entry will start at @next and will wrap
1018  * around if necessary.
1019  *
1020  * Context: Process context.  Takes and releases the xa_lock while
1021  * disabling interrupts.  May sleep if the @gfp flags permit.
1022  * Return: 0 if the allocation succeeded without wrapping.  1 if the
1023  * allocation succeeded after wrapping, -ENOMEM if memory could not be
1024  * allocated or -EBUSY if there are no free entries in @limit.
1025  */
xa_alloc_cyclic_irq(struct xarray * xa,u32 * id,void * entry,struct xa_limit limit,u32 * next,gfp_t gfp)1026 static inline int xa_alloc_cyclic_irq(struct xarray *xa, u32 *id, void *entry,
1027 		struct xa_limit limit, u32 *next, gfp_t gfp)
1028 {
1029 	int err;
1030 
1031 	might_alloc(gfp);
1032 	xa_lock_irq(xa);
1033 	err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
1034 	xa_unlock_irq(xa);
1035 
1036 	return err;
1037 }
1038 
1039 /**
1040  * xa_reserve() - Reserve this index in the XArray.
1041  * @xa: XArray.
1042  * @index: Index into array.
1043  * @gfp: Memory allocation flags.
1044  *
1045  * Ensures there is somewhere to store an entry at @index in the array.
1046  * If there is already something stored at @index, this function does
1047  * nothing.  If there was nothing there, the entry is marked as reserved.
1048  * Loading from a reserved entry returns a %NULL pointer.
1049  *
1050  * If you do not use the entry that you have reserved, call xa_release()
1051  * or xa_erase() to free any unnecessary memory.
1052  *
1053  * Context: Any context.  Takes and releases the xa_lock.
1054  * May sleep if the @gfp flags permit.
1055  * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
1056  */
1057 static inline __must_check
xa_reserve(struct xarray * xa,unsigned long index,gfp_t gfp)1058 int xa_reserve(struct xarray *xa, unsigned long index, gfp_t gfp)
1059 {
1060 	return xa_err(xa_cmpxchg(xa, index, NULL, XA_ZERO_ENTRY, gfp));
1061 }
1062 
1063 /**
1064  * xa_reserve_bh() - Reserve this index in the XArray.
1065  * @xa: XArray.
1066  * @index: Index into array.
1067  * @gfp: Memory allocation flags.
1068  *
1069  * A softirq-disabling version of xa_reserve().
1070  *
1071  * Context: Any context.  Takes and releases the xa_lock while
1072  * disabling softirqs.
1073  * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
1074  */
1075 static inline __must_check
xa_reserve_bh(struct xarray * xa,unsigned long index,gfp_t gfp)1076 int xa_reserve_bh(struct xarray *xa, unsigned long index, gfp_t gfp)
1077 {
1078 	return xa_err(xa_cmpxchg_bh(xa, index, NULL, XA_ZERO_ENTRY, gfp));
1079 }
1080 
1081 /**
1082  * xa_reserve_irq() - Reserve this index in the XArray.
1083  * @xa: XArray.
1084  * @index: Index into array.
1085  * @gfp: Memory allocation flags.
1086  *
1087  * An interrupt-disabling version of xa_reserve().
1088  *
1089  * Context: Process context.  Takes and releases the xa_lock while
1090  * disabling interrupts.
1091  * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
1092  */
1093 static inline __must_check
xa_reserve_irq(struct xarray * xa,unsigned long index,gfp_t gfp)1094 int xa_reserve_irq(struct xarray *xa, unsigned long index, gfp_t gfp)
1095 {
1096 	return xa_err(xa_cmpxchg_irq(xa, index, NULL, XA_ZERO_ENTRY, gfp));
1097 }
1098 
1099 /**
1100  * xa_release() - Release a reserved entry.
1101  * @xa: XArray.
1102  * @index: Index of entry.
1103  *
1104  * After calling xa_reserve(), you can call this function to release the
1105  * reservation.  If the entry at @index has been stored to, this function
1106  * will do nothing.
1107  */
xa_release(struct xarray * xa,unsigned long index)1108 static inline void xa_release(struct xarray *xa, unsigned long index)
1109 {
1110 	xa_cmpxchg(xa, index, XA_ZERO_ENTRY, NULL, 0);
1111 }
1112 
1113 /* Everything below here is the Advanced API.  Proceed with caution. */
1114 
1115 /*
1116  * The xarray is constructed out of a set of 'chunks' of pointers.  Choosing
1117  * the best chunk size requires some tradeoffs.  A power of two recommends
1118  * itself so that we can walk the tree based purely on shifts and masks.
1119  * Generally, the larger the better; as the number of slots per level of the
1120  * tree increases, the less tall the tree needs to be.  But that needs to be
1121  * balanced against the memory consumption of each node.  On a 64-bit system,
1122  * xa_node is currently 576 bytes, and we get 7 of them per 4kB page.  If we
1123  * doubled the number of slots per node, we'd get only 3 nodes per 4kB page.
1124  */
1125 #ifndef XA_CHUNK_SHIFT
1126 #define XA_CHUNK_SHIFT		(CONFIG_BASE_SMALL ? 4 : 6)
1127 #endif
1128 #define XA_CHUNK_SIZE		(1UL << XA_CHUNK_SHIFT)
1129 #define XA_CHUNK_MASK		(XA_CHUNK_SIZE - 1)
1130 #define XA_MAX_MARKS		3
1131 #define XA_MARK_LONGS		DIV_ROUND_UP(XA_CHUNK_SIZE, BITS_PER_LONG)
1132 
1133 /*
1134  * @count is the count of every non-NULL element in the ->slots array
1135  * whether that is a value entry, a retry entry, a user pointer,
1136  * a sibling entry or a pointer to the next level of the tree.
1137  * @nr_values is the count of every element in ->slots which is
1138  * either a value entry or a sibling of a value entry.
1139  */
1140 struct xa_node {
1141 	unsigned char	shift;		/* Bits remaining in each slot */
1142 	unsigned char	offset;		/* Slot offset in parent */
1143 	unsigned char	count;		/* Total entry count */
1144 	unsigned char	nr_values;	/* Value entry count */
1145 	struct xa_node __rcu *parent;	/* NULL at top of tree */
1146 	struct xarray	*array;		/* The array we belong to */
1147 	union {
1148 		struct list_head private_list;	/* For tree user */
1149 		struct rcu_head	rcu_head;	/* Used when freeing node */
1150 	};
1151 	void __rcu	*slots[XA_CHUNK_SIZE];
1152 	union {
1153 		unsigned long	tags[XA_MAX_MARKS][XA_MARK_LONGS];
1154 		unsigned long	marks[XA_MAX_MARKS][XA_MARK_LONGS];
1155 	};
1156 };
1157 
1158 void xa_dump(const struct xarray *);
1159 void xa_dump_node(const struct xa_node *);
1160 
1161 #ifdef XA_DEBUG
1162 #define XA_BUG_ON(xa, x) do {					\
1163 		if (x) {					\
1164 			xa_dump(xa);				\
1165 			BUG();					\
1166 		}						\
1167 	} while (0)
1168 #define XA_NODE_BUG_ON(node, x) do {				\
1169 		if (x) {					\
1170 			if (node) xa_dump_node(node);		\
1171 			BUG();					\
1172 		}						\
1173 	} while (0)
1174 #else
1175 #define XA_BUG_ON(xa, x)	do { } while (0)
1176 #define XA_NODE_BUG_ON(node, x)	do { } while (0)
1177 #endif
1178 
1179 /* Private */
xa_head(const struct xarray * xa)1180 static inline void *xa_head(const struct xarray *xa)
1181 {
1182 	return rcu_dereference_check(xa->xa_head,
1183 						lockdep_is_held(&xa->xa_lock));
1184 }
1185 
1186 /* Private */
xa_head_locked(const struct xarray * xa)1187 static inline void *xa_head_locked(const struct xarray *xa)
1188 {
1189 	return rcu_dereference_protected(xa->xa_head,
1190 						lockdep_is_held(&xa->xa_lock));
1191 }
1192 
1193 /* Private */
xa_entry(const struct xarray * xa,const struct xa_node * node,unsigned int offset)1194 static inline void *xa_entry(const struct xarray *xa,
1195 				const struct xa_node *node, unsigned int offset)
1196 {
1197 	XA_NODE_BUG_ON(node, offset >= XA_CHUNK_SIZE);
1198 	return rcu_dereference_check(node->slots[offset],
1199 						lockdep_is_held(&xa->xa_lock));
1200 }
1201 
1202 /* Private */
xa_entry_locked(const struct xarray * xa,const struct xa_node * node,unsigned int offset)1203 static inline void *xa_entry_locked(const struct xarray *xa,
1204 				const struct xa_node *node, unsigned int offset)
1205 {
1206 	XA_NODE_BUG_ON(node, offset >= XA_CHUNK_SIZE);
1207 	return rcu_dereference_protected(node->slots[offset],
1208 						lockdep_is_held(&xa->xa_lock));
1209 }
1210 
1211 /* Private */
xa_parent(const struct xarray * xa,const struct xa_node * node)1212 static inline struct xa_node *xa_parent(const struct xarray *xa,
1213 					const struct xa_node *node)
1214 {
1215 	return rcu_dereference_check(node->parent,
1216 						lockdep_is_held(&xa->xa_lock));
1217 }
1218 
1219 /* Private */
xa_parent_locked(const struct xarray * xa,const struct xa_node * node)1220 static inline struct xa_node *xa_parent_locked(const struct xarray *xa,
1221 					const struct xa_node *node)
1222 {
1223 	return rcu_dereference_protected(node->parent,
1224 						lockdep_is_held(&xa->xa_lock));
1225 }
1226 
1227 /* Private */
xa_mk_node(const struct xa_node * node)1228 static inline void *xa_mk_node(const struct xa_node *node)
1229 {
1230 	return (void *)((unsigned long)node | 2);
1231 }
1232 
1233 /* Private */
xa_to_node(const void * entry)1234 static inline struct xa_node *xa_to_node(const void *entry)
1235 {
1236 	return (struct xa_node *)((unsigned long)entry - 2);
1237 }
1238 
1239 /* Private */
xa_is_node(const void * entry)1240 static inline bool xa_is_node(const void *entry)
1241 {
1242 	return xa_is_internal(entry) && (unsigned long)entry > 4096;
1243 }
1244 
1245 /* Private */
xa_mk_sibling(unsigned int offset)1246 static inline void *xa_mk_sibling(unsigned int offset)
1247 {
1248 	return xa_mk_internal(offset);
1249 }
1250 
1251 /* Private */
xa_to_sibling(const void * entry)1252 static inline unsigned long xa_to_sibling(const void *entry)
1253 {
1254 	return xa_to_internal(entry);
1255 }
1256 
1257 /**
1258  * xa_is_sibling() - Is the entry a sibling entry?
1259  * @entry: Entry retrieved from the XArray
1260  *
1261  * Return: %true if the entry is a sibling entry.
1262  */
xa_is_sibling(const void * entry)1263 static inline bool xa_is_sibling(const void *entry)
1264 {
1265 	return IS_ENABLED(CONFIG_XARRAY_MULTI) && xa_is_internal(entry) &&
1266 		(entry < xa_mk_sibling(XA_CHUNK_SIZE - 1));
1267 }
1268 
1269 #define XA_RETRY_ENTRY		xa_mk_internal(256)
1270 
1271 /**
1272  * xa_is_retry() - Is the entry a retry entry?
1273  * @entry: Entry retrieved from the XArray
1274  *
1275  * Return: %true if the entry is a retry entry.
1276  */
xa_is_retry(const void * entry)1277 static inline bool xa_is_retry(const void *entry)
1278 {
1279 	return unlikely(entry == XA_RETRY_ENTRY);
1280 }
1281 
1282 /**
1283  * xa_is_advanced() - Is the entry only permitted for the advanced API?
1284  * @entry: Entry to be stored in the XArray.
1285  *
1286  * Return: %true if the entry cannot be stored by the normal API.
1287  */
xa_is_advanced(const void * entry)1288 static inline bool xa_is_advanced(const void *entry)
1289 {
1290 	return xa_is_internal(entry) && (entry <= XA_RETRY_ENTRY);
1291 }
1292 
1293 /**
1294  * typedef xa_update_node_t - A callback function from the XArray.
1295  * @node: The node which is being processed
1296  *
1297  * This function is called every time the XArray updates the count of
1298  * present and value entries in a node.  It allows advanced users to
1299  * maintain the private_list in the node.
1300  *
1301  * Context: The xa_lock is held and interrupts may be disabled.
1302  *	    Implementations should not drop the xa_lock, nor re-enable
1303  *	    interrupts.
1304  */
1305 typedef void (*xa_update_node_t)(struct xa_node *node);
1306 
1307 void xa_delete_node(struct xa_node *, xa_update_node_t);
1308 
1309 /*
1310  * The xa_state is opaque to its users.  It contains various different pieces
1311  * of state involved in the current operation on the XArray.  It should be
1312  * declared on the stack and passed between the various internal routines.
1313  * The various elements in it should not be accessed directly, but only
1314  * through the provided accessor functions.  The below documentation is for
1315  * the benefit of those working on the code, not for users of the XArray.
1316  *
1317  * @xa_node usually points to the xa_node containing the slot we're operating
1318  * on (and @xa_offset is the offset in the slots array).  If there is a
1319  * single entry in the array at index 0, there are no allocated xa_nodes to
1320  * point to, and so we store %NULL in @xa_node.  @xa_node is set to
1321  * the value %XAS_RESTART if the xa_state is not walked to the correct
1322  * position in the tree of nodes for this operation.  If an error occurs
1323  * during an operation, it is set to an %XAS_ERROR value.  If we run off the
1324  * end of the allocated nodes, it is set to %XAS_BOUNDS.
1325  */
1326 struct xa_state {
1327 	struct xarray *xa;
1328 	unsigned long xa_index;
1329 	unsigned char xa_shift;
1330 	unsigned char xa_sibs;
1331 	unsigned char xa_offset;
1332 	unsigned char xa_pad;		/* Helps gcc generate better code */
1333 	struct xa_node *xa_node;
1334 	struct xa_node *xa_alloc;
1335 	xa_update_node_t xa_update;
1336 	struct list_lru *xa_lru;
1337 };
1338 
1339 /*
1340  * We encode errnos in the xas->xa_node.  If an error has happened, we need to
1341  * drop the lock to fix it, and once we've done so the xa_state is invalid.
1342  */
1343 #define XA_ERROR(errno) ((struct xa_node *)(((unsigned long)errno << 2) | 2UL))
1344 #define XAS_BOUNDS	((struct xa_node *)1UL)
1345 #define XAS_RESTART	((struct xa_node *)3UL)
1346 
1347 #define __XA_STATE(array, index, shift, sibs)  {	\
1348 	.xa = array,					\
1349 	.xa_index = index,				\
1350 	.xa_shift = shift,				\
1351 	.xa_sibs = sibs,				\
1352 	.xa_offset = 0,					\
1353 	.xa_pad = 0,					\
1354 	.xa_node = XAS_RESTART,				\
1355 	.xa_alloc = NULL,				\
1356 	.xa_update = NULL,				\
1357 	.xa_lru = NULL,					\
1358 }
1359 
1360 /**
1361  * XA_STATE() - Declare an XArray operation state.
1362  * @name: Name of this operation state (usually xas).
1363  * @array: Array to operate on.
1364  * @index: Initial index of interest.
1365  *
1366  * Declare and initialise an xa_state on the stack.
1367  */
1368 #define XA_STATE(name, array, index)				\
1369 	struct xa_state name = __XA_STATE(array, index, 0, 0)
1370 
1371 /**
1372  * XA_STATE_ORDER() - Declare an XArray operation state.
1373  * @name: Name of this operation state (usually xas).
1374  * @array: Array to operate on.
1375  * @index: Initial index of interest.
1376  * @order: Order of entry.
1377  *
1378  * Declare and initialise an xa_state on the stack.  This variant of
1379  * XA_STATE() allows you to specify the 'order' of the element you
1380  * want to operate on.`
1381  */
1382 #define XA_STATE_ORDER(name, array, index, order)		\
1383 	struct xa_state name = __XA_STATE(array,		\
1384 			(index >> order) << order,		\
1385 			order - (order % XA_CHUNK_SHIFT),	\
1386 			(1U << (order % XA_CHUNK_SHIFT)) - 1)
1387 
1388 #define xas_marked(xas, mark)	xa_marked((xas)->xa, (mark))
1389 #define xas_trylock(xas)	xa_trylock((xas)->xa)
1390 #define xas_lock(xas)		xa_lock((xas)->xa)
1391 #define xas_unlock(xas)		xa_unlock((xas)->xa)
1392 #define xas_lock_bh(xas)	xa_lock_bh((xas)->xa)
1393 #define xas_unlock_bh(xas)	xa_unlock_bh((xas)->xa)
1394 #define xas_lock_irq(xas)	xa_lock_irq((xas)->xa)
1395 #define xas_unlock_irq(xas)	xa_unlock_irq((xas)->xa)
1396 #define xas_lock_irqsave(xas, flags) \
1397 				xa_lock_irqsave((xas)->xa, flags)
1398 #define xas_unlock_irqrestore(xas, flags) \
1399 				xa_unlock_irqrestore((xas)->xa, flags)
1400 
1401 /**
1402  * xas_error() - Return an errno stored in the xa_state.
1403  * @xas: XArray operation state.
1404  *
1405  * Return: 0 if no error has been noted.  A negative errno if one has.
1406  */
xas_error(const struct xa_state * xas)1407 static inline int xas_error(const struct xa_state *xas)
1408 {
1409 	return xa_err(xas->xa_node);
1410 }
1411 
1412 /**
1413  * xas_set_err() - Note an error in the xa_state.
1414  * @xas: XArray operation state.
1415  * @err: Negative error number.
1416  *
1417  * Only call this function with a negative @err; zero or positive errors
1418  * will probably not behave the way you think they should.  If you want
1419  * to clear the error from an xa_state, use xas_reset().
1420  */
xas_set_err(struct xa_state * xas,long err)1421 static inline void xas_set_err(struct xa_state *xas, long err)
1422 {
1423 	xas->xa_node = XA_ERROR(err);
1424 }
1425 
1426 /**
1427  * xas_invalid() - Is the xas in a retry or error state?
1428  * @xas: XArray operation state.
1429  *
1430  * Return: %true if the xas cannot be used for operations.
1431  */
xas_invalid(const struct xa_state * xas)1432 static inline bool xas_invalid(const struct xa_state *xas)
1433 {
1434 	return (unsigned long)xas->xa_node & 3;
1435 }
1436 
1437 /**
1438  * xas_valid() - Is the xas a valid cursor into the array?
1439  * @xas: XArray operation state.
1440  *
1441  * Return: %true if the xas can be used for operations.
1442  */
xas_valid(const struct xa_state * xas)1443 static inline bool xas_valid(const struct xa_state *xas)
1444 {
1445 	return !xas_invalid(xas);
1446 }
1447 
1448 /**
1449  * xas_is_node() - Does the xas point to a node?
1450  * @xas: XArray operation state.
1451  *
1452  * Return: %true if the xas currently references a node.
1453  */
xas_is_node(const struct xa_state * xas)1454 static inline bool xas_is_node(const struct xa_state *xas)
1455 {
1456 	return xas_valid(xas) && xas->xa_node;
1457 }
1458 
1459 /* True if the pointer is something other than a node */
xas_not_node(struct xa_node * node)1460 static inline bool xas_not_node(struct xa_node *node)
1461 {
1462 	return ((unsigned long)node & 3) || !node;
1463 }
1464 
1465 /* True if the node represents RESTART or an error */
xas_frozen(struct xa_node * node)1466 static inline bool xas_frozen(struct xa_node *node)
1467 {
1468 	return (unsigned long)node & 2;
1469 }
1470 
1471 /* True if the node represents head-of-tree, RESTART or BOUNDS */
xas_top(struct xa_node * node)1472 static inline bool xas_top(struct xa_node *node)
1473 {
1474 	return node <= XAS_RESTART;
1475 }
1476 
1477 /**
1478  * xas_reset() - Reset an XArray operation state.
1479  * @xas: XArray operation state.
1480  *
1481  * Resets the error or walk state of the @xas so future walks of the
1482  * array will start from the root.  Use this if you have dropped the
1483  * xarray lock and want to reuse the xa_state.
1484  *
1485  * Context: Any context.
1486  */
xas_reset(struct xa_state * xas)1487 static inline void xas_reset(struct xa_state *xas)
1488 {
1489 	xas->xa_node = XAS_RESTART;
1490 }
1491 
1492 /**
1493  * xas_retry() - Retry the operation if appropriate.
1494  * @xas: XArray operation state.
1495  * @entry: Entry from xarray.
1496  *
1497  * The advanced functions may sometimes return an internal entry, such as
1498  * a retry entry or a zero entry.  This function sets up the @xas to restart
1499  * the walk from the head of the array if needed.
1500  *
1501  * Context: Any context.
1502  * Return: true if the operation needs to be retried.
1503  */
xas_retry(struct xa_state * xas,const void * entry)1504 static inline bool xas_retry(struct xa_state *xas, const void *entry)
1505 {
1506 	if (xa_is_zero(entry))
1507 		return true;
1508 	if (!xa_is_retry(entry))
1509 		return false;
1510 	xas_reset(xas);
1511 	return true;
1512 }
1513 
1514 void *xas_load(struct xa_state *);
1515 void *xas_store(struct xa_state *, void *entry);
1516 void *xas_find(struct xa_state *, unsigned long max);
1517 void *xas_find_conflict(struct xa_state *);
1518 
1519 bool xas_get_mark(const struct xa_state *, xa_mark_t);
1520 void xas_set_mark(const struct xa_state *, xa_mark_t);
1521 void xas_clear_mark(const struct xa_state *, xa_mark_t);
1522 void *xas_find_marked(struct xa_state *, unsigned long max, xa_mark_t);
1523 void xas_init_marks(const struct xa_state *);
1524 
1525 bool xas_nomem(struct xa_state *, gfp_t);
1526 void xas_destroy(struct xa_state *);
1527 void xas_pause(struct xa_state *);
1528 
1529 void xas_create_range(struct xa_state *);
1530 
1531 #ifdef CONFIG_XARRAY_MULTI
1532 int xa_get_order(struct xarray *, unsigned long index);
1533 void xas_split(struct xa_state *, void *entry, unsigned int order);
1534 void xas_split_alloc(struct xa_state *, void *entry, unsigned int order, gfp_t);
1535 #else
xa_get_order(struct xarray * xa,unsigned long index)1536 static inline int xa_get_order(struct xarray *xa, unsigned long index)
1537 {
1538 	return 0;
1539 }
1540 
xas_split(struct xa_state * xas,void * entry,unsigned int order)1541 static inline void xas_split(struct xa_state *xas, void *entry,
1542 		unsigned int order)
1543 {
1544 	xas_store(xas, entry);
1545 }
1546 
xas_split_alloc(struct xa_state * xas,void * entry,unsigned int order,gfp_t gfp)1547 static inline void xas_split_alloc(struct xa_state *xas, void *entry,
1548 		unsigned int order, gfp_t gfp)
1549 {
1550 }
1551 #endif
1552 
1553 /**
1554  * xas_reload() - Refetch an entry from the xarray.
1555  * @xas: XArray operation state.
1556  *
1557  * Use this function to check that a previously loaded entry still has
1558  * the same value.  This is useful for the lockless pagecache lookup where
1559  * we walk the array with only the RCU lock to protect us, lock the page,
1560  * then check that the page hasn't moved since we looked it up.
1561  *
1562  * The caller guarantees that @xas is still valid.  If it may be in an
1563  * error or restart state, call xas_load() instead.
1564  *
1565  * Return: The entry at this location in the xarray.
1566  */
xas_reload(struct xa_state * xas)1567 static inline void *xas_reload(struct xa_state *xas)
1568 {
1569 	struct xa_node *node = xas->xa_node;
1570 	void *entry;
1571 	char offset;
1572 
1573 	if (!node)
1574 		return xa_head(xas->xa);
1575 	if (IS_ENABLED(CONFIG_XARRAY_MULTI)) {
1576 		offset = (xas->xa_index >> node->shift) & XA_CHUNK_MASK;
1577 		entry = xa_entry(xas->xa, node, offset);
1578 		if (!xa_is_sibling(entry))
1579 			return entry;
1580 		offset = xa_to_sibling(entry);
1581 	} else {
1582 		offset = xas->xa_offset;
1583 	}
1584 	return xa_entry(xas->xa, node, offset);
1585 }
1586 
1587 /**
1588  * xas_set() - Set up XArray operation state for a different index.
1589  * @xas: XArray operation state.
1590  * @index: New index into the XArray.
1591  *
1592  * Move the operation state to refer to a different index.  This will
1593  * have the effect of starting a walk from the top; see xas_next()
1594  * to move to an adjacent index.
1595  */
xas_set(struct xa_state * xas,unsigned long index)1596 static inline void xas_set(struct xa_state *xas, unsigned long index)
1597 {
1598 	xas->xa_index = index;
1599 	xas->xa_node = XAS_RESTART;
1600 }
1601 
1602 /**
1603  * xas_advance() - Skip over sibling entries.
1604  * @xas: XArray operation state.
1605  * @index: Index of last sibling entry.
1606  *
1607  * Move the operation state to refer to the last sibling entry.
1608  * This is useful for loops that normally want to see sibling
1609  * entries but sometimes want to skip them.  Use xas_set() if you
1610  * want to move to an index which is not part of this entry.
1611  */
xas_advance(struct xa_state * xas,unsigned long index)1612 static inline void xas_advance(struct xa_state *xas, unsigned long index)
1613 {
1614 	unsigned char shift = xas_is_node(xas) ? xas->xa_node->shift : 0;
1615 
1616 	xas->xa_index = index;
1617 	xas->xa_offset = (index >> shift) & XA_CHUNK_MASK;
1618 }
1619 
1620 /**
1621  * xas_set_order() - Set up XArray operation state for a multislot entry.
1622  * @xas: XArray operation state.
1623  * @index: Target of the operation.
1624  * @order: Entry occupies 2^@order indices.
1625  */
xas_set_order(struct xa_state * xas,unsigned long index,unsigned int order)1626 static inline void xas_set_order(struct xa_state *xas, unsigned long index,
1627 					unsigned int order)
1628 {
1629 #ifdef CONFIG_XARRAY_MULTI
1630 	xas->xa_index = order < BITS_PER_LONG ? (index >> order) << order : 0;
1631 	xas->xa_shift = order - (order % XA_CHUNK_SHIFT);
1632 	xas->xa_sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1;
1633 	xas->xa_node = XAS_RESTART;
1634 #else
1635 	BUG_ON(order > 0);
1636 	xas_set(xas, index);
1637 #endif
1638 }
1639 
1640 /**
1641  * xas_set_update() - Set up XArray operation state for a callback.
1642  * @xas: XArray operation state.
1643  * @update: Function to call when updating a node.
1644  *
1645  * The XArray can notify a caller after it has updated an xa_node.
1646  * This is advanced functionality and is only needed by the page cache.
1647  */
xas_set_update(struct xa_state * xas,xa_update_node_t update)1648 static inline void xas_set_update(struct xa_state *xas, xa_update_node_t update)
1649 {
1650 	xas->xa_update = update;
1651 }
1652 
xas_set_lru(struct xa_state * xas,struct list_lru * lru)1653 static inline void xas_set_lru(struct xa_state *xas, struct list_lru *lru)
1654 {
1655 	xas->xa_lru = lru;
1656 }
1657 
1658 /**
1659  * xas_next_entry() - Advance iterator to next present entry.
1660  * @xas: XArray operation state.
1661  * @max: Highest index to return.
1662  *
1663  * xas_next_entry() is an inline function to optimise xarray traversal for
1664  * speed.  It is equivalent to calling xas_find(), and will call xas_find()
1665  * for all the hard cases.
1666  *
1667  * Return: The next present entry after the one currently referred to by @xas.
1668  */
xas_next_entry(struct xa_state * xas,unsigned long max)1669 static inline void *xas_next_entry(struct xa_state *xas, unsigned long max)
1670 {
1671 	struct xa_node *node = xas->xa_node;
1672 	void *entry;
1673 
1674 	if (unlikely(xas_not_node(node) || node->shift ||
1675 			xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)))
1676 		return xas_find(xas, max);
1677 
1678 	do {
1679 		if (unlikely(xas->xa_index >= max))
1680 			return xas_find(xas, max);
1681 		if (unlikely(xas->xa_offset == XA_CHUNK_MASK))
1682 			return xas_find(xas, max);
1683 		entry = xa_entry(xas->xa, node, xas->xa_offset + 1);
1684 		if (unlikely(xa_is_internal(entry)))
1685 			return xas_find(xas, max);
1686 		xas->xa_offset++;
1687 		xas->xa_index++;
1688 	} while (!entry);
1689 
1690 	return entry;
1691 }
1692 
1693 /* Private */
xas_find_chunk(struct xa_state * xas,bool advance,xa_mark_t mark)1694 static inline unsigned int xas_find_chunk(struct xa_state *xas, bool advance,
1695 		xa_mark_t mark)
1696 {
1697 	unsigned long *addr = xas->xa_node->marks[(__force unsigned)mark];
1698 	unsigned int offset = xas->xa_offset;
1699 
1700 	if (advance)
1701 		offset++;
1702 	if (XA_CHUNK_SIZE == BITS_PER_LONG) {
1703 		if (offset < XA_CHUNK_SIZE) {
1704 			unsigned long data = *addr & (~0UL << offset);
1705 			if (data)
1706 				return __ffs(data);
1707 		}
1708 		return XA_CHUNK_SIZE;
1709 	}
1710 
1711 	return find_next_bit(addr, XA_CHUNK_SIZE, offset);
1712 }
1713 
1714 /**
1715  * xas_next_marked() - Advance iterator to next marked entry.
1716  * @xas: XArray operation state.
1717  * @max: Highest index to return.
1718  * @mark: Mark to search for.
1719  *
1720  * xas_next_marked() is an inline function to optimise xarray traversal for
1721  * speed.  It is equivalent to calling xas_find_marked(), and will call
1722  * xas_find_marked() for all the hard cases.
1723  *
1724  * Return: The next marked entry after the one currently referred to by @xas.
1725  */
xas_next_marked(struct xa_state * xas,unsigned long max,xa_mark_t mark)1726 static inline void *xas_next_marked(struct xa_state *xas, unsigned long max,
1727 								xa_mark_t mark)
1728 {
1729 	struct xa_node *node = xas->xa_node;
1730 	void *entry;
1731 	unsigned int offset;
1732 
1733 	if (unlikely(xas_not_node(node) || node->shift))
1734 		return xas_find_marked(xas, max, mark);
1735 	offset = xas_find_chunk(xas, true, mark);
1736 	xas->xa_offset = offset;
1737 	xas->xa_index = (xas->xa_index & ~XA_CHUNK_MASK) + offset;
1738 	if (xas->xa_index > max)
1739 		return NULL;
1740 	if (offset == XA_CHUNK_SIZE)
1741 		return xas_find_marked(xas, max, mark);
1742 	entry = xa_entry(xas->xa, node, offset);
1743 	if (!entry)
1744 		return xas_find_marked(xas, max, mark);
1745 	return entry;
1746 }
1747 
1748 /*
1749  * If iterating while holding a lock, drop the lock and reschedule
1750  * every %XA_CHECK_SCHED loops.
1751  */
1752 enum {
1753 	XA_CHECK_SCHED = 4096,
1754 };
1755 
1756 /**
1757  * xas_for_each() - Iterate over a range of an XArray.
1758  * @xas: XArray operation state.
1759  * @entry: Entry retrieved from the array.
1760  * @max: Maximum index to retrieve from array.
1761  *
1762  * The loop body will be executed for each entry present in the xarray
1763  * between the current xas position and @max.  @entry will be set to
1764  * the entry retrieved from the xarray.  It is safe to delete entries
1765  * from the array in the loop body.  You should hold either the RCU lock
1766  * or the xa_lock while iterating.  If you need to drop the lock, call
1767  * xas_pause() first.
1768  */
1769 #define xas_for_each(xas, entry, max) \
1770 	for (entry = xas_find(xas, max); entry; \
1771 	     entry = xas_next_entry(xas, max))
1772 
1773 /**
1774  * xas_for_each_marked() - Iterate over a range of an XArray.
1775  * @xas: XArray operation state.
1776  * @entry: Entry retrieved from the array.
1777  * @max: Maximum index to retrieve from array.
1778  * @mark: Mark to search for.
1779  *
1780  * The loop body will be executed for each marked entry in the xarray
1781  * between the current xas position and @max.  @entry will be set to
1782  * the entry retrieved from the xarray.  It is safe to delete entries
1783  * from the array in the loop body.  You should hold either the RCU lock
1784  * or the xa_lock while iterating.  If you need to drop the lock, call
1785  * xas_pause() first.
1786  */
1787 #define xas_for_each_marked(xas, entry, max, mark) \
1788 	for (entry = xas_find_marked(xas, max, mark); entry; \
1789 	     entry = xas_next_marked(xas, max, mark))
1790 
1791 /**
1792  * xas_for_each_conflict() - Iterate over a range of an XArray.
1793  * @xas: XArray operation state.
1794  * @entry: Entry retrieved from the array.
1795  *
1796  * The loop body will be executed for each entry in the XArray that
1797  * lies within the range specified by @xas.  If the loop terminates
1798  * normally, @entry will be %NULL.  The user may break out of the loop,
1799  * which will leave @entry set to the conflicting entry.  The caller
1800  * may also call xa_set_err() to exit the loop while setting an error
1801  * to record the reason.
1802  */
1803 #define xas_for_each_conflict(xas, entry) \
1804 	while ((entry = xas_find_conflict(xas)))
1805 
1806 void *__xas_next(struct xa_state *);
1807 void *__xas_prev(struct xa_state *);
1808 
1809 /**
1810  * xas_prev() - Move iterator to previous index.
1811  * @xas: XArray operation state.
1812  *
1813  * If the @xas was in an error state, it will remain in an error state
1814  * and this function will return %NULL.  If the @xas has never been walked,
1815  * it will have the effect of calling xas_load().  Otherwise one will be
1816  * subtracted from the index and the state will be walked to the correct
1817  * location in the array for the next operation.
1818  *
1819  * If the iterator was referencing index 0, this function wraps
1820  * around to %ULONG_MAX.
1821  *
1822  * Return: The entry at the new index.  This may be %NULL or an internal
1823  * entry.
1824  */
xas_prev(struct xa_state * xas)1825 static inline void *xas_prev(struct xa_state *xas)
1826 {
1827 	struct xa_node *node = xas->xa_node;
1828 
1829 	if (unlikely(xas_not_node(node) || node->shift ||
1830 				xas->xa_offset == 0))
1831 		return __xas_prev(xas);
1832 
1833 	xas->xa_index--;
1834 	xas->xa_offset--;
1835 	return xa_entry(xas->xa, node, xas->xa_offset);
1836 }
1837 
1838 /**
1839  * xas_next() - Move state to next index.
1840  * @xas: XArray operation state.
1841  *
1842  * If the @xas was in an error state, it will remain in an error state
1843  * and this function will return %NULL.  If the @xas has never been walked,
1844  * it will have the effect of calling xas_load().  Otherwise one will be
1845  * added to the index and the state will be walked to the correct
1846  * location in the array for the next operation.
1847  *
1848  * If the iterator was referencing index %ULONG_MAX, this function wraps
1849  * around to 0.
1850  *
1851  * Return: The entry at the new index.  This may be %NULL or an internal
1852  * entry.
1853  */
xas_next(struct xa_state * xas)1854 static inline void *xas_next(struct xa_state *xas)
1855 {
1856 	struct xa_node *node = xas->xa_node;
1857 
1858 	if (unlikely(xas_not_node(node) || node->shift ||
1859 				xas->xa_offset == XA_CHUNK_MASK))
1860 		return __xas_next(xas);
1861 
1862 	xas->xa_index++;
1863 	xas->xa_offset++;
1864 	return xa_entry(xas->xa, node, xas->xa_offset);
1865 }
1866 
1867 #endif /* _LINUX_XARRAY_H */
1868