xref: /openbmc/linux/include/linux/xarray.h (revision 734594d4)
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  * Must only be operated on an xarray initialized with flag XA_FLAGS_ALLOC set
860  * in xa_init_flags().
861  *
862  * Context: Any context.  Takes and releases the xa_lock.  May sleep if
863  * the @gfp flags permit.
864  * Return: 0 on success, -ENOMEM if memory could not be allocated or
865  * -EBUSY if there are no free entries in @limit.
866  */
xa_alloc(struct xarray * xa,u32 * id,void * entry,struct xa_limit limit,gfp_t gfp)867 static inline __must_check int xa_alloc(struct xarray *xa, u32 *id,
868 		void *entry, struct xa_limit limit, gfp_t gfp)
869 {
870 	int err;
871 
872 	might_alloc(gfp);
873 	xa_lock(xa);
874 	err = __xa_alloc(xa, id, entry, limit, gfp);
875 	xa_unlock(xa);
876 
877 	return err;
878 }
879 
880 /**
881  * xa_alloc_bh() - Find somewhere to store this entry in the XArray.
882  * @xa: XArray.
883  * @id: Pointer to ID.
884  * @entry: New entry.
885  * @limit: Range of ID to allocate.
886  * @gfp: Memory allocation flags.
887  *
888  * Finds an empty entry in @xa between @limit.min and @limit.max,
889  * stores the index into the @id pointer, then stores the entry at
890  * that index.  A concurrent lookup will not see an uninitialised @id.
891  *
892  * Must only be operated on an xarray initialized with flag XA_FLAGS_ALLOC set
893  * in xa_init_flags().
894  *
895  * Context: Any context.  Takes and releases the xa_lock while
896  * disabling softirqs.  May sleep if the @gfp flags permit.
897  * Return: 0 on success, -ENOMEM if memory could not be allocated or
898  * -EBUSY if there are no free entries in @limit.
899  */
xa_alloc_bh(struct xarray * xa,u32 * id,void * entry,struct xa_limit limit,gfp_t gfp)900 static inline int __must_check xa_alloc_bh(struct xarray *xa, u32 *id,
901 		void *entry, struct xa_limit limit, gfp_t gfp)
902 {
903 	int err;
904 
905 	might_alloc(gfp);
906 	xa_lock_bh(xa);
907 	err = __xa_alloc(xa, id, entry, limit, gfp);
908 	xa_unlock_bh(xa);
909 
910 	return err;
911 }
912 
913 /**
914  * xa_alloc_irq() - Find somewhere to store this entry in the XArray.
915  * @xa: XArray.
916  * @id: Pointer to ID.
917  * @entry: New entry.
918  * @limit: Range of ID to allocate.
919  * @gfp: Memory allocation flags.
920  *
921  * Finds an empty entry in @xa between @limit.min and @limit.max,
922  * stores the index into the @id pointer, then stores the entry at
923  * that index.  A concurrent lookup will not see an uninitialised @id.
924  *
925  * Must only be operated on an xarray initialized with flag XA_FLAGS_ALLOC set
926  * in xa_init_flags().
927  *
928  * Context: Process context.  Takes and releases the xa_lock while
929  * disabling interrupts.  May sleep if the @gfp flags permit.
930  * Return: 0 on success, -ENOMEM if memory could not be allocated or
931  * -EBUSY if there are no free entries in @limit.
932  */
xa_alloc_irq(struct xarray * xa,u32 * id,void * entry,struct xa_limit limit,gfp_t gfp)933 static inline int __must_check xa_alloc_irq(struct xarray *xa, u32 *id,
934 		void *entry, struct xa_limit limit, gfp_t gfp)
935 {
936 	int err;
937 
938 	might_alloc(gfp);
939 	xa_lock_irq(xa);
940 	err = __xa_alloc(xa, id, entry, limit, gfp);
941 	xa_unlock_irq(xa);
942 
943 	return err;
944 }
945 
946 /**
947  * xa_alloc_cyclic() - Find somewhere to store this entry in the XArray.
948  * @xa: XArray.
949  * @id: Pointer to ID.
950  * @entry: New entry.
951  * @limit: Range of allocated ID.
952  * @next: Pointer to next ID to allocate.
953  * @gfp: Memory allocation flags.
954  *
955  * Finds an empty entry in @xa between @limit.min and @limit.max,
956  * stores the index into the @id pointer, then stores the entry at
957  * that index.  A concurrent lookup will not see an uninitialised @id.
958  * The search for an empty entry will start at @next and will wrap
959  * around if necessary.
960  *
961  * Must only be operated on an xarray initialized with flag XA_FLAGS_ALLOC set
962  * in xa_init_flags().
963  *
964  * Context: Any context.  Takes and releases the xa_lock.  May sleep if
965  * the @gfp flags permit.
966  * Return: 0 if the allocation succeeded without wrapping.  1 if the
967  * allocation succeeded after wrapping, -ENOMEM if memory could not be
968  * allocated or -EBUSY if there are no free entries in @limit.
969  */
xa_alloc_cyclic(struct xarray * xa,u32 * id,void * entry,struct xa_limit limit,u32 * next,gfp_t gfp)970 static inline int xa_alloc_cyclic(struct xarray *xa, u32 *id, void *entry,
971 		struct xa_limit limit, u32 *next, gfp_t gfp)
972 {
973 	int err;
974 
975 	might_alloc(gfp);
976 	xa_lock(xa);
977 	err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
978 	xa_unlock(xa);
979 
980 	return err;
981 }
982 
983 /**
984  * xa_alloc_cyclic_bh() - Find somewhere to store this entry in the XArray.
985  * @xa: XArray.
986  * @id: Pointer to ID.
987  * @entry: New entry.
988  * @limit: Range of allocated ID.
989  * @next: Pointer to next ID to allocate.
990  * @gfp: Memory allocation flags.
991  *
992  * Finds an empty entry in @xa between @limit.min and @limit.max,
993  * stores the index into the @id pointer, then stores the entry at
994  * that index.  A concurrent lookup will not see an uninitialised @id.
995  * The search for an empty entry will start at @next and will wrap
996  * around if necessary.
997  *
998  * Must only be operated on an xarray initialized with flag XA_FLAGS_ALLOC set
999  * in xa_init_flags().
1000  *
1001  * Context: Any context.  Takes and releases the xa_lock while
1002  * disabling softirqs.  May sleep if the @gfp flags permit.
1003  * Return: 0 if the allocation succeeded without wrapping.  1 if the
1004  * allocation succeeded after wrapping, -ENOMEM if memory could not be
1005  * allocated or -EBUSY if there are no free entries in @limit.
1006  */
xa_alloc_cyclic_bh(struct xarray * xa,u32 * id,void * entry,struct xa_limit limit,u32 * next,gfp_t gfp)1007 static inline int xa_alloc_cyclic_bh(struct xarray *xa, u32 *id, void *entry,
1008 		struct xa_limit limit, u32 *next, gfp_t gfp)
1009 {
1010 	int err;
1011 
1012 	might_alloc(gfp);
1013 	xa_lock_bh(xa);
1014 	err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
1015 	xa_unlock_bh(xa);
1016 
1017 	return err;
1018 }
1019 
1020 /**
1021  * xa_alloc_cyclic_irq() - Find somewhere to store this entry in the XArray.
1022  * @xa: XArray.
1023  * @id: Pointer to ID.
1024  * @entry: New entry.
1025  * @limit: Range of allocated ID.
1026  * @next: Pointer to next ID to allocate.
1027  * @gfp: Memory allocation flags.
1028  *
1029  * Finds an empty entry in @xa between @limit.min and @limit.max,
1030  * stores the index into the @id pointer, then stores the entry at
1031  * that index.  A concurrent lookup will not see an uninitialised @id.
1032  * The search for an empty entry will start at @next and will wrap
1033  * around if necessary.
1034  *
1035  * Must only be operated on an xarray initialized with flag XA_FLAGS_ALLOC set
1036  * in xa_init_flags().
1037  *
1038  * Context: Process context.  Takes and releases the xa_lock while
1039  * disabling interrupts.  May sleep if the @gfp flags permit.
1040  * Return: 0 if the allocation succeeded without wrapping.  1 if the
1041  * allocation succeeded after wrapping, -ENOMEM if memory could not be
1042  * allocated or -EBUSY if there are no free entries in @limit.
1043  */
xa_alloc_cyclic_irq(struct xarray * xa,u32 * id,void * entry,struct xa_limit limit,u32 * next,gfp_t gfp)1044 static inline int xa_alloc_cyclic_irq(struct xarray *xa, u32 *id, void *entry,
1045 		struct xa_limit limit, u32 *next, gfp_t gfp)
1046 {
1047 	int err;
1048 
1049 	might_alloc(gfp);
1050 	xa_lock_irq(xa);
1051 	err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
1052 	xa_unlock_irq(xa);
1053 
1054 	return err;
1055 }
1056 
1057 /**
1058  * xa_reserve() - Reserve this index in the XArray.
1059  * @xa: XArray.
1060  * @index: Index into array.
1061  * @gfp: Memory allocation flags.
1062  *
1063  * Ensures there is somewhere to store an entry at @index in the array.
1064  * If there is already something stored at @index, this function does
1065  * nothing.  If there was nothing there, the entry is marked as reserved.
1066  * Loading from a reserved entry returns a %NULL pointer.
1067  *
1068  * If you do not use the entry that you have reserved, call xa_release()
1069  * or xa_erase() to free any unnecessary memory.
1070  *
1071  * Context: Any context.  Takes and releases the xa_lock.
1072  * May sleep if the @gfp flags permit.
1073  * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
1074  */
1075 static inline __must_check
xa_reserve(struct xarray * xa,unsigned long index,gfp_t gfp)1076 int xa_reserve(struct xarray *xa, unsigned long index, gfp_t gfp)
1077 {
1078 	return xa_err(xa_cmpxchg(xa, index, NULL, XA_ZERO_ENTRY, gfp));
1079 }
1080 
1081 /**
1082  * xa_reserve_bh() - Reserve this index in the XArray.
1083  * @xa: XArray.
1084  * @index: Index into array.
1085  * @gfp: Memory allocation flags.
1086  *
1087  * A softirq-disabling version of xa_reserve().
1088  *
1089  * Context: Any context.  Takes and releases the xa_lock while
1090  * disabling softirqs.
1091  * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
1092  */
1093 static inline __must_check
xa_reserve_bh(struct xarray * xa,unsigned long index,gfp_t gfp)1094 int xa_reserve_bh(struct xarray *xa, unsigned long index, gfp_t gfp)
1095 {
1096 	return xa_err(xa_cmpxchg_bh(xa, index, NULL, XA_ZERO_ENTRY, gfp));
1097 }
1098 
1099 /**
1100  * xa_reserve_irq() - Reserve this index in the XArray.
1101  * @xa: XArray.
1102  * @index: Index into array.
1103  * @gfp: Memory allocation flags.
1104  *
1105  * An interrupt-disabling version of xa_reserve().
1106  *
1107  * Context: Process context.  Takes and releases the xa_lock while
1108  * disabling interrupts.
1109  * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
1110  */
1111 static inline __must_check
xa_reserve_irq(struct xarray * xa,unsigned long index,gfp_t gfp)1112 int xa_reserve_irq(struct xarray *xa, unsigned long index, gfp_t gfp)
1113 {
1114 	return xa_err(xa_cmpxchg_irq(xa, index, NULL, XA_ZERO_ENTRY, gfp));
1115 }
1116 
1117 /**
1118  * xa_release() - Release a reserved entry.
1119  * @xa: XArray.
1120  * @index: Index of entry.
1121  *
1122  * After calling xa_reserve(), you can call this function to release the
1123  * reservation.  If the entry at @index has been stored to, this function
1124  * will do nothing.
1125  */
xa_release(struct xarray * xa,unsigned long index)1126 static inline void xa_release(struct xarray *xa, unsigned long index)
1127 {
1128 	xa_cmpxchg(xa, index, XA_ZERO_ENTRY, NULL, 0);
1129 }
1130 
1131 /* Everything below here is the Advanced API.  Proceed with caution. */
1132 
1133 /*
1134  * The xarray is constructed out of a set of 'chunks' of pointers.  Choosing
1135  * the best chunk size requires some tradeoffs.  A power of two recommends
1136  * itself so that we can walk the tree based purely on shifts and masks.
1137  * Generally, the larger the better; as the number of slots per level of the
1138  * tree increases, the less tall the tree needs to be.  But that needs to be
1139  * balanced against the memory consumption of each node.  On a 64-bit system,
1140  * xa_node is currently 576 bytes, and we get 7 of them per 4kB page.  If we
1141  * doubled the number of slots per node, we'd get only 3 nodes per 4kB page.
1142  */
1143 #ifndef XA_CHUNK_SHIFT
1144 #define XA_CHUNK_SHIFT		(CONFIG_BASE_SMALL ? 4 : 6)
1145 #endif
1146 #define XA_CHUNK_SIZE		(1UL << XA_CHUNK_SHIFT)
1147 #define XA_CHUNK_MASK		(XA_CHUNK_SIZE - 1)
1148 #define XA_MAX_MARKS		3
1149 #define XA_MARK_LONGS		DIV_ROUND_UP(XA_CHUNK_SIZE, BITS_PER_LONG)
1150 
1151 /*
1152  * @count is the count of every non-NULL element in the ->slots array
1153  * whether that is a value entry, a retry entry, a user pointer,
1154  * a sibling entry or a pointer to the next level of the tree.
1155  * @nr_values is the count of every element in ->slots which is
1156  * either a value entry or a sibling of a value entry.
1157  */
1158 struct xa_node {
1159 	unsigned char	shift;		/* Bits remaining in each slot */
1160 	unsigned char	offset;		/* Slot offset in parent */
1161 	unsigned char	count;		/* Total entry count */
1162 	unsigned char	nr_values;	/* Value entry count */
1163 	struct xa_node __rcu *parent;	/* NULL at top of tree */
1164 	struct xarray	*array;		/* The array we belong to */
1165 	union {
1166 		struct list_head private_list;	/* For tree user */
1167 		struct rcu_head	rcu_head;	/* Used when freeing node */
1168 	};
1169 	void __rcu	*slots[XA_CHUNK_SIZE];
1170 	union {
1171 		unsigned long	tags[XA_MAX_MARKS][XA_MARK_LONGS];
1172 		unsigned long	marks[XA_MAX_MARKS][XA_MARK_LONGS];
1173 	};
1174 };
1175 
1176 void xa_dump(const struct xarray *);
1177 void xa_dump_node(const struct xa_node *);
1178 
1179 #ifdef XA_DEBUG
1180 #define XA_BUG_ON(xa, x) do {					\
1181 		if (x) {					\
1182 			xa_dump(xa);				\
1183 			BUG();					\
1184 		}						\
1185 	} while (0)
1186 #define XA_NODE_BUG_ON(node, x) do {				\
1187 		if (x) {					\
1188 			if (node) xa_dump_node(node);		\
1189 			BUG();					\
1190 		}						\
1191 	} while (0)
1192 #else
1193 #define XA_BUG_ON(xa, x)	do { } while (0)
1194 #define XA_NODE_BUG_ON(node, x)	do { } while (0)
1195 #endif
1196 
1197 /* Private */
xa_head(const struct xarray * xa)1198 static inline void *xa_head(const struct xarray *xa)
1199 {
1200 	return rcu_dereference_check(xa->xa_head,
1201 						lockdep_is_held(&xa->xa_lock));
1202 }
1203 
1204 /* Private */
xa_head_locked(const struct xarray * xa)1205 static inline void *xa_head_locked(const struct xarray *xa)
1206 {
1207 	return rcu_dereference_protected(xa->xa_head,
1208 						lockdep_is_held(&xa->xa_lock));
1209 }
1210 
1211 /* Private */
xa_entry(const struct xarray * xa,const struct xa_node * node,unsigned int offset)1212 static inline void *xa_entry(const struct xarray *xa,
1213 				const struct xa_node *node, unsigned int offset)
1214 {
1215 	XA_NODE_BUG_ON(node, offset >= XA_CHUNK_SIZE);
1216 	return rcu_dereference_check(node->slots[offset],
1217 						lockdep_is_held(&xa->xa_lock));
1218 }
1219 
1220 /* Private */
xa_entry_locked(const struct xarray * xa,const struct xa_node * node,unsigned int offset)1221 static inline void *xa_entry_locked(const struct xarray *xa,
1222 				const struct xa_node *node, unsigned int offset)
1223 {
1224 	XA_NODE_BUG_ON(node, offset >= XA_CHUNK_SIZE);
1225 	return rcu_dereference_protected(node->slots[offset],
1226 						lockdep_is_held(&xa->xa_lock));
1227 }
1228 
1229 /* Private */
xa_parent(const struct xarray * xa,const struct xa_node * node)1230 static inline struct xa_node *xa_parent(const struct xarray *xa,
1231 					const struct xa_node *node)
1232 {
1233 	return rcu_dereference_check(node->parent,
1234 						lockdep_is_held(&xa->xa_lock));
1235 }
1236 
1237 /* Private */
xa_parent_locked(const struct xarray * xa,const struct xa_node * node)1238 static inline struct xa_node *xa_parent_locked(const struct xarray *xa,
1239 					const struct xa_node *node)
1240 {
1241 	return rcu_dereference_protected(node->parent,
1242 						lockdep_is_held(&xa->xa_lock));
1243 }
1244 
1245 /* Private */
xa_mk_node(const struct xa_node * node)1246 static inline void *xa_mk_node(const struct xa_node *node)
1247 {
1248 	return (void *)((unsigned long)node | 2);
1249 }
1250 
1251 /* Private */
xa_to_node(const void * entry)1252 static inline struct xa_node *xa_to_node(const void *entry)
1253 {
1254 	return (struct xa_node *)((unsigned long)entry - 2);
1255 }
1256 
1257 /* Private */
xa_is_node(const void * entry)1258 static inline bool xa_is_node(const void *entry)
1259 {
1260 	return xa_is_internal(entry) && (unsigned long)entry > 4096;
1261 }
1262 
1263 /* Private */
xa_mk_sibling(unsigned int offset)1264 static inline void *xa_mk_sibling(unsigned int offset)
1265 {
1266 	return xa_mk_internal(offset);
1267 }
1268 
1269 /* Private */
xa_to_sibling(const void * entry)1270 static inline unsigned long xa_to_sibling(const void *entry)
1271 {
1272 	return xa_to_internal(entry);
1273 }
1274 
1275 /**
1276  * xa_is_sibling() - Is the entry a sibling entry?
1277  * @entry: Entry retrieved from the XArray
1278  *
1279  * Return: %true if the entry is a sibling entry.
1280  */
xa_is_sibling(const void * entry)1281 static inline bool xa_is_sibling(const void *entry)
1282 {
1283 	return IS_ENABLED(CONFIG_XARRAY_MULTI) && xa_is_internal(entry) &&
1284 		(entry < xa_mk_sibling(XA_CHUNK_SIZE - 1));
1285 }
1286 
1287 #define XA_RETRY_ENTRY		xa_mk_internal(256)
1288 
1289 /**
1290  * xa_is_retry() - Is the entry a retry entry?
1291  * @entry: Entry retrieved from the XArray
1292  *
1293  * Return: %true if the entry is a retry entry.
1294  */
xa_is_retry(const void * entry)1295 static inline bool xa_is_retry(const void *entry)
1296 {
1297 	return unlikely(entry == XA_RETRY_ENTRY);
1298 }
1299 
1300 /**
1301  * xa_is_advanced() - Is the entry only permitted for the advanced API?
1302  * @entry: Entry to be stored in the XArray.
1303  *
1304  * Return: %true if the entry cannot be stored by the normal API.
1305  */
xa_is_advanced(const void * entry)1306 static inline bool xa_is_advanced(const void *entry)
1307 {
1308 	return xa_is_internal(entry) && (entry <= XA_RETRY_ENTRY);
1309 }
1310 
1311 /**
1312  * typedef xa_update_node_t - A callback function from the XArray.
1313  * @node: The node which is being processed
1314  *
1315  * This function is called every time the XArray updates the count of
1316  * present and value entries in a node.  It allows advanced users to
1317  * maintain the private_list in the node.
1318  *
1319  * Context: The xa_lock is held and interrupts may be disabled.
1320  *	    Implementations should not drop the xa_lock, nor re-enable
1321  *	    interrupts.
1322  */
1323 typedef void (*xa_update_node_t)(struct xa_node *node);
1324 
1325 void xa_delete_node(struct xa_node *, xa_update_node_t);
1326 
1327 /*
1328  * The xa_state is opaque to its users.  It contains various different pieces
1329  * of state involved in the current operation on the XArray.  It should be
1330  * declared on the stack and passed between the various internal routines.
1331  * The various elements in it should not be accessed directly, but only
1332  * through the provided accessor functions.  The below documentation is for
1333  * the benefit of those working on the code, not for users of the XArray.
1334  *
1335  * @xa_node usually points to the xa_node containing the slot we're operating
1336  * on (and @xa_offset is the offset in the slots array).  If there is a
1337  * single entry in the array at index 0, there are no allocated xa_nodes to
1338  * point to, and so we store %NULL in @xa_node.  @xa_node is set to
1339  * the value %XAS_RESTART if the xa_state is not walked to the correct
1340  * position in the tree of nodes for this operation.  If an error occurs
1341  * during an operation, it is set to an %XAS_ERROR value.  If we run off the
1342  * end of the allocated nodes, it is set to %XAS_BOUNDS.
1343  */
1344 struct xa_state {
1345 	struct xarray *xa;
1346 	unsigned long xa_index;
1347 	unsigned char xa_shift;
1348 	unsigned char xa_sibs;
1349 	unsigned char xa_offset;
1350 	unsigned char xa_pad;		/* Helps gcc generate better code */
1351 	struct xa_node *xa_node;
1352 	struct xa_node *xa_alloc;
1353 	xa_update_node_t xa_update;
1354 	struct list_lru *xa_lru;
1355 };
1356 
1357 /*
1358  * We encode errnos in the xas->xa_node.  If an error has happened, we need to
1359  * drop the lock to fix it, and once we've done so the xa_state is invalid.
1360  */
1361 #define XA_ERROR(errno) ((struct xa_node *)(((unsigned long)errno << 2) | 2UL))
1362 #define XAS_BOUNDS	((struct xa_node *)1UL)
1363 #define XAS_RESTART	((struct xa_node *)3UL)
1364 
1365 #define __XA_STATE(array, index, shift, sibs)  {	\
1366 	.xa = array,					\
1367 	.xa_index = index,				\
1368 	.xa_shift = shift,				\
1369 	.xa_sibs = sibs,				\
1370 	.xa_offset = 0,					\
1371 	.xa_pad = 0,					\
1372 	.xa_node = XAS_RESTART,				\
1373 	.xa_alloc = NULL,				\
1374 	.xa_update = NULL,				\
1375 	.xa_lru = NULL,					\
1376 }
1377 
1378 /**
1379  * XA_STATE() - Declare an XArray operation state.
1380  * @name: Name of this operation state (usually xas).
1381  * @array: Array to operate on.
1382  * @index: Initial index of interest.
1383  *
1384  * Declare and initialise an xa_state on the stack.
1385  */
1386 #define XA_STATE(name, array, index)				\
1387 	struct xa_state name = __XA_STATE(array, index, 0, 0)
1388 
1389 /**
1390  * XA_STATE_ORDER() - Declare an XArray operation state.
1391  * @name: Name of this operation state (usually xas).
1392  * @array: Array to operate on.
1393  * @index: Initial index of interest.
1394  * @order: Order of entry.
1395  *
1396  * Declare and initialise an xa_state on the stack.  This variant of
1397  * XA_STATE() allows you to specify the 'order' of the element you
1398  * want to operate on.`
1399  */
1400 #define XA_STATE_ORDER(name, array, index, order)		\
1401 	struct xa_state name = __XA_STATE(array,		\
1402 			(index >> order) << order,		\
1403 			order - (order % XA_CHUNK_SHIFT),	\
1404 			(1U << (order % XA_CHUNK_SHIFT)) - 1)
1405 
1406 #define xas_marked(xas, mark)	xa_marked((xas)->xa, (mark))
1407 #define xas_trylock(xas)	xa_trylock((xas)->xa)
1408 #define xas_lock(xas)		xa_lock((xas)->xa)
1409 #define xas_unlock(xas)		xa_unlock((xas)->xa)
1410 #define xas_lock_bh(xas)	xa_lock_bh((xas)->xa)
1411 #define xas_unlock_bh(xas)	xa_unlock_bh((xas)->xa)
1412 #define xas_lock_irq(xas)	xa_lock_irq((xas)->xa)
1413 #define xas_unlock_irq(xas)	xa_unlock_irq((xas)->xa)
1414 #define xas_lock_irqsave(xas, flags) \
1415 				xa_lock_irqsave((xas)->xa, flags)
1416 #define xas_unlock_irqrestore(xas, flags) \
1417 				xa_unlock_irqrestore((xas)->xa, flags)
1418 
1419 /**
1420  * xas_error() - Return an errno stored in the xa_state.
1421  * @xas: XArray operation state.
1422  *
1423  * Return: 0 if no error has been noted.  A negative errno if one has.
1424  */
xas_error(const struct xa_state * xas)1425 static inline int xas_error(const struct xa_state *xas)
1426 {
1427 	return xa_err(xas->xa_node);
1428 }
1429 
1430 /**
1431  * xas_set_err() - Note an error in the xa_state.
1432  * @xas: XArray operation state.
1433  * @err: Negative error number.
1434  *
1435  * Only call this function with a negative @err; zero or positive errors
1436  * will probably not behave the way you think they should.  If you want
1437  * to clear the error from an xa_state, use xas_reset().
1438  */
xas_set_err(struct xa_state * xas,long err)1439 static inline void xas_set_err(struct xa_state *xas, long err)
1440 {
1441 	xas->xa_node = XA_ERROR(err);
1442 }
1443 
1444 /**
1445  * xas_invalid() - Is the xas in a retry or error state?
1446  * @xas: XArray operation state.
1447  *
1448  * Return: %true if the xas cannot be used for operations.
1449  */
xas_invalid(const struct xa_state * xas)1450 static inline bool xas_invalid(const struct xa_state *xas)
1451 {
1452 	return (unsigned long)xas->xa_node & 3;
1453 }
1454 
1455 /**
1456  * xas_valid() - Is the xas a valid cursor into the array?
1457  * @xas: XArray operation state.
1458  *
1459  * Return: %true if the xas can be used for operations.
1460  */
xas_valid(const struct xa_state * xas)1461 static inline bool xas_valid(const struct xa_state *xas)
1462 {
1463 	return !xas_invalid(xas);
1464 }
1465 
1466 /**
1467  * xas_is_node() - Does the xas point to a node?
1468  * @xas: XArray operation state.
1469  *
1470  * Return: %true if the xas currently references a node.
1471  */
xas_is_node(const struct xa_state * xas)1472 static inline bool xas_is_node(const struct xa_state *xas)
1473 {
1474 	return xas_valid(xas) && xas->xa_node;
1475 }
1476 
1477 /* True if the pointer is something other than a node */
xas_not_node(struct xa_node * node)1478 static inline bool xas_not_node(struct xa_node *node)
1479 {
1480 	return ((unsigned long)node & 3) || !node;
1481 }
1482 
1483 /* True if the node represents RESTART or an error */
xas_frozen(struct xa_node * node)1484 static inline bool xas_frozen(struct xa_node *node)
1485 {
1486 	return (unsigned long)node & 2;
1487 }
1488 
1489 /* True if the node represents head-of-tree, RESTART or BOUNDS */
xas_top(struct xa_node * node)1490 static inline bool xas_top(struct xa_node *node)
1491 {
1492 	return node <= XAS_RESTART;
1493 }
1494 
1495 /**
1496  * xas_reset() - Reset an XArray operation state.
1497  * @xas: XArray operation state.
1498  *
1499  * Resets the error or walk state of the @xas so future walks of the
1500  * array will start from the root.  Use this if you have dropped the
1501  * xarray lock and want to reuse the xa_state.
1502  *
1503  * Context: Any context.
1504  */
xas_reset(struct xa_state * xas)1505 static inline void xas_reset(struct xa_state *xas)
1506 {
1507 	xas->xa_node = XAS_RESTART;
1508 }
1509 
1510 /**
1511  * xas_retry() - Retry the operation if appropriate.
1512  * @xas: XArray operation state.
1513  * @entry: Entry from xarray.
1514  *
1515  * The advanced functions may sometimes return an internal entry, such as
1516  * a retry entry or a zero entry.  This function sets up the @xas to restart
1517  * the walk from the head of the array if needed.
1518  *
1519  * Context: Any context.
1520  * Return: true if the operation needs to be retried.
1521  */
xas_retry(struct xa_state * xas,const void * entry)1522 static inline bool xas_retry(struct xa_state *xas, const void *entry)
1523 {
1524 	if (xa_is_zero(entry))
1525 		return true;
1526 	if (!xa_is_retry(entry))
1527 		return false;
1528 	xas_reset(xas);
1529 	return true;
1530 }
1531 
1532 void *xas_load(struct xa_state *);
1533 void *xas_store(struct xa_state *, void *entry);
1534 void *xas_find(struct xa_state *, unsigned long max);
1535 void *xas_find_conflict(struct xa_state *);
1536 
1537 bool xas_get_mark(const struct xa_state *, xa_mark_t);
1538 void xas_set_mark(const struct xa_state *, xa_mark_t);
1539 void xas_clear_mark(const struct xa_state *, xa_mark_t);
1540 void *xas_find_marked(struct xa_state *, unsigned long max, xa_mark_t);
1541 void xas_init_marks(const struct xa_state *);
1542 
1543 bool xas_nomem(struct xa_state *, gfp_t);
1544 void xas_destroy(struct xa_state *);
1545 void xas_pause(struct xa_state *);
1546 
1547 void xas_create_range(struct xa_state *);
1548 
1549 #ifdef CONFIG_XARRAY_MULTI
1550 int xa_get_order(struct xarray *, unsigned long index);
1551 int xas_get_order(struct xa_state *xas);
1552 void xas_split(struct xa_state *, void *entry, unsigned int order);
1553 void xas_split_alloc(struct xa_state *, void *entry, unsigned int order, gfp_t);
1554 #else
xa_get_order(struct xarray * xa,unsigned long index)1555 static inline int xa_get_order(struct xarray *xa, unsigned long index)
1556 {
1557 	return 0;
1558 }
1559 
xas_get_order(struct xa_state * xas)1560 static inline int xas_get_order(struct xa_state *xas)
1561 {
1562 	return 0;
1563 }
1564 
xas_split(struct xa_state * xas,void * entry,unsigned int order)1565 static inline void xas_split(struct xa_state *xas, void *entry,
1566 		unsigned int order)
1567 {
1568 	xas_store(xas, entry);
1569 }
1570 
xas_split_alloc(struct xa_state * xas,void * entry,unsigned int order,gfp_t gfp)1571 static inline void xas_split_alloc(struct xa_state *xas, void *entry,
1572 		unsigned int order, gfp_t gfp)
1573 {
1574 }
1575 #endif
1576 
1577 /**
1578  * xas_reload() - Refetch an entry from the xarray.
1579  * @xas: XArray operation state.
1580  *
1581  * Use this function to check that a previously loaded entry still has
1582  * the same value.  This is useful for the lockless pagecache lookup where
1583  * we walk the array with only the RCU lock to protect us, lock the page,
1584  * then check that the page hasn't moved since we looked it up.
1585  *
1586  * The caller guarantees that @xas is still valid.  If it may be in an
1587  * error or restart state, call xas_load() instead.
1588  *
1589  * Return: The entry at this location in the xarray.
1590  */
xas_reload(struct xa_state * xas)1591 static inline void *xas_reload(struct xa_state *xas)
1592 {
1593 	struct xa_node *node = xas->xa_node;
1594 	void *entry;
1595 	char offset;
1596 
1597 	if (!node)
1598 		return xa_head(xas->xa);
1599 	if (IS_ENABLED(CONFIG_XARRAY_MULTI)) {
1600 		offset = (xas->xa_index >> node->shift) & XA_CHUNK_MASK;
1601 		entry = xa_entry(xas->xa, node, offset);
1602 		if (!xa_is_sibling(entry))
1603 			return entry;
1604 		offset = xa_to_sibling(entry);
1605 	} else {
1606 		offset = xas->xa_offset;
1607 	}
1608 	return xa_entry(xas->xa, node, offset);
1609 }
1610 
1611 /**
1612  * xas_set() - Set up XArray operation state for a different index.
1613  * @xas: XArray operation state.
1614  * @index: New index into the XArray.
1615  *
1616  * Move the operation state to refer to a different index.  This will
1617  * have the effect of starting a walk from the top; see xas_next()
1618  * to move to an adjacent index.
1619  */
xas_set(struct xa_state * xas,unsigned long index)1620 static inline void xas_set(struct xa_state *xas, unsigned long index)
1621 {
1622 	xas->xa_index = index;
1623 	xas->xa_node = XAS_RESTART;
1624 }
1625 
1626 /**
1627  * xas_advance() - Skip over sibling entries.
1628  * @xas: XArray operation state.
1629  * @index: Index of last sibling entry.
1630  *
1631  * Move the operation state to refer to the last sibling entry.
1632  * This is useful for loops that normally want to see sibling
1633  * entries but sometimes want to skip them.  Use xas_set() if you
1634  * want to move to an index which is not part of this entry.
1635  */
xas_advance(struct xa_state * xas,unsigned long index)1636 static inline void xas_advance(struct xa_state *xas, unsigned long index)
1637 {
1638 	unsigned char shift = xas_is_node(xas) ? xas->xa_node->shift : 0;
1639 
1640 	xas->xa_index = index;
1641 	xas->xa_offset = (index >> shift) & XA_CHUNK_MASK;
1642 }
1643 
1644 /**
1645  * xas_set_order() - Set up XArray operation state for a multislot entry.
1646  * @xas: XArray operation state.
1647  * @index: Target of the operation.
1648  * @order: Entry occupies 2^@order indices.
1649  */
xas_set_order(struct xa_state * xas,unsigned long index,unsigned int order)1650 static inline void xas_set_order(struct xa_state *xas, unsigned long index,
1651 					unsigned int order)
1652 {
1653 #ifdef CONFIG_XARRAY_MULTI
1654 	xas->xa_index = order < BITS_PER_LONG ? (index >> order) << order : 0;
1655 	xas->xa_shift = order - (order % XA_CHUNK_SHIFT);
1656 	xas->xa_sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1;
1657 	xas->xa_node = XAS_RESTART;
1658 #else
1659 	BUG_ON(order > 0);
1660 	xas_set(xas, index);
1661 #endif
1662 }
1663 
1664 /**
1665  * xas_set_update() - Set up XArray operation state for a callback.
1666  * @xas: XArray operation state.
1667  * @update: Function to call when updating a node.
1668  *
1669  * The XArray can notify a caller after it has updated an xa_node.
1670  * This is advanced functionality and is only needed by the page
1671  * cache and swap cache.
1672  */
xas_set_update(struct xa_state * xas,xa_update_node_t update)1673 static inline void xas_set_update(struct xa_state *xas, xa_update_node_t update)
1674 {
1675 	xas->xa_update = update;
1676 }
1677 
xas_set_lru(struct xa_state * xas,struct list_lru * lru)1678 static inline void xas_set_lru(struct xa_state *xas, struct list_lru *lru)
1679 {
1680 	xas->xa_lru = lru;
1681 }
1682 
1683 /**
1684  * xas_next_entry() - Advance iterator to next present entry.
1685  * @xas: XArray operation state.
1686  * @max: Highest index to return.
1687  *
1688  * xas_next_entry() is an inline function to optimise xarray traversal for
1689  * speed.  It is equivalent to calling xas_find(), and will call xas_find()
1690  * for all the hard cases.
1691  *
1692  * Return: The next present entry after the one currently referred to by @xas.
1693  */
xas_next_entry(struct xa_state * xas,unsigned long max)1694 static inline void *xas_next_entry(struct xa_state *xas, unsigned long max)
1695 {
1696 	struct xa_node *node = xas->xa_node;
1697 	void *entry;
1698 
1699 	if (unlikely(xas_not_node(node) || node->shift ||
1700 			xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)))
1701 		return xas_find(xas, max);
1702 
1703 	do {
1704 		if (unlikely(xas->xa_index >= max))
1705 			return xas_find(xas, max);
1706 		if (unlikely(xas->xa_offset == XA_CHUNK_MASK))
1707 			return xas_find(xas, max);
1708 		entry = xa_entry(xas->xa, node, xas->xa_offset + 1);
1709 		if (unlikely(xa_is_internal(entry)))
1710 			return xas_find(xas, max);
1711 		xas->xa_offset++;
1712 		xas->xa_index++;
1713 	} while (!entry);
1714 
1715 	return entry;
1716 }
1717 
1718 /* Private */
xas_find_chunk(struct xa_state * xas,bool advance,xa_mark_t mark)1719 static inline unsigned int xas_find_chunk(struct xa_state *xas, bool advance,
1720 		xa_mark_t mark)
1721 {
1722 	unsigned long *addr = xas->xa_node->marks[(__force unsigned)mark];
1723 	unsigned int offset = xas->xa_offset;
1724 
1725 	if (advance)
1726 		offset++;
1727 	if (XA_CHUNK_SIZE == BITS_PER_LONG) {
1728 		if (offset < XA_CHUNK_SIZE) {
1729 			unsigned long data = *addr & (~0UL << offset);
1730 			if (data)
1731 				return __ffs(data);
1732 		}
1733 		return XA_CHUNK_SIZE;
1734 	}
1735 
1736 	return find_next_bit(addr, XA_CHUNK_SIZE, offset);
1737 }
1738 
1739 /**
1740  * xas_next_marked() - Advance iterator to next marked entry.
1741  * @xas: XArray operation state.
1742  * @max: Highest index to return.
1743  * @mark: Mark to search for.
1744  *
1745  * xas_next_marked() is an inline function to optimise xarray traversal for
1746  * speed.  It is equivalent to calling xas_find_marked(), and will call
1747  * xas_find_marked() for all the hard cases.
1748  *
1749  * Return: The next marked entry after the one currently referred to by @xas.
1750  */
xas_next_marked(struct xa_state * xas,unsigned long max,xa_mark_t mark)1751 static inline void *xas_next_marked(struct xa_state *xas, unsigned long max,
1752 								xa_mark_t mark)
1753 {
1754 	struct xa_node *node = xas->xa_node;
1755 	void *entry;
1756 	unsigned int offset;
1757 
1758 	if (unlikely(xas_not_node(node) || node->shift))
1759 		return xas_find_marked(xas, max, mark);
1760 	offset = xas_find_chunk(xas, true, mark);
1761 	xas->xa_offset = offset;
1762 	xas->xa_index = (xas->xa_index & ~XA_CHUNK_MASK) + offset;
1763 	if (xas->xa_index > max)
1764 		return NULL;
1765 	if (offset == XA_CHUNK_SIZE)
1766 		return xas_find_marked(xas, max, mark);
1767 	entry = xa_entry(xas->xa, node, offset);
1768 	if (!entry)
1769 		return xas_find_marked(xas, max, mark);
1770 	return entry;
1771 }
1772 
1773 /*
1774  * If iterating while holding a lock, drop the lock and reschedule
1775  * every %XA_CHECK_SCHED loops.
1776  */
1777 enum {
1778 	XA_CHECK_SCHED = 4096,
1779 };
1780 
1781 /**
1782  * xas_for_each() - Iterate over a range of an XArray.
1783  * @xas: XArray operation state.
1784  * @entry: Entry retrieved from the array.
1785  * @max: Maximum index to retrieve from array.
1786  *
1787  * The loop body will be executed for each entry present in the xarray
1788  * between the current xas position and @max.  @entry will be set to
1789  * the entry retrieved from the xarray.  It is safe to delete entries
1790  * from the array in the loop body.  You should hold either the RCU lock
1791  * or the xa_lock while iterating.  If you need to drop the lock, call
1792  * xas_pause() first.
1793  */
1794 #define xas_for_each(xas, entry, max) \
1795 	for (entry = xas_find(xas, max); entry; \
1796 	     entry = xas_next_entry(xas, max))
1797 
1798 /**
1799  * xas_for_each_marked() - Iterate over a range of an XArray.
1800  * @xas: XArray operation state.
1801  * @entry: Entry retrieved from the array.
1802  * @max: Maximum index to retrieve from array.
1803  * @mark: Mark to search for.
1804  *
1805  * The loop body will be executed for each marked entry in the xarray
1806  * between the current xas position and @max.  @entry will be set to
1807  * the entry retrieved from the xarray.  It is safe to delete entries
1808  * from the array in the loop body.  You should hold either the RCU lock
1809  * or the xa_lock while iterating.  If you need to drop the lock, call
1810  * xas_pause() first.
1811  */
1812 #define xas_for_each_marked(xas, entry, max, mark) \
1813 	for (entry = xas_find_marked(xas, max, mark); entry; \
1814 	     entry = xas_next_marked(xas, max, mark))
1815 
1816 /**
1817  * xas_for_each_conflict() - Iterate over a range of an XArray.
1818  * @xas: XArray operation state.
1819  * @entry: Entry retrieved from the array.
1820  *
1821  * The loop body will be executed for each entry in the XArray that
1822  * lies within the range specified by @xas.  If the loop terminates
1823  * normally, @entry will be %NULL.  The user may break out of the loop,
1824  * which will leave @entry set to the conflicting entry.  The caller
1825  * may also call xa_set_err() to exit the loop while setting an error
1826  * to record the reason.
1827  */
1828 #define xas_for_each_conflict(xas, entry) \
1829 	while ((entry = xas_find_conflict(xas)))
1830 
1831 void *__xas_next(struct xa_state *);
1832 void *__xas_prev(struct xa_state *);
1833 
1834 /**
1835  * xas_prev() - Move iterator to previous index.
1836  * @xas: XArray operation state.
1837  *
1838  * If the @xas was in an error state, it will remain in an error state
1839  * and this function will return %NULL.  If the @xas has never been walked,
1840  * it will have the effect of calling xas_load().  Otherwise one will be
1841  * subtracted from the index and the state will be walked to the correct
1842  * location in the array for the next operation.
1843  *
1844  * If the iterator was referencing index 0, this function wraps
1845  * around to %ULONG_MAX.
1846  *
1847  * Return: The entry at the new index.  This may be %NULL or an internal
1848  * entry.
1849  */
xas_prev(struct xa_state * xas)1850 static inline void *xas_prev(struct xa_state *xas)
1851 {
1852 	struct xa_node *node = xas->xa_node;
1853 
1854 	if (unlikely(xas_not_node(node) || node->shift ||
1855 				xas->xa_offset == 0))
1856 		return __xas_prev(xas);
1857 
1858 	xas->xa_index--;
1859 	xas->xa_offset--;
1860 	return xa_entry(xas->xa, node, xas->xa_offset);
1861 }
1862 
1863 /**
1864  * xas_next() - Move state to next index.
1865  * @xas: XArray operation state.
1866  *
1867  * If the @xas was in an error state, it will remain in an error state
1868  * and this function will return %NULL.  If the @xas has never been walked,
1869  * it will have the effect of calling xas_load().  Otherwise one will be
1870  * added to the index and the state will be walked to the correct
1871  * location in the array for the next operation.
1872  *
1873  * If the iterator was referencing index %ULONG_MAX, this function wraps
1874  * around to 0.
1875  *
1876  * Return: The entry at the new index.  This may be %NULL or an internal
1877  * entry.
1878  */
xas_next(struct xa_state * xas)1879 static inline void *xas_next(struct xa_state *xas)
1880 {
1881 	struct xa_node *node = xas->xa_node;
1882 
1883 	if (unlikely(xas_not_node(node) || node->shift ||
1884 				xas->xa_offset == XA_CHUNK_MASK))
1885 		return __xas_next(xas);
1886 
1887 	xas->xa_index++;
1888 	xas->xa_offset++;
1889 	return xa_entry(xas->xa, node, xas->xa_offset);
1890 }
1891 
1892 #endif /* _LINUX_XARRAY_H */
1893