1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * XArray implementation
4 * Copyright (c) 2017-2018 Microsoft Corporation
5 * Copyright (c) 2018-2020 Oracle
6 * Author: Matthew Wilcox <willy@infradead.org>
7 */
8
9 #include <linux/bitmap.h>
10 #include <linux/export.h>
11 #include <linux/list.h>
12 #include <linux/slab.h>
13 #include <linux/xarray.h>
14
15 #include "radix-tree.h"
16
17 /*
18 * Coding conventions in this file:
19 *
20 * @xa is used to refer to the entire xarray.
21 * @xas is the 'xarray operation state'. It may be either a pointer to
22 * an xa_state, or an xa_state stored on the stack. This is an unfortunate
23 * ambiguity.
24 * @index is the index of the entry being operated on
25 * @mark is an xa_mark_t; a small number indicating one of the mark bits.
26 * @node refers to an xa_node; usually the primary one being operated on by
27 * this function.
28 * @offset is the index into the slots array inside an xa_node.
29 * @parent refers to the @xa_node closer to the head than @node.
30 * @entry refers to something stored in a slot in the xarray
31 */
32
33 static inline unsigned int xa_lock_type(const struct xarray *xa)
34 {
35 return (__force unsigned int)xa->xa_flags & 3;
36 }
37
38 static inline void xas_lock_type(struct xa_state *xas, unsigned int lock_type)
39 {
40 if (lock_type == XA_LOCK_IRQ)
41 xas_lock_irq(xas);
42 else if (lock_type == XA_LOCK_BH)
43 xas_lock_bh(xas);
44 else
45 xas_lock(xas);
46 }
47
48 static inline void xas_unlock_type(struct xa_state *xas, unsigned int lock_type)
49 {
50 if (lock_type == XA_LOCK_IRQ)
51 xas_unlock_irq(xas);
52 else if (lock_type == XA_LOCK_BH)
53 xas_unlock_bh(xas);
54 else
55 xas_unlock(xas);
56 }
57
58 static inline bool xa_track_free(const struct xarray *xa)
59 {
60 return xa->xa_flags & XA_FLAGS_TRACK_FREE;
61 }
62
63 static inline bool xa_zero_busy(const struct xarray *xa)
64 {
65 return xa->xa_flags & XA_FLAGS_ZERO_BUSY;
66 }
67
68 static inline void xa_mark_set(struct xarray *xa, xa_mark_t mark)
69 {
70 if (!(xa->xa_flags & XA_FLAGS_MARK(mark)))
71 xa->xa_flags |= XA_FLAGS_MARK(mark);
72 }
73
74 static inline void xa_mark_clear(struct xarray *xa, xa_mark_t mark)
75 {
76 if (xa->xa_flags & XA_FLAGS_MARK(mark))
77 xa->xa_flags &= ~(XA_FLAGS_MARK(mark));
78 }
79
80 static inline unsigned long *node_marks(struct xa_node *node, xa_mark_t mark)
81 {
82 return node->marks[(__force unsigned)mark];
83 }
84
85 static inline bool node_get_mark(struct xa_node *node,
86 unsigned int offset, xa_mark_t mark)
87 {
88 return test_bit(offset, node_marks(node, mark));
89 }
90
91 /* returns true if the bit was set */
92 static inline bool node_set_mark(struct xa_node *node, unsigned int offset,
93 xa_mark_t mark)
94 {
95 return __test_and_set_bit(offset, node_marks(node, mark));
96 }
97
98 /* returns true if the bit was set */
99 static inline bool node_clear_mark(struct xa_node *node, unsigned int offset,
100 xa_mark_t mark)
101 {
102 return __test_and_clear_bit(offset, node_marks(node, mark));
103 }
104
105 static inline bool node_any_mark(struct xa_node *node, xa_mark_t mark)
106 {
107 return !bitmap_empty(node_marks(node, mark), XA_CHUNK_SIZE);
108 }
109
110 static inline void node_mark_all(struct xa_node *node, xa_mark_t mark)
111 {
112 bitmap_fill(node_marks(node, mark), XA_CHUNK_SIZE);
113 }
114
115 #define mark_inc(mark) do { \
116 mark = (__force xa_mark_t)((__force unsigned)(mark) + 1); \
117 } while (0)
118
119 /*
120 * xas_squash_marks() - Merge all marks to the first entry
121 * @xas: Array operation state.
122 *
123 * Set a mark on the first entry if any entry has it set. Clear marks on
124 * all sibling entries.
125 */
126 static void xas_squash_marks(const struct xa_state *xas)
127 {
128 unsigned int mark = 0;
129 unsigned int limit = xas->xa_offset + xas->xa_sibs + 1;
130
131 if (!xas->xa_sibs)
132 return;
133
134 do {
135 unsigned long *marks = xas->xa_node->marks[mark];
136 if (find_next_bit(marks, limit, xas->xa_offset + 1) == limit)
137 continue;
138 __set_bit(xas->xa_offset, marks);
139 bitmap_clear(marks, xas->xa_offset + 1, xas->xa_sibs);
140 } while (mark++ != (__force unsigned)XA_MARK_MAX);
141 }
142
143 /* extracts the offset within this node from the index */
144 static unsigned int get_offset(unsigned long index, struct xa_node *node)
145 {
146 return (index >> node->shift) & XA_CHUNK_MASK;
147 }
148
149 static void xas_set_offset(struct xa_state *xas)
150 {
151 xas->xa_offset = get_offset(xas->xa_index, xas->xa_node);
152 }
153
154 /* move the index either forwards (find) or backwards (sibling slot) */
155 static void xas_move_index(struct xa_state *xas, unsigned long offset)
156 {
157 unsigned int shift = xas->xa_node->shift;
158 xas->xa_index &= ~XA_CHUNK_MASK << shift;
159 xas->xa_index += offset << shift;
160 }
161
162 static void xas_next_offset(struct xa_state *xas)
163 {
164 xas->xa_offset++;
165 xas_move_index(xas, xas->xa_offset);
166 }
167
168 static void *set_bounds(struct xa_state *xas)
169 {
170 xas->xa_node = XAS_BOUNDS;
171 return NULL;
172 }
173
174 /*
175 * Starts a walk. If the @xas is already valid, we assume that it's on
176 * the right path and just return where we've got to. If we're in an
177 * error state, return NULL. If the index is outside the current scope
178 * of the xarray, return NULL without changing @xas->xa_node. Otherwise
179 * set @xas->xa_node to NULL and return the current head of the array.
180 */
181 static void *xas_start(struct xa_state *xas)
182 {
183 void *entry;
184
185 if (xas_valid(xas))
186 return xas_reload(xas);
187 if (xas_error(xas))
188 return NULL;
189
190 entry = xa_head(xas->xa);
191 if (!xa_is_node(entry)) {
192 if (xas->xa_index)
193 return set_bounds(xas);
194 } else {
195 if ((xas->xa_index >> xa_to_node(entry)->shift) > XA_CHUNK_MASK)
196 return set_bounds(xas);
197 }
198
199 xas->xa_node = NULL;
200 return entry;
201 }
202
203 static __always_inline void *xas_descend(struct xa_state *xas,
204 struct xa_node *node)
205 {
206 unsigned int offset = get_offset(xas->xa_index, node);
207 void *entry = xa_entry(xas->xa, node, offset);
208
209 xas->xa_node = node;
210 while (xa_is_sibling(entry)) {
211 offset = xa_to_sibling(entry);
212 entry = xa_entry(xas->xa, node, offset);
213 if (node->shift && xa_is_node(entry))
214 entry = XA_RETRY_ENTRY;
215 }
216
217 xas->xa_offset = offset;
218 return entry;
219 }
220
221 /**
222 * xas_load() - Load an entry from the XArray (advanced).
223 * @xas: XArray operation state.
224 *
225 * Usually walks the @xas to the appropriate state to load the entry
226 * stored at xa_index. However, it will do nothing and return %NULL if
227 * @xas is in an error state. xas_load() will never expand the tree.
228 *
229 * If the xa_state is set up to operate on a multi-index entry, xas_load()
230 * may return %NULL or an internal entry, even if there are entries
231 * present within the range specified by @xas.
232 *
233 * Context: Any context. The caller should hold the xa_lock or the RCU lock.
234 * Return: Usually an entry in the XArray, but see description for exceptions.
235 */
236 void *xas_load(struct xa_state *xas)
237 {
238 void *entry = xas_start(xas);
239
240 while (xa_is_node(entry)) {
241 struct xa_node *node = xa_to_node(entry);
242
243 if (xas->xa_shift > node->shift)
244 break;
245 entry = xas_descend(xas, node);
246 if (node->shift == 0)
247 break;
248 }
249 return entry;
250 }
251 EXPORT_SYMBOL_GPL(xas_load);
252
253 #define XA_RCU_FREE ((struct xarray *)1)
254
255 static void xa_node_free(struct xa_node *node)
256 {
257 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
258 node->array = XA_RCU_FREE;
259 call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
260 }
261
262 /*
263 * xas_destroy() - Free any resources allocated during the XArray operation.
264 * @xas: XArray operation state.
265 *
266 * Most users will not need to call this function; it is called for you
267 * by xas_nomem().
268 */
269 void xas_destroy(struct xa_state *xas)
270 {
271 struct xa_node *next, *node = xas->xa_alloc;
272
273 while (node) {
274 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
275 next = rcu_dereference_raw(node->parent);
276 radix_tree_node_rcu_free(&node->rcu_head);
277 xas->xa_alloc = node = next;
278 }
279 }
280
281 /**
282 * xas_nomem() - Allocate memory if needed.
283 * @xas: XArray operation state.
284 * @gfp: Memory allocation flags.
285 *
286 * If we need to add new nodes to the XArray, we try to allocate memory
287 * with GFP_NOWAIT while holding the lock, which will usually succeed.
288 * If it fails, @xas is flagged as needing memory to continue. The caller
289 * should drop the lock and call xas_nomem(). If xas_nomem() succeeds,
290 * the caller should retry the operation.
291 *
292 * Forward progress is guaranteed as one node is allocated here and
293 * stored in the xa_state where it will be found by xas_alloc(). More
294 * nodes will likely be found in the slab allocator, but we do not tie
295 * them up here.
296 *
297 * Return: true if memory was needed, and was successfully allocated.
298 */
299 bool xas_nomem(struct xa_state *xas, gfp_t gfp)
300 {
301 if (xas->xa_node != XA_ERROR(-ENOMEM)) {
302 xas_destroy(xas);
303 return false;
304 }
305 if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
306 gfp |= __GFP_ACCOUNT;
307 xas->xa_alloc = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp);
308 if (!xas->xa_alloc)
309 return false;
310 xas->xa_alloc->parent = NULL;
311 XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list));
312 xas->xa_node = XAS_RESTART;
313 return true;
314 }
315 EXPORT_SYMBOL_GPL(xas_nomem);
316
317 /*
318 * __xas_nomem() - Drop locks and allocate memory if needed.
319 * @xas: XArray operation state.
320 * @gfp: Memory allocation flags.
321 *
322 * Internal variant of xas_nomem().
323 *
324 * Return: true if memory was needed, and was successfully allocated.
325 */
326 static bool __xas_nomem(struct xa_state *xas, gfp_t gfp)
327 __must_hold(xas->xa->xa_lock)
328 {
329 unsigned int lock_type = xa_lock_type(xas->xa);
330
331 if (xas->xa_node != XA_ERROR(-ENOMEM)) {
332 xas_destroy(xas);
333 return false;
334 }
335 if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
336 gfp |= __GFP_ACCOUNT;
337 if (gfpflags_allow_blocking(gfp)) {
338 xas_unlock_type(xas, lock_type);
339 xas->xa_alloc = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp);
340 xas_lock_type(xas, lock_type);
341 } else {
342 xas->xa_alloc = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp);
343 }
344 if (!xas->xa_alloc)
345 return false;
346 xas->xa_alloc->parent = NULL;
347 XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list));
348 xas->xa_node = XAS_RESTART;
349 return true;
350 }
351
352 static void xas_update(struct xa_state *xas, struct xa_node *node)
353 {
354 if (xas->xa_update)
355 xas->xa_update(node);
356 else
357 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
358 }
359
360 static void *xas_alloc(struct xa_state *xas, unsigned int shift)
361 {
362 struct xa_node *parent = xas->xa_node;
363 struct xa_node *node = xas->xa_alloc;
364
365 if (xas_invalid(xas))
366 return NULL;
367
368 if (node) {
369 xas->xa_alloc = NULL;
370 } else {
371 gfp_t gfp = GFP_NOWAIT | __GFP_NOWARN;
372
373 if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
374 gfp |= __GFP_ACCOUNT;
375
376 node = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp);
377 if (!node) {
378 xas_set_err(xas, -ENOMEM);
379 return NULL;
380 }
381 }
382
383 if (parent) {
384 node->offset = xas->xa_offset;
385 parent->count++;
386 XA_NODE_BUG_ON(node, parent->count > XA_CHUNK_SIZE);
387 xas_update(xas, parent);
388 }
389 XA_NODE_BUG_ON(node, shift > BITS_PER_LONG);
390 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
391 node->shift = shift;
392 node->count = 0;
393 node->nr_values = 0;
394 RCU_INIT_POINTER(node->parent, xas->xa_node);
395 node->array = xas->xa;
396
397 return node;
398 }
399
400 #ifdef CONFIG_XARRAY_MULTI
401 /* Returns the number of indices covered by a given xa_state */
402 static unsigned long xas_size(const struct xa_state *xas)
403 {
404 return (xas->xa_sibs + 1UL) << xas->xa_shift;
405 }
406 #endif
407
408 /*
409 * Use this to calculate the maximum index that will need to be created
410 * in order to add the entry described by @xas. Because we cannot store a
411 * multi-index entry at index 0, the calculation is a little more complex
412 * than you might expect.
413 */
414 static unsigned long xas_max(struct xa_state *xas)
415 {
416 unsigned long max = xas->xa_index;
417
418 #ifdef CONFIG_XARRAY_MULTI
419 if (xas->xa_shift || xas->xa_sibs) {
420 unsigned long mask = xas_size(xas) - 1;
421 max |= mask;
422 if (mask == max)
423 max++;
424 }
425 #endif
426
427 return max;
428 }
429
430 /* The maximum index that can be contained in the array without expanding it */
431 static unsigned long max_index(void *entry)
432 {
433 if (!xa_is_node(entry))
434 return 0;
435 return (XA_CHUNK_SIZE << xa_to_node(entry)->shift) - 1;
436 }
437
438 static void xas_shrink(struct xa_state *xas)
439 {
440 struct xarray *xa = xas->xa;
441 struct xa_node *node = xas->xa_node;
442
443 for (;;) {
444 void *entry;
445
446 XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
447 if (node->count != 1)
448 break;
449 entry = xa_entry_locked(xa, node, 0);
450 if (!entry)
451 break;
452 if (!xa_is_node(entry) && node->shift)
453 break;
454 if (xa_is_zero(entry) && xa_zero_busy(xa))
455 entry = NULL;
456 xas->xa_node = XAS_BOUNDS;
457
458 RCU_INIT_POINTER(xa->xa_head, entry);
459 if (xa_track_free(xa) && !node_get_mark(node, 0, XA_FREE_MARK))
460 xa_mark_clear(xa, XA_FREE_MARK);
461
462 node->count = 0;
463 node->nr_values = 0;
464 if (!xa_is_node(entry))
465 RCU_INIT_POINTER(node->slots[0], XA_RETRY_ENTRY);
466 xas_update(xas, node);
467 xa_node_free(node);
468 if (!xa_is_node(entry))
469 break;
470 node = xa_to_node(entry);
471 node->parent = NULL;
472 }
473 }
474
475 /*
476 * xas_delete_node() - Attempt to delete an xa_node
477 * @xas: Array operation state.
478 *
479 * Attempts to delete the @xas->xa_node. This will fail if xa->node has
480 * a non-zero reference count.
481 */
482 static void xas_delete_node(struct xa_state *xas)
483 {
484 struct xa_node *node = xas->xa_node;
485
486 for (;;) {
487 struct xa_node *parent;
488
489 XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
490 if (node->count)
491 break;
492
493 parent = xa_parent_locked(xas->xa, node);
494 xas->xa_node = parent;
495 xas->xa_offset = node->offset;
496 xa_node_free(node);
497
498 if (!parent) {
499 xas->xa->xa_head = NULL;
500 xas->xa_node = XAS_BOUNDS;
501 return;
502 }
503
504 parent->slots[xas->xa_offset] = NULL;
505 parent->count--;
506 XA_NODE_BUG_ON(parent, parent->count > XA_CHUNK_SIZE);
507 node = parent;
508 xas_update(xas, node);
509 }
510
511 if (!node->parent)
512 xas_shrink(xas);
513 }
514
515 /**
516 * xas_free_nodes() - Free this node and all nodes that it references
517 * @xas: Array operation state.
518 * @top: Node to free
519 *
520 * This node has been removed from the tree. We must now free it and all
521 * of its subnodes. There may be RCU walkers with references into the tree,
522 * so we must replace all entries with retry markers.
523 */
524 static void xas_free_nodes(struct xa_state *xas, struct xa_node *top)
525 {
526 unsigned int offset = 0;
527 struct xa_node *node = top;
528
529 for (;;) {
530 void *entry = xa_entry_locked(xas->xa, node, offset);
531
532 if (node->shift && xa_is_node(entry)) {
533 node = xa_to_node(entry);
534 offset = 0;
535 continue;
536 }
537 if (entry)
538 RCU_INIT_POINTER(node->slots[offset], XA_RETRY_ENTRY);
539 offset++;
540 while (offset == XA_CHUNK_SIZE) {
541 struct xa_node *parent;
542
543 parent = xa_parent_locked(xas->xa, node);
544 offset = node->offset + 1;
545 node->count = 0;
546 node->nr_values = 0;
547 xas_update(xas, node);
548 xa_node_free(node);
549 if (node == top)
550 return;
551 node = parent;
552 }
553 }
554 }
555
556 /*
557 * xas_expand adds nodes to the head of the tree until it has reached
558 * sufficient height to be able to contain @xas->xa_index
559 */
560 static int xas_expand(struct xa_state *xas, void *head)
561 {
562 struct xarray *xa = xas->xa;
563 struct xa_node *node = NULL;
564 unsigned int shift = 0;
565 unsigned long max = xas_max(xas);
566
567 if (!head) {
568 if (max == 0)
569 return 0;
570 while ((max >> shift) >= XA_CHUNK_SIZE)
571 shift += XA_CHUNK_SHIFT;
572 return shift + XA_CHUNK_SHIFT;
573 } else if (xa_is_node(head)) {
574 node = xa_to_node(head);
575 shift = node->shift + XA_CHUNK_SHIFT;
576 }
577 xas->xa_node = NULL;
578
579 while (max > max_index(head)) {
580 xa_mark_t mark = 0;
581
582 XA_NODE_BUG_ON(node, shift > BITS_PER_LONG);
583 node = xas_alloc(xas, shift);
584 if (!node)
585 return -ENOMEM;
586
587 node->count = 1;
588 if (xa_is_value(head))
589 node->nr_values = 1;
590 RCU_INIT_POINTER(node->slots[0], head);
591
592 /* Propagate the aggregated mark info to the new child */
593 for (;;) {
594 if (xa_track_free(xa) && mark == XA_FREE_MARK) {
595 node_mark_all(node, XA_FREE_MARK);
596 if (!xa_marked(xa, XA_FREE_MARK)) {
597 node_clear_mark(node, 0, XA_FREE_MARK);
598 xa_mark_set(xa, XA_FREE_MARK);
599 }
600 } else if (xa_marked(xa, mark)) {
601 node_set_mark(node, 0, mark);
602 }
603 if (mark == XA_MARK_MAX)
604 break;
605 mark_inc(mark);
606 }
607
608 /*
609 * Now that the new node is fully initialised, we can add
610 * it to the tree
611 */
612 if (xa_is_node(head)) {
613 xa_to_node(head)->offset = 0;
614 rcu_assign_pointer(xa_to_node(head)->parent, node);
615 }
616 head = xa_mk_node(node);
617 rcu_assign_pointer(xa->xa_head, head);
618 xas_update(xas, node);
619
620 shift += XA_CHUNK_SHIFT;
621 }
622
623 xas->xa_node = node;
624 return shift;
625 }
626
627 /*
628 * xas_create() - Create a slot to store an entry in.
629 * @xas: XArray operation state.
630 * @allow_root: %true if we can store the entry in the root directly
631 *
632 * Most users will not need to call this function directly, as it is called
633 * by xas_store(). It is useful for doing conditional store operations
634 * (see the xa_cmpxchg() implementation for an example).
635 *
636 * Return: If the slot already existed, returns the contents of this slot.
637 * If the slot was newly created, returns %NULL. If it failed to create the
638 * slot, returns %NULL and indicates the error in @xas.
639 */
640 static void *xas_create(struct xa_state *xas, bool allow_root)
641 {
642 struct xarray *xa = xas->xa;
643 void *entry;
644 void __rcu **slot;
645 struct xa_node *node = xas->xa_node;
646 int shift;
647 unsigned int order = xas->xa_shift;
648
649 if (xas_top(node)) {
650 entry = xa_head_locked(xa);
651 xas->xa_node = NULL;
652 if (!entry && xa_zero_busy(xa))
653 entry = XA_ZERO_ENTRY;
654 shift = xas_expand(xas, entry);
655 if (shift < 0)
656 return NULL;
657 if (!shift && !allow_root)
658 shift = XA_CHUNK_SHIFT;
659 entry = xa_head_locked(xa);
660 slot = &xa->xa_head;
661 } else if (xas_error(xas)) {
662 return NULL;
663 } else if (node) {
664 unsigned int offset = xas->xa_offset;
665
666 shift = node->shift;
667 entry = xa_entry_locked(xa, node, offset);
668 slot = &node->slots[offset];
669 } else {
670 shift = 0;
671 entry = xa_head_locked(xa);
672 slot = &xa->xa_head;
673 }
674
675 while (shift > order) {
676 shift -= XA_CHUNK_SHIFT;
677 if (!entry) {
678 node = xas_alloc(xas, shift);
679 if (!node)
680 break;
681 if (xa_track_free(xa))
682 node_mark_all(node, XA_FREE_MARK);
683 rcu_assign_pointer(*slot, xa_mk_node(node));
684 } else if (xa_is_node(entry)) {
685 node = xa_to_node(entry);
686 } else {
687 break;
688 }
689 entry = xas_descend(xas, node);
690 slot = &node->slots[xas->xa_offset];
691 }
692
693 return entry;
694 }
695
696 /**
697 * xas_create_range() - Ensure that stores to this range will succeed
698 * @xas: XArray operation state.
699 *
700 * Creates all of the slots in the range covered by @xas. Sets @xas to
701 * create single-index entries and positions it at the beginning of the
702 * range. This is for the benefit of users which have not yet been
703 * converted to use multi-index entries.
704 */
705 void xas_create_range(struct xa_state *xas)
706 {
707 unsigned long index = xas->xa_index;
708 unsigned char shift = xas->xa_shift;
709 unsigned char sibs = xas->xa_sibs;
710
711 xas->xa_index |= ((sibs + 1UL) << shift) - 1;
712 if (xas_is_node(xas) && xas->xa_node->shift == xas->xa_shift)
713 xas->xa_offset |= sibs;
714 xas->xa_shift = 0;
715 xas->xa_sibs = 0;
716
717 for (;;) {
718 xas_create(xas, true);
719 if (xas_error(xas))
720 goto restore;
721 if (xas->xa_index <= (index | XA_CHUNK_MASK))
722 goto success;
723 xas->xa_index -= XA_CHUNK_SIZE;
724
725 for (;;) {
726 struct xa_node *node = xas->xa_node;
727 if (node->shift >= shift)
728 break;
729 xas->xa_node = xa_parent_locked(xas->xa, node);
730 xas->xa_offset = node->offset - 1;
731 if (node->offset != 0)
732 break;
733 }
734 }
735
736 restore:
737 xas->xa_shift = shift;
738 xas->xa_sibs = sibs;
739 xas->xa_index = index;
740 return;
741 success:
742 xas->xa_index = index;
743 if (xas->xa_node)
744 xas_set_offset(xas);
745 }
746 EXPORT_SYMBOL_GPL(xas_create_range);
747
748 static void update_node(struct xa_state *xas, struct xa_node *node,
749 int count, int values)
750 {
751 if (!node || (!count && !values))
752 return;
753
754 node->count += count;
755 node->nr_values += values;
756 XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
757 XA_NODE_BUG_ON(node, node->nr_values > XA_CHUNK_SIZE);
758 xas_update(xas, node);
759 if (count < 0)
760 xas_delete_node(xas);
761 }
762
763 /**
764 * xas_store() - Store this entry in the XArray.
765 * @xas: XArray operation state.
766 * @entry: New entry.
767 *
768 * If @xas is operating on a multi-index entry, the entry returned by this
769 * function is essentially meaningless (it may be an internal entry or it
770 * may be %NULL, even if there are non-NULL entries at some of the indices
771 * covered by the range). This is not a problem for any current users,
772 * and can be changed if needed.
773 *
774 * Return: The old entry at this index.
775 */
776 void *xas_store(struct xa_state *xas, void *entry)
777 {
778 struct xa_node *node;
779 void __rcu **slot = &xas->xa->xa_head;
780 unsigned int offset, max;
781 int count = 0;
782 int values = 0;
783 void *first, *next;
784 bool value = xa_is_value(entry);
785
786 if (entry) {
787 bool allow_root = !xa_is_node(entry) && !xa_is_zero(entry);
788 first = xas_create(xas, allow_root);
789 } else {
790 first = xas_load(xas);
791 }
792
793 if (xas_invalid(xas))
794 return first;
795 node = xas->xa_node;
796 if (node && (xas->xa_shift < node->shift))
797 xas->xa_sibs = 0;
798 if ((first == entry) && !xas->xa_sibs)
799 return first;
800
801 next = first;
802 offset = xas->xa_offset;
803 max = xas->xa_offset + xas->xa_sibs;
804 if (node) {
805 slot = &node->slots[offset];
806 if (xas->xa_sibs)
807 xas_squash_marks(xas);
808 }
809 if (!entry)
810 xas_init_marks(xas);
811
812 for (;;) {
813 /*
814 * Must clear the marks before setting the entry to NULL,
815 * otherwise xas_for_each_marked may find a NULL entry and
816 * stop early. rcu_assign_pointer contains a release barrier
817 * so the mark clearing will appear to happen before the
818 * entry is set to NULL.
819 */
820 rcu_assign_pointer(*slot, entry);
821 if (xa_is_node(next) && (!node || node->shift))
822 xas_free_nodes(xas, xa_to_node(next));
823 if (!node)
824 break;
825 count += !next - !entry;
826 values += !xa_is_value(first) - !value;
827 if (entry) {
828 if (offset == max)
829 break;
830 if (!xa_is_sibling(entry))
831 entry = xa_mk_sibling(xas->xa_offset);
832 } else {
833 if (offset == XA_CHUNK_MASK)
834 break;
835 }
836 next = xa_entry_locked(xas->xa, node, ++offset);
837 if (!xa_is_sibling(next)) {
838 if (!entry && (offset > max))
839 break;
840 first = next;
841 }
842 slot++;
843 }
844
845 update_node(xas, node, count, values);
846 return first;
847 }
848 EXPORT_SYMBOL_GPL(xas_store);
849
850 /**
851 * xas_get_mark() - Returns the state of this mark.
852 * @xas: XArray operation state.
853 * @mark: Mark number.
854 *
855 * Return: true if the mark is set, false if the mark is clear or @xas
856 * is in an error state.
857 */
858 bool xas_get_mark(const struct xa_state *xas, xa_mark_t mark)
859 {
860 if (xas_invalid(xas))
861 return false;
862 if (!xas->xa_node)
863 return xa_marked(xas->xa, mark);
864 return node_get_mark(xas->xa_node, xas->xa_offset, mark);
865 }
866 EXPORT_SYMBOL_GPL(xas_get_mark);
867
868 /**
869 * xas_set_mark() - Sets the mark on this entry and its parents.
870 * @xas: XArray operation state.
871 * @mark: Mark number.
872 *
873 * Sets the specified mark on this entry, and walks up the tree setting it
874 * on all the ancestor entries. Does nothing if @xas has not been walked to
875 * an entry, or is in an error state.
876 */
877 void xas_set_mark(const struct xa_state *xas, xa_mark_t mark)
878 {
879 struct xa_node *node = xas->xa_node;
880 unsigned int offset = xas->xa_offset;
881
882 if (xas_invalid(xas))
883 return;
884
885 while (node) {
886 if (node_set_mark(node, offset, mark))
887 return;
888 offset = node->offset;
889 node = xa_parent_locked(xas->xa, node);
890 }
891
892 if (!xa_marked(xas->xa, mark))
893 xa_mark_set(xas->xa, mark);
894 }
895 EXPORT_SYMBOL_GPL(xas_set_mark);
896
897 /**
898 * xas_clear_mark() - Clears the mark on this entry and its parents.
899 * @xas: XArray operation state.
900 * @mark: Mark number.
901 *
902 * Clears the specified mark on this entry, and walks back to the head
903 * attempting to clear it on all the ancestor entries. Does nothing if
904 * @xas has not been walked to an entry, or is in an error state.
905 */
906 void xas_clear_mark(const struct xa_state *xas, xa_mark_t mark)
907 {
908 struct xa_node *node = xas->xa_node;
909 unsigned int offset = xas->xa_offset;
910
911 if (xas_invalid(xas))
912 return;
913
914 while (node) {
915 if (!node_clear_mark(node, offset, mark))
916 return;
917 if (node_any_mark(node, mark))
918 return;
919
920 offset = node->offset;
921 node = xa_parent_locked(xas->xa, node);
922 }
923
924 if (xa_marked(xas->xa, mark))
925 xa_mark_clear(xas->xa, mark);
926 }
927 EXPORT_SYMBOL_GPL(xas_clear_mark);
928
929 /**
930 * xas_init_marks() - Initialise all marks for the entry
931 * @xas: Array operations state.
932 *
933 * Initialise all marks for the entry specified by @xas. If we're tracking
934 * free entries with a mark, we need to set it on all entries. All other
935 * marks are cleared.
936 *
937 * This implementation is not as efficient as it could be; we may walk
938 * up the tree multiple times.
939 */
940 void xas_init_marks(const struct xa_state *xas)
941 {
942 xa_mark_t mark = 0;
943
944 for (;;) {
945 if (xa_track_free(xas->xa) && mark == XA_FREE_MARK)
946 xas_set_mark(xas, mark);
947 else
948 xas_clear_mark(xas, mark);
949 if (mark == XA_MARK_MAX)
950 break;
951 mark_inc(mark);
952 }
953 }
954 EXPORT_SYMBOL_GPL(xas_init_marks);
955
956 #ifdef CONFIG_XARRAY_MULTI
957 static unsigned int node_get_marks(struct xa_node *node, unsigned int offset)
958 {
959 unsigned int marks = 0;
960 xa_mark_t mark = XA_MARK_0;
961
962 for (;;) {
963 if (node_get_mark(node, offset, mark))
964 marks |= 1 << (__force unsigned int)mark;
965 if (mark == XA_MARK_MAX)
966 break;
967 mark_inc(mark);
968 }
969
970 return marks;
971 }
972
973 static inline void node_mark_slots(struct xa_node *node, unsigned int sibs,
974 xa_mark_t mark)
975 {
976 int i;
977
978 if (sibs == 0)
979 node_mark_all(node, mark);
980 else {
981 for (i = 0; i < XA_CHUNK_SIZE; i += sibs + 1)
982 node_set_mark(node, i, mark);
983 }
984 }
985
986 static void node_set_marks(struct xa_node *node, unsigned int offset,
987 struct xa_node *child, unsigned int sibs,
988 unsigned int marks)
989 {
990 xa_mark_t mark = XA_MARK_0;
991
992 for (;;) {
993 if (marks & (1 << (__force unsigned int)mark)) {
994 node_set_mark(node, offset, mark);
995 if (child)
996 node_mark_slots(child, sibs, mark);
997 }
998 if (mark == XA_MARK_MAX)
999 break;
1000 mark_inc(mark);
1001 }
1002 }
1003
1004 /**
1005 * xas_split_alloc() - Allocate memory for splitting an entry.
1006 * @xas: XArray operation state.
1007 * @entry: New entry which will be stored in the array.
1008 * @order: Current entry order.
1009 * @gfp: Memory allocation flags.
1010 *
1011 * This function should be called before calling xas_split().
1012 * If necessary, it will allocate new nodes (and fill them with @entry)
1013 * to prepare for the upcoming split of an entry of @order size into
1014 * entries of the order stored in the @xas.
1015 *
1016 * Context: May sleep if @gfp flags permit.
1017 */
1018 void xas_split_alloc(struct xa_state *xas, void *entry, unsigned int order,
1019 gfp_t gfp)
1020 {
1021 unsigned int sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1;
1022 unsigned int mask = xas->xa_sibs;
1023
1024 /* XXX: no support for splitting really large entries yet */
1025 if (WARN_ON(xas->xa_shift + 2 * XA_CHUNK_SHIFT < order))
1026 goto nomem;
1027 if (xas->xa_shift + XA_CHUNK_SHIFT > order)
1028 return;
1029
1030 do {
1031 unsigned int i;
1032 void *sibling = NULL;
1033 struct xa_node *node;
1034
1035 node = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp);
1036 if (!node)
1037 goto nomem;
1038 node->array = xas->xa;
1039 for (i = 0; i < XA_CHUNK_SIZE; i++) {
1040 if ((i & mask) == 0) {
1041 RCU_INIT_POINTER(node->slots[i], entry);
1042 sibling = xa_mk_sibling(i);
1043 } else {
1044 RCU_INIT_POINTER(node->slots[i], sibling);
1045 }
1046 }
1047 RCU_INIT_POINTER(node->parent, xas->xa_alloc);
1048 xas->xa_alloc = node;
1049 } while (sibs-- > 0);
1050
1051 return;
1052 nomem:
1053 xas_destroy(xas);
1054 xas_set_err(xas, -ENOMEM);
1055 }
1056 EXPORT_SYMBOL_GPL(xas_split_alloc);
1057
1058 /**
1059 * xas_split() - Split a multi-index entry into smaller entries.
1060 * @xas: XArray operation state.
1061 * @entry: New entry to store in the array.
1062 * @order: Current entry order.
1063 *
1064 * The size of the new entries is set in @xas. The value in @entry is
1065 * copied to all the replacement entries.
1066 *
1067 * Context: Any context. The caller should hold the xa_lock.
1068 */
1069 void xas_split(struct xa_state *xas, void *entry, unsigned int order)
1070 {
1071 unsigned int sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1;
1072 unsigned int offset, marks;
1073 struct xa_node *node;
1074 void *curr = xas_load(xas);
1075 int values = 0;
1076
1077 node = xas->xa_node;
1078 if (xas_top(node))
1079 return;
1080
1081 marks = node_get_marks(node, xas->xa_offset);
1082
1083 offset = xas->xa_offset + sibs;
1084 do {
1085 if (xas->xa_shift < node->shift) {
1086 struct xa_node *child = xas->xa_alloc;
1087
1088 xas->xa_alloc = rcu_dereference_raw(child->parent);
1089 child->shift = node->shift - XA_CHUNK_SHIFT;
1090 child->offset = offset;
1091 child->count = XA_CHUNK_SIZE;
1092 child->nr_values = xa_is_value(entry) ?
1093 XA_CHUNK_SIZE : 0;
1094 RCU_INIT_POINTER(child->parent, node);
1095 node_set_marks(node, offset, child, xas->xa_sibs,
1096 marks);
1097 rcu_assign_pointer(node->slots[offset],
1098 xa_mk_node(child));
1099 if (xa_is_value(curr))
1100 values--;
1101 xas_update(xas, child);
1102 } else {
1103 unsigned int canon = offset - xas->xa_sibs;
1104
1105 node_set_marks(node, canon, NULL, 0, marks);
1106 rcu_assign_pointer(node->slots[canon], entry);
1107 while (offset > canon)
1108 rcu_assign_pointer(node->slots[offset--],
1109 xa_mk_sibling(canon));
1110 values += (xa_is_value(entry) - xa_is_value(curr)) *
1111 (xas->xa_sibs + 1);
1112 }
1113 } while (offset-- > xas->xa_offset);
1114
1115 node->nr_values += values;
1116 xas_update(xas, node);
1117 }
1118 EXPORT_SYMBOL_GPL(xas_split);
1119 #endif
1120
1121 /**
1122 * xas_pause() - Pause a walk to drop a lock.
1123 * @xas: XArray operation state.
1124 *
1125 * Some users need to pause a walk and drop the lock they're holding in
1126 * order to yield to a higher priority thread or carry out an operation
1127 * on an entry. Those users should call this function before they drop
1128 * the lock. It resets the @xas to be suitable for the next iteration
1129 * of the loop after the user has reacquired the lock. If most entries
1130 * found during a walk require you to call xas_pause(), the xa_for_each()
1131 * iterator may be more appropriate.
1132 *
1133 * Note that xas_pause() only works for forward iteration. If a user needs
1134 * to pause a reverse iteration, we will need a xas_pause_rev().
1135 */
1136 void xas_pause(struct xa_state *xas)
1137 {
1138 struct xa_node *node = xas->xa_node;
1139
1140 if (xas_invalid(xas))
1141 return;
1142
1143 xas->xa_node = XAS_RESTART;
1144 if (node) {
1145 unsigned long offset = xas->xa_offset;
1146 while (++offset < XA_CHUNK_SIZE) {
1147 if (!xa_is_sibling(xa_entry(xas->xa, node, offset)))
1148 break;
1149 }
1150 xas->xa_index += (offset - xas->xa_offset) << node->shift;
1151 if (xas->xa_index == 0)
1152 xas->xa_node = XAS_BOUNDS;
1153 } else {
1154 xas->xa_index++;
1155 }
1156 }
1157 EXPORT_SYMBOL_GPL(xas_pause);
1158
1159 /*
1160 * __xas_prev() - Find the previous entry in the XArray.
1161 * @xas: XArray operation state.
1162 *
1163 * Helper function for xas_prev() which handles all the complex cases
1164 * out of line.
1165 */
1166 void *__xas_prev(struct xa_state *xas)
1167 {
1168 void *entry;
1169
1170 if (!xas_frozen(xas->xa_node))
1171 xas->xa_index--;
1172 if (!xas->xa_node)
1173 return set_bounds(xas);
1174 if (xas_not_node(xas->xa_node))
1175 return xas_load(xas);
1176
1177 if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node))
1178 xas->xa_offset--;
1179
1180 while (xas->xa_offset == 255) {
1181 xas->xa_offset = xas->xa_node->offset - 1;
1182 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1183 if (!xas->xa_node)
1184 return set_bounds(xas);
1185 }
1186
1187 for (;;) {
1188 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1189 if (!xa_is_node(entry))
1190 return entry;
1191
1192 xas->xa_node = xa_to_node(entry);
1193 xas_set_offset(xas);
1194 }
1195 }
1196 EXPORT_SYMBOL_GPL(__xas_prev);
1197
1198 /*
1199 * __xas_next() - Find the next entry in the XArray.
1200 * @xas: XArray operation state.
1201 *
1202 * Helper function for xas_next() which handles all the complex cases
1203 * out of line.
1204 */
1205 void *__xas_next(struct xa_state *xas)
1206 {
1207 void *entry;
1208
1209 if (!xas_frozen(xas->xa_node))
1210 xas->xa_index++;
1211 if (!xas->xa_node)
1212 return set_bounds(xas);
1213 if (xas_not_node(xas->xa_node))
1214 return xas_load(xas);
1215
1216 if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node))
1217 xas->xa_offset++;
1218
1219 while (xas->xa_offset == XA_CHUNK_SIZE) {
1220 xas->xa_offset = xas->xa_node->offset + 1;
1221 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1222 if (!xas->xa_node)
1223 return set_bounds(xas);
1224 }
1225
1226 for (;;) {
1227 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1228 if (!xa_is_node(entry))
1229 return entry;
1230
1231 xas->xa_node = xa_to_node(entry);
1232 xas_set_offset(xas);
1233 }
1234 }
1235 EXPORT_SYMBOL_GPL(__xas_next);
1236
1237 /**
1238 * xas_find() - Find the next present entry in the XArray.
1239 * @xas: XArray operation state.
1240 * @max: Highest index to return.
1241 *
1242 * If the @xas has not yet been walked to an entry, return the entry
1243 * which has an index >= xas.xa_index. If it has been walked, the entry
1244 * currently being pointed at has been processed, and so we move to the
1245 * next entry.
1246 *
1247 * If no entry is found and the array is smaller than @max, the iterator
1248 * is set to the smallest index not yet in the array. This allows @xas
1249 * to be immediately passed to xas_store().
1250 *
1251 * Return: The entry, if found, otherwise %NULL.
1252 */
1253 void *xas_find(struct xa_state *xas, unsigned long max)
1254 {
1255 void *entry;
1256
1257 if (xas_error(xas) || xas->xa_node == XAS_BOUNDS)
1258 return NULL;
1259 if (xas->xa_index > max)
1260 return set_bounds(xas);
1261
1262 if (!xas->xa_node) {
1263 xas->xa_index = 1;
1264 return set_bounds(xas);
1265 } else if (xas->xa_node == XAS_RESTART) {
1266 entry = xas_load(xas);
1267 if (entry || xas_not_node(xas->xa_node))
1268 return entry;
1269 } else if (!xas->xa_node->shift &&
1270 xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)) {
1271 xas->xa_offset = ((xas->xa_index - 1) & XA_CHUNK_MASK) + 1;
1272 }
1273
1274 xas_next_offset(xas);
1275
1276 while (xas->xa_node && (xas->xa_index <= max)) {
1277 if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
1278 xas->xa_offset = xas->xa_node->offset + 1;
1279 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1280 continue;
1281 }
1282
1283 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1284 if (xa_is_node(entry)) {
1285 xas->xa_node = xa_to_node(entry);
1286 xas->xa_offset = 0;
1287 continue;
1288 }
1289 if (entry && !xa_is_sibling(entry))
1290 return entry;
1291
1292 xas_next_offset(xas);
1293 }
1294
1295 if (!xas->xa_node)
1296 xas->xa_node = XAS_BOUNDS;
1297 return NULL;
1298 }
1299 EXPORT_SYMBOL_GPL(xas_find);
1300
1301 /**
1302 * xas_find_marked() - Find the next marked entry in the XArray.
1303 * @xas: XArray operation state.
1304 * @max: Highest index to return.
1305 * @mark: Mark number to search for.
1306 *
1307 * If the @xas has not yet been walked to an entry, return the marked entry
1308 * which has an index >= xas.xa_index. If it has been walked, the entry
1309 * currently being pointed at has been processed, and so we return the
1310 * first marked entry with an index > xas.xa_index.
1311 *
1312 * If no marked entry is found and the array is smaller than @max, @xas is
1313 * set to the bounds state and xas->xa_index is set to the smallest index
1314 * not yet in the array. This allows @xas to be immediately passed to
1315 * xas_store().
1316 *
1317 * If no entry is found before @max is reached, @xas is set to the restart
1318 * state.
1319 *
1320 * Return: The entry, if found, otherwise %NULL.
1321 */
1322 void *xas_find_marked(struct xa_state *xas, unsigned long max, xa_mark_t mark)
1323 {
1324 bool advance = true;
1325 unsigned int offset;
1326 void *entry;
1327
1328 if (xas_error(xas))
1329 return NULL;
1330 if (xas->xa_index > max)
1331 goto max;
1332
1333 if (!xas->xa_node) {
1334 xas->xa_index = 1;
1335 goto out;
1336 } else if (xas_top(xas->xa_node)) {
1337 advance = false;
1338 entry = xa_head(xas->xa);
1339 xas->xa_node = NULL;
1340 if (xas->xa_index > max_index(entry))
1341 goto out;
1342 if (!xa_is_node(entry)) {
1343 if (xa_marked(xas->xa, mark))
1344 return entry;
1345 xas->xa_index = 1;
1346 goto out;
1347 }
1348 xas->xa_node = xa_to_node(entry);
1349 xas->xa_offset = xas->xa_index >> xas->xa_node->shift;
1350 }
1351
1352 while (xas->xa_index <= max) {
1353 if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
1354 xas->xa_offset = xas->xa_node->offset + 1;
1355 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1356 if (!xas->xa_node)
1357 break;
1358 advance = false;
1359 continue;
1360 }
1361
1362 if (!advance) {
1363 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1364 if (xa_is_sibling(entry)) {
1365 xas->xa_offset = xa_to_sibling(entry);
1366 xas_move_index(xas, xas->xa_offset);
1367 }
1368 }
1369
1370 offset = xas_find_chunk(xas, advance, mark);
1371 if (offset > xas->xa_offset) {
1372 advance = false;
1373 xas_move_index(xas, offset);
1374 /* Mind the wrap */
1375 if ((xas->xa_index - 1) >= max)
1376 goto max;
1377 xas->xa_offset = offset;
1378 if (offset == XA_CHUNK_SIZE)
1379 continue;
1380 }
1381
1382 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1383 if (!entry && !(xa_track_free(xas->xa) && mark == XA_FREE_MARK))
1384 continue;
1385 if (!xa_is_node(entry))
1386 return entry;
1387 xas->xa_node = xa_to_node(entry);
1388 xas_set_offset(xas);
1389 }
1390
1391 out:
1392 if (xas->xa_index > max)
1393 goto max;
1394 return set_bounds(xas);
1395 max:
1396 xas->xa_node = XAS_RESTART;
1397 return NULL;
1398 }
1399 EXPORT_SYMBOL_GPL(xas_find_marked);
1400
1401 /**
1402 * xas_find_conflict() - Find the next present entry in a range.
1403 * @xas: XArray operation state.
1404 *
1405 * The @xas describes both a range and a position within that range.
1406 *
1407 * Context: Any context. Expects xa_lock to be held.
1408 * Return: The next entry in the range covered by @xas or %NULL.
1409 */
1410 void *xas_find_conflict(struct xa_state *xas)
1411 {
1412 void *curr;
1413
1414 if (xas_error(xas))
1415 return NULL;
1416
1417 if (!xas->xa_node)
1418 return NULL;
1419
1420 if (xas_top(xas->xa_node)) {
1421 curr = xas_start(xas);
1422 if (!curr)
1423 return NULL;
1424 while (xa_is_node(curr)) {
1425 struct xa_node *node = xa_to_node(curr);
1426 curr = xas_descend(xas, node);
1427 }
1428 if (curr)
1429 return curr;
1430 }
1431
1432 if (xas->xa_node->shift > xas->xa_shift)
1433 return NULL;
1434
1435 for (;;) {
1436 if (xas->xa_node->shift == xas->xa_shift) {
1437 if ((xas->xa_offset & xas->xa_sibs) == xas->xa_sibs)
1438 break;
1439 } else if (xas->xa_offset == XA_CHUNK_MASK) {
1440 xas->xa_offset = xas->xa_node->offset;
1441 xas->xa_node = xa_parent_locked(xas->xa, xas->xa_node);
1442 if (!xas->xa_node)
1443 break;
1444 continue;
1445 }
1446 curr = xa_entry_locked(xas->xa, xas->xa_node, ++xas->xa_offset);
1447 if (xa_is_sibling(curr))
1448 continue;
1449 while (xa_is_node(curr)) {
1450 xas->xa_node = xa_to_node(curr);
1451 xas->xa_offset = 0;
1452 curr = xa_entry_locked(xas->xa, xas->xa_node, 0);
1453 }
1454 if (curr)
1455 return curr;
1456 }
1457 xas->xa_offset -= xas->xa_sibs;
1458 return NULL;
1459 }
1460 EXPORT_SYMBOL_GPL(xas_find_conflict);
1461
1462 /**
1463 * xa_load() - Load an entry from an XArray.
1464 * @xa: XArray.
1465 * @index: index into array.
1466 *
1467 * Context: Any context. Takes and releases the RCU lock.
1468 * Return: The entry at @index in @xa.
1469 */
1470 void *xa_load(struct xarray *xa, unsigned long index)
1471 {
1472 XA_STATE(xas, xa, index);
1473 void *entry;
1474
1475 rcu_read_lock();
1476 do {
1477 entry = xas_load(&xas);
1478 if (xa_is_zero(entry))
1479 entry = NULL;
1480 } while (xas_retry(&xas, entry));
1481 rcu_read_unlock();
1482
1483 return entry;
1484 }
1485 EXPORT_SYMBOL(xa_load);
1486
1487 static void *xas_result(struct xa_state *xas, void *curr)
1488 {
1489 if (xa_is_zero(curr))
1490 return NULL;
1491 if (xas_error(xas))
1492 curr = xas->xa_node;
1493 return curr;
1494 }
1495
1496 /**
1497 * __xa_erase() - Erase this entry from the XArray while locked.
1498 * @xa: XArray.
1499 * @index: Index into array.
1500 *
1501 * After this function returns, loading from @index will return %NULL.
1502 * If the index is part of a multi-index entry, all indices will be erased
1503 * and none of the entries will be part of a multi-index entry.
1504 *
1505 * Context: Any context. Expects xa_lock to be held on entry.
1506 * Return: The entry which used to be at this index.
1507 */
1508 void *__xa_erase(struct xarray *xa, unsigned long index)
1509 {
1510 XA_STATE(xas, xa, index);
1511 return xas_result(&xas, xas_store(&xas, NULL));
1512 }
1513 EXPORT_SYMBOL(__xa_erase);
1514
1515 /**
1516 * xa_erase() - Erase this entry from the XArray.
1517 * @xa: XArray.
1518 * @index: Index of entry.
1519 *
1520 * After this function returns, loading from @index will return %NULL.
1521 * If the index is part of a multi-index entry, all indices will be erased
1522 * and none of the entries will be part of a multi-index entry.
1523 *
1524 * Context: Any context. Takes and releases the xa_lock.
1525 * Return: The entry which used to be at this index.
1526 */
1527 void *xa_erase(struct xarray *xa, unsigned long index)
1528 {
1529 void *entry;
1530
1531 xa_lock(xa);
1532 entry = __xa_erase(xa, index);
1533 xa_unlock(xa);
1534
1535 return entry;
1536 }
1537 EXPORT_SYMBOL(xa_erase);
1538
1539 /**
1540 * __xa_store() - Store this entry in the XArray.
1541 * @xa: XArray.
1542 * @index: Index into array.
1543 * @entry: New entry.
1544 * @gfp: Memory allocation flags.
1545 *
1546 * You must already be holding the xa_lock when calling this function.
1547 * It will drop the lock if needed to allocate memory, and then reacquire
1548 * it afterwards.
1549 *
1550 * Context: Any context. Expects xa_lock to be held on entry. May
1551 * release and reacquire xa_lock if @gfp flags permit.
1552 * Return: The old entry at this index or xa_err() if an error happened.
1553 */
1554 void *__xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1555 {
1556 XA_STATE(xas, xa, index);
1557 void *curr;
1558
1559 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1560 return XA_ERROR(-EINVAL);
1561 if (xa_track_free(xa) && !entry)
1562 entry = XA_ZERO_ENTRY;
1563
1564 do {
1565 curr = xas_store(&xas, entry);
1566 if (xa_track_free(xa))
1567 xas_clear_mark(&xas, XA_FREE_MARK);
1568 } while (__xas_nomem(&xas, gfp));
1569
1570 return xas_result(&xas, curr);
1571 }
1572 EXPORT_SYMBOL(__xa_store);
1573
1574 /**
1575 * xa_store() - Store this entry in the XArray.
1576 * @xa: XArray.
1577 * @index: Index into array.
1578 * @entry: New entry.
1579 * @gfp: Memory allocation flags.
1580 *
1581 * After this function returns, loads from this index will return @entry.
1582 * Storing into an existing multi-index entry updates the entry of every index.
1583 * The marks associated with @index are unaffected unless @entry is %NULL.
1584 *
1585 * Context: Any context. Takes and releases the xa_lock.
1586 * May sleep if the @gfp flags permit.
1587 * Return: The old entry at this index on success, xa_err(-EINVAL) if @entry
1588 * cannot be stored in an XArray, or xa_err(-ENOMEM) if memory allocation
1589 * failed.
1590 */
1591 void *xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1592 {
1593 void *curr;
1594
1595 xa_lock(xa);
1596 curr = __xa_store(xa, index, entry, gfp);
1597 xa_unlock(xa);
1598
1599 return curr;
1600 }
1601 EXPORT_SYMBOL(xa_store);
1602
1603 /**
1604 * __xa_cmpxchg() - Store this entry in the XArray.
1605 * @xa: XArray.
1606 * @index: Index into array.
1607 * @old: Old value to test against.
1608 * @entry: New entry.
1609 * @gfp: Memory allocation flags.
1610 *
1611 * You must already be holding the xa_lock when calling this function.
1612 * It will drop the lock if needed to allocate memory, and then reacquire
1613 * it afterwards.
1614 *
1615 * Context: Any context. Expects xa_lock to be held on entry. May
1616 * release and reacquire xa_lock if @gfp flags permit.
1617 * Return: The old entry at this index or xa_err() if an error happened.
1618 */
1619 void *__xa_cmpxchg(struct xarray *xa, unsigned long index,
1620 void *old, void *entry, gfp_t gfp)
1621 {
1622 XA_STATE(xas, xa, index);
1623 void *curr;
1624
1625 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1626 return XA_ERROR(-EINVAL);
1627
1628 do {
1629 curr = xas_load(&xas);
1630 if (curr == old) {
1631 xas_store(&xas, entry);
1632 if (xa_track_free(xa) && entry && !curr)
1633 xas_clear_mark(&xas, XA_FREE_MARK);
1634 }
1635 } while (__xas_nomem(&xas, gfp));
1636
1637 return xas_result(&xas, curr);
1638 }
1639 EXPORT_SYMBOL(__xa_cmpxchg);
1640
1641 /**
1642 * __xa_insert() - Store this entry in the XArray if no entry is present.
1643 * @xa: XArray.
1644 * @index: Index into array.
1645 * @entry: New entry.
1646 * @gfp: Memory allocation flags.
1647 *
1648 * Inserting a NULL entry will store a reserved entry (like xa_reserve())
1649 * if no entry is present. Inserting will fail if a reserved entry is
1650 * present, even though loading from this index will return NULL.
1651 *
1652 * Context: Any context. Expects xa_lock to be held on entry. May
1653 * release and reacquire xa_lock if @gfp flags permit.
1654 * Return: 0 if the store succeeded. -EBUSY if another entry was present.
1655 * -ENOMEM if memory could not be allocated.
1656 */
1657 int __xa_insert(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1658 {
1659 XA_STATE(xas, xa, index);
1660 void *curr;
1661
1662 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1663 return -EINVAL;
1664 if (!entry)
1665 entry = XA_ZERO_ENTRY;
1666
1667 do {
1668 curr = xas_load(&xas);
1669 if (!curr) {
1670 xas_store(&xas, entry);
1671 if (xa_track_free(xa))
1672 xas_clear_mark(&xas, XA_FREE_MARK);
1673 } else {
1674 xas_set_err(&xas, -EBUSY);
1675 }
1676 } while (__xas_nomem(&xas, gfp));
1677
1678 return xas_error(&xas);
1679 }
1680 EXPORT_SYMBOL(__xa_insert);
1681
1682 #ifdef CONFIG_XARRAY_MULTI
1683 static void xas_set_range(struct xa_state *xas, unsigned long first,
1684 unsigned long last)
1685 {
1686 unsigned int shift = 0;
1687 unsigned long sibs = last - first;
1688 unsigned int offset = XA_CHUNK_MASK;
1689
1690 xas_set(xas, first);
1691
1692 while ((first & XA_CHUNK_MASK) == 0) {
1693 if (sibs < XA_CHUNK_MASK)
1694 break;
1695 if ((sibs == XA_CHUNK_MASK) && (offset < XA_CHUNK_MASK))
1696 break;
1697 shift += XA_CHUNK_SHIFT;
1698 if (offset == XA_CHUNK_MASK)
1699 offset = sibs & XA_CHUNK_MASK;
1700 sibs >>= XA_CHUNK_SHIFT;
1701 first >>= XA_CHUNK_SHIFT;
1702 }
1703
1704 offset = first & XA_CHUNK_MASK;
1705 if (offset + sibs > XA_CHUNK_MASK)
1706 sibs = XA_CHUNK_MASK - offset;
1707 if ((((first + sibs + 1) << shift) - 1) > last)
1708 sibs -= 1;
1709
1710 xas->xa_shift = shift;
1711 xas->xa_sibs = sibs;
1712 }
1713
1714 /**
1715 * xa_store_range() - Store this entry at a range of indices in the XArray.
1716 * @xa: XArray.
1717 * @first: First index to affect.
1718 * @last: Last index to affect.
1719 * @entry: New entry.
1720 * @gfp: Memory allocation flags.
1721 *
1722 * After this function returns, loads from any index between @first and @last,
1723 * inclusive will return @entry.
1724 * Storing into an existing multi-index entry updates the entry of every index.
1725 * The marks associated with @index are unaffected unless @entry is %NULL.
1726 *
1727 * Context: Process context. Takes and releases the xa_lock. May sleep
1728 * if the @gfp flags permit.
1729 * Return: %NULL on success, xa_err(-EINVAL) if @entry cannot be stored in
1730 * an XArray, or xa_err(-ENOMEM) if memory allocation failed.
1731 */
1732 void *xa_store_range(struct xarray *xa, unsigned long first,
1733 unsigned long last, void *entry, gfp_t gfp)
1734 {
1735 XA_STATE(xas, xa, 0);
1736
1737 if (WARN_ON_ONCE(xa_is_internal(entry)))
1738 return XA_ERROR(-EINVAL);
1739 if (last < first)
1740 return XA_ERROR(-EINVAL);
1741
1742 do {
1743 xas_lock(&xas);
1744 if (entry) {
1745 unsigned int order = BITS_PER_LONG;
1746 if (last + 1)
1747 order = __ffs(last + 1);
1748 xas_set_order(&xas, last, order);
1749 xas_create(&xas, true);
1750 if (xas_error(&xas))
1751 goto unlock;
1752 }
1753 do {
1754 xas_set_range(&xas, first, last);
1755 xas_store(&xas, entry);
1756 if (xas_error(&xas))
1757 goto unlock;
1758 first += xas_size(&xas);
1759 } while (first <= last);
1760 unlock:
1761 xas_unlock(&xas);
1762 } while (xas_nomem(&xas, gfp));
1763
1764 return xas_result(&xas, NULL);
1765 }
1766 EXPORT_SYMBOL(xa_store_range);
1767
1768 /**
1769 * xas_get_order() - Get the order of an entry.
1770 * @xas: XArray operation state.
1771 *
1772 * Called after xas_load, the xas should not be in an error state.
1773 *
1774 * Return: A number between 0 and 63 indicating the order of the entry.
1775 */
1776 int xas_get_order(struct xa_state *xas)
1777 {
1778 int order = 0;
1779
1780 if (!xas->xa_node)
1781 return 0;
1782
1783 for (;;) {
1784 unsigned int slot = xas->xa_offset + (1 << order);
1785
1786 if (slot >= XA_CHUNK_SIZE)
1787 break;
1788 if (!xa_is_sibling(xa_entry(xas->xa, xas->xa_node, slot)))
1789 break;
1790 order++;
1791 }
1792
1793 order += xas->xa_node->shift;
1794 return order;
1795 }
1796 EXPORT_SYMBOL_GPL(xas_get_order);
1797
1798 /**
1799 * xa_get_order() - Get the order of an entry.
1800 * @xa: XArray.
1801 * @index: Index of the entry.
1802 *
1803 * Return: A number between 0 and 63 indicating the order of the entry.
1804 */
1805 int xa_get_order(struct xarray *xa, unsigned long index)
1806 {
1807 XA_STATE(xas, xa, index);
1808 int order = 0;
1809 void *entry;
1810
1811 rcu_read_lock();
1812 entry = xas_load(&xas);
1813 if (entry)
1814 order = xas_get_order(&xas);
1815 rcu_read_unlock();
1816
1817 return order;
1818 }
1819 EXPORT_SYMBOL(xa_get_order);
1820 #endif /* CONFIG_XARRAY_MULTI */
1821
1822 /**
1823 * __xa_alloc() - Find somewhere to store this entry in the XArray.
1824 * @xa: XArray.
1825 * @id: Pointer to ID.
1826 * @limit: Range for allocated ID.
1827 * @entry: New entry.
1828 * @gfp: Memory allocation flags.
1829 *
1830 * Finds an empty entry in @xa between @limit.min and @limit.max,
1831 * stores the index into the @id pointer, then stores the entry at
1832 * that index. A concurrent lookup will not see an uninitialised @id.
1833 *
1834 * Must only be operated on an xarray initialized with flag XA_FLAGS_ALLOC set
1835 * in xa_init_flags().
1836 *
1837 * Context: Any context. Expects xa_lock to be held on entry. May
1838 * release and reacquire xa_lock if @gfp flags permit.
1839 * Return: 0 on success, -ENOMEM if memory could not be allocated or
1840 * -EBUSY if there are no free entries in @limit.
1841 */
1842 int __xa_alloc(struct xarray *xa, u32 *id, void *entry,
1843 struct xa_limit limit, gfp_t gfp)
1844 {
1845 XA_STATE(xas, xa, 0);
1846
1847 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1848 return -EINVAL;
1849 if (WARN_ON_ONCE(!xa_track_free(xa)))
1850 return -EINVAL;
1851
1852 if (!entry)
1853 entry = XA_ZERO_ENTRY;
1854
1855 do {
1856 xas.xa_index = limit.min;
1857 xas_find_marked(&xas, limit.max, XA_FREE_MARK);
1858 if (xas.xa_node == XAS_RESTART)
1859 xas_set_err(&xas, -EBUSY);
1860 else
1861 *id = xas.xa_index;
1862 xas_store(&xas, entry);
1863 xas_clear_mark(&xas, XA_FREE_MARK);
1864 } while (__xas_nomem(&xas, gfp));
1865
1866 return xas_error(&xas);
1867 }
1868 EXPORT_SYMBOL(__xa_alloc);
1869
1870 /**
1871 * __xa_alloc_cyclic() - Find somewhere to store this entry in the XArray.
1872 * @xa: XArray.
1873 * @id: Pointer to ID.
1874 * @entry: New entry.
1875 * @limit: Range of allocated ID.
1876 * @next: Pointer to next ID to allocate.
1877 * @gfp: Memory allocation flags.
1878 *
1879 * Finds an empty entry in @xa between @limit.min and @limit.max,
1880 * stores the index into the @id pointer, then stores the entry at
1881 * that index. A concurrent lookup will not see an uninitialised @id.
1882 * The search for an empty entry will start at @next and will wrap
1883 * around if necessary.
1884 *
1885 * Must only be operated on an xarray initialized with flag XA_FLAGS_ALLOC set
1886 * in xa_init_flags().
1887 *
1888 * Context: Any context. Expects xa_lock to be held on entry. May
1889 * release and reacquire xa_lock if @gfp flags permit.
1890 * Return: 0 if the allocation succeeded without wrapping. 1 if the
1891 * allocation succeeded after wrapping, -ENOMEM if memory could not be
1892 * allocated or -EBUSY if there are no free entries in @limit.
1893 */
1894 int __xa_alloc_cyclic(struct xarray *xa, u32 *id, void *entry,
1895 struct xa_limit limit, u32 *next, gfp_t gfp)
1896 {
1897 u32 min = limit.min;
1898 int ret;
1899
1900 limit.min = max(min, *next);
1901 ret = __xa_alloc(xa, id, entry, limit, gfp);
1902 if ((xa->xa_flags & XA_FLAGS_ALLOC_WRAPPED) && ret == 0) {
1903 xa->xa_flags &= ~XA_FLAGS_ALLOC_WRAPPED;
1904 ret = 1;
1905 }
1906
1907 if (ret < 0 && limit.min > min) {
1908 limit.min = min;
1909 ret = __xa_alloc(xa, id, entry, limit, gfp);
1910 if (ret == 0)
1911 ret = 1;
1912 }
1913
1914 if (ret >= 0) {
1915 *next = *id + 1;
1916 if (*next == 0)
1917 xa->xa_flags |= XA_FLAGS_ALLOC_WRAPPED;
1918 }
1919 return ret;
1920 }
1921 EXPORT_SYMBOL(__xa_alloc_cyclic);
1922
1923 /**
1924 * __xa_set_mark() - Set this mark on this entry while locked.
1925 * @xa: XArray.
1926 * @index: Index of entry.
1927 * @mark: Mark number.
1928 *
1929 * Attempting to set a mark on a %NULL entry does not succeed.
1930 *
1931 * Context: Any context. Expects xa_lock to be held on entry.
1932 */
1933 void __xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1934 {
1935 XA_STATE(xas, xa, index);
1936 void *entry = xas_load(&xas);
1937
1938 if (entry)
1939 xas_set_mark(&xas, mark);
1940 }
1941 EXPORT_SYMBOL(__xa_set_mark);
1942
1943 /**
1944 * __xa_clear_mark() - Clear this mark on this entry while locked.
1945 * @xa: XArray.
1946 * @index: Index of entry.
1947 * @mark: Mark number.
1948 *
1949 * Context: Any context. Expects xa_lock to be held on entry.
1950 */
1951 void __xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1952 {
1953 XA_STATE(xas, xa, index);
1954 void *entry = xas_load(&xas);
1955
1956 if (entry)
1957 xas_clear_mark(&xas, mark);
1958 }
1959 EXPORT_SYMBOL(__xa_clear_mark);
1960
1961 /**
1962 * xa_get_mark() - Inquire whether this mark is set on this entry.
1963 * @xa: XArray.
1964 * @index: Index of entry.
1965 * @mark: Mark number.
1966 *
1967 * This function uses the RCU read lock, so the result may be out of date
1968 * by the time it returns. If you need the result to be stable, use a lock.
1969 *
1970 * Context: Any context. Takes and releases the RCU lock.
1971 * Return: True if the entry at @index has this mark set, false if it doesn't.
1972 */
1973 bool xa_get_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1974 {
1975 XA_STATE(xas, xa, index);
1976 void *entry;
1977
1978 rcu_read_lock();
1979 entry = xas_start(&xas);
1980 while (xas_get_mark(&xas, mark)) {
1981 if (!xa_is_node(entry))
1982 goto found;
1983 entry = xas_descend(&xas, xa_to_node(entry));
1984 }
1985 rcu_read_unlock();
1986 return false;
1987 found:
1988 rcu_read_unlock();
1989 return true;
1990 }
1991 EXPORT_SYMBOL(xa_get_mark);
1992
1993 /**
1994 * xa_set_mark() - Set this mark on this entry.
1995 * @xa: XArray.
1996 * @index: Index of entry.
1997 * @mark: Mark number.
1998 *
1999 * Attempting to set a mark on a %NULL entry does not succeed.
2000 *
2001 * Context: Process context. Takes and releases the xa_lock.
2002 */
2003 void xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
2004 {
2005 xa_lock(xa);
2006 __xa_set_mark(xa, index, mark);
2007 xa_unlock(xa);
2008 }
2009 EXPORT_SYMBOL(xa_set_mark);
2010
2011 /**
2012 * xa_clear_mark() - Clear this mark on this entry.
2013 * @xa: XArray.
2014 * @index: Index of entry.
2015 * @mark: Mark number.
2016 *
2017 * Clearing a mark always succeeds.
2018 *
2019 * Context: Process context. Takes and releases the xa_lock.
2020 */
2021 void xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
2022 {
2023 xa_lock(xa);
2024 __xa_clear_mark(xa, index, mark);
2025 xa_unlock(xa);
2026 }
2027 EXPORT_SYMBOL(xa_clear_mark);
2028
2029 /**
2030 * xa_find() - Search the XArray for an entry.
2031 * @xa: XArray.
2032 * @indexp: Pointer to an index.
2033 * @max: Maximum index to search to.
2034 * @filter: Selection criterion.
2035 *
2036 * Finds the entry in @xa which matches the @filter, and has the lowest
2037 * index that is at least @indexp and no more than @max.
2038 * If an entry is found, @indexp is updated to be the index of the entry.
2039 * This function is protected by the RCU read lock, so it may not find
2040 * entries which are being simultaneously added. It will not return an
2041 * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
2042 *
2043 * Context: Any context. Takes and releases the RCU lock.
2044 * Return: The entry, if found, otherwise %NULL.
2045 */
2046 void *xa_find(struct xarray *xa, unsigned long *indexp,
2047 unsigned long max, xa_mark_t filter)
2048 {
2049 XA_STATE(xas, xa, *indexp);
2050 void *entry;
2051
2052 rcu_read_lock();
2053 do {
2054 if ((__force unsigned int)filter < XA_MAX_MARKS)
2055 entry = xas_find_marked(&xas, max, filter);
2056 else
2057 entry = xas_find(&xas, max);
2058 } while (xas_retry(&xas, entry));
2059 rcu_read_unlock();
2060
2061 if (entry)
2062 *indexp = xas.xa_index;
2063 return entry;
2064 }
2065 EXPORT_SYMBOL(xa_find);
2066
2067 static bool xas_sibling(struct xa_state *xas)
2068 {
2069 struct xa_node *node = xas->xa_node;
2070 unsigned long mask;
2071
2072 if (!IS_ENABLED(CONFIG_XARRAY_MULTI) || !node)
2073 return false;
2074 mask = (XA_CHUNK_SIZE << node->shift) - 1;
2075 return (xas->xa_index & mask) >
2076 ((unsigned long)xas->xa_offset << node->shift);
2077 }
2078
2079 /**
2080 * xa_find_after() - Search the XArray for a present entry.
2081 * @xa: XArray.
2082 * @indexp: Pointer to an index.
2083 * @max: Maximum index to search to.
2084 * @filter: Selection criterion.
2085 *
2086 * Finds the entry in @xa which matches the @filter and has the lowest
2087 * index that is above @indexp and no more than @max.
2088 * If an entry is found, @indexp is updated to be the index of the entry.
2089 * This function is protected by the RCU read lock, so it may miss entries
2090 * which are being simultaneously added. It will not return an
2091 * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
2092 *
2093 * Context: Any context. Takes and releases the RCU lock.
2094 * Return: The pointer, if found, otherwise %NULL.
2095 */
2096 void *xa_find_after(struct xarray *xa, unsigned long *indexp,
2097 unsigned long max, xa_mark_t filter)
2098 {
2099 XA_STATE(xas, xa, *indexp + 1);
2100 void *entry;
2101
2102 if (xas.xa_index == 0)
2103 return NULL;
2104
2105 rcu_read_lock();
2106 for (;;) {
2107 if ((__force unsigned int)filter < XA_MAX_MARKS)
2108 entry = xas_find_marked(&xas, max, filter);
2109 else
2110 entry = xas_find(&xas, max);
2111
2112 if (xas_invalid(&xas))
2113 break;
2114 if (xas_sibling(&xas))
2115 continue;
2116 if (!xas_retry(&xas, entry))
2117 break;
2118 }
2119 rcu_read_unlock();
2120
2121 if (entry)
2122 *indexp = xas.xa_index;
2123 return entry;
2124 }
2125 EXPORT_SYMBOL(xa_find_after);
2126
2127 static unsigned int xas_extract_present(struct xa_state *xas, void **dst,
2128 unsigned long max, unsigned int n)
2129 {
2130 void *entry;
2131 unsigned int i = 0;
2132
2133 rcu_read_lock();
2134 xas_for_each(xas, entry, max) {
2135 if (xas_retry(xas, entry))
2136 continue;
2137 dst[i++] = entry;
2138 if (i == n)
2139 break;
2140 }
2141 rcu_read_unlock();
2142
2143 return i;
2144 }
2145
2146 static unsigned int xas_extract_marked(struct xa_state *xas, void **dst,
2147 unsigned long max, unsigned int n, xa_mark_t mark)
2148 {
2149 void *entry;
2150 unsigned int i = 0;
2151
2152 rcu_read_lock();
2153 xas_for_each_marked(xas, entry, max, mark) {
2154 if (xas_retry(xas, entry))
2155 continue;
2156 dst[i++] = entry;
2157 if (i == n)
2158 break;
2159 }
2160 rcu_read_unlock();
2161
2162 return i;
2163 }
2164
2165 /**
2166 * xa_extract() - Copy selected entries from the XArray into a normal array.
2167 * @xa: The source XArray to copy from.
2168 * @dst: The buffer to copy entries into.
2169 * @start: The first index in the XArray eligible to be selected.
2170 * @max: The last index in the XArray eligible to be selected.
2171 * @n: The maximum number of entries to copy.
2172 * @filter: Selection criterion.
2173 *
2174 * Copies up to @n entries that match @filter from the XArray. The
2175 * copied entries will have indices between @start and @max, inclusive.
2176 *
2177 * The @filter may be an XArray mark value, in which case entries which are
2178 * marked with that mark will be copied. It may also be %XA_PRESENT, in
2179 * which case all entries which are not %NULL will be copied.
2180 *
2181 * The entries returned may not represent a snapshot of the XArray at a
2182 * moment in time. For example, if another thread stores to index 5, then
2183 * index 10, calling xa_extract() may return the old contents of index 5
2184 * and the new contents of index 10. Indices not modified while this
2185 * function is running will not be skipped.
2186 *
2187 * If you need stronger guarantees, holding the xa_lock across calls to this
2188 * function will prevent concurrent modification.
2189 *
2190 * Context: Any context. Takes and releases the RCU lock.
2191 * Return: The number of entries copied.
2192 */
2193 unsigned int xa_extract(struct xarray *xa, void **dst, unsigned long start,
2194 unsigned long max, unsigned int n, xa_mark_t filter)
2195 {
2196 XA_STATE(xas, xa, start);
2197
2198 if (!n)
2199 return 0;
2200
2201 if ((__force unsigned int)filter < XA_MAX_MARKS)
2202 return xas_extract_marked(&xas, dst, max, n, filter);
2203 return xas_extract_present(&xas, dst, max, n);
2204 }
2205 EXPORT_SYMBOL(xa_extract);
2206
2207 /**
2208 * xa_delete_node() - Private interface for workingset code.
2209 * @node: Node to be removed from the tree.
2210 * @update: Function to call to update ancestor nodes.
2211 *
2212 * Context: xa_lock must be held on entry and will not be released.
2213 */
2214 void xa_delete_node(struct xa_node *node, xa_update_node_t update)
2215 {
2216 struct xa_state xas = {
2217 .xa = node->array,
2218 .xa_index = (unsigned long)node->offset <<
2219 (node->shift + XA_CHUNK_SHIFT),
2220 .xa_shift = node->shift + XA_CHUNK_SHIFT,
2221 .xa_offset = node->offset,
2222 .xa_node = xa_parent_locked(node->array, node),
2223 .xa_update = update,
2224 };
2225
2226 xas_store(&xas, NULL);
2227 }
2228 EXPORT_SYMBOL_GPL(xa_delete_node); /* For the benefit of the test suite */
2229
2230 /**
2231 * xa_destroy() - Free all internal data structures.
2232 * @xa: XArray.
2233 *
2234 * After calling this function, the XArray is empty and has freed all memory
2235 * allocated for its internal data structures. You are responsible for
2236 * freeing the objects referenced by the XArray.
2237 *
2238 * Context: Any context. Takes and releases the xa_lock, interrupt-safe.
2239 */
2240 void xa_destroy(struct xarray *xa)
2241 {
2242 XA_STATE(xas, xa, 0);
2243 unsigned long flags;
2244 void *entry;
2245
2246 xas.xa_node = NULL;
2247 xas_lock_irqsave(&xas, flags);
2248 entry = xa_head_locked(xa);
2249 RCU_INIT_POINTER(xa->xa_head, NULL);
2250 xas_init_marks(&xas);
2251 if (xa_zero_busy(xa))
2252 xa_mark_clear(xa, XA_FREE_MARK);
2253 /* lockdep checks we're still holding the lock in xas_free_nodes() */
2254 if (xa_is_node(entry))
2255 xas_free_nodes(&xas, xa_to_node(entry));
2256 xas_unlock_irqrestore(&xas, flags);
2257 }
2258 EXPORT_SYMBOL(xa_destroy);
2259
2260 #ifdef XA_DEBUG
2261 void xa_dump_node(const struct xa_node *node)
2262 {
2263 unsigned i, j;
2264
2265 if (!node)
2266 return;
2267 if ((unsigned long)node & 3) {
2268 pr_cont("node %px\n", node);
2269 return;
2270 }
2271
2272 pr_cont("node %px %s %d parent %px shift %d count %d values %d "
2273 "array %px list %px %px marks",
2274 node, node->parent ? "offset" : "max", node->offset,
2275 node->parent, node->shift, node->count, node->nr_values,
2276 node->array, node->private_list.prev, node->private_list.next);
2277 for (i = 0; i < XA_MAX_MARKS; i++)
2278 for (j = 0; j < XA_MARK_LONGS; j++)
2279 pr_cont(" %lx", node->marks[i][j]);
2280 pr_cont("\n");
2281 }
2282
2283 void xa_dump_index(unsigned long index, unsigned int shift)
2284 {
2285 if (!shift)
2286 pr_info("%lu: ", index);
2287 else if (shift >= BITS_PER_LONG)
2288 pr_info("0-%lu: ", ~0UL);
2289 else
2290 pr_info("%lu-%lu: ", index, index | ((1UL << shift) - 1));
2291 }
2292
2293 void xa_dump_entry(const void *entry, unsigned long index, unsigned long shift)
2294 {
2295 if (!entry)
2296 return;
2297
2298 xa_dump_index(index, shift);
2299
2300 if (xa_is_node(entry)) {
2301 if (shift == 0) {
2302 pr_cont("%px\n", entry);
2303 } else {
2304 unsigned long i;
2305 struct xa_node *node = xa_to_node(entry);
2306 xa_dump_node(node);
2307 for (i = 0; i < XA_CHUNK_SIZE; i++)
2308 xa_dump_entry(node->slots[i],
2309 index + (i << node->shift), node->shift);
2310 }
2311 } else if (xa_is_value(entry))
2312 pr_cont("value %ld (0x%lx) [%px]\n", xa_to_value(entry),
2313 xa_to_value(entry), entry);
2314 else if (!xa_is_internal(entry))
2315 pr_cont("%px\n", entry);
2316 else if (xa_is_retry(entry))
2317 pr_cont("retry (%ld)\n", xa_to_internal(entry));
2318 else if (xa_is_sibling(entry))
2319 pr_cont("sibling (slot %ld)\n", xa_to_sibling(entry));
2320 else if (xa_is_zero(entry))
2321 pr_cont("zero (%ld)\n", xa_to_internal(entry));
2322 else
2323 pr_cont("UNKNOWN ENTRY (%px)\n", entry);
2324 }
2325
2326 void xa_dump(const struct xarray *xa)
2327 {
2328 void *entry = xa->xa_head;
2329 unsigned int shift = 0;
2330
2331 pr_info("xarray: %px head %px flags %x marks %d %d %d\n", xa, entry,
2332 xa->xa_flags, xa_marked(xa, XA_MARK_0),
2333 xa_marked(xa, XA_MARK_1), xa_marked(xa, XA_MARK_2));
2334 if (xa_is_node(entry))
2335 shift = xa_to_node(entry)->shift + XA_CHUNK_SHIFT;
2336 xa_dump_entry(entry, 0, shift);
2337 }
2338 #endif
2339
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