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