projects/linux·blob v6.4-rc7 · refs

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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 <[email protected]>
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 if (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 void node_set_marks(struct xa_node *node, unsigned int offset,
973 struct xa_node *child, unsigned int marks)
974{
975 xa_mark_t mark = XA_MARK_0;
976
977 for (;;) {
978 if (marks & (1 << (__force unsigned int)mark)) {
979 node_set_mark(node, offset, mark);
980 if (child)
981 node_mark_all(child, mark);
982 }
983 if (mark == XA_MARK_MAX)
984 break;
985 mark_inc(mark);
986 }
987}
988
989/**
990 * xas_split_alloc() - Allocate memory for splitting an entry.
991 * @xas: XArray operation state.
992 * @entry: New entry which will be stored in the array.
993 * @order: Current entry order.
994 * @gfp: Memory allocation flags.
995 *
996 * This function should be called before calling xas_split().
997 * If necessary, it will allocate new nodes (and fill them with @entry)
998 * to prepare for the upcoming split of an entry of @order size into
999 * entries of the order stored in the @xas.
1000 *
1001 * Context: May sleep if @gfp flags permit.
1002 */
1003void xas_split_alloc(struct xa_state *xas, void *entry, unsigned int order,
1004 gfp_t gfp)
1005{
1006 unsigned int sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1;
1007 unsigned int mask = xas->xa_sibs;
1008
1009 /* XXX: no support for splitting really large entries yet */
1010 if (WARN_ON(xas->xa_shift + 2 * XA_CHUNK_SHIFT < order))
1011 goto nomem;
1012 if (xas->xa_shift + XA_CHUNK_SHIFT > order)
1013 return;
1014
1015 do {
1016 unsigned int i;
1017 void *sibling = NULL;
1018 struct xa_node *node;
1019
1020 node = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp);
1021 if (!node)
1022 goto nomem;
1023 node->array = xas->xa;
1024 for (i = 0; i < XA_CHUNK_SIZE; i++) {
1025 if ((i & mask) == 0) {
1026 RCU_INIT_POINTER(node->slots[i], entry);
1027 sibling = xa_mk_sibling(i);
1028 } else {
1029 RCU_INIT_POINTER(node->slots[i], sibling);
1030 }
1031 }
1032 RCU_INIT_POINTER(node->parent, xas->xa_alloc);
1033 xas->xa_alloc = node;
1034 } while (sibs-- > 0);
1035
1036 return;
1037nomem:
1038 xas_destroy(xas);
1039 xas_set_err(xas, -ENOMEM);
1040}
1041EXPORT_SYMBOL_GPL(xas_split_alloc);
1042
1043/**
1044 * xas_split() - Split a multi-index entry into smaller entries.
1045 * @xas: XArray operation state.
1046 * @entry: New entry to store in the array.
1047 * @order: Current entry order.
1048 *
1049 * The size of the new entries is set in @xas. The value in @entry is
1050 * copied to all the replacement entries.
1051 *
1052 * Context: Any context. The caller should hold the xa_lock.
1053 */
1054void xas_split(struct xa_state *xas, void *entry, unsigned int order)
1055{
1056 unsigned int sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1;
1057 unsigned int offset, marks;
1058 struct xa_node *node;
1059 void *curr = xas_load(xas);
1060 int values = 0;
1061
1062 node = xas->xa_node;
1063 if (xas_top(node))
1064 return;
1065
1066 marks = node_get_marks(node, xas->xa_offset);
1067
1068 offset = xas->xa_offset + sibs;
1069 do {
1070 if (xas->xa_shift < node->shift) {
1071 struct xa_node *child = xas->xa_alloc;
1072
1073 xas->xa_alloc = rcu_dereference_raw(child->parent);
1074 child->shift = node->shift - XA_CHUNK_SHIFT;
1075 child->offset = offset;
1076 child->count = XA_CHUNK_SIZE;
1077 child->nr_values = xa_is_value(entry) ?
1078 XA_CHUNK_SIZE : 0;
1079 RCU_INIT_POINTER(child->parent, node);
1080 node_set_marks(node, offset, child, marks);
1081 rcu_assign_pointer(node->slots[offset],
1082 xa_mk_node(child));
1083 if (xa_is_value(curr))
1084 values--;
1085 xas_update(xas, child);
1086 } else {
1087 unsigned int canon = offset - xas->xa_sibs;
1088
1089 node_set_marks(node, canon, NULL, marks);
1090 rcu_assign_pointer(node->slots[canon], entry);
1091 while (offset > canon)
1092 rcu_assign_pointer(node->slots[offset--],
1093 xa_mk_sibling(canon));
1094 values += (xa_is_value(entry) - xa_is_value(curr)) *
1095 (xas->xa_sibs + 1);
1096 }
1097 } while (offset-- > xas->xa_offset);
1098
1099 node->nr_values += values;
1100 xas_update(xas, node);
1101}
1102EXPORT_SYMBOL_GPL(xas_split);
1103#endif
1104
1105/**
1106 * xas_pause() - Pause a walk to drop a lock.
1107 * @xas: XArray operation state.
1108 *
1109 * Some users need to pause a walk and drop the lock they're holding in
1110 * order to yield to a higher priority thread or carry out an operation
1111 * on an entry. Those users should call this function before they drop
1112 * the lock. It resets the @xas to be suitable for the next iteration
1113 * of the loop after the user has reacquired the lock. If most entries
1114 * found during a walk require you to call xas_pause(), the xa_for_each()
1115 * iterator may be more appropriate.
1116 *
1117 * Note that xas_pause() only works for forward iteration. If a user needs
1118 * to pause a reverse iteration, we will need a xas_pause_rev().
1119 */
1120void xas_pause(struct xa_state *xas)
1121{
1122 struct xa_node *node = xas->xa_node;
1123
1124 if (xas_invalid(xas))
1125 return;
1126
1127 xas->xa_node = XAS_RESTART;
1128 if (node) {
1129 unsigned long offset = xas->xa_offset;
1130 while (++offset < XA_CHUNK_SIZE) {
1131 if (!xa_is_sibling(xa_entry(xas->xa, node, offset)))
1132 break;
1133 }
1134 xas->xa_index += (offset - xas->xa_offset) << node->shift;
1135 if (xas->xa_index == 0)
1136 xas->xa_node = XAS_BOUNDS;
1137 } else {
1138 xas->xa_index++;
1139 }
1140}
1141EXPORT_SYMBOL_GPL(xas_pause);
1142
1143/*
1144 * __xas_prev() - Find the previous entry in the XArray.
1145 * @xas: XArray operation state.
1146 *
1147 * Helper function for xas_prev() which handles all the complex cases
1148 * out of line.
1149 */
1150void *__xas_prev(struct xa_state *xas)
1151{
1152 void *entry;
1153
1154 if (!xas_frozen(xas->xa_node))
1155 xas->xa_index--;
1156 if (!xas->xa_node)
1157 return set_bounds(xas);
1158 if (xas_not_node(xas->xa_node))
1159 return xas_load(xas);
1160
1161 if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node))
1162 xas->xa_offset--;
1163
1164 while (xas->xa_offset == 255) {
1165 xas->xa_offset = xas->xa_node->offset - 1;
1166 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1167 if (!xas->xa_node)
1168 return set_bounds(xas);
1169 }
1170
1171 for (;;) {
1172 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1173 if (!xa_is_node(entry))
1174 return entry;
1175
1176 xas->xa_node = xa_to_node(entry);
1177 xas_set_offset(xas);
1178 }
1179}
1180EXPORT_SYMBOL_GPL(__xas_prev);
1181
1182/*
1183 * __xas_next() - Find the next entry in the XArray.
1184 * @xas: XArray operation state.
1185 *
1186 * Helper function for xas_next() which handles all the complex cases
1187 * out of line.
1188 */
1189void *__xas_next(struct xa_state *xas)
1190{
1191 void *entry;
1192
1193 if (!xas_frozen(xas->xa_node))
1194 xas->xa_index++;
1195 if (!xas->xa_node)
1196 return set_bounds(xas);
1197 if (xas_not_node(xas->xa_node))
1198 return xas_load(xas);
1199
1200 if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node))
1201 xas->xa_offset++;
1202
1203 while (xas->xa_offset == XA_CHUNK_SIZE) {
1204 xas->xa_offset = xas->xa_node->offset + 1;
1205 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1206 if (!xas->xa_node)
1207 return set_bounds(xas);
1208 }
1209
1210 for (;;) {
1211 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1212 if (!xa_is_node(entry))
1213 return entry;
1214
1215 xas->xa_node = xa_to_node(entry);
1216 xas_set_offset(xas);
1217 }
1218}
1219EXPORT_SYMBOL_GPL(__xas_next);
1220
1221/**
1222 * xas_find() - Find the next present entry in the XArray.
1223 * @xas: XArray operation state.
1224 * @max: Highest index to return.
1225 *
1226 * If the @xas has not yet been walked to an entry, return the entry
1227 * which has an index >= xas.xa_index. If it has been walked, the entry
1228 * currently being pointed at has been processed, and so we move to the
1229 * next entry.
1230 *
1231 * If no entry is found and the array is smaller than @max, the iterator
1232 * is set to the smallest index not yet in the array. This allows @xas
1233 * to be immediately passed to xas_store().
1234 *
1235 * Return: The entry, if found, otherwise %NULL.
1236 */
1237void *xas_find(struct xa_state *xas, unsigned long max)
1238{
1239 void *entry;
1240
1241 if (xas_error(xas) || xas->xa_node == XAS_BOUNDS)
1242 return NULL;
1243 if (xas->xa_index > max)
1244 return set_bounds(xas);
1245
1246 if (!xas->xa_node) {
1247 xas->xa_index = 1;
1248 return set_bounds(xas);
1249 } else if (xas->xa_node == XAS_RESTART) {
1250 entry = xas_load(xas);
1251 if (entry || xas_not_node(xas->xa_node))
1252 return entry;
1253 } else if (!xas->xa_node->shift &&
1254 xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)) {
1255 xas->xa_offset = ((xas->xa_index - 1) & XA_CHUNK_MASK) + 1;
1256 }
1257
1258 xas_next_offset(xas);
1259
1260 while (xas->xa_node && (xas->xa_index <= max)) {
1261 if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
1262 xas->xa_offset = xas->xa_node->offset + 1;
1263 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1264 continue;
1265 }
1266
1267 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1268 if (xa_is_node(entry)) {
1269 xas->xa_node = xa_to_node(entry);
1270 xas->xa_offset = 0;
1271 continue;
1272 }
1273 if (entry && !xa_is_sibling(entry))
1274 return entry;
1275
1276 xas_next_offset(xas);
1277 }
1278
1279 if (!xas->xa_node)
1280 xas->xa_node = XAS_BOUNDS;
1281 return NULL;
1282}
1283EXPORT_SYMBOL_GPL(xas_find);
1284
1285/**
1286 * xas_find_marked() - Find the next marked entry in the XArray.
1287 * @xas: XArray operation state.
1288 * @max: Highest index to return.
1289 * @mark: Mark number to search for.
1290 *
1291 * If the @xas has not yet been walked to an entry, return the marked entry
1292 * which has an index >= xas.xa_index. If it has been walked, the entry
1293 * currently being pointed at has been processed, and so we return the
1294 * first marked entry with an index > xas.xa_index.
1295 *
1296 * If no marked entry is found and the array is smaller than @max, @xas is
1297 * set to the bounds state and xas->xa_index is set to the smallest index
1298 * not yet in the array. This allows @xas to be immediately passed to
1299 * xas_store().
1300 *
1301 * If no entry is found before @max is reached, @xas is set to the restart
1302 * state.
1303 *
1304 * Return: The entry, if found, otherwise %NULL.
1305 */
1306void *xas_find_marked(struct xa_state *xas, unsigned long max, xa_mark_t mark)
1307{
1308 bool advance = true;
1309 unsigned int offset;
1310 void *entry;
1311
1312 if (xas_error(xas))
1313 return NULL;
1314 if (xas->xa_index > max)
1315 goto max;
1316
1317 if (!xas->xa_node) {
1318 xas->xa_index = 1;
1319 goto out;
1320 } else if (xas_top(xas->xa_node)) {
1321 advance = false;
1322 entry = xa_head(xas->xa);
1323 xas->xa_node = NULL;
1324 if (xas->xa_index > max_index(entry))
1325 goto out;
1326 if (!xa_is_node(entry)) {
1327 if (xa_marked(xas->xa, mark))
1328 return entry;
1329 xas->xa_index = 1;
1330 goto out;
1331 }
1332 xas->xa_node = xa_to_node(entry);
1333 xas->xa_offset = xas->xa_index >> xas->xa_node->shift;
1334 }
1335
1336 while (xas->xa_index <= max) {
1337 if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
1338 xas->xa_offset = xas->xa_node->offset + 1;
1339 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1340 if (!xas->xa_node)
1341 break;
1342 advance = false;
1343 continue;
1344 }
1345
1346 if (!advance) {
1347 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1348 if (xa_is_sibling(entry)) {
1349 xas->xa_offset = xa_to_sibling(entry);
1350 xas_move_index(xas, xas->xa_offset);
1351 }
1352 }
1353
1354 offset = xas_find_chunk(xas, advance, mark);
1355 if (offset > xas->xa_offset) {
1356 advance = false;
1357 xas_move_index(xas, offset);
1358 /* Mind the wrap */
1359 if ((xas->xa_index - 1) >= max)
1360 goto max;
1361 xas->xa_offset = offset;
1362 if (offset == XA_CHUNK_SIZE)
1363 continue;
1364 }
1365
1366 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1367 if (!entry && !(xa_track_free(xas->xa) && mark == XA_FREE_MARK))
1368 continue;
1369 if (!xa_is_node(entry))
1370 return entry;
1371 xas->xa_node = xa_to_node(entry);
1372 xas_set_offset(xas);
1373 }
1374
1375out:
1376 if (xas->xa_index > max)
1377 goto max;
1378 return set_bounds(xas);
1379max:
1380 xas->xa_node = XAS_RESTART;
1381 return NULL;
1382}
1383EXPORT_SYMBOL_GPL(xas_find_marked);
1384
1385/**
1386 * xas_find_conflict() - Find the next present entry in a range.
1387 * @xas: XArray operation state.
1388 *
1389 * The @xas describes both a range and a position within that range.
1390 *
1391 * Context: Any context. Expects xa_lock to be held.
1392 * Return: The next entry in the range covered by @xas or %NULL.
1393 */
1394void *xas_find_conflict(struct xa_state *xas)
1395{
1396 void *curr;
1397
1398 if (xas_error(xas))
1399 return NULL;
1400
1401 if (!xas->xa_node)
1402 return NULL;
1403
1404 if (xas_top(xas->xa_node)) {
1405 curr = xas_start(xas);
1406 if (!curr)
1407 return NULL;
1408 while (xa_is_node(curr)) {
1409 struct xa_node *node = xa_to_node(curr);
1410 curr = xas_descend(xas, node);
1411 }
1412 if (curr)
1413 return curr;
1414 }
1415
1416 if (xas->xa_node->shift > xas->xa_shift)
1417 return NULL;
1418
1419 for (;;) {
1420 if (xas->xa_node->shift == xas->xa_shift) {
1421 if ((xas->xa_offset & xas->xa_sibs) == xas->xa_sibs)
1422 break;
1423 } else if (xas->xa_offset == XA_CHUNK_MASK) {
1424 xas->xa_offset = xas->xa_node->offset;
1425 xas->xa_node = xa_parent_locked(xas->xa, xas->xa_node);
1426 if (!xas->xa_node)
1427 break;
1428 continue;
1429 }
1430 curr = xa_entry_locked(xas->xa, xas->xa_node, ++xas->xa_offset);
1431 if (xa_is_sibling(curr))
1432 continue;
1433 while (xa_is_node(curr)) {
1434 xas->xa_node = xa_to_node(curr);
1435 xas->xa_offset = 0;
1436 curr = xa_entry_locked(xas->xa, xas->xa_node, 0);
1437 }
1438 if (curr)
1439 return curr;
1440 }
1441 xas->xa_offset -= xas->xa_sibs;
1442 return NULL;
1443}
1444EXPORT_SYMBOL_GPL(xas_find_conflict);
1445
1446/**
1447 * xa_load() - Load an entry from an XArray.
1448 * @xa: XArray.
1449 * @index: index into array.
1450 *
1451 * Context: Any context. Takes and releases the RCU lock.
1452 * Return: The entry at @index in @xa.
1453 */
1454void *xa_load(struct xarray *xa, unsigned long index)
1455{
1456 XA_STATE(xas, xa, index);
1457 void *entry;
1458
1459 rcu_read_lock();
1460 do {
1461 entry = xas_load(&xas);
1462 if (xa_is_zero(entry))
1463 entry = NULL;
1464 } while (xas_retry(&xas, entry));
1465 rcu_read_unlock();
1466
1467 return entry;
1468}
1469EXPORT_SYMBOL(xa_load);
1470
1471static void *xas_result(struct xa_state *xas, void *curr)
1472{
1473 if (xa_is_zero(curr))
1474 return NULL;
1475 if (xas_error(xas))
1476 curr = xas->xa_node;
1477 return curr;
1478}
1479
1480/**
1481 * __xa_erase() - Erase this entry from the XArray while locked.
1482 * @xa: XArray.
1483 * @index: Index into array.
1484 *
1485 * After this function returns, loading from @index will return %NULL.
1486 * If the index is part of a multi-index entry, all indices will be erased
1487 * and none of the entries will be part of a multi-index entry.
1488 *
1489 * Context: Any context. Expects xa_lock to be held on entry.
1490 * Return: The entry which used to be at this index.
1491 */
1492void *__xa_erase(struct xarray *xa, unsigned long index)
1493{
1494 XA_STATE(xas, xa, index);
1495 return xas_result(&xas, xas_store(&xas, NULL));
1496}
1497EXPORT_SYMBOL(__xa_erase);
1498
1499/**
1500 * xa_erase() - Erase this entry from the XArray.
1501 * @xa: XArray.
1502 * @index: Index of entry.
1503 *
1504 * After this function returns, loading from @index will return %NULL.
1505 * If the index is part of a multi-index entry, all indices will be erased
1506 * and none of the entries will be part of a multi-index entry.
1507 *
1508 * Context: Any context. Takes and releases the xa_lock.
1509 * Return: The entry which used to be at this index.
1510 */
1511void *xa_erase(struct xarray *xa, unsigned long index)
1512{
1513 void *entry;
1514
1515 xa_lock(xa);
1516 entry = __xa_erase(xa, index);
1517 xa_unlock(xa);
1518
1519 return entry;
1520}
1521EXPORT_SYMBOL(xa_erase);
1522
1523/**
1524 * __xa_store() - Store this entry in the XArray.
1525 * @xa: XArray.
1526 * @index: Index into array.
1527 * @entry: New entry.
1528 * @gfp: Memory allocation flags.
1529 *
1530 * You must already be holding the xa_lock when calling this function.
1531 * It will drop the lock if needed to allocate memory, and then reacquire
1532 * it afterwards.
1533 *
1534 * Context: Any context. Expects xa_lock to be held on entry. May
1535 * release and reacquire xa_lock if @gfp flags permit.
1536 * Return: The old entry at this index or xa_err() if an error happened.
1537 */
1538void *__xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1539{
1540 XA_STATE(xas, xa, index);
1541 void *curr;
1542
1543 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1544 return XA_ERROR(-EINVAL);
1545 if (xa_track_free(xa) && !entry)
1546 entry = XA_ZERO_ENTRY;
1547
1548 do {
1549 curr = xas_store(&xas, entry);
1550 if (xa_track_free(xa))
1551 xas_clear_mark(&xas, XA_FREE_MARK);
1552 } while (__xas_nomem(&xas, gfp));
1553
1554 return xas_result(&xas, curr);
1555}
1556EXPORT_SYMBOL(__xa_store);
1557
1558/**
1559 * xa_store() - Store this entry in the XArray.
1560 * @xa: XArray.
1561 * @index: Index into array.
1562 * @entry: New entry.
1563 * @gfp: Memory allocation flags.
1564 *
1565 * After this function returns, loads from this index will return @entry.
1566 * Storing into an existing multi-index entry updates the entry of every index.
1567 * The marks associated with @index are unaffected unless @entry is %NULL.
1568 *
1569 * Context: Any context. Takes and releases the xa_lock.
1570 * May sleep if the @gfp flags permit.
1571 * Return: The old entry at this index on success, xa_err(-EINVAL) if @entry
1572 * cannot be stored in an XArray, or xa_err(-ENOMEM) if memory allocation
1573 * failed.
1574 */
1575void *xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1576{
1577 void *curr;
1578
1579 xa_lock(xa);
1580 curr = __xa_store(xa, index, entry, gfp);
1581 xa_unlock(xa);
1582
1583 return curr;
1584}
1585EXPORT_SYMBOL(xa_store);
1586
1587/**
1588 * __xa_cmpxchg() - Store this entry in the XArray.
1589 * @xa: XArray.
1590 * @index: Index into array.
1591 * @old: Old value to test against.
1592 * @entry: New entry.
1593 * @gfp: Memory allocation flags.
1594 *
1595 * You must already be holding the xa_lock when calling this function.
1596 * It will drop the lock if needed to allocate memory, and then reacquire
1597 * it afterwards.
1598 *
1599 * Context: Any context. Expects xa_lock to be held on entry. May
1600 * release and reacquire xa_lock if @gfp flags permit.
1601 * Return: The old entry at this index or xa_err() if an error happened.
1602 */
1603void *__xa_cmpxchg(struct xarray *xa, unsigned long index,
1604 void *old, void *entry, gfp_t gfp)
1605{
1606 XA_STATE(xas, xa, index);
1607 void *curr;
1608
1609 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1610 return XA_ERROR(-EINVAL);
1611
1612 do {
1613 curr = xas_load(&xas);
1614 if (curr == old) {
1615 xas_store(&xas, entry);
1616 if (xa_track_free(xa) && entry && !curr)
1617 xas_clear_mark(&xas, XA_FREE_MARK);
1618 }
1619 } while (__xas_nomem(&xas, gfp));
1620
1621 return xas_result(&xas, curr);
1622}
1623EXPORT_SYMBOL(__xa_cmpxchg);
1624
1625/**
1626 * __xa_insert() - Store this entry in the XArray if no entry is present.
1627 * @xa: XArray.
1628 * @index: Index into array.
1629 * @entry: New entry.
1630 * @gfp: Memory allocation flags.
1631 *
1632 * Inserting a NULL entry will store a reserved entry (like xa_reserve())
1633 * if no entry is present. Inserting will fail if a reserved entry is
1634 * present, even though loading from this index will return NULL.
1635 *
1636 * Context: Any context. Expects xa_lock to be held on entry. May
1637 * release and reacquire xa_lock if @gfp flags permit.
1638 * Return: 0 if the store succeeded. -EBUSY if another entry was present.
1639 * -ENOMEM if memory could not be allocated.
1640 */
1641int __xa_insert(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1642{
1643 XA_STATE(xas, xa, index);
1644 void *curr;
1645
1646 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1647 return -EINVAL;
1648 if (!entry)
1649 entry = XA_ZERO_ENTRY;
1650
1651 do {
1652 curr = xas_load(&xas);
1653 if (!curr) {
1654 xas_store(&xas, entry);
1655 if (xa_track_free(xa))
1656 xas_clear_mark(&xas, XA_FREE_MARK);
1657 } else {
1658 xas_set_err(&xas, -EBUSY);
1659 }
1660 } while (__xas_nomem(&xas, gfp));
1661
1662 return xas_error(&xas);
1663}
1664EXPORT_SYMBOL(__xa_insert);
1665
1666#ifdef CONFIG_XARRAY_MULTI
1667static void xas_set_range(struct xa_state *xas, unsigned long first,
1668 unsigned long last)
1669{
1670 unsigned int shift = 0;
1671 unsigned long sibs = last - first;
1672 unsigned int offset = XA_CHUNK_MASK;
1673
1674 xas_set(xas, first);
1675
1676 while ((first & XA_CHUNK_MASK) == 0) {
1677 if (sibs < XA_CHUNK_MASK)
1678 break;
1679 if ((sibs == XA_CHUNK_MASK) && (offset < XA_CHUNK_MASK))
1680 break;
1681 shift += XA_CHUNK_SHIFT;
1682 if (offset == XA_CHUNK_MASK)
1683 offset = sibs & XA_CHUNK_MASK;
1684 sibs >>= XA_CHUNK_SHIFT;
1685 first >>= XA_CHUNK_SHIFT;
1686 }
1687
1688 offset = first & XA_CHUNK_MASK;
1689 if (offset + sibs > XA_CHUNK_MASK)
1690 sibs = XA_CHUNK_MASK - offset;
1691 if ((((first + sibs + 1) << shift) - 1) > last)
1692 sibs -= 1;
1693
1694 xas->xa_shift = shift;
1695 xas->xa_sibs = sibs;
1696}
1697
1698/**
1699 * xa_store_range() - Store this entry at a range of indices in the XArray.
1700 * @xa: XArray.
1701 * @first: First index to affect.
1702 * @last: Last index to affect.
1703 * @entry: New entry.
1704 * @gfp: Memory allocation flags.
1705 *
1706 * After this function returns, loads from any index between @first and @last,
1707 * inclusive will return @entry.
1708 * Storing into an existing multi-index entry updates the entry of every index.
1709 * The marks associated with @index are unaffected unless @entry is %NULL.
1710 *
1711 * Context: Process context. Takes and releases the xa_lock. May sleep
1712 * if the @gfp flags permit.
1713 * Return: %NULL on success, xa_err(-EINVAL) if @entry cannot be stored in
1714 * an XArray, or xa_err(-ENOMEM) if memory allocation failed.
1715 */
1716void *xa_store_range(struct xarray *xa, unsigned long first,
1717 unsigned long last, void *entry, gfp_t gfp)
1718{
1719 XA_STATE(xas, xa, 0);
1720
1721 if (WARN_ON_ONCE(xa_is_internal(entry)))
1722 return XA_ERROR(-EINVAL);
1723 if (last < first)
1724 return XA_ERROR(-EINVAL);
1725
1726 do {
1727 xas_lock(&xas);
1728 if (entry) {
1729 unsigned int order = BITS_PER_LONG;
1730 if (last + 1)
1731 order = __ffs(last + 1);
1732 xas_set_order(&xas, last, order);
1733 xas_create(&xas, true);
1734 if (xas_error(&xas))
1735 goto unlock;
1736 }
1737 do {
1738 xas_set_range(&xas, first, last);
1739 xas_store(&xas, entry);
1740 if (xas_error(&xas))
1741 goto unlock;
1742 first += xas_size(&xas);
1743 } while (first <= last);
1744unlock:
1745 xas_unlock(&xas);
1746 } while (xas_nomem(&xas, gfp));
1747
1748 return xas_result(&xas, NULL);
1749}
1750EXPORT_SYMBOL(xa_store_range);
1751
1752/**
1753 * xa_get_order() - Get the order of an entry.
1754 * @xa: XArray.
1755 * @index: Index of the entry.
1756 *
1757 * Return: A number between 0 and 63 indicating the order of the entry.
1758 */
1759int xa_get_order(struct xarray *xa, unsigned long index)
1760{
1761 XA_STATE(xas, xa, index);
1762 void *entry;
1763 int order = 0;
1764
1765 rcu_read_lock();
1766 entry = xas_load(&xas);
1767
1768 if (!entry)
1769 goto unlock;
1770
1771 if (!xas.xa_node)
1772 goto unlock;
1773
1774 for (;;) {
1775 unsigned int slot = xas.xa_offset + (1 << order);
1776
1777 if (slot >= XA_CHUNK_SIZE)
1778 break;
1779 if (!xa_is_sibling(xas.xa_node->slots[slot]))
1780 break;
1781 order++;
1782 }
1783
1784 order += xas.xa_node->shift;
1785unlock:
1786 rcu_read_unlock();
1787
1788 return order;
1789}
1790EXPORT_SYMBOL(xa_get_order);
1791#endif /* CONFIG_XARRAY_MULTI */
1792
1793/**
1794 * __xa_alloc() - Find somewhere to store this entry in the XArray.
1795 * @xa: XArray.
1796 * @id: Pointer to ID.
1797 * @limit: Range for allocated ID.
1798 * @entry: New entry.
1799 * @gfp: Memory allocation flags.
1800 *
1801 * Finds an empty entry in @xa between @limit.min and @limit.max,
1802 * stores the index into the @id pointer, then stores the entry at
1803 * that index. A concurrent lookup will not see an uninitialised @id.
1804 *
1805 * Context: Any context. Expects xa_lock to be held on entry. May
1806 * release and reacquire xa_lock if @gfp flags permit.
1807 * Return: 0 on success, -ENOMEM if memory could not be allocated or
1808 * -EBUSY if there are no free entries in @limit.
1809 */
1810int __xa_alloc(struct xarray *xa, u32 *id, void *entry,
1811 struct xa_limit limit, gfp_t gfp)
1812{
1813 XA_STATE(xas, xa, 0);
1814
1815 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1816 return -EINVAL;
1817 if (WARN_ON_ONCE(!xa_track_free(xa)))
1818 return -EINVAL;
1819
1820 if (!entry)
1821 entry = XA_ZERO_ENTRY;
1822
1823 do {
1824 xas.xa_index = limit.min;
1825 xas_find_marked(&xas, limit.max, XA_FREE_MARK);
1826 if (xas.xa_node == XAS_RESTART)
1827 xas_set_err(&xas, -EBUSY);
1828 else
1829 *id = xas.xa_index;
1830 xas_store(&xas, entry);
1831 xas_clear_mark(&xas, XA_FREE_MARK);
1832 } while (__xas_nomem(&xas, gfp));
1833
1834 return xas_error(&xas);
1835}
1836EXPORT_SYMBOL(__xa_alloc);
1837
1838/**
1839 * __xa_alloc_cyclic() - Find somewhere to store this entry in the XArray.
1840 * @xa: XArray.
1841 * @id: Pointer to ID.
1842 * @entry: New entry.
1843 * @limit: Range of allocated ID.
1844 * @next: Pointer to next ID to allocate.
1845 * @gfp: Memory allocation flags.
1846 *
1847 * Finds an empty entry in @xa between @limit.min and @limit.max,
1848 * stores the index into the @id pointer, then stores the entry at
1849 * that index. A concurrent lookup will not see an uninitialised @id.
1850 * The search for an empty entry will start at @next and will wrap
1851 * around if necessary.
1852 *
1853 * Context: Any context. Expects xa_lock to be held on entry. May
1854 * release and reacquire xa_lock if @gfp flags permit.
1855 * Return: 0 if the allocation succeeded without wrapping. 1 if the
1856 * allocation succeeded after wrapping, -ENOMEM if memory could not be
1857 * allocated or -EBUSY if there are no free entries in @limit.
1858 */
1859int __xa_alloc_cyclic(struct xarray *xa, u32 *id, void *entry,
1860 struct xa_limit limit, u32 *next, gfp_t gfp)
1861{
1862 u32 min = limit.min;
1863 int ret;
1864
1865 limit.min = max(min, *next);
1866 ret = __xa_alloc(xa, id, entry, limit, gfp);
1867 if ((xa->xa_flags & XA_FLAGS_ALLOC_WRAPPED) && ret == 0) {
1868 xa->xa_flags &= ~XA_FLAGS_ALLOC_WRAPPED;
1869 ret = 1;
1870 }
1871
1872 if (ret < 0 && limit.min > min) {
1873 limit.min = min;
1874 ret = __xa_alloc(xa, id, entry, limit, gfp);
1875 if (ret == 0)
1876 ret = 1;
1877 }
1878
1879 if (ret >= 0) {
1880 *next = *id + 1;
1881 if (*next == 0)
1882 xa->xa_flags |= XA_FLAGS_ALLOC_WRAPPED;
1883 }
1884 return ret;
1885}
1886EXPORT_SYMBOL(__xa_alloc_cyclic);
1887
1888/**
1889 * __xa_set_mark() - Set this mark on this entry while locked.
1890 * @xa: XArray.
1891 * @index: Index of entry.
1892 * @mark: Mark number.
1893 *
1894 * Attempting to set a mark on a %NULL entry does not succeed.
1895 *
1896 * Context: Any context. Expects xa_lock to be held on entry.
1897 */
1898void __xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1899{
1900 XA_STATE(xas, xa, index);
1901 void *entry = xas_load(&xas);
1902
1903 if (entry)
1904 xas_set_mark(&xas, mark);
1905}
1906EXPORT_SYMBOL(__xa_set_mark);
1907
1908/**
1909 * __xa_clear_mark() - Clear this mark on this entry while locked.
1910 * @xa: XArray.
1911 * @index: Index of entry.
1912 * @mark: Mark number.
1913 *
1914 * Context: Any context. Expects xa_lock to be held on entry.
1915 */
1916void __xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1917{
1918 XA_STATE(xas, xa, index);
1919 void *entry = xas_load(&xas);
1920
1921 if (entry)
1922 xas_clear_mark(&xas, mark);
1923}
1924EXPORT_SYMBOL(__xa_clear_mark);
1925
1926/**
1927 * xa_get_mark() - Inquire whether this mark is set on this entry.
1928 * @xa: XArray.
1929 * @index: Index of entry.
1930 * @mark: Mark number.
1931 *
1932 * This function uses the RCU read lock, so the result may be out of date
1933 * by the time it returns. If you need the result to be stable, use a lock.
1934 *
1935 * Context: Any context. Takes and releases the RCU lock.
1936 * Return: True if the entry at @index has this mark set, false if it doesn't.
1937 */
1938bool xa_get_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1939{
1940 XA_STATE(xas, xa, index);
1941 void *entry;
1942
1943 rcu_read_lock();
1944 entry = xas_start(&xas);
1945 while (xas_get_mark(&xas, mark)) {
1946 if (!xa_is_node(entry))
1947 goto found;
1948 entry = xas_descend(&xas, xa_to_node(entry));
1949 }
1950 rcu_read_unlock();
1951 return false;
1952 found:
1953 rcu_read_unlock();
1954 return true;
1955}
1956EXPORT_SYMBOL(xa_get_mark);
1957
1958/**
1959 * xa_set_mark() - Set this mark on this entry.
1960 * @xa: XArray.
1961 * @index: Index of entry.
1962 * @mark: Mark number.
1963 *
1964 * Attempting to set a mark on a %NULL entry does not succeed.
1965 *
1966 * Context: Process context. Takes and releases the xa_lock.
1967 */
1968void xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1969{
1970 xa_lock(xa);
1971 __xa_set_mark(xa, index, mark);
1972 xa_unlock(xa);
1973}
1974EXPORT_SYMBOL(xa_set_mark);
1975
1976/**
1977 * xa_clear_mark() - Clear this mark on this entry.
1978 * @xa: XArray.
1979 * @index: Index of entry.
1980 * @mark: Mark number.
1981 *
1982 * Clearing a mark always succeeds.
1983 *
1984 * Context: Process context. Takes and releases the xa_lock.
1985 */
1986void xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1987{
1988 xa_lock(xa);
1989 __xa_clear_mark(xa, index, mark);
1990 xa_unlock(xa);
1991}
1992EXPORT_SYMBOL(xa_clear_mark);
1993
1994/**
1995 * xa_find() - Search the XArray for an entry.
1996 * @xa: XArray.
1997 * @indexp: Pointer to an index.
1998 * @max: Maximum index to search to.
1999 * @filter: Selection criterion.
2000 *
2001 * Finds the entry in @xa which matches the @filter, and has the lowest
2002 * index that is at least @indexp and no more than @max.
2003 * If an entry is found, @indexp is updated to be the index of the entry.
2004 * This function is protected by the RCU read lock, so it may not find
2005 * entries which are being simultaneously added. It will not return an
2006 * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
2007 *
2008 * Context: Any context. Takes and releases the RCU lock.
2009 * Return: The entry, if found, otherwise %NULL.
2010 */
2011void *xa_find(struct xarray *xa, unsigned long *indexp,
2012 unsigned long max, xa_mark_t filter)
2013{
2014 XA_STATE(xas, xa, *indexp);
2015 void *entry;
2016
2017 rcu_read_lock();
2018 do {
2019 if ((__force unsigned int)filter < XA_MAX_MARKS)
2020 entry = xas_find_marked(&xas, max, filter);
2021 else
2022 entry = xas_find(&xas, max);
2023 } while (xas_retry(&xas, entry));
2024 rcu_read_unlock();
2025
2026 if (entry)
2027 *indexp = xas.xa_index;
2028 return entry;
2029}
2030EXPORT_SYMBOL(xa_find);
2031
2032static bool xas_sibling(struct xa_state *xas)
2033{
2034 struct xa_node *node = xas->xa_node;
2035 unsigned long mask;
2036
2037 if (!IS_ENABLED(CONFIG_XARRAY_MULTI) || !node)
2038 return false;
2039 mask = (XA_CHUNK_SIZE << node->shift) - 1;
2040 return (xas->xa_index & mask) >
2041 ((unsigned long)xas->xa_offset << node->shift);
2042}
2043
2044/**
2045 * xa_find_after() - Search the XArray for a present entry.
2046 * @xa: XArray.
2047 * @indexp: Pointer to an index.
2048 * @max: Maximum index to search to.
2049 * @filter: Selection criterion.
2050 *
2051 * Finds the entry in @xa which matches the @filter and has the lowest
2052 * index that is above @indexp and no more than @max.
2053 * If an entry is found, @indexp is updated to be the index of the entry.
2054 * This function is protected by the RCU read lock, so it may miss entries
2055 * which are being simultaneously added. It will not return an
2056 * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
2057 *
2058 * Context: Any context. Takes and releases the RCU lock.
2059 * Return: The pointer, if found, otherwise %NULL.
2060 */
2061void *xa_find_after(struct xarray *xa, unsigned long *indexp,
2062 unsigned long max, xa_mark_t filter)
2063{
2064 XA_STATE(xas, xa, *indexp + 1);
2065 void *entry;
2066
2067 if (xas.xa_index == 0)
2068 return NULL;
2069
2070 rcu_read_lock();
2071 for (;;) {
2072 if ((__force unsigned int)filter < XA_MAX_MARKS)
2073 entry = xas_find_marked(&xas, max, filter);
2074 else
2075 entry = xas_find(&xas, max);
2076
2077 if (xas_invalid(&xas))
2078 break;
2079 if (xas_sibling(&xas))
2080 continue;
2081 if (!xas_retry(&xas, entry))
2082 break;
2083 }
2084 rcu_read_unlock();
2085
2086 if (entry)
2087 *indexp = xas.xa_index;
2088 return entry;
2089}
2090EXPORT_SYMBOL(xa_find_after);
2091
2092static unsigned int xas_extract_present(struct xa_state *xas, void **dst,
2093 unsigned long max, unsigned int n)
2094{
2095 void *entry;
2096 unsigned int i = 0;
2097
2098 rcu_read_lock();
2099 xas_for_each(xas, entry, max) {
2100 if (xas_retry(xas, entry))
2101 continue;
2102 dst[i++] = entry;
2103 if (i == n)
2104 break;
2105 }
2106 rcu_read_unlock();
2107
2108 return i;
2109}
2110
2111static unsigned int xas_extract_marked(struct xa_state *xas, void **dst,
2112 unsigned long max, unsigned int n, xa_mark_t mark)
2113{
2114 void *entry;
2115 unsigned int i = 0;
2116
2117 rcu_read_lock();
2118 xas_for_each_marked(xas, entry, max, mark) {
2119 if (xas_retry(xas, entry))
2120 continue;
2121 dst[i++] = entry;
2122 if (i == n)
2123 break;
2124 }
2125 rcu_read_unlock();
2126
2127 return i;
2128}
2129
2130/**
2131 * xa_extract() - Copy selected entries from the XArray into a normal array.
2132 * @xa: The source XArray to copy from.
2133 * @dst: The buffer to copy entries into.
2134 * @start: The first index in the XArray eligible to be selected.
2135 * @max: The last index in the XArray eligible to be selected.
2136 * @n: The maximum number of entries to copy.
2137 * @filter: Selection criterion.
2138 *
2139 * Copies up to @n entries that match @filter from the XArray. The
2140 * copied entries will have indices between @start and @max, inclusive.
2141 *
2142 * The @filter may be an XArray mark value, in which case entries which are
2143 * marked with that mark will be copied. It may also be %XA_PRESENT, in
2144 * which case all entries which are not %NULL will be copied.
2145 *
2146 * The entries returned may not represent a snapshot of the XArray at a
2147 * moment in time. For example, if another thread stores to index 5, then
2148 * index 10, calling xa_extract() may return the old contents of index 5
2149 * and the new contents of index 10. Indices not modified while this
2150 * function is running will not be skipped.
2151 *
2152 * If you need stronger guarantees, holding the xa_lock across calls to this
2153 * function will prevent concurrent modification.
2154 *
2155 * Context: Any context. Takes and releases the RCU lock.
2156 * Return: The number of entries copied.
2157 */
2158unsigned int xa_extract(struct xarray *xa, void **dst, unsigned long start,
2159 unsigned long max, unsigned int n, xa_mark_t filter)
2160{
2161 XA_STATE(xas, xa, start);
2162
2163 if (!n)
2164 return 0;
2165
2166 if ((__force unsigned int)filter < XA_MAX_MARKS)
2167 return xas_extract_marked(&xas, dst, max, n, filter);
2168 return xas_extract_present(&xas, dst, max, n);
2169}
2170EXPORT_SYMBOL(xa_extract);
2171
2172/**
2173 * xa_delete_node() - Private interface for workingset code.
2174 * @node: Node to be removed from the tree.
2175 * @update: Function to call to update ancestor nodes.
2176 *
2177 * Context: xa_lock must be held on entry and will not be released.
2178 */
2179void xa_delete_node(struct xa_node *node, xa_update_node_t update)
2180{
2181 struct xa_state xas = {
2182 .xa = node->array,
2183 .xa_index = (unsigned long)node->offset <<
2184 (node->shift + XA_CHUNK_SHIFT),
2185 .xa_shift = node->shift + XA_CHUNK_SHIFT,
2186 .xa_offset = node->offset,
2187 .xa_node = xa_parent_locked(node->array, node),
2188 .xa_update = update,
2189 };
2190
2191 xas_store(&xas, NULL);
2192}
2193EXPORT_SYMBOL_GPL(xa_delete_node); /* For the benefit of the test suite */
2194
2195/**
2196 * xa_destroy() - Free all internal data structures.
2197 * @xa: XArray.
2198 *
2199 * After calling this function, the XArray is empty and has freed all memory
2200 * allocated for its internal data structures. You are responsible for
2201 * freeing the objects referenced by the XArray.
2202 *
2203 * Context: Any context. Takes and releases the xa_lock, interrupt-safe.
2204 */
2205void xa_destroy(struct xarray *xa)
2206{
2207 XA_STATE(xas, xa, 0);
2208 unsigned long flags;
2209 void *entry;
2210
2211 xas.xa_node = NULL;
2212 xas_lock_irqsave(&xas, flags);
2213 entry = xa_head_locked(xa);
2214 RCU_INIT_POINTER(xa->xa_head, NULL);
2215 xas_init_marks(&xas);
2216 if (xa_zero_busy(xa))
2217 xa_mark_clear(xa, XA_FREE_MARK);
2218 /* lockdep checks we're still holding the lock in xas_free_nodes() */
2219 if (xa_is_node(entry))
2220 xas_free_nodes(&xas, xa_to_node(entry));
2221 xas_unlock_irqrestore(&xas, flags);
2222}
2223EXPORT_SYMBOL(xa_destroy);
2224
2225#ifdef XA_DEBUG
2226void xa_dump_node(const struct xa_node *node)
2227{
2228 unsigned i, j;
2229
2230 if (!node)
2231 return;
2232 if ((unsigned long)node & 3) {
2233 pr_cont("node %px\n", node);
2234 return;
2235 }
2236
2237 pr_cont("node %px %s %d parent %px shift %d count %d values %d "
2238 "array %px list %px %px marks",
2239 node, node->parent ? "offset" : "max", node->offset,
2240 node->parent, node->shift, node->count, node->nr_values,
2241 node->array, node->private_list.prev, node->private_list.next);
2242 for (i = 0; i < XA_MAX_MARKS; i++)
2243 for (j = 0; j < XA_MARK_LONGS; j++)
2244 pr_cont(" %lx", node->marks[i][j]);
2245 pr_cont("\n");
2246}
2247
2248void xa_dump_index(unsigned long index, unsigned int shift)
2249{
2250 if (!shift)
2251 pr_info("%lu: ", index);
2252 else if (shift >= BITS_PER_LONG)
2253 pr_info("0-%lu: ", ~0UL);
2254 else
2255 pr_info("%lu-%lu: ", index, index | ((1UL << shift) - 1));
2256}
2257
2258void xa_dump_entry(const void *entry, unsigned long index, unsigned long shift)
2259{
2260 if (!entry)
2261 return;
2262
2263 xa_dump_index(index, shift);
2264
2265 if (xa_is_node(entry)) {
2266 if (shift == 0) {
2267 pr_cont("%px\n", entry);
2268 } else {
2269 unsigned long i;
2270 struct xa_node *node = xa_to_node(entry);
2271 xa_dump_node(node);
2272 for (i = 0; i < XA_CHUNK_SIZE; i++)
2273 xa_dump_entry(node->slots[i],
2274 index + (i << node->shift), node->shift);
2275 }
2276 } else if (xa_is_value(entry))
2277 pr_cont("value %ld (0x%lx) [%px]\n", xa_to_value(entry),
2278 xa_to_value(entry), entry);
2279 else if (!xa_is_internal(entry))
2280 pr_cont("%px\n", entry);
2281 else if (xa_is_retry(entry))
2282 pr_cont("retry (%ld)\n", xa_to_internal(entry));
2283 else if (xa_is_sibling(entry))
2284 pr_cont("sibling (slot %ld)\n", xa_to_sibling(entry));
2285 else if (xa_is_zero(entry))
2286 pr_cont("zero (%ld)\n", xa_to_internal(entry));
2287 else
2288 pr_cont("UNKNOWN ENTRY (%px)\n", entry);
2289}
2290
2291void xa_dump(const struct xarray *xa)
2292{
2293 void *entry = xa->xa_head;
2294 unsigned int shift = 0;
2295
2296 pr_info("xarray: %px head %px flags %x marks %d %d %d\n", xa, entry,
2297 xa->xa_flags, xa_marked(xa, XA_MARK_0),
2298 xa_marked(xa, XA_MARK_1), xa_marked(xa, XA_MARK_2));
2299 if (xa_is_node(entry))
2300 shift = xa_to_node(entry)->shift + XA_CHUNK_SHIFT;
2301 xa_dump_entry(entry, 0, shift);
2302}
2303#endif