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