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