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(src: 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(dst: 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 xa_mark_t mark = 0;
129 unsigned int limit = xas->xa_offset + xas->xa_sibs + 1;
130
131 for (;;) {
132 unsigned long *marks = node_marks(node: xas->xa_node, mark);
133
134 if (find_next_bit(addr: marks, size: limit, offset: xas->xa_offset + 1) != limit) {
135 __set_bit(xas->xa_offset, marks);
136 bitmap_clear(map: marks, start: xas->xa_offset + 1, nbits: xas->xa_sibs);
137 }
138 if (mark == XA_MARK_MAX)
139 break;
140 mark_inc(mark);
141 }
142}
143
144/* extracts the offset within this node from the index */
145static unsigned int get_offset(unsigned long index, struct xa_node *node)
146{
147 return (index >> node->shift) & XA_CHUNK_MASK;
148}
149
150static void xas_set_offset(struct xa_state *xas)
151{
152 xas->xa_offset = get_offset(index: xas->xa_index, node: xas->xa_node);
153}
154
155/* move the index either forwards (find) or backwards (sibling slot) */
156static void xas_move_index(struct xa_state *xas, unsigned long offset)
157{
158 unsigned int shift = xas->xa_node->shift;
159 xas->xa_index &= ~XA_CHUNK_MASK << shift;
160 xas->xa_index += offset << shift;
161}
162
163static void xas_next_offset(struct xa_state *xas)
164{
165 xas->xa_offset++;
166 xas_move_index(xas, offset: xas->xa_offset);
167}
168
169static void *set_bounds(struct xa_state *xas)
170{
171 xas->xa_node = XAS_BOUNDS;
172 return NULL;
173}
174
175/*
176 * Starts a walk. If the @xas is already valid, we assume that it's on
177 * the right path and just return where we've got to. If we're in an
178 * error state, return NULL. If the index is outside the current scope
179 * of the xarray, return NULL without changing @xas->xa_node. Otherwise
180 * set @xas->xa_node to NULL and return the current head of the array.
181 */
182static void *xas_start(struct xa_state *xas)
183{
184 void *entry;
185
186 if (xas_valid(xas))
187 return xas_reload(xas);
188 if (xas_error(xas))
189 return NULL;
190
191 entry = xa_head(xa: xas->xa);
192 if (!xa_is_node(entry)) {
193 if (xas->xa_index)
194 return set_bounds(xas);
195 } else {
196 if ((xas->xa_index >> xa_to_node(entry)->shift) > XA_CHUNK_MASK)
197 return set_bounds(xas);
198 }
199
200 xas->xa_node = NULL;
201 return entry;
202}
203
204static __always_inline void *xas_descend(struct xa_state *xas,
205 struct xa_node *node)
206{
207 unsigned int offset = get_offset(index: xas->xa_index, node);
208 void *entry = xa_entry(xa: xas->xa, node, offset);
209
210 xas->xa_node = node;
211 while (xa_is_sibling(entry)) {
212 offset = xa_to_sibling(entry);
213 entry = xa_entry(xa: xas->xa, node, offset);
214 if (node->shift && xa_is_node(entry))
215 entry = XA_RETRY_ENTRY;
216 }
217
218 xas->xa_offset = offset;
219 return entry;
220}
221
222/**
223 * xas_load() - Load an entry from the XArray (advanced).
224 * @xas: XArray operation state.
225 *
226 * Usually walks the @xas to the appropriate state to load the entry
227 * stored at xa_index. However, it will do nothing and return %NULL if
228 * @xas is in an error state. xas_load() will never expand the tree.
229 *
230 * If the xa_state is set up to operate on a multi-index entry, xas_load()
231 * may return %NULL or an internal entry, even if there are entries
232 * present within the range specified by @xas.
233 *
234 * Context: Any context. The caller should hold the xa_lock or the RCU lock.
235 * Return: Usually an entry in the XArray, but see description for exceptions.
236 */
237void *xas_load(struct xa_state *xas)
238{
239 void *entry = xas_start(xas);
240
241 while (xa_is_node(entry)) {
242 struct xa_node *node = xa_to_node(entry);
243
244 if (xas->xa_shift > node->shift)
245 break;
246 entry = xas_descend(xas, node);
247 if (node->shift == 0)
248 break;
249 }
250 return entry;
251}
252EXPORT_SYMBOL_GPL(xas_load);
253
254#define XA_RCU_FREE ((struct xarray *)1)
255
256static void xa_node_free(struct xa_node *node)
257{
258 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
259 node->array = XA_RCU_FREE;
260 call_rcu(head: &node->rcu_head, func: radix_tree_node_rcu_free);
261}
262
263/*
264 * xas_destroy() - Free any resources allocated during the XArray operation.
265 * @xas: XArray operation state.
266 *
267 * Most users will not need to call this function; it is called for you
268 * by xas_nomem().
269 */
270void xas_destroy(struct xa_state *xas)
271{
272 struct xa_node *next, *node = xas->xa_alloc;
273
274 while (node) {
275 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
276 next = rcu_dereference_raw(node->parent);
277 radix_tree_node_rcu_free(head: &node->rcu_head);
278 xas->xa_alloc = node = next;
279 }
280}
281EXPORT_SYMBOL_GPL(xas_destroy);
282
283/**
284 * xas_nomem() - Allocate memory if needed.
285 * @xas: XArray operation state.
286 * @gfp: Memory allocation flags.
287 *
288 * If we need to add new nodes to the XArray, we try to allocate memory
289 * with GFP_NOWAIT while holding the lock, which will usually succeed.
290 * If it fails, @xas is flagged as needing memory to continue. The caller
291 * should drop the lock and call xas_nomem(). If xas_nomem() succeeds,
292 * the caller should retry the operation.
293 *
294 * Forward progress is guaranteed as one node is allocated here and
295 * stored in the xa_state where it will be found by xas_alloc(). More
296 * nodes will likely be found in the slab allocator, but we do not tie
297 * them up here.
298 *
299 * Return: true if memory was needed, and was successfully allocated.
300 */
301bool xas_nomem(struct xa_state *xas, gfp_t gfp)
302{
303 if (xas->xa_node != XA_ERROR(-ENOMEM)) {
304 xas_destroy(xas);
305 return false;
306 }
307 if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
308 gfp |= __GFP_ACCOUNT;
309 xas->xa_alloc = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp);
310 if (!xas->xa_alloc)
311 return false;
312 xas->xa_alloc->parent = NULL;
313 XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list));
314 xas->xa_node = XAS_RESTART;
315 return true;
316}
317EXPORT_SYMBOL_GPL(xas_nomem);
318
319/*
320 * __xas_nomem() - Drop locks and allocate memory if needed.
321 * @xas: XArray operation state.
322 * @gfp: Memory allocation flags.
323 *
324 * Internal variant of xas_nomem().
325 *
326 * Return: true if memory was needed, and was successfully allocated.
327 */
328static bool __xas_nomem(struct xa_state *xas, gfp_t gfp)
329 __must_hold(xas->xa->xa_lock)
330{
331 unsigned int lock_type = xa_lock_type(xa: xas->xa);
332
333 if (xas->xa_node != XA_ERROR(-ENOMEM)) {
334 xas_destroy(xas);
335 return false;
336 }
337 if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
338 gfp |= __GFP_ACCOUNT;
339 if (gfpflags_allow_blocking(gfp_flags: gfp)) {
340 xas_unlock_type(xas, lock_type);
341 xas->xa_alloc = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp);
342 xas_lock_type(xas, lock_type);
343 } else {
344 xas->xa_alloc = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp);
345 }
346 if (!xas->xa_alloc)
347 return false;
348 xas->xa_alloc->parent = NULL;
349 XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list));
350 xas->xa_node = XAS_RESTART;
351 return true;
352}
353
354static void xas_update(struct xa_state *xas, struct xa_node *node)
355{
356 if (xas->xa_update)
357 xas->xa_update(node);
358 else
359 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
360}
361
362static void *xas_alloc(struct xa_state *xas, unsigned int shift)
363{
364 struct xa_node *parent = xas->xa_node;
365 struct xa_node *node = xas->xa_alloc;
366
367 if (xas_invalid(xas))
368 return NULL;
369
370 if (node) {
371 xas->xa_alloc = NULL;
372 } else {
373 gfp_t gfp = GFP_NOWAIT;
374
375 if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
376 gfp |= __GFP_ACCOUNT;
377
378 node = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp);
379 if (!node) {
380 xas_set_err(xas, err: -ENOMEM);
381 return NULL;
382 }
383 }
384
385 if (parent) {
386 node->offset = xas->xa_offset;
387 parent->count++;
388 XA_NODE_BUG_ON(node, parent->count > XA_CHUNK_SIZE);
389 xas_update(xas, node: parent);
390 }
391 XA_NODE_BUG_ON(node, shift > BITS_PER_LONG);
392 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
393 node->shift = shift;
394 node->count = 0;
395 node->nr_values = 0;
396 RCU_INIT_POINTER(node->parent, xas->xa_node);
397 node->array = xas->xa;
398
399 return node;
400}
401
402#ifdef CONFIG_XARRAY_MULTI
403/* Returns the number of indices covered by a given xa_state */
404static unsigned long xas_size(const struct xa_state *xas)
405{
406 return (xas->xa_sibs + 1UL) << xas->xa_shift;
407}
408#endif
409
410/*
411 * Use this to calculate the maximum index that will need to be created
412 * in order to add the entry described by @xas. Because we cannot store a
413 * multi-index entry at index 0, the calculation is a little more complex
414 * than you might expect.
415 */
416static unsigned long xas_max(struct xa_state *xas)
417{
418 unsigned long max = xas->xa_index;
419
420#ifdef CONFIG_XARRAY_MULTI
421 if (xas->xa_shift || xas->xa_sibs) {
422 unsigned long mask = xas_size(xas) - 1;
423 max |= mask;
424 if (mask == max)
425 max++;
426 }
427#endif
428
429 return max;
430}
431
432/* The maximum index that can be contained in the array without expanding it */
433static unsigned long max_index(void *entry)
434{
435 if (!xa_is_node(entry))
436 return 0;
437 return (XA_CHUNK_SIZE << xa_to_node(entry)->shift) - 1;
438}
439
440static inline void *xa_zero_to_null(void *entry)
441{
442 return xa_is_zero(entry) ? NULL : entry;
443}
444
445static void xas_shrink(struct xa_state *xas)
446{
447 struct xarray *xa = xas->xa;
448 struct xa_node *node = xas->xa_node;
449
450 for (;;) {
451 void *entry;
452
453 XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
454 if (node->count != 1)
455 break;
456 entry = xa_entry_locked(xa, node, offset: 0);
457 if (!entry)
458 break;
459 if (!xa_is_node(entry) && node->shift)
460 break;
461 if (xa_zero_busy(xa))
462 entry = xa_zero_to_null(entry);
463 xas->xa_node = XAS_BOUNDS;
464
465 RCU_INIT_POINTER(xa->xa_head, entry);
466 if (xa_track_free(xa) && !node_get_mark(node, offset: 0, XA_FREE_MARK))
467 xa_mark_clear(xa, XA_FREE_MARK);
468
469 node->count = 0;
470 node->nr_values = 0;
471 if (!xa_is_node(entry))
472 RCU_INIT_POINTER(node->slots[0], XA_RETRY_ENTRY);
473 xas_update(xas, node);
474 xa_node_free(node);
475 if (!xa_is_node(entry))
476 break;
477 node = xa_to_node(entry);
478 node->parent = NULL;
479 }
480}
481
482/*
483 * xas_delete_node() - Attempt to delete an xa_node
484 * @xas: Array operation state.
485 *
486 * Attempts to delete the @xas->xa_node. This will fail if xa->node has
487 * a non-zero reference count.
488 */
489static void xas_delete_node(struct xa_state *xas)
490{
491 struct xa_node *node = xas->xa_node;
492
493 for (;;) {
494 struct xa_node *parent;
495
496 XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
497 if (node->count)
498 break;
499
500 parent = xa_parent_locked(xa: xas->xa, node);
501 xas->xa_node = parent;
502 xas->xa_offset = node->offset;
503 xa_node_free(node);
504
505 if (!parent) {
506 xas->xa->xa_head = NULL;
507 xas->xa_node = XAS_BOUNDS;
508 return;
509 }
510
511 parent->slots[xas->xa_offset] = NULL;
512 parent->count--;
513 XA_NODE_BUG_ON(parent, parent->count > XA_CHUNK_SIZE);
514 node = parent;
515 xas_update(xas, node);
516 }
517
518 if (!node->parent)
519 xas_shrink(xas);
520}
521
522/**
523 * xas_free_nodes() - Free this node and all nodes that it references
524 * @xas: Array operation state.
525 * @top: Node to free
526 *
527 * This node has been removed from the tree. We must now free it and all
528 * of its subnodes. There may be RCU walkers with references into the tree,
529 * so we must replace all entries with retry markers.
530 */
531static void xas_free_nodes(struct xa_state *xas, struct xa_node *top)
532{
533 unsigned int offset = 0;
534 struct xa_node *node = top;
535
536 for (;;) {
537 void *entry = xa_entry_locked(xa: xas->xa, node, offset);
538
539 if (node->shift && xa_is_node(entry)) {
540 node = xa_to_node(entry);
541 offset = 0;
542 continue;
543 }
544 if (entry)
545 RCU_INIT_POINTER(node->slots[offset], XA_RETRY_ENTRY);
546 offset++;
547 while (offset == XA_CHUNK_SIZE) {
548 struct xa_node *parent;
549
550 parent = xa_parent_locked(xa: xas->xa, node);
551 offset = node->offset + 1;
552 node->count = 0;
553 node->nr_values = 0;
554 xas_update(xas, node);
555 xa_node_free(node);
556 if (node == top)
557 return;
558 node = parent;
559 }
560 }
561}
562
563/*
564 * xas_expand adds nodes to the head of the tree until it has reached
565 * sufficient height to be able to contain @xas->xa_index
566 */
567static int xas_expand(struct xa_state *xas, void *head)
568{
569 struct xarray *xa = xas->xa;
570 struct xa_node *node = NULL;
571 unsigned int shift = 0;
572 unsigned long max = xas_max(xas);
573
574 if (!head) {
575 if (max == 0)
576 return 0;
577 while ((max >> shift) >= XA_CHUNK_SIZE)
578 shift += XA_CHUNK_SHIFT;
579 return shift + XA_CHUNK_SHIFT;
580 } else if (xa_is_node(entry: head)) {
581 node = xa_to_node(entry: head);
582 shift = node->shift + XA_CHUNK_SHIFT;
583 }
584 xas->xa_node = NULL;
585
586 while (max > max_index(entry: head)) {
587 xa_mark_t mark = 0;
588
589 XA_NODE_BUG_ON(node, shift > BITS_PER_LONG);
590 node = xas_alloc(xas, shift);
591 if (!node)
592 return -ENOMEM;
593
594 node->count = 1;
595 if (xa_is_value(entry: head))
596 node->nr_values = 1;
597 RCU_INIT_POINTER(node->slots[0], head);
598
599 /* Propagate the aggregated mark info to the new child */
600 for (;;) {
601 if (xa_track_free(xa) && mark == XA_FREE_MARK) {
602 node_mark_all(node, XA_FREE_MARK);
603 if (!xa_marked(xa, XA_FREE_MARK)) {
604 node_clear_mark(node, offset: 0, XA_FREE_MARK);
605 xa_mark_set(xa, XA_FREE_MARK);
606 }
607 } else if (xa_marked(xa, mark)) {
608 node_set_mark(node, offset: 0, mark);
609 }
610 if (mark == XA_MARK_MAX)
611 break;
612 mark_inc(mark);
613 }
614
615 /*
616 * Now that the new node is fully initialised, we can add
617 * it to the tree
618 */
619 if (xa_is_node(entry: head)) {
620 xa_to_node(entry: head)->offset = 0;
621 rcu_assign_pointer(xa_to_node(head)->parent, node);
622 }
623 head = xa_mk_node(node);
624 rcu_assign_pointer(xa->xa_head, head);
625 xas_update(xas, node);
626
627 shift += XA_CHUNK_SHIFT;
628 }
629
630 xas->xa_node = node;
631 return shift;
632}
633
634/*
635 * xas_create() - Create a slot to store an entry in.
636 * @xas: XArray operation state.
637 * @allow_root: %true if we can store the entry in the root directly
638 *
639 * Most users will not need to call this function directly, as it is called
640 * by xas_store(). It is useful for doing conditional store operations
641 * (see the xa_cmpxchg() implementation for an example).
642 *
643 * Return: If the slot already existed, returns the contents of this slot.
644 * If the slot was newly created, returns %NULL. If it failed to create the
645 * slot, returns %NULL and indicates the error in @xas.
646 */
647static void *xas_create(struct xa_state *xas, bool allow_root)
648{
649 struct xarray *xa = xas->xa;
650 void *entry;
651 void __rcu **slot;
652 struct xa_node *node = xas->xa_node;
653 int shift;
654 unsigned int order = xas->xa_shift;
655
656 if (xas_top(node)) {
657 entry = xa_head_locked(xa);
658 xas->xa_node = NULL;
659 if (!entry && xa_zero_busy(xa))
660 entry = XA_ZERO_ENTRY;
661 shift = xas_expand(xas, head: entry);
662 if (shift < 0)
663 return NULL;
664 if (!shift && !allow_root)
665 shift = XA_CHUNK_SHIFT;
666 entry = xa_head_locked(xa);
667 slot = &xa->xa_head;
668 } else if (xas_error(xas)) {
669 return NULL;
670 } else if (node) {
671 unsigned int offset = xas->xa_offset;
672
673 shift = node->shift;
674 entry = xa_entry_locked(xa, node, offset);
675 slot = &node->slots[offset];
676 } else {
677 shift = 0;
678 entry = xa_head_locked(xa);
679 slot = &xa->xa_head;
680 }
681
682 while (shift > order) {
683 shift -= XA_CHUNK_SHIFT;
684 if (!entry) {
685 node = xas_alloc(xas, shift);
686 if (!node)
687 break;
688 if (xa_track_free(xa))
689 node_mark_all(node, XA_FREE_MARK);
690 rcu_assign_pointer(*slot, xa_mk_node(node));
691 } else if (xa_is_node(entry)) {
692 node = xa_to_node(entry);
693 } else {
694 break;
695 }
696 entry = xas_descend(xas, node);
697 slot = &node->slots[xas->xa_offset];
698 }
699
700 return entry;
701}
702
703/**
704 * xas_create_range() - Ensure that stores to this range will succeed
705 * @xas: XArray operation state.
706 *
707 * Creates all of the slots in the range covered by @xas. Sets @xas to
708 * create single-index entries and positions it at the beginning of the
709 * range. This is for the benefit of users which have not yet been
710 * converted to use multi-index entries.
711 */
712void xas_create_range(struct xa_state *xas)
713{
714 unsigned long index = xas->xa_index;
715 unsigned char shift = xas->xa_shift;
716 unsigned char sibs = xas->xa_sibs;
717
718 xas->xa_index |= ((sibs + 1UL) << shift) - 1;
719 if (xas_is_node(xas) && xas->xa_node->shift == xas->xa_shift)
720 xas->xa_offset |= sibs;
721 xas->xa_shift = 0;
722 xas->xa_sibs = 0;
723
724 for (;;) {
725 xas_create(xas, allow_root: true);
726 if (xas_error(xas))
727 goto restore;
728 if (xas->xa_index <= (index | XA_CHUNK_MASK))
729 goto success;
730 xas->xa_index -= XA_CHUNK_SIZE;
731
732 for (;;) {
733 struct xa_node *node = xas->xa_node;
734 if (node->shift >= shift)
735 break;
736 xas->xa_node = xa_parent_locked(xa: xas->xa, node);
737 xas->xa_offset = node->offset - 1;
738 if (node->offset != 0)
739 break;
740 }
741 }
742
743restore:
744 xas->xa_shift = shift;
745 xas->xa_sibs = sibs;
746 xas->xa_index = index;
747 return;
748success:
749 xas->xa_index = index;
750 if (xas->xa_node)
751 xas_set_offset(xas);
752}
753EXPORT_SYMBOL_GPL(xas_create_range);
754
755static void update_node(struct xa_state *xas, struct xa_node *node,
756 int count, int values)
757{
758 if (!node || (!count && !values))
759 return;
760
761 node->count += count;
762 node->nr_values += values;
763 XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
764 XA_NODE_BUG_ON(node, node->nr_values > XA_CHUNK_SIZE);
765 xas_update(xas, node);
766 if (count < 0)
767 xas_delete_node(xas);
768}
769
770/**
771 * xas_store() - Store this entry in the XArray.
772 * @xas: XArray operation state.
773 * @entry: New entry.
774 *
775 * If @xas is operating on a multi-index entry, the entry returned by this
776 * function is essentially meaningless (it may be an internal entry or it
777 * may be %NULL, even if there are non-NULL entries at some of the indices
778 * covered by the range). This is not a problem for any current users,
779 * and can be changed if needed.
780 *
781 * Return: The old entry at this index.
782 */
783void *xas_store(struct xa_state *xas, void *entry)
784{
785 struct xa_node *node;
786 void __rcu **slot = &xas->xa->xa_head;
787 unsigned int offset, max;
788 int count = 0;
789 int values = 0;
790 void *first, *next;
791 bool value = xa_is_value(entry);
792
793 if (entry) {
794 bool allow_root = !xa_is_node(entry) && !xa_is_zero(entry);
795 first = xas_create(xas, allow_root);
796 } else {
797 first = xas_load(xas);
798 }
799
800 if (xas_invalid(xas))
801 return first;
802 node = xas->xa_node;
803 if (node && (xas->xa_shift < node->shift))
804 xas->xa_sibs = 0;
805 if ((first == entry) && !xas->xa_sibs)
806 return first;
807
808 next = first;
809 offset = xas->xa_offset;
810 max = xas->xa_offset + xas->xa_sibs;
811 if (node) {
812 slot = &node->slots[offset];
813 if (xas->xa_sibs)
814 xas_squash_marks(xas);
815 }
816 if (!entry)
817 xas_init_marks(xas);
818
819 for (;;) {
820 /*
821 * Must clear the marks before setting the entry to NULL,
822 * otherwise xas_for_each_marked may find a NULL entry and
823 * stop early. rcu_assign_pointer contains a release barrier
824 * so the mark clearing will appear to happen before the
825 * entry is set to NULL.
826 */
827 rcu_assign_pointer(*slot, entry);
828 if (xa_is_node(entry: next) && (!node || node->shift))
829 xas_free_nodes(xas, top: xa_to_node(entry: next));
830 if (!node)
831 break;
832 count += !next - !entry;
833 values += !xa_is_value(entry: first) - !value;
834 if (entry) {
835 if (offset == max)
836 break;
837 if (!xa_is_sibling(entry))
838 entry = xa_mk_sibling(offset: xas->xa_offset);
839 } else {
840 if (offset == XA_CHUNK_MASK)
841 break;
842 }
843 next = xa_entry_locked(xa: xas->xa, node, offset: ++offset);
844 if (!xa_is_sibling(entry: next)) {
845 if (!entry && (offset > max))
846 break;
847 first = next;
848 }
849 slot++;
850 }
851
852 update_node(xas, node, count, values);
853 return first;
854}
855EXPORT_SYMBOL_GPL(xas_store);
856
857/**
858 * xas_get_mark() - Returns the state of this mark.
859 * @xas: XArray operation state.
860 * @mark: Mark number.
861 *
862 * Return: true if the mark is set, false if the mark is clear or @xas
863 * is in an error state.
864 */
865bool xas_get_mark(const struct xa_state *xas, xa_mark_t mark)
866{
867 if (xas_invalid(xas))
868 return false;
869 if (!xas->xa_node)
870 return xa_marked(xa: xas->xa, mark);
871 return node_get_mark(node: xas->xa_node, offset: xas->xa_offset, mark);
872}
873EXPORT_SYMBOL_GPL(xas_get_mark);
874
875/**
876 * xas_set_mark() - Sets the mark on this entry and its parents.
877 * @xas: XArray operation state.
878 * @mark: Mark number.
879 *
880 * Sets the specified mark on this entry, and walks up the tree setting it
881 * on all the ancestor entries. Does nothing if @xas has not been walked to
882 * an entry, or is in an error state.
883 */
884void xas_set_mark(const struct xa_state *xas, xa_mark_t mark)
885{
886 struct xa_node *node = xas->xa_node;
887 unsigned int offset = xas->xa_offset;
888
889 if (xas_invalid(xas))
890 return;
891
892 while (node) {
893 if (node_set_mark(node, offset, mark))
894 return;
895 offset = node->offset;
896 node = xa_parent_locked(xa: xas->xa, node);
897 }
898
899 if (!xa_marked(xa: xas->xa, mark))
900 xa_mark_set(xa: xas->xa, mark);
901}
902EXPORT_SYMBOL_GPL(xas_set_mark);
903
904/**
905 * xas_clear_mark() - Clears the mark on this entry and its parents.
906 * @xas: XArray operation state.
907 * @mark: Mark number.
908 *
909 * Clears the specified mark on this entry, and walks back to the head
910 * attempting to clear it on all the ancestor entries. Does nothing if
911 * @xas has not been walked to an entry, or is in an error state.
912 */
913void xas_clear_mark(const struct xa_state *xas, xa_mark_t mark)
914{
915 struct xa_node *node = xas->xa_node;
916 unsigned int offset = xas->xa_offset;
917
918 if (xas_invalid(xas))
919 return;
920
921 while (node) {
922 if (!node_clear_mark(node, offset, mark))
923 return;
924 if (node_any_mark(node, mark))
925 return;
926
927 offset = node->offset;
928 node = xa_parent_locked(xa: xas->xa, node);
929 }
930
931 if (xa_marked(xa: xas->xa, mark))
932 xa_mark_clear(xa: xas->xa, mark);
933}
934EXPORT_SYMBOL_GPL(xas_clear_mark);
935
936/**
937 * xas_init_marks() - Initialise all marks for the entry
938 * @xas: Array operations state.
939 *
940 * Initialise all marks for the entry specified by @xas. If we're tracking
941 * free entries with a mark, we need to set it on all entries. All other
942 * marks are cleared.
943 *
944 * This implementation is not as efficient as it could be; we may walk
945 * up the tree multiple times.
946 */
947void xas_init_marks(const struct xa_state *xas)
948{
949 xa_mark_t mark = 0;
950
951 for (;;) {
952 if (xa_track_free(xa: xas->xa) && mark == XA_FREE_MARK)
953 xas_set_mark(xas, mark);
954 else
955 xas_clear_mark(xas, mark);
956 if (mark == XA_MARK_MAX)
957 break;
958 mark_inc(mark);
959 }
960}
961EXPORT_SYMBOL_GPL(xas_init_marks);
962
963#ifdef CONFIG_XARRAY_MULTI
964static unsigned int node_get_marks(struct xa_node *node, unsigned int offset)
965{
966 unsigned int marks = 0;
967 xa_mark_t mark = XA_MARK_0;
968
969 for (;;) {
970 if (node_get_mark(node, offset, mark))
971 marks |= 1 << (__force unsigned int)mark;
972 if (mark == XA_MARK_MAX)
973 break;
974 mark_inc(mark);
975 }
976
977 return marks;
978}
979
980static inline void node_mark_slots(struct xa_node *node, unsigned int sibs,
981 xa_mark_t mark)
982{
983 int i;
984
985 if (sibs == 0)
986 node_mark_all(node, mark);
987 else {
988 for (i = 0; i < XA_CHUNK_SIZE; i += sibs + 1)
989 node_set_mark(node, offset: i, mark);
990 }
991}
992
993static void node_set_marks(struct xa_node *node, unsigned int offset,
994 struct xa_node *child, unsigned int sibs,
995 unsigned int marks)
996{
997 xa_mark_t mark = XA_MARK_0;
998
999 for (;;) {
1000 if (marks & (1 << (__force unsigned int)mark)) {
1001 node_set_mark(node, offset, mark);
1002 if (child)
1003 node_mark_slots(node: child, sibs, mark);
1004 }
1005 if (mark == XA_MARK_MAX)
1006 break;
1007 mark_inc(mark);
1008 }
1009}
1010
1011static void __xas_init_node_for_split(struct xa_state *xas,
1012 struct xa_node *node, void *entry)
1013{
1014 unsigned int i;
1015 void *sibling = NULL;
1016 unsigned int mask = xas->xa_sibs;
1017
1018 if (!node)
1019 return;
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(offset: i);
1025 } else {
1026 RCU_INIT_POINTER(node->slots[i], sibling);
1027 }
1028 }
1029}
1030
1031/**
1032 * xas_split_alloc() - Allocate memory for splitting an entry.
1033 * @xas: XArray operation state.
1034 * @entry: New entry which will be stored in the array.
1035 * @order: Current entry order.
1036 * @gfp: Memory allocation flags.
1037 *
1038 * This function should be called before calling xas_split().
1039 * If necessary, it will allocate new nodes (and fill them with @entry)
1040 * to prepare for the upcoming split of an entry of @order size into
1041 * entries of the order stored in the @xas.
1042 *
1043 * Context: May sleep if @gfp flags permit.
1044 */
1045void xas_split_alloc(struct xa_state *xas, void *entry, unsigned int order,
1046 gfp_t gfp)
1047{
1048 unsigned int sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1;
1049
1050 /* XXX: no support for splitting really large entries yet */
1051 if (WARN_ON(xas->xa_shift + 2 * XA_CHUNK_SHIFT <= order))
1052 goto nomem;
1053 if (xas->xa_shift + XA_CHUNK_SHIFT > order)
1054 return;
1055
1056 do {
1057 struct xa_node *node;
1058
1059 node = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp);
1060 if (!node)
1061 goto nomem;
1062
1063 __xas_init_node_for_split(xas, node, entry);
1064 RCU_INIT_POINTER(node->parent, xas->xa_alloc);
1065 xas->xa_alloc = node;
1066 } while (sibs-- > 0);
1067
1068 return;
1069nomem:
1070 xas_destroy(xas);
1071 xas_set_err(xas, err: -ENOMEM);
1072}
1073EXPORT_SYMBOL_GPL(xas_split_alloc);
1074
1075/**
1076 * xas_split() - Split a multi-index entry into smaller entries.
1077 * @xas: XArray operation state.
1078 * @entry: New entry to store in the array.
1079 * @order: Current entry order.
1080 *
1081 * The size of the new entries is set in @xas. The value in @entry is
1082 * copied to all the replacement entries.
1083 *
1084 * Context: Any context. The caller should hold the xa_lock.
1085 */
1086void xas_split(struct xa_state *xas, void *entry, unsigned int order)
1087{
1088 unsigned int sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1;
1089 unsigned int offset, marks;
1090 struct xa_node *node;
1091 void *curr = xas_load(xas);
1092 int values = 0;
1093
1094 node = xas->xa_node;
1095 if (xas_top(node))
1096 return;
1097
1098 marks = node_get_marks(node, offset: xas->xa_offset);
1099
1100 offset = xas->xa_offset + sibs;
1101 do {
1102 if (xas->xa_shift < node->shift) {
1103 struct xa_node *child = xas->xa_alloc;
1104
1105 xas->xa_alloc = rcu_dereference_raw(child->parent);
1106 child->shift = node->shift - XA_CHUNK_SHIFT;
1107 child->offset = offset;
1108 child->count = XA_CHUNK_SIZE;
1109 child->nr_values = xa_is_value(entry) ?
1110 XA_CHUNK_SIZE : 0;
1111 RCU_INIT_POINTER(child->parent, node);
1112 node_set_marks(node, offset, child, sibs: xas->xa_sibs,
1113 marks);
1114 rcu_assign_pointer(node->slots[offset],
1115 xa_mk_node(child));
1116 if (xa_is_value(entry: curr))
1117 values--;
1118 xas_update(xas, node: child);
1119 } else {
1120 unsigned int canon = offset - xas->xa_sibs;
1121
1122 node_set_marks(node, offset: canon, NULL, sibs: 0, marks);
1123 rcu_assign_pointer(node->slots[canon], entry);
1124 while (offset > canon)
1125 rcu_assign_pointer(node->slots[offset--],
1126 xa_mk_sibling(canon));
1127 values += (xa_is_value(entry) - xa_is_value(entry: curr)) *
1128 (xas->xa_sibs + 1);
1129 }
1130 } while (offset-- > xas->xa_offset);
1131
1132 node->nr_values += values;
1133 xas_update(xas, node);
1134}
1135EXPORT_SYMBOL_GPL(xas_split);
1136
1137/**
1138 * xas_try_split_min_order() - Minimal split order xas_try_split() can accept
1139 * @order: Current entry order.
1140 *
1141 * xas_try_split() can split a multi-index entry to smaller than @order - 1 if
1142 * no new xa_node is needed. This function provides the minimal order
1143 * xas_try_split() supports.
1144 *
1145 * Return: the minimal order xas_try_split() supports
1146 *
1147 * Context: Any context.
1148 *
1149 */
1150unsigned int xas_try_split_min_order(unsigned int order)
1151{
1152 if (order % XA_CHUNK_SHIFT == 0)
1153 return order == 0 ? 0 : order - 1;
1154
1155 return order - (order % XA_CHUNK_SHIFT);
1156}
1157EXPORT_SYMBOL_GPL(xas_try_split_min_order);
1158
1159/**
1160 * xas_try_split() - Try to split a multi-index entry.
1161 * @xas: XArray operation state.
1162 * @entry: New entry to store in the array.
1163 * @order: Current entry order.
1164 *
1165 * The size of the new entries is set in @xas. The value in @entry is
1166 * copied to all the replacement entries. If and only if one new xa_node is
1167 * needed, the function will use GFP_NOWAIT to get one if xas->xa_alloc is
1168 * NULL. If more new xa_node are needed, the function gives EINVAL error.
1169 *
1170 * NOTE: use xas_try_split_min_order() to get next split order instead of
1171 * @order - 1 if you want to minmize xas_try_split() calls.
1172 *
1173 * Context: Any context. The caller should hold the xa_lock.
1174 */
1175void xas_try_split(struct xa_state *xas, void *entry, unsigned int order)
1176{
1177 unsigned int sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1;
1178 unsigned int offset, marks;
1179 struct xa_node *node;
1180 void *curr = xas_load(xas);
1181 int values = 0;
1182 gfp_t gfp = GFP_NOWAIT;
1183
1184 node = xas->xa_node;
1185 if (xas_top(node))
1186 return;
1187
1188 if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
1189 gfp |= __GFP_ACCOUNT;
1190
1191 marks = node_get_marks(node, offset: xas->xa_offset);
1192
1193 offset = xas->xa_offset + sibs;
1194
1195 if (xas->xa_shift < node->shift) {
1196 struct xa_node *child = xas->xa_alloc;
1197 unsigned int expected_sibs =
1198 (1 << ((order - 1) % XA_CHUNK_SHIFT)) - 1;
1199
1200 /*
1201 * No support for splitting sibling entries
1202 * (horizontally) or cascade split (vertically), which
1203 * requires two or more new xa_nodes.
1204 * Since if one xa_node allocation fails,
1205 * it is hard to free the prior allocations.
1206 */
1207 if (sibs || xas->xa_sibs != expected_sibs) {
1208 xas_destroy(xas);
1209 xas_set_err(xas, err: -EINVAL);
1210 return;
1211 }
1212
1213 if (!child) {
1214 child = kmem_cache_alloc_lru(radix_tree_node_cachep,
1215 xas->xa_lru, gfp);
1216 if (!child) {
1217 xas_destroy(xas);
1218 xas_set_err(xas, err: -ENOMEM);
1219 return;
1220 }
1221 RCU_INIT_POINTER(child->parent, xas->xa_alloc);
1222 }
1223 __xas_init_node_for_split(xas, node: child, entry);
1224
1225 xas->xa_alloc = rcu_dereference_raw(child->parent);
1226 child->shift = node->shift - XA_CHUNK_SHIFT;
1227 child->offset = offset;
1228 child->count = XA_CHUNK_SIZE;
1229 child->nr_values = xa_is_value(entry) ?
1230 XA_CHUNK_SIZE : 0;
1231 RCU_INIT_POINTER(child->parent, node);
1232 node_set_marks(node, offset, child, sibs: xas->xa_sibs,
1233 marks);
1234 rcu_assign_pointer(node->slots[offset],
1235 xa_mk_node(child));
1236 if (xa_is_value(entry: curr))
1237 values--;
1238 xas_update(xas, node: child);
1239
1240 } else {
1241 do {
1242 unsigned int canon = offset - xas->xa_sibs;
1243
1244 node_set_marks(node, offset: canon, NULL, sibs: 0, marks);
1245 rcu_assign_pointer(node->slots[canon], entry);
1246 while (offset > canon)
1247 rcu_assign_pointer(node->slots[offset--],
1248 xa_mk_sibling(canon));
1249 values += (xa_is_value(entry) - xa_is_value(entry: curr)) *
1250 (xas->xa_sibs + 1);
1251 } while (offset-- > xas->xa_offset);
1252 }
1253
1254 node->nr_values += values;
1255 xas_update(xas, node);
1256}
1257EXPORT_SYMBOL_GPL(xas_try_split);
1258#endif
1259
1260/**
1261 * xas_pause() - Pause a walk to drop a lock.
1262 * @xas: XArray operation state.
1263 *
1264 * Some users need to pause a walk and drop the lock they're holding in
1265 * order to yield to a higher priority thread or carry out an operation
1266 * on an entry. Those users should call this function before they drop
1267 * the lock. It resets the @xas to be suitable for the next iteration
1268 * of the loop after the user has reacquired the lock. If most entries
1269 * found during a walk require you to call xas_pause(), the xa_for_each()
1270 * iterator may be more appropriate.
1271 *
1272 * Note that xas_pause() only works for forward iteration. If a user needs
1273 * to pause a reverse iteration, we will need a xas_pause_rev().
1274 */
1275void xas_pause(struct xa_state *xas)
1276{
1277 struct xa_node *node = xas->xa_node;
1278
1279 if (xas_invalid(xas))
1280 return;
1281
1282 xas->xa_node = XAS_RESTART;
1283 if (node) {
1284 unsigned long offset = xas->xa_offset;
1285 while (++offset < XA_CHUNK_SIZE) {
1286 if (!xa_is_sibling(entry: xa_entry(xa: xas->xa, node, offset)))
1287 break;
1288 }
1289 xas->xa_index &= ~0UL << node->shift;
1290 xas->xa_index += (offset - xas->xa_offset) << node->shift;
1291 if (xas->xa_index == 0)
1292 xas->xa_node = XAS_BOUNDS;
1293 } else {
1294 xas->xa_index++;
1295 }
1296}
1297EXPORT_SYMBOL_GPL(xas_pause);
1298
1299/*
1300 * __xas_prev() - Find the previous entry in the XArray.
1301 * @xas: XArray operation state.
1302 *
1303 * Helper function for xas_prev() which handles all the complex cases
1304 * out of line.
1305 */
1306void *__xas_prev(struct xa_state *xas)
1307{
1308 void *entry;
1309
1310 if (!xas_frozen(node: xas->xa_node))
1311 xas->xa_index--;
1312 if (!xas->xa_node)
1313 return set_bounds(xas);
1314 if (xas_not_node(node: xas->xa_node))
1315 return xas_load(xas);
1316
1317 if (xas->xa_offset != get_offset(index: xas->xa_index, node: xas->xa_node))
1318 xas->xa_offset--;
1319
1320 while (xas->xa_offset == 255) {
1321 xas->xa_offset = xas->xa_node->offset - 1;
1322 xas->xa_node = xa_parent(xa: xas->xa, node: xas->xa_node);
1323 if (!xas->xa_node)
1324 return set_bounds(xas);
1325 }
1326
1327 for (;;) {
1328 entry = xa_entry(xa: xas->xa, node: xas->xa_node, offset: xas->xa_offset);
1329 if (!xa_is_node(entry))
1330 return entry;
1331
1332 xas->xa_node = xa_to_node(entry);
1333 xas_set_offset(xas);
1334 }
1335}
1336EXPORT_SYMBOL_GPL(__xas_prev);
1337
1338/*
1339 * __xas_next() - Find the next entry in the XArray.
1340 * @xas: XArray operation state.
1341 *
1342 * Helper function for xas_next() which handles all the complex cases
1343 * out of line.
1344 */
1345void *__xas_next(struct xa_state *xas)
1346{
1347 void *entry;
1348
1349 if (!xas_frozen(node: xas->xa_node))
1350 xas->xa_index++;
1351 if (!xas->xa_node)
1352 return set_bounds(xas);
1353 if (xas_not_node(node: xas->xa_node))
1354 return xas_load(xas);
1355
1356 if (xas->xa_offset != get_offset(index: xas->xa_index, node: xas->xa_node))
1357 xas->xa_offset++;
1358
1359 while (xas->xa_offset == XA_CHUNK_SIZE) {
1360 xas->xa_offset = xas->xa_node->offset + 1;
1361 xas->xa_node = xa_parent(xa: xas->xa, node: xas->xa_node);
1362 if (!xas->xa_node)
1363 return set_bounds(xas);
1364 }
1365
1366 for (;;) {
1367 entry = xa_entry(xa: xas->xa, node: xas->xa_node, offset: xas->xa_offset);
1368 if (!xa_is_node(entry))
1369 return entry;
1370
1371 xas->xa_node = xa_to_node(entry);
1372 xas_set_offset(xas);
1373 }
1374}
1375EXPORT_SYMBOL_GPL(__xas_next);
1376
1377/**
1378 * xas_find() - Find the next present entry in the XArray.
1379 * @xas: XArray operation state.
1380 * @max: Highest index to return.
1381 *
1382 * If the @xas has not yet been walked to an entry, return the entry
1383 * which has an index >= xas.xa_index. If it has been walked, the entry
1384 * currently being pointed at has been processed, and so we move to the
1385 * next entry.
1386 *
1387 * If no entry is found and the array is smaller than @max, the iterator
1388 * is set to the smallest index not yet in the array. This allows @xas
1389 * to be immediately passed to xas_store().
1390 *
1391 * Return: The entry, if found, otherwise %NULL.
1392 */
1393void *xas_find(struct xa_state *xas, unsigned long max)
1394{
1395 void *entry;
1396
1397 if (xas_error(xas) || xas->xa_node == XAS_BOUNDS)
1398 return NULL;
1399 if (xas->xa_index > max)
1400 return set_bounds(xas);
1401
1402 if (!xas->xa_node) {
1403 xas->xa_index = 1;
1404 return set_bounds(xas);
1405 } else if (xas->xa_node == XAS_RESTART) {
1406 entry = xas_load(xas);
1407 if (entry || xas_not_node(node: xas->xa_node))
1408 return entry;
1409 } else if (!xas->xa_node->shift &&
1410 xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)) {
1411 xas->xa_offset = ((xas->xa_index - 1) & XA_CHUNK_MASK) + 1;
1412 }
1413
1414 xas_next_offset(xas);
1415
1416 while (xas->xa_node && (xas->xa_index <= max)) {
1417 if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
1418 xas->xa_offset = xas->xa_node->offset + 1;
1419 xas->xa_node = xa_parent(xa: xas->xa, node: xas->xa_node);
1420 continue;
1421 }
1422
1423 entry = xa_entry(xa: xas->xa, node: xas->xa_node, offset: xas->xa_offset);
1424 if (xa_is_node(entry)) {
1425 xas->xa_node = xa_to_node(entry);
1426 xas->xa_offset = 0;
1427 continue;
1428 }
1429 if (entry && !xa_is_sibling(entry))
1430 return entry;
1431
1432 xas_next_offset(xas);
1433 }
1434
1435 if (!xas->xa_node)
1436 xas->xa_node = XAS_BOUNDS;
1437 return NULL;
1438}
1439EXPORT_SYMBOL_GPL(xas_find);
1440
1441/**
1442 * xas_find_marked() - Find the next marked entry in the XArray.
1443 * @xas: XArray operation state.
1444 * @max: Highest index to return.
1445 * @mark: Mark number to search for.
1446 *
1447 * If the @xas has not yet been walked to an entry, return the marked entry
1448 * which has an index >= xas.xa_index. If it has been walked, the entry
1449 * currently being pointed at has been processed, and so we return the
1450 * first marked entry with an index > xas.xa_index.
1451 *
1452 * If no marked entry is found and the array is smaller than @max, @xas is
1453 * set to the bounds state and xas->xa_index is set to the smallest index
1454 * not yet in the array. This allows @xas to be immediately passed to
1455 * xas_store().
1456 *
1457 * If no entry is found before @max is reached, @xas is set to the restart
1458 * state.
1459 *
1460 * Return: The entry, if found, otherwise %NULL.
1461 */
1462void *xas_find_marked(struct xa_state *xas, unsigned long max, xa_mark_t mark)
1463{
1464 bool advance = true;
1465 unsigned int offset;
1466 void *entry;
1467
1468 if (xas_error(xas))
1469 return NULL;
1470 if (xas->xa_index > max)
1471 goto max;
1472
1473 if (!xas->xa_node) {
1474 xas->xa_index = 1;
1475 goto out;
1476 } else if (xas_top(node: xas->xa_node)) {
1477 advance = false;
1478 entry = xa_head(xa: xas->xa);
1479 xas->xa_node = NULL;
1480 if (xas->xa_index > max_index(entry))
1481 goto out;
1482 if (!xa_is_node(entry)) {
1483 if (xa_marked(xa: xas->xa, mark))
1484 return entry;
1485 xas->xa_index = 1;
1486 goto out;
1487 }
1488 xas->xa_node = xa_to_node(entry);
1489 xas->xa_offset = xas->xa_index >> xas->xa_node->shift;
1490 }
1491
1492 while (xas->xa_index <= max) {
1493 if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
1494 xas->xa_offset = xas->xa_node->offset + 1;
1495 xas->xa_node = xa_parent(xa: xas->xa, node: xas->xa_node);
1496 if (!xas->xa_node)
1497 break;
1498 advance = false;
1499 continue;
1500 }
1501
1502 if (!advance) {
1503 entry = xa_entry(xa: xas->xa, node: xas->xa_node, offset: xas->xa_offset);
1504 if (xa_is_sibling(entry)) {
1505 xas->xa_offset = xa_to_sibling(entry);
1506 xas_move_index(xas, offset: xas->xa_offset);
1507 }
1508 }
1509
1510 offset = xas_find_chunk(xas, advance, mark);
1511 if (offset > xas->xa_offset) {
1512 advance = false;
1513 xas_move_index(xas, offset);
1514 /* Mind the wrap */
1515 if ((xas->xa_index - 1) >= max)
1516 goto max;
1517 xas->xa_offset = offset;
1518 if (offset == XA_CHUNK_SIZE)
1519 continue;
1520 }
1521
1522 entry = xa_entry(xa: xas->xa, node: xas->xa_node, offset: xas->xa_offset);
1523 if (!entry && !(xa_track_free(xa: xas->xa) && mark == XA_FREE_MARK))
1524 continue;
1525 if (xa_is_sibling(entry))
1526 continue;
1527 if (!xa_is_node(entry))
1528 return entry;
1529 xas->xa_node = xa_to_node(entry);
1530 xas_set_offset(xas);
1531 }
1532
1533out:
1534 if (xas->xa_index > max)
1535 goto max;
1536 return set_bounds(xas);
1537max:
1538 xas->xa_node = XAS_RESTART;
1539 return NULL;
1540}
1541EXPORT_SYMBOL_GPL(xas_find_marked);
1542
1543/**
1544 * xas_find_conflict() - Find the next present entry in a range.
1545 * @xas: XArray operation state.
1546 *
1547 * The @xas describes both a range and a position within that range.
1548 *
1549 * Context: Any context. Expects xa_lock to be held.
1550 * Return: The next entry in the range covered by @xas or %NULL.
1551 */
1552void *xas_find_conflict(struct xa_state *xas)
1553{
1554 void *curr;
1555
1556 if (xas_error(xas))
1557 return NULL;
1558
1559 if (!xas->xa_node)
1560 return NULL;
1561
1562 if (xas_top(node: xas->xa_node)) {
1563 curr = xas_start(xas);
1564 if (!curr)
1565 return NULL;
1566 while (xa_is_node(entry: curr)) {
1567 struct xa_node *node = xa_to_node(entry: curr);
1568 curr = xas_descend(xas, node);
1569 }
1570 if (curr)
1571 return curr;
1572 }
1573
1574 if (xas->xa_node->shift > xas->xa_shift)
1575 return NULL;
1576
1577 for (;;) {
1578 if (xas->xa_node->shift == xas->xa_shift) {
1579 if ((xas->xa_offset & xas->xa_sibs) == xas->xa_sibs)
1580 break;
1581 } else if (xas->xa_offset == XA_CHUNK_MASK) {
1582 xas->xa_offset = xas->xa_node->offset;
1583 xas->xa_node = xa_parent_locked(xa: xas->xa, node: xas->xa_node);
1584 if (!xas->xa_node)
1585 break;
1586 continue;
1587 }
1588 curr = xa_entry_locked(xa: xas->xa, node: xas->xa_node, offset: ++xas->xa_offset);
1589 if (xa_is_sibling(entry: curr))
1590 continue;
1591 while (xa_is_node(entry: curr)) {
1592 xas->xa_node = xa_to_node(entry: curr);
1593 xas->xa_offset = 0;
1594 curr = xa_entry_locked(xa: xas->xa, node: xas->xa_node, offset: 0);
1595 }
1596 if (curr)
1597 return curr;
1598 }
1599 xas->xa_offset -= xas->xa_sibs;
1600 return NULL;
1601}
1602EXPORT_SYMBOL_GPL(xas_find_conflict);
1603
1604/**
1605 * xa_load() - Load an entry from an XArray.
1606 * @xa: XArray.
1607 * @index: index into array.
1608 *
1609 * Context: Any context. Takes and releases the RCU lock.
1610 * Return: The entry at @index in @xa.
1611 */
1612void *xa_load(struct xarray *xa, unsigned long index)
1613{
1614 XA_STATE(xas, xa, index);
1615 void *entry;
1616
1617 rcu_read_lock();
1618 do {
1619 entry = xa_zero_to_null(entry: xas_load(&xas));
1620 } while (xas_retry(xas: &xas, entry));
1621 rcu_read_unlock();
1622
1623 return entry;
1624}
1625EXPORT_SYMBOL(xa_load);
1626
1627static void *xas_result(struct xa_state *xas, void *curr)
1628{
1629 if (xas_error(xas))
1630 curr = xas->xa_node;
1631 return curr;
1632}
1633
1634/**
1635 * __xa_erase() - Erase this entry from the XArray while locked.
1636 * @xa: XArray.
1637 * @index: Index into array.
1638 *
1639 * After this function returns, loading from @index will return %NULL.
1640 * If the index is part of a multi-index entry, all indices will be erased
1641 * and none of the entries will be part of a multi-index entry.
1642 *
1643 * Context: Any context. Expects xa_lock to be held on entry.
1644 * Return: The entry which used to be at this index.
1645 */
1646void *__xa_erase(struct xarray *xa, unsigned long index)
1647{
1648 XA_STATE(xas, xa, index);
1649 return xas_result(xas: &xas, curr: xa_zero_to_null(entry: xas_store(&xas, NULL)));
1650}
1651EXPORT_SYMBOL(__xa_erase);
1652
1653/**
1654 * xa_erase() - Erase this entry from the XArray.
1655 * @xa: XArray.
1656 * @index: Index of entry.
1657 *
1658 * After this function returns, loading from @index will return %NULL.
1659 * If the index is part of a multi-index entry, all indices will be erased
1660 * and none of the entries will be part of a multi-index entry.
1661 *
1662 * Context: Any context. Takes and releases the xa_lock.
1663 * Return: The entry which used to be at this index.
1664 */
1665void *xa_erase(struct xarray *xa, unsigned long index)
1666{
1667 void *entry;
1668
1669 xa_lock(xa);
1670 entry = __xa_erase(xa, index);
1671 xa_unlock(xa);
1672
1673 return entry;
1674}
1675EXPORT_SYMBOL(xa_erase);
1676
1677/**
1678 * __xa_store() - Store this entry in the XArray.
1679 * @xa: XArray.
1680 * @index: Index into array.
1681 * @entry: New entry.
1682 * @gfp: Memory allocation flags.
1683 *
1684 * You must already be holding the xa_lock when calling this function.
1685 * It will drop the lock if needed to allocate memory, and then reacquire
1686 * it afterwards.
1687 *
1688 * Context: Any context. Expects xa_lock to be held on entry. May
1689 * release and reacquire xa_lock if @gfp flags permit.
1690 * Return: The old entry at this index or xa_err() if an error happened.
1691 */
1692void *__xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1693{
1694 XA_STATE(xas, xa, index);
1695 void *curr;
1696
1697 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1698 return XA_ERROR(-EINVAL);
1699 if (xa_track_free(xa) && !entry)
1700 entry = XA_ZERO_ENTRY;
1701
1702 do {
1703 curr = xas_store(&xas, entry);
1704 if (xa_track_free(xa))
1705 xas_clear_mark(&xas, XA_FREE_MARK);
1706 } while (__xas_nomem(xas: &xas, gfp));
1707
1708 return xas_result(xas: &xas, curr: xa_zero_to_null(entry: curr));
1709}
1710EXPORT_SYMBOL(__xa_store);
1711
1712/**
1713 * xa_store() - Store this entry in the XArray.
1714 * @xa: XArray.
1715 * @index: Index into array.
1716 * @entry: New entry.
1717 * @gfp: Memory allocation flags.
1718 *
1719 * After this function returns, loads from this index will return @entry.
1720 * Storing into an existing multi-index entry updates the entry of every index.
1721 * The marks associated with @index are unaffected unless @entry is %NULL.
1722 *
1723 * Context: Any context. Takes and releases the xa_lock.
1724 * May sleep if the @gfp flags permit.
1725 * Return: The old entry at this index on success, xa_err(-EINVAL) if @entry
1726 * cannot be stored in an XArray, or xa_err(-ENOMEM) if memory allocation
1727 * failed.
1728 */
1729void *xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1730{
1731 void *curr;
1732
1733 xa_lock(xa);
1734 curr = __xa_store(xa, index, entry, gfp);
1735 xa_unlock(xa);
1736
1737 return curr;
1738}
1739EXPORT_SYMBOL(xa_store);
1740
1741static inline void *__xa_cmpxchg_raw(struct xarray *xa, unsigned long index,
1742 void *old, void *entry, gfp_t gfp);
1743
1744/**
1745 * __xa_cmpxchg() - Conditionally replace an entry in the XArray.
1746 * @xa: XArray.
1747 * @index: Index into array.
1748 * @old: Old value to test against.
1749 * @entry: New value to place in array.
1750 * @gfp: Memory allocation flags.
1751 *
1752 * You must already be holding the xa_lock when calling this function.
1753 * It will drop the lock if needed to allocate memory, and then reacquire
1754 * it afterwards.
1755 *
1756 * If the entry at @index is the same as @old, replace it with @entry.
1757 * If the return value is equal to @old, then the exchange was successful.
1758 *
1759 * Context: Any context. Expects xa_lock to be held on entry. May
1760 * release and reacquire xa_lock if @gfp flags permit.
1761 * Return: The old value at this index or xa_err() if an error happened.
1762 */
1763void *__xa_cmpxchg(struct xarray *xa, unsigned long index,
1764 void *old, void *entry, gfp_t gfp)
1765{
1766 return xa_zero_to_null(entry: __xa_cmpxchg_raw(xa, index, old, entry, gfp));
1767}
1768EXPORT_SYMBOL(__xa_cmpxchg);
1769
1770static inline void *__xa_cmpxchg_raw(struct xarray *xa, unsigned long index,
1771 void *old, void *entry, gfp_t gfp)
1772{
1773 XA_STATE(xas, xa, index);
1774 void *curr;
1775
1776 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1777 return XA_ERROR(-EINVAL);
1778
1779 do {
1780 curr = xas_load(&xas);
1781 if (curr == old) {
1782 xas_store(&xas, entry);
1783 if (xa_track_free(xa) && entry && !curr)
1784 xas_clear_mark(&xas, XA_FREE_MARK);
1785 }
1786 } while (__xas_nomem(xas: &xas, gfp));
1787
1788 return xas_result(xas: &xas, curr);
1789}
1790
1791/**
1792 * __xa_insert() - Store this entry in the XArray if no entry is present.
1793 * @xa: XArray.
1794 * @index: Index into array.
1795 * @entry: New entry.
1796 * @gfp: Memory allocation flags.
1797 *
1798 * Inserting a NULL entry will store a reserved entry (like xa_reserve())
1799 * if no entry is present. Inserting will fail if a reserved entry is
1800 * present, even though loading from this index will return NULL.
1801 *
1802 * Context: Any context. Expects xa_lock to be held on entry. May
1803 * release and reacquire xa_lock if @gfp flags permit.
1804 * Return: 0 if the store succeeded. -EBUSY if another entry was present.
1805 * -ENOMEM if memory could not be allocated.
1806 */
1807int __xa_insert(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1808{
1809 void *curr;
1810 int errno;
1811
1812 if (!entry)
1813 entry = XA_ZERO_ENTRY;
1814 curr = __xa_cmpxchg_raw(xa, index, NULL, entry, gfp);
1815 errno = xa_err(entry: curr);
1816 if (errno)
1817 return errno;
1818 return (curr != NULL) ? -EBUSY : 0;
1819}
1820EXPORT_SYMBOL(__xa_insert);
1821
1822#ifdef CONFIG_XARRAY_MULTI
1823static void xas_set_range(struct xa_state *xas, unsigned long first,
1824 unsigned long last)
1825{
1826 unsigned int shift = 0;
1827 unsigned long sibs = last - first;
1828 unsigned int offset = XA_CHUNK_MASK;
1829
1830 xas_set(xas, index: first);
1831
1832 while ((first & XA_CHUNK_MASK) == 0) {
1833 if (sibs < XA_CHUNK_MASK)
1834 break;
1835 if ((sibs == XA_CHUNK_MASK) && (offset < XA_CHUNK_MASK))
1836 break;
1837 shift += XA_CHUNK_SHIFT;
1838 if (offset == XA_CHUNK_MASK)
1839 offset = sibs & XA_CHUNK_MASK;
1840 sibs >>= XA_CHUNK_SHIFT;
1841 first >>= XA_CHUNK_SHIFT;
1842 }
1843
1844 offset = first & XA_CHUNK_MASK;
1845 if (offset + sibs > XA_CHUNK_MASK)
1846 sibs = XA_CHUNK_MASK - offset;
1847 if ((((first + sibs + 1) << shift) - 1) > last)
1848 sibs -= 1;
1849
1850 xas->xa_shift = shift;
1851 xas->xa_sibs = sibs;
1852}
1853
1854/**
1855 * xa_store_range() - Store this entry at a range of indices in the XArray.
1856 * @xa: XArray.
1857 * @first: First index to affect.
1858 * @last: Last index to affect.
1859 * @entry: New entry.
1860 * @gfp: Memory allocation flags.
1861 *
1862 * After this function returns, loads from any index between @first and @last,
1863 * inclusive will return @entry.
1864 * Storing into an existing multi-index entry updates the entry of every index.
1865 * The marks associated with @index are unaffected unless @entry is %NULL.
1866 *
1867 * Context: Process context. Takes and releases the xa_lock. May sleep
1868 * if the @gfp flags permit.
1869 * Return: %NULL on success, xa_err(-EINVAL) if @entry cannot be stored in
1870 * an XArray, or xa_err(-ENOMEM) if memory allocation failed.
1871 */
1872void *xa_store_range(struct xarray *xa, unsigned long first,
1873 unsigned long last, void *entry, gfp_t gfp)
1874{
1875 XA_STATE(xas, xa, 0);
1876
1877 if (WARN_ON_ONCE(xa_is_internal(entry)))
1878 return XA_ERROR(-EINVAL);
1879 if (last < first)
1880 return XA_ERROR(-EINVAL);
1881
1882 do {
1883 xas_lock(&xas);
1884 if (entry) {
1885 unsigned int order = BITS_PER_LONG;
1886 if (last + 1)
1887 order = __ffs(last + 1);
1888 xas_set_order(xas: &xas, index: last, order);
1889 xas_create(xas: &xas, allow_root: true);
1890 if (xas_error(xas: &xas))
1891 goto unlock;
1892 }
1893 do {
1894 xas_set_range(xas: &xas, first, last);
1895 xas_store(&xas, entry);
1896 if (xas_error(xas: &xas))
1897 goto unlock;
1898 first += xas_size(xas: &xas);
1899 } while (first <= last);
1900unlock:
1901 xas_unlock(&xas);
1902 } while (xas_nomem(&xas, gfp));
1903
1904 return xas_result(xas: &xas, NULL);
1905}
1906EXPORT_SYMBOL(xa_store_range);
1907
1908/**
1909 * xas_get_order() - Get the order of an entry.
1910 * @xas: XArray operation state.
1911 *
1912 * Called after xas_load, the xas should not be in an error state.
1913 * The xas should not be pointing to a sibling entry.
1914 *
1915 * Return: A number between 0 and 63 indicating the order of the entry.
1916 */
1917int xas_get_order(struct xa_state *xas)
1918{
1919 int order = 0;
1920
1921 if (!xas->xa_node)
1922 return 0;
1923
1924 XA_NODE_BUG_ON(xas->xa_node, xa_is_sibling(xa_entry(xas->xa,
1925 xas->xa_node, xas->xa_offset)));
1926 for (;;) {
1927 unsigned int slot = xas->xa_offset + (1 << order);
1928
1929 if (slot >= XA_CHUNK_SIZE)
1930 break;
1931 if (!xa_is_sibling(entry: xa_entry(xa: xas->xa, node: xas->xa_node, offset: slot)))
1932 break;
1933 order++;
1934 }
1935
1936 order += xas->xa_node->shift;
1937 return order;
1938}
1939EXPORT_SYMBOL_GPL(xas_get_order);
1940
1941/**
1942 * xa_get_order() - Get the order of an entry.
1943 * @xa: XArray.
1944 * @index: Index of the entry.
1945 *
1946 * Return: A number between 0 and 63 indicating the order of the entry.
1947 */
1948int xa_get_order(struct xarray *xa, unsigned long index)
1949{
1950 XA_STATE(xas, xa, index);
1951 int order = 0;
1952 void *entry;
1953
1954 rcu_read_lock();
1955 entry = xas_load(&xas);
1956 if (entry)
1957 order = xas_get_order(&xas);
1958 rcu_read_unlock();
1959
1960 return order;
1961}
1962EXPORT_SYMBOL(xa_get_order);
1963#endif /* CONFIG_XARRAY_MULTI */
1964
1965/**
1966 * __xa_alloc() - Find somewhere to store this entry in the XArray.
1967 * @xa: XArray.
1968 * @id: Pointer to ID.
1969 * @limit: Range for allocated ID.
1970 * @entry: New entry.
1971 * @gfp: Memory allocation flags.
1972 *
1973 * Finds an empty entry in @xa between @limit.min and @limit.max,
1974 * stores the index into the @id pointer, then stores the entry at
1975 * that index. A concurrent lookup will not see an uninitialised @id.
1976 *
1977 * Must only be operated on an xarray initialized with flag XA_FLAGS_ALLOC set
1978 * in xa_init_flags().
1979 *
1980 * Context: Any context. Expects xa_lock to be held on entry. May
1981 * release and reacquire xa_lock if @gfp flags permit.
1982 * Return: 0 on success, -ENOMEM if memory could not be allocated or
1983 * -EBUSY if there are no free entries in @limit.
1984 */
1985int __xa_alloc(struct xarray *xa, u32 *id, void *entry,
1986 struct xa_limit limit, gfp_t gfp)
1987{
1988 XA_STATE(xas, xa, 0);
1989
1990 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1991 return -EINVAL;
1992 if (WARN_ON_ONCE(!xa_track_free(xa)))
1993 return -EINVAL;
1994
1995 if (!entry)
1996 entry = XA_ZERO_ENTRY;
1997
1998 do {
1999 xas.xa_index = limit.min;
2000 xas_find_marked(&xas, limit.max, XA_FREE_MARK);
2001 if (xas.xa_node == XAS_RESTART)
2002 xas_set_err(xas: &xas, err: -EBUSY);
2003 else
2004 *id = xas.xa_index;
2005 xas_store(&xas, entry);
2006 xas_clear_mark(&xas, XA_FREE_MARK);
2007 } while (__xas_nomem(xas: &xas, gfp));
2008
2009 return xas_error(xas: &xas);
2010}
2011EXPORT_SYMBOL(__xa_alloc);
2012
2013/**
2014 * __xa_alloc_cyclic() - Find somewhere to store this entry in the XArray.
2015 * @xa: XArray.
2016 * @id: Pointer to ID.
2017 * @entry: New entry.
2018 * @limit: Range of allocated ID.
2019 * @next: Pointer to next ID to allocate.
2020 * @gfp: Memory allocation flags.
2021 *
2022 * Finds an empty entry in @xa between @limit.min and @limit.max,
2023 * stores the index into the @id pointer, then stores the entry at
2024 * that index. A concurrent lookup will not see an uninitialised @id.
2025 * The search for an empty entry will start at @next and will wrap
2026 * around if necessary.
2027 *
2028 * Must only be operated on an xarray initialized with flag XA_FLAGS_ALLOC set
2029 * in xa_init_flags().
2030 *
2031 * Context: Any context. Expects xa_lock to be held on entry. May
2032 * release and reacquire xa_lock if @gfp flags permit.
2033 * Return: 0 if the allocation succeeded without wrapping. 1 if the
2034 * allocation succeeded after wrapping, -ENOMEM if memory could not be
2035 * allocated or -EBUSY if there are no free entries in @limit.
2036 */
2037int __xa_alloc_cyclic(struct xarray *xa, u32 *id, void *entry,
2038 struct xa_limit limit, u32 *next, gfp_t gfp)
2039{
2040 u32 min = limit.min;
2041 int ret;
2042
2043 limit.min = max(min, *next);
2044 ret = __xa_alloc(xa, id, entry, limit, gfp);
2045 if ((xa->xa_flags & XA_FLAGS_ALLOC_WRAPPED) && ret == 0) {
2046 xa->xa_flags &= ~XA_FLAGS_ALLOC_WRAPPED;
2047 ret = 1;
2048 }
2049
2050 if (ret < 0 && limit.min > min) {
2051 limit.min = min;
2052 ret = __xa_alloc(xa, id, entry, limit, gfp);
2053 if (ret == 0)
2054 ret = 1;
2055 }
2056
2057 if (ret >= 0) {
2058 *next = *id + 1;
2059 if (*next == 0)
2060 xa->xa_flags |= XA_FLAGS_ALLOC_WRAPPED;
2061 }
2062 return ret;
2063}
2064EXPORT_SYMBOL(__xa_alloc_cyclic);
2065
2066/**
2067 * __xa_set_mark() - Set this mark on this entry while locked.
2068 * @xa: XArray.
2069 * @index: Index of entry.
2070 * @mark: Mark number.
2071 *
2072 * Attempting to set a mark on a %NULL entry does not succeed.
2073 *
2074 * Context: Any context. Expects xa_lock to be held on entry.
2075 */
2076void __xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
2077{
2078 XA_STATE(xas, xa, index);
2079 void *entry = xas_load(&xas);
2080
2081 if (entry)
2082 xas_set_mark(&xas, mark);
2083}
2084EXPORT_SYMBOL(__xa_set_mark);
2085
2086/**
2087 * __xa_clear_mark() - Clear this mark on this entry while locked.
2088 * @xa: XArray.
2089 * @index: Index of entry.
2090 * @mark: Mark number.
2091 *
2092 * Context: Any context. Expects xa_lock to be held on entry.
2093 */
2094void __xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
2095{
2096 XA_STATE(xas, xa, index);
2097 void *entry = xas_load(&xas);
2098
2099 if (entry)
2100 xas_clear_mark(&xas, mark);
2101}
2102EXPORT_SYMBOL(__xa_clear_mark);
2103
2104/**
2105 * xa_get_mark() - Inquire whether this mark is set on this entry.
2106 * @xa: XArray.
2107 * @index: Index of entry.
2108 * @mark: Mark number.
2109 *
2110 * This function uses the RCU read lock, so the result may be out of date
2111 * by the time it returns. If you need the result to be stable, use a lock.
2112 *
2113 * Context: Any context. Takes and releases the RCU lock.
2114 * Return: True if the entry at @index has this mark set, false if it doesn't.
2115 */
2116bool xa_get_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
2117{
2118 XA_STATE(xas, xa, index);
2119 void *entry;
2120
2121 rcu_read_lock();
2122 entry = xas_start(xas: &xas);
2123 while (xas_get_mark(&xas, mark)) {
2124 if (!xa_is_node(entry))
2125 goto found;
2126 entry = xas_descend(xas: &xas, node: xa_to_node(entry));
2127 }
2128 rcu_read_unlock();
2129 return false;
2130 found:
2131 rcu_read_unlock();
2132 return true;
2133}
2134EXPORT_SYMBOL(xa_get_mark);
2135
2136/**
2137 * xa_set_mark() - Set this mark on this entry.
2138 * @xa: XArray.
2139 * @index: Index of entry.
2140 * @mark: Mark number.
2141 *
2142 * Attempting to set a mark on a %NULL entry does not succeed.
2143 *
2144 * Context: Process context. Takes and releases the xa_lock.
2145 */
2146void xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
2147{
2148 xa_lock(xa);
2149 __xa_set_mark(xa, index, mark);
2150 xa_unlock(xa);
2151}
2152EXPORT_SYMBOL(xa_set_mark);
2153
2154/**
2155 * xa_clear_mark() - Clear this mark on this entry.
2156 * @xa: XArray.
2157 * @index: Index of entry.
2158 * @mark: Mark number.
2159 *
2160 * Clearing a mark always succeeds.
2161 *
2162 * Context: Process context. Takes and releases the xa_lock.
2163 */
2164void xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
2165{
2166 xa_lock(xa);
2167 __xa_clear_mark(xa, index, mark);
2168 xa_unlock(xa);
2169}
2170EXPORT_SYMBOL(xa_clear_mark);
2171
2172/**
2173 * xa_find() - Search the XArray for an entry.
2174 * @xa: XArray.
2175 * @indexp: Pointer to an index.
2176 * @max: Maximum index to search to.
2177 * @filter: Selection criterion.
2178 *
2179 * Finds the entry in @xa which matches the @filter, and has the lowest
2180 * index that is at least @indexp and no more than @max.
2181 * If an entry is found, @indexp is updated to be the index of the entry.
2182 * This function is protected by the RCU read lock, so it may not find
2183 * entries which are being simultaneously added. It will not return an
2184 * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
2185 *
2186 * Context: Any context. Takes and releases the RCU lock.
2187 * Return: The entry, if found, otherwise %NULL.
2188 */
2189void *xa_find(struct xarray *xa, unsigned long *indexp,
2190 unsigned long max, xa_mark_t filter)
2191{
2192 XA_STATE(xas, xa, *indexp);
2193 void *entry;
2194
2195 rcu_read_lock();
2196 do {
2197 if ((__force unsigned int)filter < XA_MAX_MARKS)
2198 entry = xas_find_marked(&xas, max, filter);
2199 else
2200 entry = xas_find(&xas, max);
2201 } while (xas_retry(xas: &xas, entry));
2202 rcu_read_unlock();
2203
2204 if (entry)
2205 *indexp = xas.xa_index;
2206 return entry;
2207}
2208EXPORT_SYMBOL(xa_find);
2209
2210static bool xas_sibling(struct xa_state *xas)
2211{
2212 struct xa_node *node = xas->xa_node;
2213 unsigned long mask;
2214
2215 if (!IS_ENABLED(CONFIG_XARRAY_MULTI) || !node)
2216 return false;
2217 mask = (XA_CHUNK_SIZE << node->shift) - 1;
2218 return (xas->xa_index & mask) >
2219 ((unsigned long)xas->xa_offset << node->shift);
2220}
2221
2222/**
2223 * xa_find_after() - Search the XArray for a present entry.
2224 * @xa: XArray.
2225 * @indexp: Pointer to an index.
2226 * @max: Maximum index to search to.
2227 * @filter: Selection criterion.
2228 *
2229 * Finds the entry in @xa which matches the @filter and has the lowest
2230 * index that is above @indexp and no more than @max.
2231 * If an entry is found, @indexp is updated to be the index of the entry.
2232 * This function is protected by the RCU read lock, so it may miss entries
2233 * which are being simultaneously added. It will not return an
2234 * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
2235 *
2236 * Context: Any context. Takes and releases the RCU lock.
2237 * Return: The pointer, if found, otherwise %NULL.
2238 */
2239void *xa_find_after(struct xarray *xa, unsigned long *indexp,
2240 unsigned long max, xa_mark_t filter)
2241{
2242 XA_STATE(xas, xa, *indexp + 1);
2243 void *entry;
2244
2245 if (xas.xa_index == 0)
2246 return NULL;
2247
2248 rcu_read_lock();
2249 for (;;) {
2250 if ((__force unsigned int)filter < XA_MAX_MARKS)
2251 entry = xas_find_marked(&xas, max, filter);
2252 else
2253 entry = xas_find(&xas, max);
2254
2255 if (xas_invalid(xas: &xas))
2256 break;
2257 if (xas_sibling(xas: &xas))
2258 continue;
2259 if (!xas_retry(xas: &xas, entry))
2260 break;
2261 }
2262 rcu_read_unlock();
2263
2264 if (entry)
2265 *indexp = xas.xa_index;
2266 return entry;
2267}
2268EXPORT_SYMBOL(xa_find_after);
2269
2270static unsigned int xas_extract_present(struct xa_state *xas, void **dst,
2271 unsigned long max, unsigned int n)
2272{
2273 void *entry;
2274 unsigned int i = 0;
2275
2276 rcu_read_lock();
2277 xas_for_each(xas, entry, max) {
2278 if (xas_retry(xas, entry))
2279 continue;
2280 dst[i++] = entry;
2281 if (i == n)
2282 break;
2283 }
2284 rcu_read_unlock();
2285
2286 return i;
2287}
2288
2289static unsigned int xas_extract_marked(struct xa_state *xas, void **dst,
2290 unsigned long max, unsigned int n, xa_mark_t mark)
2291{
2292 void *entry;
2293 unsigned int i = 0;
2294
2295 rcu_read_lock();
2296 xas_for_each_marked(xas, entry, max, mark) {
2297 if (xas_retry(xas, entry))
2298 continue;
2299 dst[i++] = entry;
2300 if (i == n)
2301 break;
2302 }
2303 rcu_read_unlock();
2304
2305 return i;
2306}
2307
2308/**
2309 * xa_extract() - Copy selected entries from the XArray into a normal array.
2310 * @xa: The source XArray to copy from.
2311 * @dst: The buffer to copy entries into.
2312 * @start: The first index in the XArray eligible to be selected.
2313 * @max: The last index in the XArray eligible to be selected.
2314 * @n: The maximum number of entries to copy.
2315 * @filter: Selection criterion.
2316 *
2317 * Copies up to @n entries that match @filter from the XArray. The
2318 * copied entries will have indices between @start and @max, inclusive.
2319 *
2320 * The @filter may be an XArray mark value, in which case entries which are
2321 * marked with that mark will be copied. It may also be %XA_PRESENT, in
2322 * which case all entries which are not %NULL will be copied.
2323 *
2324 * The entries returned may not represent a snapshot of the XArray at a
2325 * moment in time. For example, if another thread stores to index 5, then
2326 * index 10, calling xa_extract() may return the old contents of index 5
2327 * and the new contents of index 10. Indices not modified while this
2328 * function is running will not be skipped.
2329 *
2330 * If you need stronger guarantees, holding the xa_lock across calls to this
2331 * function will prevent concurrent modification.
2332 *
2333 * Context: Any context. Takes and releases the RCU lock.
2334 * Return: The number of entries copied.
2335 */
2336unsigned int xa_extract(struct xarray *xa, void **dst, unsigned long start,
2337 unsigned long max, unsigned int n, xa_mark_t filter)
2338{
2339 XA_STATE(xas, xa, start);
2340
2341 if (!n)
2342 return 0;
2343
2344 if ((__force unsigned int)filter < XA_MAX_MARKS)
2345 return xas_extract_marked(xas: &xas, dst, max, n, mark: filter);
2346 return xas_extract_present(xas: &xas, dst, max, n);
2347}
2348EXPORT_SYMBOL(xa_extract);
2349
2350/**
2351 * xa_delete_node() - Private interface for workingset code.
2352 * @node: Node to be removed from the tree.
2353 * @update: Function to call to update ancestor nodes.
2354 *
2355 * Context: xa_lock must be held on entry and will not be released.
2356 */
2357void xa_delete_node(struct xa_node *node, xa_update_node_t update)
2358{
2359 struct xa_state xas = {
2360 .xa = node->array,
2361 .xa_index = (unsigned long)node->offset <<
2362 (node->shift + XA_CHUNK_SHIFT),
2363 .xa_shift = node->shift + XA_CHUNK_SHIFT,
2364 .xa_offset = node->offset,
2365 .xa_node = xa_parent_locked(xa: node->array, node),
2366 .xa_update = update,
2367 };
2368
2369 xas_store(&xas, NULL);
2370}
2371EXPORT_SYMBOL_GPL(xa_delete_node); /* For the benefit of the test suite */
2372
2373/**
2374 * xa_destroy() - Free all internal data structures.
2375 * @xa: XArray.
2376 *
2377 * After calling this function, the XArray is empty and has freed all memory
2378 * allocated for its internal data structures. You are responsible for
2379 * freeing the objects referenced by the XArray.
2380 *
2381 * Context: Any context. Takes and releases the xa_lock, interrupt-safe.
2382 */
2383void xa_destroy(struct xarray *xa)
2384{
2385 XA_STATE(xas, xa, 0);
2386 unsigned long flags;
2387 void *entry;
2388
2389 xas.xa_node = NULL;
2390 xas_lock_irqsave(&xas, flags);
2391 entry = xa_head_locked(xa);
2392 RCU_INIT_POINTER(xa->xa_head, NULL);
2393 xas_init_marks(&xas);
2394 if (xa_zero_busy(xa))
2395 xa_mark_clear(xa, XA_FREE_MARK);
2396 /* lockdep checks we're still holding the lock in xas_free_nodes() */
2397 if (xa_is_node(entry))
2398 xas_free_nodes(xas: &xas, top: xa_to_node(entry));
2399 xas_unlock_irqrestore(&xas, flags);
2400}
2401EXPORT_SYMBOL(xa_destroy);
2402
2403#ifdef XA_DEBUG
2404void xa_dump_node(const struct xa_node *node)
2405{
2406 unsigned i, j;
2407
2408 if (!node)
2409 return;
2410 if ((unsigned long)node & 3) {
2411 pr_cont("node %px\n", node);
2412 return;
2413 }
2414
2415 pr_cont("node %px %s %d parent %px shift %d count %d values %d "
2416 "array %px list %px %px marks",
2417 node, node->parent ? "offset" : "max", node->offset,
2418 node->parent, node->shift, node->count, node->nr_values,
2419 node->array, node->private_list.prev, node->private_list.next);
2420 for (i = 0; i < XA_MAX_MARKS; i++)
2421 for (j = 0; j < XA_MARK_LONGS; j++)
2422 pr_cont(" %lx", node->marks[i][j]);
2423 pr_cont("\n");
2424}
2425
2426void xa_dump_index(unsigned long index, unsigned int shift)
2427{
2428 if (!shift)
2429 pr_info("%lu: ", index);
2430 else if (shift >= BITS_PER_LONG)
2431 pr_info("0-%lu: ", ~0UL);
2432 else
2433 pr_info("%lu-%lu: ", index, index | ((1UL << shift) - 1));
2434}
2435
2436void xa_dump_entry(const void *entry, unsigned long index, unsigned long shift)
2437{
2438 if (!entry)
2439 return;
2440
2441 xa_dump_index(index, shift);
2442
2443 if (xa_is_node(entry)) {
2444 if (shift == 0) {
2445 pr_cont("%px\n", entry);
2446 } else {
2447 unsigned long i;
2448 struct xa_node *node = xa_to_node(entry);
2449 xa_dump_node(node);
2450 for (i = 0; i < XA_CHUNK_SIZE; i++)
2451 xa_dump_entry(node->slots[i],
2452 index + (i << node->shift), node->shift);
2453 }
2454 } else if (xa_is_value(entry))
2455 pr_cont("value %ld (0x%lx) [%px]\n", xa_to_value(entry),
2456 xa_to_value(entry), entry);
2457 else if (!xa_is_internal(entry))
2458 pr_cont("%px\n", entry);
2459 else if (xa_is_retry(entry))
2460 pr_cont("retry (%ld)\n", xa_to_internal(entry));
2461 else if (xa_is_sibling(entry))
2462 pr_cont("sibling (slot %ld)\n", xa_to_sibling(entry));
2463 else if (xa_is_zero(entry))
2464 pr_cont("zero (%ld)\n", xa_to_internal(entry));
2465 else
2466 pr_cont("UNKNOWN ENTRY (%px)\n", entry);
2467}
2468
2469void xa_dump(const struct xarray *xa)
2470{
2471 void *entry = xa->xa_head;
2472 unsigned int shift = 0;
2473
2474 pr_info("xarray: %px head %px flags %x marks %d %d %d\n", xa, entry,
2475 xa->xa_flags, xa_marked(xa, XA_MARK_0),
2476 xa_marked(xa, XA_MARK_1), xa_marked(xa, XA_MARK_2));
2477 if (xa_is_node(entry))
2478 shift = xa_to_node(entry)->shift + XA_CHUNK_SHIFT;
2479 xa_dump_entry(entry, 0, shift);
2480}
2481#endif
2482