projects/linux·blob v5.0-rc7 · refs

2031 lines · 51.9 KiB

1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * XArray implementation
4 * Copyright (c) 2017 Microsoft Corporation
5 * Author: Matthew Wilcox <[email protected]>
6 */
7
8#include <linux/bitmap.h>
9#include <linux/export.h>
10#include <linux/list.h>
11#include <linux/slab.h>
12#include <linux/xarray.h>
13
14/*
15 * Coding conventions in this file:
16 *
17 * @xa is used to refer to the entire xarray.
18 * @xas is the 'xarray operation state'. It may be either a pointer to
19 * an xa_state, or an xa_state stored on the stack. This is an unfortunate
20 * ambiguity.
21 * @index is the index of the entry being operated on
22 * @mark is an xa_mark_t; a small number indicating one of the mark bits.
23 * @node refers to an xa_node; usually the primary one being operated on by
24 * this function.
25 * @offset is the index into the slots array inside an xa_node.
26 * @parent refers to the @xa_node closer to the head than @node.
27 * @entry refers to something stored in a slot in the xarray
28 */
29
30static inline unsigned int xa_lock_type(const struct xarray *xa)
31{
32 return (__force unsigned int)xa->xa_flags & 3;
33}
34
35static inline void xas_lock_type(struct xa_state *xas, unsigned int lock_type)
36{
37 if (lock_type == XA_LOCK_IRQ)
38 xas_lock_irq(xas);
39 else if (lock_type == XA_LOCK_BH)
40 xas_lock_bh(xas);
41 else
42 xas_lock(xas);
43}
44
45static inline void xas_unlock_type(struct xa_state *xas, unsigned int lock_type)
46{
47 if (lock_type == XA_LOCK_IRQ)
48 xas_unlock_irq(xas);
49 else if (lock_type == XA_LOCK_BH)
50 xas_unlock_bh(xas);
51 else
52 xas_unlock(xas);
53}
54
55static inline bool xa_track_free(const struct xarray *xa)
56{
57 return xa->xa_flags & XA_FLAGS_TRACK_FREE;
58}
59
60static inline void xa_mark_set(struct xarray *xa, xa_mark_t mark)
61{
62 if (!(xa->xa_flags & XA_FLAGS_MARK(mark)))
63 xa->xa_flags |= XA_FLAGS_MARK(mark);
64}
65
66static inline void xa_mark_clear(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 unsigned long *node_marks(struct xa_node *node, xa_mark_t mark)
73{
74 return node->marks[(__force unsigned)mark];
75}
76
77static inline bool node_get_mark(struct xa_node *node,
78 unsigned int offset, xa_mark_t mark)
79{
80 return test_bit(offset, node_marks(node, mark));
81}
82
83/* returns true if the bit was set */
84static inline bool node_set_mark(struct xa_node *node, unsigned int offset,
85 xa_mark_t mark)
86{
87 return __test_and_set_bit(offset, node_marks(node, mark));
88}
89
90/* returns true if the bit was set */
91static inline bool node_clear_mark(struct xa_node *node, unsigned int offset,
92 xa_mark_t mark)
93{
94 return __test_and_clear_bit(offset, node_marks(node, mark));
95}
96
97static inline bool node_any_mark(struct xa_node *node, xa_mark_t mark)
98{
99 return !bitmap_empty(node_marks(node, mark), XA_CHUNK_SIZE);
100}
101
102static inline void node_mark_all(struct xa_node *node, xa_mark_t mark)
103{
104 bitmap_fill(node_marks(node, mark), XA_CHUNK_SIZE);
105}
106
107#define mark_inc(mark) do { \
108 mark = (__force xa_mark_t)((__force unsigned)(mark) + 1); \
109} while (0)
110
111/*
112 * xas_squash_marks() - Merge all marks to the first entry
113 * @xas: Array operation state.
114 *
115 * Set a mark on the first entry if any entry has it set. Clear marks on
116 * all sibling entries.
117 */
118static void xas_squash_marks(const struct xa_state *xas)
119{
120 unsigned int mark = 0;
121 unsigned int limit = xas->xa_offset + xas->xa_sibs + 1;
122
123 if (!xas->xa_sibs)
124 return;
125
126 do {
127 unsigned long *marks = xas->xa_node->marks[mark];
128 if (find_next_bit(marks, limit, xas->xa_offset + 1) == limit)
129 continue;
130 __set_bit(xas->xa_offset, marks);
131 bitmap_clear(marks, xas->xa_offset + 1, xas->xa_sibs);
132 } while (mark++ != (__force unsigned)XA_MARK_MAX);
133}
134
135/* extracts the offset within this node from the index */
136static unsigned int get_offset(unsigned long index, struct xa_node *node)
137{
138 return (index >> node->shift) & XA_CHUNK_MASK;
139}
140
141static void xas_set_offset(struct xa_state *xas)
142{
143 xas->xa_offset = get_offset(xas->xa_index, xas->xa_node);
144}
145
146/* move the index either forwards (find) or backwards (sibling slot) */
147static void xas_move_index(struct xa_state *xas, unsigned long offset)
148{
149 unsigned int shift = xas->xa_node->shift;
150 xas->xa_index &= ~XA_CHUNK_MASK << shift;
151 xas->xa_index += offset << shift;
152}
153
154static void xas_advance(struct xa_state *xas)
155{
156 xas->xa_offset++;
157 xas_move_index(xas, xas->xa_offset);
158}
159
160static void *set_bounds(struct xa_state *xas)
161{
162 xas->xa_node = XAS_BOUNDS;
163 return NULL;
164}
165
166/*
167 * Starts a walk. If the @xas is already valid, we assume that it's on
168 * the right path and just return where we've got to. If we're in an
169 * error state, return NULL. If the index is outside the current scope
170 * of the xarray, return NULL without changing @xas->xa_node. Otherwise
171 * set @xas->xa_node to NULL and return the current head of the array.
172 */
173static void *xas_start(struct xa_state *xas)
174{
175 void *entry;
176
177 if (xas_valid(xas))
178 return xas_reload(xas);
179 if (xas_error(xas))
180 return NULL;
181
182 entry = xa_head(xas->xa);
183 if (!xa_is_node(entry)) {
184 if (xas->xa_index)
185 return set_bounds(xas);
186 } else {
187 if ((xas->xa_index >> xa_to_node(entry)->shift) > XA_CHUNK_MASK)
188 return set_bounds(xas);
189 }
190
191 xas->xa_node = NULL;
192 return entry;
193}
194
195static void *xas_descend(struct xa_state *xas, struct xa_node *node)
196{
197 unsigned int offset = get_offset(xas->xa_index, node);
198 void *entry = xa_entry(xas->xa, node, offset);
199
200 xas->xa_node = node;
201 if (xa_is_sibling(entry)) {
202 offset = xa_to_sibling(entry);
203 entry = xa_entry(xas->xa, node, offset);
204 }
205
206 xas->xa_offset = offset;
207 return entry;
208}
209
210/**
211 * xas_load() - Load an entry from the XArray (advanced).
212 * @xas: XArray operation state.
213 *
214 * Usually walks the @xas to the appropriate state to load the entry
215 * stored at xa_index. However, it will do nothing and return %NULL if
216 * @xas is in an error state. xas_load() will never expand the tree.
217 *
218 * If the xa_state is set up to operate on a multi-index entry, xas_load()
219 * may return %NULL or an internal entry, even if there are entries
220 * present within the range specified by @xas.
221 *
222 * Context: Any context. The caller should hold the xa_lock or the RCU lock.
223 * Return: Usually an entry in the XArray, but see description for exceptions.
224 */
225void *xas_load(struct xa_state *xas)
226{
227 void *entry = xas_start(xas);
228
229 while (xa_is_node(entry)) {
230 struct xa_node *node = xa_to_node(entry);
231
232 if (xas->xa_shift > node->shift)
233 break;
234 entry = xas_descend(xas, node);
235 if (node->shift == 0)
236 break;
237 }
238 return entry;
239}
240EXPORT_SYMBOL_GPL(xas_load);
241
242/* Move the radix tree node cache here */
243extern struct kmem_cache *radix_tree_node_cachep;
244extern void radix_tree_node_rcu_free(struct rcu_head *head);
245
246#define XA_RCU_FREE ((struct xarray *)1)
247
248static void xa_node_free(struct xa_node *node)
249{
250 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
251 node->array = XA_RCU_FREE;
252 call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
253}
254
255/*
256 * xas_destroy() - Free any resources allocated during the XArray operation.
257 * @xas: XArray operation state.
258 *
259 * This function is now internal-only.
260 */
261static void xas_destroy(struct xa_state *xas)
262{
263 struct xa_node *node = xas->xa_alloc;
264
265 if (!node)
266 return;
267 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
268 kmem_cache_free(radix_tree_node_cachep, node);
269 xas->xa_alloc = NULL;
270}
271
272/**
273 * xas_nomem() - Allocate memory if needed.
274 * @xas: XArray operation state.
275 * @gfp: Memory allocation flags.
276 *
277 * If we need to add new nodes to the XArray, we try to allocate memory
278 * with GFP_NOWAIT while holding the lock, which will usually succeed.
279 * If it fails, @xas is flagged as needing memory to continue. The caller
280 * should drop the lock and call xas_nomem(). If xas_nomem() succeeds,
281 * the caller should retry the operation.
282 *
283 * Forward progress is guaranteed as one node is allocated here and
284 * stored in the xa_state where it will be found by xas_alloc(). More
285 * nodes will likely be found in the slab allocator, but we do not tie
286 * them up here.
287 *
288 * Return: true if memory was needed, and was successfully allocated.
289 */
290bool xas_nomem(struct xa_state *xas, gfp_t gfp)
291{
292 if (xas->xa_node != XA_ERROR(-ENOMEM)) {
293 xas_destroy(xas);
294 return false;
295 }
296 xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
297 if (!xas->xa_alloc)
298 return false;
299 XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list));
300 xas->xa_node = XAS_RESTART;
301 return true;
302}
303EXPORT_SYMBOL_GPL(xas_nomem);
304
305/*
306 * __xas_nomem() - Drop locks and allocate memory if needed.
307 * @xas: XArray operation state.
308 * @gfp: Memory allocation flags.
309 *
310 * Internal variant of xas_nomem().
311 *
312 * Return: true if memory was needed, and was successfully allocated.
313 */
314static bool __xas_nomem(struct xa_state *xas, gfp_t gfp)
315 __must_hold(xas->xa->xa_lock)
316{
317 unsigned int lock_type = xa_lock_type(xas->xa);
318
319 if (xas->xa_node != XA_ERROR(-ENOMEM)) {
320 xas_destroy(xas);
321 return false;
322 }
323 if (gfpflags_allow_blocking(gfp)) {
324 xas_unlock_type(xas, lock_type);
325 xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
326 xas_lock_type(xas, lock_type);
327 } else {
328 xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
329 }
330 if (!xas->xa_alloc)
331 return false;
332 XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list));
333 xas->xa_node = XAS_RESTART;
334 return true;
335}
336
337static void xas_update(struct xa_state *xas, struct xa_node *node)
338{
339 if (xas->xa_update)
340 xas->xa_update(node);
341 else
342 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
343}
344
345static void *xas_alloc(struct xa_state *xas, unsigned int shift)
346{
347 struct xa_node *parent = xas->xa_node;
348 struct xa_node *node = xas->xa_alloc;
349
350 if (xas_invalid(xas))
351 return NULL;
352
353 if (node) {
354 xas->xa_alloc = NULL;
355 } else {
356 node = kmem_cache_alloc(radix_tree_node_cachep,
357 GFP_NOWAIT | __GFP_NOWARN);
358 if (!node) {
359 xas_set_err(xas, -ENOMEM);
360 return NULL;
361 }
362 }
363
364 if (parent) {
365 node->offset = xas->xa_offset;
366 parent->count++;
367 XA_NODE_BUG_ON(node, parent->count > XA_CHUNK_SIZE);
368 xas_update(xas, parent);
369 }
370 XA_NODE_BUG_ON(node, shift > BITS_PER_LONG);
371 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
372 node->shift = shift;
373 node->count = 0;
374 node->nr_values = 0;
375 RCU_INIT_POINTER(node->parent, xas->xa_node);
376 node->array = xas->xa;
377
378 return node;
379}
380
381#ifdef CONFIG_XARRAY_MULTI
382/* Returns the number of indices covered by a given xa_state */
383static unsigned long xas_size(const struct xa_state *xas)
384{
385 return (xas->xa_sibs + 1UL) << xas->xa_shift;
386}
387#endif
388
389/*
390 * Use this to calculate the maximum index that will need to be created
391 * in order to add the entry described by @xas. Because we cannot store a
392 * multiple-index entry at index 0, the calculation is a little more complex
393 * than you might expect.
394 */
395static unsigned long xas_max(struct xa_state *xas)
396{
397 unsigned long max = xas->xa_index;
398
399#ifdef CONFIG_XARRAY_MULTI
400 if (xas->xa_shift || xas->xa_sibs) {
401 unsigned long mask = xas_size(xas) - 1;
402 max |= mask;
403 if (mask == max)
404 max++;
405 }
406#endif
407
408 return max;
409}
410
411/* The maximum index that can be contained in the array without expanding it */
412static unsigned long max_index(void *entry)
413{
414 if (!xa_is_node(entry))
415 return 0;
416 return (XA_CHUNK_SIZE << xa_to_node(entry)->shift) - 1;
417}
418
419static void xas_shrink(struct xa_state *xas)
420{
421 struct xarray *xa = xas->xa;
422 struct xa_node *node = xas->xa_node;
423
424 for (;;) {
425 void *entry;
426
427 XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
428 if (node->count != 1)
429 break;
430 entry = xa_entry_locked(xa, node, 0);
431 if (!entry)
432 break;
433 if (!xa_is_node(entry) && node->shift)
434 break;
435 xas->xa_node = XAS_BOUNDS;
436
437 RCU_INIT_POINTER(xa->xa_head, entry);
438 if (xa_track_free(xa) && !node_get_mark(node, 0, XA_FREE_MARK))
439 xa_mark_clear(xa, XA_FREE_MARK);
440
441 node->count = 0;
442 node->nr_values = 0;
443 if (!xa_is_node(entry))
444 RCU_INIT_POINTER(node->slots[0], XA_RETRY_ENTRY);
445 xas_update(xas, node);
446 xa_node_free(node);
447 if (!xa_is_node(entry))
448 break;
449 node = xa_to_node(entry);
450 node->parent = NULL;
451 }
452}
453
454/*
455 * xas_delete_node() - Attempt to delete an xa_node
456 * @xas: Array operation state.
457 *
458 * Attempts to delete the @xas->xa_node. This will fail if xa->node has
459 * a non-zero reference count.
460 */
461static void xas_delete_node(struct xa_state *xas)
462{
463 struct xa_node *node = xas->xa_node;
464
465 for (;;) {
466 struct xa_node *parent;
467
468 XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
469 if (node->count)
470 break;
471
472 parent = xa_parent_locked(xas->xa, node);
473 xas->xa_node = parent;
474 xas->xa_offset = node->offset;
475 xa_node_free(node);
476
477 if (!parent) {
478 xas->xa->xa_head = NULL;
479 xas->xa_node = XAS_BOUNDS;
480 return;
481 }
482
483 parent->slots[xas->xa_offset] = NULL;
484 parent->count--;
485 XA_NODE_BUG_ON(parent, parent->count > XA_CHUNK_SIZE);
486 node = parent;
487 xas_update(xas, node);
488 }
489
490 if (!node->parent)
491 xas_shrink(xas);
492}
493
494/**
495 * xas_free_nodes() - Free this node and all nodes that it references
496 * @xas: Array operation state.
497 * @top: Node to free
498 *
499 * This node has been removed from the tree. We must now free it and all
500 * of its subnodes. There may be RCU walkers with references into the tree,
501 * so we must replace all entries with retry markers.
502 */
503static void xas_free_nodes(struct xa_state *xas, struct xa_node *top)
504{
505 unsigned int offset = 0;
506 struct xa_node *node = top;
507
508 for (;;) {
509 void *entry = xa_entry_locked(xas->xa, node, offset);
510
511 if (node->shift && xa_is_node(entry)) {
512 node = xa_to_node(entry);
513 offset = 0;
514 continue;
515 }
516 if (entry)
517 RCU_INIT_POINTER(node->slots[offset], XA_RETRY_ENTRY);
518 offset++;
519 while (offset == XA_CHUNK_SIZE) {
520 struct xa_node *parent;
521
522 parent = xa_parent_locked(xas->xa, node);
523 offset = node->offset + 1;
524 node->count = 0;
525 node->nr_values = 0;
526 xas_update(xas, node);
527 xa_node_free(node);
528 if (node == top)
529 return;
530 node = parent;
531 }
532 }
533}
534
535/*
536 * xas_expand adds nodes to the head of the tree until it has reached
537 * sufficient height to be able to contain @xas->xa_index
538 */
539static int xas_expand(struct xa_state *xas, void *head)
540{
541 struct xarray *xa = xas->xa;
542 struct xa_node *node = NULL;
543 unsigned int shift = 0;
544 unsigned long max = xas_max(xas);
545
546 if (!head) {
547 if (max == 0)
548 return 0;
549 while ((max >> shift) >= XA_CHUNK_SIZE)
550 shift += XA_CHUNK_SHIFT;
551 return shift + XA_CHUNK_SHIFT;
552 } else if (xa_is_node(head)) {
553 node = xa_to_node(head);
554 shift = node->shift + XA_CHUNK_SHIFT;
555 }
556 xas->xa_node = NULL;
557
558 while (max > max_index(head)) {
559 xa_mark_t mark = 0;
560
561 XA_NODE_BUG_ON(node, shift > BITS_PER_LONG);
562 node = xas_alloc(xas, shift);
563 if (!node)
564 return -ENOMEM;
565
566 node->count = 1;
567 if (xa_is_value(head))
568 node->nr_values = 1;
569 RCU_INIT_POINTER(node->slots[0], head);
570
571 /* Propagate the aggregated mark info to the new child */
572 for (;;) {
573 if (xa_track_free(xa) && mark == XA_FREE_MARK) {
574 node_mark_all(node, XA_FREE_MARK);
575 if (!xa_marked(xa, XA_FREE_MARK)) {
576 node_clear_mark(node, 0, XA_FREE_MARK);
577 xa_mark_set(xa, XA_FREE_MARK);
578 }
579 } else if (xa_marked(xa, mark)) {
580 node_set_mark(node, 0, mark);
581 }
582 if (mark == XA_MARK_MAX)
583 break;
584 mark_inc(mark);
585 }
586
587 /*
588 * Now that the new node is fully initialised, we can add
589 * it to the tree
590 */
591 if (xa_is_node(head)) {
592 xa_to_node(head)->offset = 0;
593 rcu_assign_pointer(xa_to_node(head)->parent, node);
594 }
595 head = xa_mk_node(node);
596 rcu_assign_pointer(xa->xa_head, head);
597 xas_update(xas, node);
598
599 shift += XA_CHUNK_SHIFT;
600 }
601
602 xas->xa_node = node;
603 return shift;
604}
605
606/*
607 * xas_create() - Create a slot to store an entry in.
608 * @xas: XArray operation state.
609 * @allow_root: %true if we can store the entry in the root directly
610 *
611 * Most users will not need to call this function directly, as it is called
612 * by xas_store(). It is useful for doing conditional store operations
613 * (see the xa_cmpxchg() implementation for an example).
614 *
615 * Return: If the slot already existed, returns the contents of this slot.
616 * If the slot was newly created, returns %NULL. If it failed to create the
617 * slot, returns %NULL and indicates the error in @xas.
618 */
619static void *xas_create(struct xa_state *xas, bool allow_root)
620{
621 struct xarray *xa = xas->xa;
622 void *entry;
623 void __rcu **slot;
624 struct xa_node *node = xas->xa_node;
625 int shift;
626 unsigned int order = xas->xa_shift;
627
628 if (xas_top(node)) {
629 entry = xa_head_locked(xa);
630 xas->xa_node = NULL;
631 shift = xas_expand(xas, entry);
632 if (shift < 0)
633 return NULL;
634 if (!shift && !allow_root)
635 shift = XA_CHUNK_SHIFT;
636 entry = xa_head_locked(xa);
637 slot = &xa->xa_head;
638 } else if (xas_error(xas)) {
639 return NULL;
640 } else if (node) {
641 unsigned int offset = xas->xa_offset;
642
643 shift = node->shift;
644 entry = xa_entry_locked(xa, node, offset);
645 slot = &node->slots[offset];
646 } else {
647 shift = 0;
648 entry = xa_head_locked(xa);
649 slot = &xa->xa_head;
650 }
651
652 while (shift > order) {
653 shift -= XA_CHUNK_SHIFT;
654 if (!entry) {
655 node = xas_alloc(xas, shift);
656 if (!node)
657 break;
658 if (xa_track_free(xa))
659 node_mark_all(node, XA_FREE_MARK);
660 rcu_assign_pointer(*slot, xa_mk_node(node));
661 } else if (xa_is_node(entry)) {
662 node = xa_to_node(entry);
663 } else {
664 break;
665 }
666 entry = xas_descend(xas, node);
667 slot = &node->slots[xas->xa_offset];
668 }
669
670 return entry;
671}
672
673/**
674 * xas_create_range() - Ensure that stores to this range will succeed
675 * @xas: XArray operation state.
676 *
677 * Creates all of the slots in the range covered by @xas. Sets @xas to
678 * create single-index entries and positions it at the beginning of the
679 * range. This is for the benefit of users which have not yet been
680 * converted to use multi-index entries.
681 */
682void xas_create_range(struct xa_state *xas)
683{
684 unsigned long index = xas->xa_index;
685 unsigned char shift = xas->xa_shift;
686 unsigned char sibs = xas->xa_sibs;
687
688 xas->xa_index |= ((sibs + 1) << shift) - 1;
689 if (xas_is_node(xas) && xas->xa_node->shift == xas->xa_shift)
690 xas->xa_offset |= sibs;
691 xas->xa_shift = 0;
692 xas->xa_sibs = 0;
693
694 for (;;) {
695 xas_create(xas, true);
696 if (xas_error(xas))
697 goto restore;
698 if (xas->xa_index <= (index | XA_CHUNK_MASK))
699 goto success;
700 xas->xa_index -= XA_CHUNK_SIZE;
701
702 for (;;) {
703 struct xa_node *node = xas->xa_node;
704 xas->xa_node = xa_parent_locked(xas->xa, node);
705 xas->xa_offset = node->offset - 1;
706 if (node->offset != 0)
707 break;
708 }
709 }
710
711restore:
712 xas->xa_shift = shift;
713 xas->xa_sibs = sibs;
714 xas->xa_index = index;
715 return;
716success:
717 xas->xa_index = index;
718 if (xas->xa_node)
719 xas_set_offset(xas);
720}
721EXPORT_SYMBOL_GPL(xas_create_range);
722
723static void update_node(struct xa_state *xas, struct xa_node *node,
724 int count, int values)
725{
726 if (!node || (!count && !values))
727 return;
728
729 node->count += count;
730 node->nr_values += values;
731 XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
732 XA_NODE_BUG_ON(node, node->nr_values > XA_CHUNK_SIZE);
733 xas_update(xas, node);
734 if (count < 0)
735 xas_delete_node(xas);
736}
737
738/**
739 * xas_store() - Store this entry in the XArray.
740 * @xas: XArray operation state.
741 * @entry: New entry.
742 *
743 * If @xas is operating on a multi-index entry, the entry returned by this
744 * function is essentially meaningless (it may be an internal entry or it
745 * may be %NULL, even if there are non-NULL entries at some of the indices
746 * covered by the range). This is not a problem for any current users,
747 * and can be changed if needed.
748 *
749 * Return: The old entry at this index.
750 */
751void *xas_store(struct xa_state *xas, void *entry)
752{
753 struct xa_node *node;
754 void __rcu **slot = &xas->xa->xa_head;
755 unsigned int offset, max;
756 int count = 0;
757 int values = 0;
758 void *first, *next;
759 bool value = xa_is_value(entry);
760
761 if (entry)
762 first = xas_create(xas, !xa_is_node(entry));
763 else
764 first = xas_load(xas);
765
766 if (xas_invalid(xas))
767 return first;
768 node = xas->xa_node;
769 if (node && (xas->xa_shift < node->shift))
770 xas->xa_sibs = 0;
771 if ((first == entry) && !xas->xa_sibs)
772 return first;
773
774 next = first;
775 offset = xas->xa_offset;
776 max = xas->xa_offset + xas->xa_sibs;
777 if (node) {
778 slot = &node->slots[offset];
779 if (xas->xa_sibs)
780 xas_squash_marks(xas);
781 }
782 if (!entry)
783 xas_init_marks(xas);
784
785 for (;;) {
786 /*
787 * Must clear the marks before setting the entry to NULL,
788 * otherwise xas_for_each_marked may find a NULL entry and
789 * stop early. rcu_assign_pointer contains a release barrier
790 * so the mark clearing will appear to happen before the
791 * entry is set to NULL.
792 */
793 rcu_assign_pointer(*slot, entry);
794 if (xa_is_node(next))
795 xas_free_nodes(xas, xa_to_node(next));
796 if (!node)
797 break;
798 count += !next - !entry;
799 values += !xa_is_value(first) - !value;
800 if (entry) {
801 if (offset == max)
802 break;
803 if (!xa_is_sibling(entry))
804 entry = xa_mk_sibling(xas->xa_offset);
805 } else {
806 if (offset == XA_CHUNK_MASK)
807 break;
808 }
809 next = xa_entry_locked(xas->xa, node, ++offset);
810 if (!xa_is_sibling(next)) {
811 if (!entry && (offset > max))
812 break;
813 first = next;
814 }
815 slot++;
816 }
817
818 update_node(xas, node, count, values);
819 return first;
820}
821EXPORT_SYMBOL_GPL(xas_store);
822
823/**
824 * xas_get_mark() - Returns the state of this mark.
825 * @xas: XArray operation state.
826 * @mark: Mark number.
827 *
828 * Return: true if the mark is set, false if the mark is clear or @xas
829 * is in an error state.
830 */
831bool xas_get_mark(const struct xa_state *xas, xa_mark_t mark)
832{
833 if (xas_invalid(xas))
834 return false;
835 if (!xas->xa_node)
836 return xa_marked(xas->xa, mark);
837 return node_get_mark(xas->xa_node, xas->xa_offset, mark);
838}
839EXPORT_SYMBOL_GPL(xas_get_mark);
840
841/**
842 * xas_set_mark() - Sets the mark on this entry and its parents.
843 * @xas: XArray operation state.
844 * @mark: Mark number.
845 *
846 * Sets the specified mark on this entry, and walks up the tree setting it
847 * on all the ancestor entries. Does nothing if @xas has not been walked to
848 * an entry, or is in an error state.
849 */
850void xas_set_mark(const struct xa_state *xas, xa_mark_t mark)
851{
852 struct xa_node *node = xas->xa_node;
853 unsigned int offset = xas->xa_offset;
854
855 if (xas_invalid(xas))
856 return;
857
858 while (node) {
859 if (node_set_mark(node, offset, mark))
860 return;
861 offset = node->offset;
862 node = xa_parent_locked(xas->xa, node);
863 }
864
865 if (!xa_marked(xas->xa, mark))
866 xa_mark_set(xas->xa, mark);
867}
868EXPORT_SYMBOL_GPL(xas_set_mark);
869
870/**
871 * xas_clear_mark() - Clears the mark on this entry and its parents.
872 * @xas: XArray operation state.
873 * @mark: Mark number.
874 *
875 * Clears the specified mark on this entry, and walks back to the head
876 * attempting to clear it on all the ancestor entries. Does nothing if
877 * @xas has not been walked to an entry, or is in an error state.
878 */
879void xas_clear_mark(const struct xa_state *xas, xa_mark_t mark)
880{
881 struct xa_node *node = xas->xa_node;
882 unsigned int offset = xas->xa_offset;
883
884 if (xas_invalid(xas))
885 return;
886
887 while (node) {
888 if (!node_clear_mark(node, offset, mark))
889 return;
890 if (node_any_mark(node, mark))
891 return;
892
893 offset = node->offset;
894 node = xa_parent_locked(xas->xa, node);
895 }
896
897 if (xa_marked(xas->xa, mark))
898 xa_mark_clear(xas->xa, mark);
899}
900EXPORT_SYMBOL_GPL(xas_clear_mark);
901
902/**
903 * xas_init_marks() - Initialise all marks for the entry
904 * @xas: Array operations state.
905 *
906 * Initialise all marks for the entry specified by @xas. If we're tracking
907 * free entries with a mark, we need to set it on all entries. All other
908 * marks are cleared.
909 *
910 * This implementation is not as efficient as it could be; we may walk
911 * up the tree multiple times.
912 */
913void xas_init_marks(const struct xa_state *xas)
914{
915 xa_mark_t mark = 0;
916
917 for (;;) {
918 if (xa_track_free(xas->xa) && mark == XA_FREE_MARK)
919 xas_set_mark(xas, mark);
920 else
921 xas_clear_mark(xas, mark);
922 if (mark == XA_MARK_MAX)
923 break;
924 mark_inc(mark);
925 }
926}
927EXPORT_SYMBOL_GPL(xas_init_marks);
928
929/**
930 * xas_pause() - Pause a walk to drop a lock.
931 * @xas: XArray operation state.
932 *
933 * Some users need to pause a walk and drop the lock they're holding in
934 * order to yield to a higher priority thread or carry out an operation
935 * on an entry. Those users should call this function before they drop
936 * the lock. It resets the @xas to be suitable for the next iteration
937 * of the loop after the user has reacquired the lock. If most entries
938 * found during a walk require you to call xas_pause(), the xa_for_each()
939 * iterator may be more appropriate.
940 *
941 * Note that xas_pause() only works for forward iteration. If a user needs
942 * to pause a reverse iteration, we will need a xas_pause_rev().
943 */
944void xas_pause(struct xa_state *xas)
945{
946 struct xa_node *node = xas->xa_node;
947
948 if (xas_invalid(xas))
949 return;
950
951 if (node) {
952 unsigned int offset = xas->xa_offset;
953 while (++offset < XA_CHUNK_SIZE) {
954 if (!xa_is_sibling(xa_entry(xas->xa, node, offset)))
955 break;
956 }
957 xas->xa_index += (offset - xas->xa_offset) << node->shift;
958 } else {
959 xas->xa_index++;
960 }
961 xas->xa_node = XAS_RESTART;
962}
963EXPORT_SYMBOL_GPL(xas_pause);
964
965/*
966 * __xas_prev() - Find the previous entry in the XArray.
967 * @xas: XArray operation state.
968 *
969 * Helper function for xas_prev() which handles all the complex cases
970 * out of line.
971 */
972void *__xas_prev(struct xa_state *xas)
973{
974 void *entry;
975
976 if (!xas_frozen(xas->xa_node))
977 xas->xa_index--;
978 if (xas_not_node(xas->xa_node))
979 return xas_load(xas);
980
981 if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node))
982 xas->xa_offset--;
983
984 while (xas->xa_offset == 255) {
985 xas->xa_offset = xas->xa_node->offset - 1;
986 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
987 if (!xas->xa_node)
988 return set_bounds(xas);
989 }
990
991 for (;;) {
992 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
993 if (!xa_is_node(entry))
994 return entry;
995
996 xas->xa_node = xa_to_node(entry);
997 xas_set_offset(xas);
998 }
999}
1000EXPORT_SYMBOL_GPL(__xas_prev);
1001
1002/*
1003 * __xas_next() - Find the next entry in the XArray.
1004 * @xas: XArray operation state.
1005 *
1006 * Helper function for xas_next() which handles all the complex cases
1007 * out of line.
1008 */
1009void *__xas_next(struct xa_state *xas)
1010{
1011 void *entry;
1012
1013 if (!xas_frozen(xas->xa_node))
1014 xas->xa_index++;
1015 if (xas_not_node(xas->xa_node))
1016 return xas_load(xas);
1017
1018 if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node))
1019 xas->xa_offset++;
1020
1021 while (xas->xa_offset == XA_CHUNK_SIZE) {
1022 xas->xa_offset = xas->xa_node->offset + 1;
1023 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1024 if (!xas->xa_node)
1025 return set_bounds(xas);
1026 }
1027
1028 for (;;) {
1029 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1030 if (!xa_is_node(entry))
1031 return entry;
1032
1033 xas->xa_node = xa_to_node(entry);
1034 xas_set_offset(xas);
1035 }
1036}
1037EXPORT_SYMBOL_GPL(__xas_next);
1038
1039/**
1040 * xas_find() - Find the next present entry in the XArray.
1041 * @xas: XArray operation state.
1042 * @max: Highest index to return.
1043 *
1044 * If the @xas has not yet been walked to an entry, return the entry
1045 * which has an index >= xas.xa_index. If it has been walked, the entry
1046 * currently being pointed at has been processed, and so we move to the
1047 * next entry.
1048 *
1049 * If no entry is found and the array is smaller than @max, the iterator
1050 * is set to the smallest index not yet in the array. This allows @xas
1051 * to be immediately passed to xas_store().
1052 *
1053 * Return: The entry, if found, otherwise %NULL.
1054 */
1055void *xas_find(struct xa_state *xas, unsigned long max)
1056{
1057 void *entry;
1058
1059 if (xas_error(xas))
1060 return NULL;
1061
1062 if (!xas->xa_node) {
1063 xas->xa_index = 1;
1064 return set_bounds(xas);
1065 } else if (xas_top(xas->xa_node)) {
1066 entry = xas_load(xas);
1067 if (entry || xas_not_node(xas->xa_node))
1068 return entry;
1069 } else if (!xas->xa_node->shift &&
1070 xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)) {
1071 xas->xa_offset = ((xas->xa_index - 1) & XA_CHUNK_MASK) + 1;
1072 }
1073
1074 xas_advance(xas);
1075
1076 while (xas->xa_node && (xas->xa_index <= max)) {
1077 if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
1078 xas->xa_offset = xas->xa_node->offset + 1;
1079 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1080 continue;
1081 }
1082
1083 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1084 if (xa_is_node(entry)) {
1085 xas->xa_node = xa_to_node(entry);
1086 xas->xa_offset = 0;
1087 continue;
1088 }
1089 if (entry && !xa_is_sibling(entry))
1090 return entry;
1091
1092 xas_advance(xas);
1093 }
1094
1095 if (!xas->xa_node)
1096 xas->xa_node = XAS_BOUNDS;
1097 return NULL;
1098}
1099EXPORT_SYMBOL_GPL(xas_find);
1100
1101/**
1102 * xas_find_marked() - Find the next marked entry in the XArray.
1103 * @xas: XArray operation state.
1104 * @max: Highest index to return.
1105 * @mark: Mark number to search for.
1106 *
1107 * If the @xas has not yet been walked to an entry, return the marked entry
1108 * which has an index >= xas.xa_index. If it has been walked, the entry
1109 * currently being pointed at has been processed, and so we return the
1110 * first marked entry with an index > xas.xa_index.
1111 *
1112 * If no marked entry is found and the array is smaller than @max, @xas is
1113 * set to the bounds state and xas->xa_index is set to the smallest index
1114 * not yet in the array. This allows @xas to be immediately passed to
1115 * xas_store().
1116 *
1117 * If no entry is found before @max is reached, @xas is set to the restart
1118 * state.
1119 *
1120 * Return: The entry, if found, otherwise %NULL.
1121 */
1122void *xas_find_marked(struct xa_state *xas, unsigned long max, xa_mark_t mark)
1123{
1124 bool advance = true;
1125 unsigned int offset;
1126 void *entry;
1127
1128 if (xas_error(xas))
1129 return NULL;
1130
1131 if (!xas->xa_node) {
1132 xas->xa_index = 1;
1133 goto out;
1134 } else if (xas_top(xas->xa_node)) {
1135 advance = false;
1136 entry = xa_head(xas->xa);
1137 xas->xa_node = NULL;
1138 if (xas->xa_index > max_index(entry))
1139 goto out;
1140 if (!xa_is_node(entry)) {
1141 if (xa_marked(xas->xa, mark))
1142 return entry;
1143 xas->xa_index = 1;
1144 goto out;
1145 }
1146 xas->xa_node = xa_to_node(entry);
1147 xas->xa_offset = xas->xa_index >> xas->xa_node->shift;
1148 }
1149
1150 while (xas->xa_index <= max) {
1151 if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
1152 xas->xa_offset = xas->xa_node->offset + 1;
1153 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1154 if (!xas->xa_node)
1155 break;
1156 advance = false;
1157 continue;
1158 }
1159
1160 if (!advance) {
1161 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1162 if (xa_is_sibling(entry)) {
1163 xas->xa_offset = xa_to_sibling(entry);
1164 xas_move_index(xas, xas->xa_offset);
1165 }
1166 }
1167
1168 offset = xas_find_chunk(xas, advance, mark);
1169 if (offset > xas->xa_offset) {
1170 advance = false;
1171 xas_move_index(xas, offset);
1172 /* Mind the wrap */
1173 if ((xas->xa_index - 1) >= max)
1174 goto max;
1175 xas->xa_offset = offset;
1176 if (offset == XA_CHUNK_SIZE)
1177 continue;
1178 }
1179
1180 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1181 if (!xa_is_node(entry))
1182 return entry;
1183 xas->xa_node = xa_to_node(entry);
1184 xas_set_offset(xas);
1185 }
1186
1187out:
1188 if (xas->xa_index > max)
1189 goto max;
1190 return set_bounds(xas);
1191max:
1192 xas->xa_node = XAS_RESTART;
1193 return NULL;
1194}
1195EXPORT_SYMBOL_GPL(xas_find_marked);
1196
1197/**
1198 * xas_find_conflict() - Find the next present entry in a range.
1199 * @xas: XArray operation state.
1200 *
1201 * The @xas describes both a range and a position within that range.
1202 *
1203 * Context: Any context. Expects xa_lock to be held.
1204 * Return: The next entry in the range covered by @xas or %NULL.
1205 */
1206void *xas_find_conflict(struct xa_state *xas)
1207{
1208 void *curr;
1209
1210 if (xas_error(xas))
1211 return NULL;
1212
1213 if (!xas->xa_node)
1214 return NULL;
1215
1216 if (xas_top(xas->xa_node)) {
1217 curr = xas_start(xas);
1218 if (!curr)
1219 return NULL;
1220 while (xa_is_node(curr)) {
1221 struct xa_node *node = xa_to_node(curr);
1222 curr = xas_descend(xas, node);
1223 }
1224 if (curr)
1225 return curr;
1226 }
1227
1228 if (xas->xa_node->shift > xas->xa_shift)
1229 return NULL;
1230
1231 for (;;) {
1232 if (xas->xa_node->shift == xas->xa_shift) {
1233 if ((xas->xa_offset & xas->xa_sibs) == xas->xa_sibs)
1234 break;
1235 } else if (xas->xa_offset == XA_CHUNK_MASK) {
1236 xas->xa_offset = xas->xa_node->offset;
1237 xas->xa_node = xa_parent_locked(xas->xa, xas->xa_node);
1238 if (!xas->xa_node)
1239 break;
1240 continue;
1241 }
1242 curr = xa_entry_locked(xas->xa, xas->xa_node, ++xas->xa_offset);
1243 if (xa_is_sibling(curr))
1244 continue;
1245 while (xa_is_node(curr)) {
1246 xas->xa_node = xa_to_node(curr);
1247 xas->xa_offset = 0;
1248 curr = xa_entry_locked(xas->xa, xas->xa_node, 0);
1249 }
1250 if (curr)
1251 return curr;
1252 }
1253 xas->xa_offset -= xas->xa_sibs;
1254 return NULL;
1255}
1256EXPORT_SYMBOL_GPL(xas_find_conflict);
1257
1258/**
1259 * xa_load() - Load an entry from an XArray.
1260 * @xa: XArray.
1261 * @index: index into array.
1262 *
1263 * Context: Any context. Takes and releases the RCU lock.
1264 * Return: The entry at @index in @xa.
1265 */
1266void *xa_load(struct xarray *xa, unsigned long index)
1267{
1268 XA_STATE(xas, xa, index);
1269 void *entry;
1270
1271 rcu_read_lock();
1272 do {
1273 entry = xas_load(&xas);
1274 if (xa_is_zero(entry))
1275 entry = NULL;
1276 } while (xas_retry(&xas, entry));
1277 rcu_read_unlock();
1278
1279 return entry;
1280}
1281EXPORT_SYMBOL(xa_load);
1282
1283static void *xas_result(struct xa_state *xas, void *curr)
1284{
1285 if (xa_is_zero(curr))
1286 return NULL;
1287 if (xas_error(xas))
1288 curr = xas->xa_node;
1289 return curr;
1290}
1291
1292/**
1293 * __xa_erase() - Erase this entry from the XArray while locked.
1294 * @xa: XArray.
1295 * @index: Index into array.
1296 *
1297 * If the entry at this index is a multi-index entry then all indices will
1298 * be erased, and the entry will no longer be a multi-index entry.
1299 * This function expects the xa_lock to be held on entry.
1300 *
1301 * Context: Any context. Expects xa_lock to be held on entry. May
1302 * release and reacquire xa_lock if @gfp flags permit.
1303 * Return: The old entry at this index.
1304 */
1305void *__xa_erase(struct xarray *xa, unsigned long index)
1306{
1307 XA_STATE(xas, xa, index);
1308 return xas_result(&xas, xas_store(&xas, NULL));
1309}
1310EXPORT_SYMBOL(__xa_erase);
1311
1312/**
1313 * xa_erase() - Erase this entry from the XArray.
1314 * @xa: XArray.
1315 * @index: Index of entry.
1316 *
1317 * This function is the equivalent of calling xa_store() with %NULL as
1318 * the third argument. The XArray does not need to allocate memory, so
1319 * the user does not need to provide GFP flags.
1320 *
1321 * Context: Any context. Takes and releases the xa_lock.
1322 * Return: The entry which used to be at this index.
1323 */
1324void *xa_erase(struct xarray *xa, unsigned long index)
1325{
1326 void *entry;
1327
1328 xa_lock(xa);
1329 entry = __xa_erase(xa, index);
1330 xa_unlock(xa);
1331
1332 return entry;
1333}
1334EXPORT_SYMBOL(xa_erase);
1335
1336/**
1337 * __xa_store() - Store this entry in the XArray.
1338 * @xa: XArray.
1339 * @index: Index into array.
1340 * @entry: New entry.
1341 * @gfp: Memory allocation flags.
1342 *
1343 * You must already be holding the xa_lock when calling this function.
1344 * It will drop the lock if needed to allocate memory, and then reacquire
1345 * it afterwards.
1346 *
1347 * Context: Any context. Expects xa_lock to be held on entry. May
1348 * release and reacquire xa_lock if @gfp flags permit.
1349 * Return: The old entry at this index or xa_err() if an error happened.
1350 */
1351void *__xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1352{
1353 XA_STATE(xas, xa, index);
1354 void *curr;
1355
1356 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1357 return XA_ERROR(-EINVAL);
1358 if (xa_track_free(xa) && !entry)
1359 entry = XA_ZERO_ENTRY;
1360
1361 do {
1362 curr = xas_store(&xas, entry);
1363 if (xa_track_free(xa))
1364 xas_clear_mark(&xas, XA_FREE_MARK);
1365 } while (__xas_nomem(&xas, gfp));
1366
1367 return xas_result(&xas, curr);
1368}
1369EXPORT_SYMBOL(__xa_store);
1370
1371/**
1372 * xa_store() - Store this entry in the XArray.
1373 * @xa: XArray.
1374 * @index: Index into array.
1375 * @entry: New entry.
1376 * @gfp: Memory allocation flags.
1377 *
1378 * After this function returns, loads from this index will return @entry.
1379 * Storing into an existing multislot entry updates the entry of every index.
1380 * The marks associated with @index are unaffected unless @entry is %NULL.
1381 *
1382 * Context: Any context. Takes and releases the xa_lock.
1383 * May sleep if the @gfp flags permit.
1384 * Return: The old entry at this index on success, xa_err(-EINVAL) if @entry
1385 * cannot be stored in an XArray, or xa_err(-ENOMEM) if memory allocation
1386 * failed.
1387 */
1388void *xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1389{
1390 void *curr;
1391
1392 xa_lock(xa);
1393 curr = __xa_store(xa, index, entry, gfp);
1394 xa_unlock(xa);
1395
1396 return curr;
1397}
1398EXPORT_SYMBOL(xa_store);
1399
1400/**
1401 * __xa_cmpxchg() - Store this entry in the XArray.
1402 * @xa: XArray.
1403 * @index: Index into array.
1404 * @old: Old value to test against.
1405 * @entry: New entry.
1406 * @gfp: Memory allocation flags.
1407 *
1408 * You must already be holding the xa_lock when calling this function.
1409 * It will drop the lock if needed to allocate memory, and then reacquire
1410 * it afterwards.
1411 *
1412 * Context: Any context. Expects xa_lock to be held on entry. May
1413 * release and reacquire xa_lock if @gfp flags permit.
1414 * Return: The old entry at this index or xa_err() if an error happened.
1415 */
1416void *__xa_cmpxchg(struct xarray *xa, unsigned long index,
1417 void *old, void *entry, gfp_t gfp)
1418{
1419 XA_STATE(xas, xa, index);
1420 void *curr;
1421
1422 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1423 return XA_ERROR(-EINVAL);
1424 if (xa_track_free(xa) && !entry)
1425 entry = XA_ZERO_ENTRY;
1426
1427 do {
1428 curr = xas_load(&xas);
1429 if (curr == XA_ZERO_ENTRY)
1430 curr = NULL;
1431 if (curr == old) {
1432 xas_store(&xas, entry);
1433 if (xa_track_free(xa))
1434 xas_clear_mark(&xas, XA_FREE_MARK);
1435 }
1436 } while (__xas_nomem(&xas, gfp));
1437
1438 return xas_result(&xas, curr);
1439}
1440EXPORT_SYMBOL(__xa_cmpxchg);
1441
1442/**
1443 * __xa_insert() - Store this entry in the XArray if no entry is present.
1444 * @xa: XArray.
1445 * @index: Index into array.
1446 * @entry: New entry.
1447 * @gfp: Memory allocation flags.
1448 *
1449 * Inserting a NULL entry will store a reserved entry (like xa_reserve())
1450 * if no entry is present. Inserting will fail if a reserved entry is
1451 * present, even though loading from this index will return NULL.
1452 *
1453 * Context: Any context. Expects xa_lock to be held on entry. May
1454 * release and reacquire xa_lock if @gfp flags permit.
1455 * Return: 0 if the store succeeded. -EEXIST if another entry was present.
1456 * -ENOMEM if memory could not be allocated.
1457 */
1458int __xa_insert(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1459{
1460 XA_STATE(xas, xa, index);
1461 void *curr;
1462
1463 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1464 return -EINVAL;
1465 if (!entry)
1466 entry = XA_ZERO_ENTRY;
1467
1468 do {
1469 curr = xas_load(&xas);
1470 if (!curr) {
1471 xas_store(&xas, entry);
1472 if (xa_track_free(xa))
1473 xas_clear_mark(&xas, XA_FREE_MARK);
1474 } else {
1475 xas_set_err(&xas, -EEXIST);
1476 }
1477 } while (__xas_nomem(&xas, gfp));
1478
1479 return xas_error(&xas);
1480}
1481EXPORT_SYMBOL(__xa_insert);
1482
1483/**
1484 * __xa_reserve() - Reserve this index in the XArray.
1485 * @xa: XArray.
1486 * @index: Index into array.
1487 * @gfp: Memory allocation flags.
1488 *
1489 * Ensures there is somewhere to store an entry at @index in the array.
1490 * If there is already something stored at @index, this function does
1491 * nothing. If there was nothing there, the entry is marked as reserved.
1492 * Loading from a reserved entry returns a %NULL pointer.
1493 *
1494 * If you do not use the entry that you have reserved, call xa_release()
1495 * or xa_erase() to free any unnecessary memory.
1496 *
1497 * Context: Any context. Expects the xa_lock to be held on entry. May
1498 * release the lock, sleep and reacquire the lock if the @gfp flags permit.
1499 * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
1500 */
1501int __xa_reserve(struct xarray *xa, unsigned long index, gfp_t gfp)
1502{
1503 XA_STATE(xas, xa, index);
1504 void *curr;
1505
1506 do {
1507 curr = xas_load(&xas);
1508 if (!curr) {
1509 xas_store(&xas, XA_ZERO_ENTRY);
1510 if (xa_track_free(xa))
1511 xas_clear_mark(&xas, XA_FREE_MARK);
1512 }
1513 } while (__xas_nomem(&xas, gfp));
1514
1515 return xas_error(&xas);
1516}
1517EXPORT_SYMBOL(__xa_reserve);
1518
1519#ifdef CONFIG_XARRAY_MULTI
1520static void xas_set_range(struct xa_state *xas, unsigned long first,
1521 unsigned long last)
1522{
1523 unsigned int shift = 0;
1524 unsigned long sibs = last - first;
1525 unsigned int offset = XA_CHUNK_MASK;
1526
1527 xas_set(xas, first);
1528
1529 while ((first & XA_CHUNK_MASK) == 0) {
1530 if (sibs < XA_CHUNK_MASK)
1531 break;
1532 if ((sibs == XA_CHUNK_MASK) && (offset < XA_CHUNK_MASK))
1533 break;
1534 shift += XA_CHUNK_SHIFT;
1535 if (offset == XA_CHUNK_MASK)
1536 offset = sibs & XA_CHUNK_MASK;
1537 sibs >>= XA_CHUNK_SHIFT;
1538 first >>= XA_CHUNK_SHIFT;
1539 }
1540
1541 offset = first & XA_CHUNK_MASK;
1542 if (offset + sibs > XA_CHUNK_MASK)
1543 sibs = XA_CHUNK_MASK - offset;
1544 if ((((first + sibs + 1) << shift) - 1) > last)
1545 sibs -= 1;
1546
1547 xas->xa_shift = shift;
1548 xas->xa_sibs = sibs;
1549}
1550
1551/**
1552 * xa_store_range() - Store this entry at a range of indices in the XArray.
1553 * @xa: XArray.
1554 * @first: First index to affect.
1555 * @last: Last index to affect.
1556 * @entry: New entry.
1557 * @gfp: Memory allocation flags.
1558 *
1559 * After this function returns, loads from any index between @first and @last,
1560 * inclusive will return @entry.
1561 * Storing into an existing multislot entry updates the entry of every index.
1562 * The marks associated with @index are unaffected unless @entry is %NULL.
1563 *
1564 * Context: Process context. Takes and releases the xa_lock. May sleep
1565 * if the @gfp flags permit.
1566 * Return: %NULL on success, xa_err(-EINVAL) if @entry cannot be stored in
1567 * an XArray, or xa_err(-ENOMEM) if memory allocation failed.
1568 */
1569void *xa_store_range(struct xarray *xa, unsigned long first,
1570 unsigned long last, void *entry, gfp_t gfp)
1571{
1572 XA_STATE(xas, xa, 0);
1573
1574 if (WARN_ON_ONCE(xa_is_internal(entry)))
1575 return XA_ERROR(-EINVAL);
1576 if (last < first)
1577 return XA_ERROR(-EINVAL);
1578
1579 do {
1580 xas_lock(&xas);
1581 if (entry) {
1582 unsigned int order = BITS_PER_LONG;
1583 if (last + 1)
1584 order = __ffs(last + 1);
1585 xas_set_order(&xas, last, order);
1586 xas_create(&xas, true);
1587 if (xas_error(&xas))
1588 goto unlock;
1589 }
1590 do {
1591 xas_set_range(&xas, first, last);
1592 xas_store(&xas, entry);
1593 if (xas_error(&xas))
1594 goto unlock;
1595 first += xas_size(&xas);
1596 } while (first <= last);
1597unlock:
1598 xas_unlock(&xas);
1599 } while (xas_nomem(&xas, gfp));
1600
1601 return xas_result(&xas, NULL);
1602}
1603EXPORT_SYMBOL(xa_store_range);
1604#endif /* CONFIG_XARRAY_MULTI */
1605
1606/**
1607 * __xa_alloc() - Find somewhere to store this entry in the XArray.
1608 * @xa: XArray.
1609 * @id: Pointer to ID.
1610 * @max: Maximum ID to allocate (inclusive).
1611 * @entry: New entry.
1612 * @gfp: Memory allocation flags.
1613 *
1614 * Allocates an unused ID in the range specified by @id and @max.
1615 * Updates the @id pointer with the index, then stores the entry at that
1616 * index. A concurrent lookup will not see an uninitialised @id.
1617 *
1618 * Context: Any context. Expects xa_lock to be held on entry. May
1619 * release and reacquire xa_lock if @gfp flags permit.
1620 * Return: 0 on success, -ENOMEM if memory allocation fails or -ENOSPC if
1621 * there is no more space in the XArray.
1622 */
1623int __xa_alloc(struct xarray *xa, u32 *id, u32 max, void *entry, gfp_t gfp)
1624{
1625 XA_STATE(xas, xa, 0);
1626 int err;
1627
1628 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1629 return -EINVAL;
1630 if (WARN_ON_ONCE(!xa_track_free(xa)))
1631 return -EINVAL;
1632
1633 if (!entry)
1634 entry = XA_ZERO_ENTRY;
1635
1636 do {
1637 xas.xa_index = *id;
1638 xas_find_marked(&xas, max, XA_FREE_MARK);
1639 if (xas.xa_node == XAS_RESTART)
1640 xas_set_err(&xas, -ENOSPC);
1641 xas_store(&xas, entry);
1642 xas_clear_mark(&xas, XA_FREE_MARK);
1643 } while (__xas_nomem(&xas, gfp));
1644
1645 err = xas_error(&xas);
1646 if (!err)
1647 *id = xas.xa_index;
1648 return err;
1649}
1650EXPORT_SYMBOL(__xa_alloc);
1651
1652/**
1653 * __xa_set_mark() - Set this mark on this entry while locked.
1654 * @xa: XArray.
1655 * @index: Index of entry.
1656 * @mark: Mark number.
1657 *
1658 * Attempting to set a mark on a %NULL entry does not succeed.
1659 *
1660 * Context: Any context. Expects xa_lock to be held on entry.
1661 */
1662void __xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1663{
1664 XA_STATE(xas, xa, index);
1665 void *entry = xas_load(&xas);
1666
1667 if (entry)
1668 xas_set_mark(&xas, mark);
1669}
1670EXPORT_SYMBOL(__xa_set_mark);
1671
1672/**
1673 * __xa_clear_mark() - Clear this mark on this entry while locked.
1674 * @xa: XArray.
1675 * @index: Index of entry.
1676 * @mark: Mark number.
1677 *
1678 * Context: Any context. Expects xa_lock to be held on entry.
1679 */
1680void __xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1681{
1682 XA_STATE(xas, xa, index);
1683 void *entry = xas_load(&xas);
1684
1685 if (entry)
1686 xas_clear_mark(&xas, mark);
1687}
1688EXPORT_SYMBOL(__xa_clear_mark);
1689
1690/**
1691 * xa_get_mark() - Inquire whether this mark is set on this entry.
1692 * @xa: XArray.
1693 * @index: Index of entry.
1694 * @mark: Mark number.
1695 *
1696 * This function uses the RCU read lock, so the result may be out of date
1697 * by the time it returns. If you need the result to be stable, use a lock.
1698 *
1699 * Context: Any context. Takes and releases the RCU lock.
1700 * Return: True if the entry at @index has this mark set, false if it doesn't.
1701 */
1702bool xa_get_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1703{
1704 XA_STATE(xas, xa, index);
1705 void *entry;
1706
1707 rcu_read_lock();
1708 entry = xas_start(&xas);
1709 while (xas_get_mark(&xas, mark)) {
1710 if (!xa_is_node(entry))
1711 goto found;
1712 entry = xas_descend(&xas, xa_to_node(entry));
1713 }
1714 rcu_read_unlock();
1715 return false;
1716 found:
1717 rcu_read_unlock();
1718 return true;
1719}
1720EXPORT_SYMBOL(xa_get_mark);
1721
1722/**
1723 * xa_set_mark() - Set this mark on this entry.
1724 * @xa: XArray.
1725 * @index: Index of entry.
1726 * @mark: Mark number.
1727 *
1728 * Attempting to set a mark on a %NULL entry does not succeed.
1729 *
1730 * Context: Process context. Takes and releases the xa_lock.
1731 */
1732void xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1733{
1734 xa_lock(xa);
1735 __xa_set_mark(xa, index, mark);
1736 xa_unlock(xa);
1737}
1738EXPORT_SYMBOL(xa_set_mark);
1739
1740/**
1741 * xa_clear_mark() - Clear this mark on this entry.
1742 * @xa: XArray.
1743 * @index: Index of entry.
1744 * @mark: Mark number.
1745 *
1746 * Clearing a mark always succeeds.
1747 *
1748 * Context: Process context. Takes and releases the xa_lock.
1749 */
1750void xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1751{
1752 xa_lock(xa);
1753 __xa_clear_mark(xa, index, mark);
1754 xa_unlock(xa);
1755}
1756EXPORT_SYMBOL(xa_clear_mark);
1757
1758/**
1759 * xa_find() - Search the XArray for an entry.
1760 * @xa: XArray.
1761 * @indexp: Pointer to an index.
1762 * @max: Maximum index to search to.
1763 * @filter: Selection criterion.
1764 *
1765 * Finds the entry in @xa which matches the @filter, and has the lowest
1766 * index that is at least @indexp and no more than @max.
1767 * If an entry is found, @indexp is updated to be the index of the entry.
1768 * This function is protected by the RCU read lock, so it may not find
1769 * entries which are being simultaneously added. It will not return an
1770 * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
1771 *
1772 * Context: Any context. Takes and releases the RCU lock.
1773 * Return: The entry, if found, otherwise %NULL.
1774 */
1775void *xa_find(struct xarray *xa, unsigned long *indexp,
1776 unsigned long max, xa_mark_t filter)
1777{
1778 XA_STATE(xas, xa, *indexp);
1779 void *entry;
1780
1781 rcu_read_lock();
1782 do {
1783 if ((__force unsigned int)filter < XA_MAX_MARKS)
1784 entry = xas_find_marked(&xas, max, filter);
1785 else
1786 entry = xas_find(&xas, max);
1787 } while (xas_retry(&xas, entry));
1788 rcu_read_unlock();
1789
1790 if (entry)
1791 *indexp = xas.xa_index;
1792 return entry;
1793}
1794EXPORT_SYMBOL(xa_find);
1795
1796/**
1797 * xa_find_after() - Search the XArray for a present entry.
1798 * @xa: XArray.
1799 * @indexp: Pointer to an index.
1800 * @max: Maximum index to search to.
1801 * @filter: Selection criterion.
1802 *
1803 * Finds the entry in @xa which matches the @filter and has the lowest
1804 * index that is above @indexp and no more than @max.
1805 * If an entry is found, @indexp is updated to be the index of the entry.
1806 * This function is protected by the RCU read lock, so it may miss entries
1807 * which are being simultaneously added. It will not return an
1808 * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
1809 *
1810 * Context: Any context. Takes and releases the RCU lock.
1811 * Return: The pointer, if found, otherwise %NULL.
1812 */
1813void *xa_find_after(struct xarray *xa, unsigned long *indexp,
1814 unsigned long max, xa_mark_t filter)
1815{
1816 XA_STATE(xas, xa, *indexp + 1);
1817 void *entry;
1818
1819 rcu_read_lock();
1820 for (;;) {
1821 if ((__force unsigned int)filter < XA_MAX_MARKS)
1822 entry = xas_find_marked(&xas, max, filter);
1823 else
1824 entry = xas_find(&xas, max);
1825 if (xas.xa_node == XAS_BOUNDS)
1826 break;
1827 if (xas.xa_shift) {
1828 if (xas.xa_index & ((1UL << xas.xa_shift) - 1))
1829 continue;
1830 } else {
1831 if (xas.xa_offset < (xas.xa_index & XA_CHUNK_MASK))
1832 continue;
1833 }
1834 if (!xas_retry(&xas, entry))
1835 break;
1836 }
1837 rcu_read_unlock();
1838
1839 if (entry)
1840 *indexp = xas.xa_index;
1841 return entry;
1842}
1843EXPORT_SYMBOL(xa_find_after);
1844
1845static unsigned int xas_extract_present(struct xa_state *xas, void **dst,
1846 unsigned long max, unsigned int n)
1847{
1848 void *entry;
1849 unsigned int i = 0;
1850
1851 rcu_read_lock();
1852 xas_for_each(xas, entry, max) {
1853 if (xas_retry(xas, entry))
1854 continue;
1855 dst[i++] = entry;
1856 if (i == n)
1857 break;
1858 }
1859 rcu_read_unlock();
1860
1861 return i;
1862}
1863
1864static unsigned int xas_extract_marked(struct xa_state *xas, void **dst,
1865 unsigned long max, unsigned int n, xa_mark_t mark)
1866{
1867 void *entry;
1868 unsigned int i = 0;
1869
1870 rcu_read_lock();
1871 xas_for_each_marked(xas, entry, max, mark) {
1872 if (xas_retry(xas, entry))
1873 continue;
1874 dst[i++] = entry;
1875 if (i == n)
1876 break;
1877 }
1878 rcu_read_unlock();
1879
1880 return i;
1881}
1882
1883/**
1884 * xa_extract() - Copy selected entries from the XArray into a normal array.
1885 * @xa: The source XArray to copy from.
1886 * @dst: The buffer to copy entries into.
1887 * @start: The first index in the XArray eligible to be selected.
1888 * @max: The last index in the XArray eligible to be selected.
1889 * @n: The maximum number of entries to copy.
1890 * @filter: Selection criterion.
1891 *
1892 * Copies up to @n entries that match @filter from the XArray. The
1893 * copied entries will have indices between @start and @max, inclusive.
1894 *
1895 * The @filter may be an XArray mark value, in which case entries which are
1896 * marked with that mark will be copied. It may also be %XA_PRESENT, in
1897 * which case all entries which are not %NULL will be copied.
1898 *
1899 * The entries returned may not represent a snapshot of the XArray at a
1900 * moment in time. For example, if another thread stores to index 5, then
1901 * index 10, calling xa_extract() may return the old contents of index 5
1902 * and the new contents of index 10. Indices not modified while this
1903 * function is running will not be skipped.
1904 *
1905 * If you need stronger guarantees, holding the xa_lock across calls to this
1906 * function will prevent concurrent modification.
1907 *
1908 * Context: Any context. Takes and releases the RCU lock.
1909 * Return: The number of entries copied.
1910 */
1911unsigned int xa_extract(struct xarray *xa, void **dst, unsigned long start,
1912 unsigned long max, unsigned int n, xa_mark_t filter)
1913{
1914 XA_STATE(xas, xa, start);
1915
1916 if (!n)
1917 return 0;
1918
1919 if ((__force unsigned int)filter < XA_MAX_MARKS)
1920 return xas_extract_marked(&xas, dst, max, n, filter);
1921 return xas_extract_present(&xas, dst, max, n);
1922}
1923EXPORT_SYMBOL(xa_extract);
1924
1925/**
1926 * xa_destroy() - Free all internal data structures.
1927 * @xa: XArray.
1928 *
1929 * After calling this function, the XArray is empty and has freed all memory
1930 * allocated for its internal data structures. You are responsible for
1931 * freeing the objects referenced by the XArray.
1932 *
1933 * Context: Any context. Takes and releases the xa_lock, interrupt-safe.
1934 */
1935void xa_destroy(struct xarray *xa)
1936{
1937 XA_STATE(xas, xa, 0);
1938 unsigned long flags;
1939 void *entry;
1940
1941 xas.xa_node = NULL;
1942 xas_lock_irqsave(&xas, flags);
1943 entry = xa_head_locked(xa);
1944 RCU_INIT_POINTER(xa->xa_head, NULL);
1945 xas_init_marks(&xas);
1946 /* lockdep checks we're still holding the lock in xas_free_nodes() */
1947 if (xa_is_node(entry))
1948 xas_free_nodes(&xas, xa_to_node(entry));
1949 xas_unlock_irqrestore(&xas, flags);
1950}
1951EXPORT_SYMBOL(xa_destroy);
1952
1953#ifdef XA_DEBUG
1954void xa_dump_node(const struct xa_node *node)
1955{
1956 unsigned i, j;
1957
1958 if (!node)
1959 return;
1960 if ((unsigned long)node & 3) {
1961 pr_cont("node %px\n", node);
1962 return;
1963 }
1964
1965 pr_cont("node %px %s %d parent %px shift %d count %d values %d "
1966 "array %px list %px %px marks",
1967 node, node->parent ? "offset" : "max", node->offset,
1968 node->parent, node->shift, node->count, node->nr_values,
1969 node->array, node->private_list.prev, node->private_list.next);
1970 for (i = 0; i < XA_MAX_MARKS; i++)
1971 for (j = 0; j < XA_MARK_LONGS; j++)
1972 pr_cont(" %lx", node->marks[i][j]);
1973 pr_cont("\n");
1974}
1975
1976void xa_dump_index(unsigned long index, unsigned int shift)
1977{
1978 if (!shift)
1979 pr_info("%lu: ", index);
1980 else if (shift >= BITS_PER_LONG)
1981 pr_info("0-%lu: ", ~0UL);
1982 else
1983 pr_info("%lu-%lu: ", index, index | ((1UL << shift) - 1));
1984}
1985
1986void xa_dump_entry(const void *entry, unsigned long index, unsigned long shift)
1987{
1988 if (!entry)
1989 return;
1990
1991 xa_dump_index(index, shift);
1992
1993 if (xa_is_node(entry)) {
1994 if (shift == 0) {
1995 pr_cont("%px\n", entry);
1996 } else {
1997 unsigned long i;
1998 struct xa_node *node = xa_to_node(entry);
1999 xa_dump_node(node);
2000 for (i = 0; i < XA_CHUNK_SIZE; i++)
2001 xa_dump_entry(node->slots[i],
2002 index + (i << node->shift), node->shift);
2003 }
2004 } else if (xa_is_value(entry))
2005 pr_cont("value %ld (0x%lx) [%px]\n", xa_to_value(entry),
2006 xa_to_value(entry), entry);
2007 else if (!xa_is_internal(entry))
2008 pr_cont("%px\n", entry);
2009 else if (xa_is_retry(entry))
2010 pr_cont("retry (%ld)\n", xa_to_internal(entry));
2011 else if (xa_is_sibling(entry))
2012 pr_cont("sibling (slot %ld)\n", xa_to_sibling(entry));
2013 else if (xa_is_zero(entry))
2014 pr_cont("zero (%ld)\n", xa_to_internal(entry));
2015 else
2016 pr_cont("UNKNOWN ENTRY (%px)\n", entry);
2017}
2018
2019void xa_dump(const struct xarray *xa)
2020{
2021 void *entry = xa->xa_head;
2022 unsigned int shift = 0;
2023
2024 pr_info("xarray: %px head %px flags %x marks %d %d %d\n", xa, entry,
2025 xa->xa_flags, xa_marked(xa, XA_MARK_0),
2026 xa_marked(xa, XA_MARK_1), xa_marked(xa, XA_MARK_2));
2027 if (xa_is_node(entry))
2028 shift = xa_to_node(entry)->shift + XA_CHUNK_SHIFT;
2029 xa_dump_entry(entry, 0, shift);
2030}
2031#endif