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