Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0+
2 : /*
3 : * XArray implementation
4 : * Copyright (c) 2017-2018 Microsoft Corporation
5 : * Copyright (c) 2018-2020 Oracle
6 : * Author: Matthew Wilcox <willy@infradead.org>
7 : */
8 :
9 : #include <linux/bitmap.h>
10 : #include <linux/export.h>
11 : #include <linux/list.h>
12 : #include <linux/slab.h>
13 : #include <linux/xarray.h>
14 :
15 : /*
16 : * Coding conventions in this file:
17 : *
18 : * @xa is used to refer to the entire xarray.
19 : * @xas is the 'xarray operation state'. It may be either a pointer to
20 : * an xa_state, or an xa_state stored on the stack. This is an unfortunate
21 : * ambiguity.
22 : * @index is the index of the entry being operated on
23 : * @mark is an xa_mark_t; a small number indicating one of the mark bits.
24 : * @node refers to an xa_node; usually the primary one being operated on by
25 : * this function.
26 : * @offset is the index into the slots array inside an xa_node.
27 : * @parent refers to the @xa_node closer to the head than @node.
28 : * @entry refers to something stored in a slot in the xarray
29 : */
30 :
31 14 : static inline unsigned int xa_lock_type(const struct xarray *xa)
32 : {
33 14 : return (__force unsigned int)xa->xa_flags & 3;
34 : }
35 :
36 0 : static inline void xas_lock_type(struct xa_state *xas, unsigned int lock_type)
37 : {
38 0 : if (lock_type == XA_LOCK_IRQ)
39 0 : xas_lock_irq(xas);
40 0 : else if (lock_type == XA_LOCK_BH)
41 0 : xas_lock_bh(xas);
42 : else
43 0 : xas_lock(xas);
44 0 : }
45 :
46 0 : static inline void xas_unlock_type(struct xa_state *xas, unsigned int lock_type)
47 : {
48 0 : if (lock_type == XA_LOCK_IRQ)
49 0 : xas_unlock_irq(xas);
50 0 : else if (lock_type == XA_LOCK_BH)
51 0 : xas_unlock_bh(xas);
52 : else
53 0 : xas_unlock(xas);
54 0 : }
55 :
56 10478 : static inline bool xa_track_free(const struct xarray *xa)
57 : {
58 10478 : return xa->xa_flags & XA_FLAGS_TRACK_FREE;
59 : }
60 :
61 1815 : static inline bool xa_zero_busy(const struct xarray *xa)
62 : {
63 1815 : return xa->xa_flags & XA_FLAGS_ZERO_BUSY;
64 : }
65 :
66 1431 : static inline void xa_mark_set(struct xarray *xa, xa_mark_t mark)
67 : {
68 1431 : if (!(xa->xa_flags & XA_FLAGS_MARK(mark)))
69 0 : xa->xa_flags |= XA_FLAGS_MARK(mark);
70 1431 : }
71 :
72 956 : static inline void xa_mark_clear(struct xarray *xa, xa_mark_t mark)
73 : {
74 956 : if (xa->xa_flags & XA_FLAGS_MARK(mark))
75 0 : xa->xa_flags &= ~(XA_FLAGS_MARK(mark));
76 956 : }
77 :
78 28408 : static inline unsigned long *node_marks(struct xa_node *node, xa_mark_t mark)
79 : {
80 28408 : return node->marks[(__force unsigned)mark];
81 : }
82 :
83 0 : static inline bool node_get_mark(struct xa_node *node,
84 : unsigned int offset, xa_mark_t mark)
85 : {
86 0 : return test_bit(offset, node_marks(node, mark));
87 : }
88 :
89 : /* returns true if the bit was set */
90 8801 : static inline bool node_set_mark(struct xa_node *node, unsigned int offset,
91 : xa_mark_t mark)
92 : {
93 8801 : return __test_and_set_bit(offset, node_marks(node, mark));
94 : }
95 :
96 : /* returns true if the bit was set */
97 14129 : static inline bool node_clear_mark(struct xa_node *node, unsigned int offset,
98 : xa_mark_t mark)
99 : {
100 14129 : return __test_and_clear_bit(offset, node_marks(node, mark));
101 : }
102 :
103 5478 : static inline bool node_any_mark(struct xa_node *node, xa_mark_t mark)
104 : {
105 5478 : return !bitmap_empty(node_marks(node, mark), XA_CHUNK_SIZE);
106 : }
107 :
108 0 : static inline void node_mark_all(struct xa_node *node, xa_mark_t mark)
109 : {
110 0 : bitmap_fill(node_marks(node, mark), XA_CHUNK_SIZE);
111 0 : }
112 :
113 : #define mark_inc(mark) do { \
114 : mark = (__force xa_mark_t)((__force unsigned)(mark) + 1); \
115 : } while (0)
116 :
117 : /*
118 : * xas_squash_marks() - Merge all marks to the first entry
119 : * @xas: Array operation state.
120 : *
121 : * Set a mark on the first entry if any entry has it set. Clear marks on
122 : * all sibling entries.
123 : */
124 0 : static void xas_squash_marks(const struct xa_state *xas)
125 : {
126 0 : unsigned int mark = 0;
127 0 : unsigned int limit = xas->xa_offset + xas->xa_sibs + 1;
128 :
129 0 : if (!xas->xa_sibs)
130 : return;
131 :
132 0 : do {
133 0 : unsigned long *marks = xas->xa_node->marks[mark];
134 0 : if (find_next_bit(marks, limit, xas->xa_offset + 1) == limit)
135 0 : continue;
136 0 : __set_bit(xas->xa_offset, marks);
137 0 : bitmap_clear(marks, xas->xa_offset + 1, xas->xa_sibs);
138 0 : } while (mark++ != (__force unsigned)XA_MARK_MAX);
139 : }
140 :
141 : /* extracts the offset within this node from the index */
142 593326 : static unsigned int get_offset(unsigned long index, struct xa_node *node)
143 : {
144 593326 : return (index >> node->shift) & XA_CHUNK_MASK;
145 : }
146 :
147 2350 : static void xas_set_offset(struct xa_state *xas)
148 : {
149 2350 : xas->xa_offset = get_offset(xas->xa_index, xas->xa_node);
150 2350 : }
151 :
152 : /* move the index either forwards (find) or backwards (sibling slot) */
153 163041 : static void xas_move_index(struct xa_state *xas, unsigned long offset)
154 : {
155 163041 : unsigned int shift = xas->xa_node->shift;
156 163041 : xas->xa_index &= ~XA_CHUNK_MASK << shift;
157 163041 : xas->xa_index += offset << shift;
158 0 : }
159 :
160 159144 : static void xas_advance(struct xa_state *xas)
161 : {
162 159144 : xas->xa_offset++;
163 159144 : xas_move_index(xas, xas->xa_offset);
164 159144 : }
165 :
166 11016 : static void *set_bounds(struct xa_state *xas)
167 : {
168 11016 : xas->xa_node = XAS_BOUNDS;
169 11016 : return NULL;
170 : }
171 :
172 : /*
173 : * Starts a walk. If the @xas is already valid, we assume that it's on
174 : * the right path and just return where we've got to. If we're in an
175 : * error state, return NULL. If the index is outside the current scope
176 : * of the xarray, return NULL without changing @xas->xa_node. Otherwise
177 : * set @xas->xa_node to NULL and return the current head of the array.
178 : */
179 319351 : static void *xas_start(struct xa_state *xas)
180 : {
181 319351 : void *entry;
182 :
183 319351 : if (xas_valid(xas))
184 1312 : return xas_reload(xas);
185 318039 : if (xas_error(xas))
186 : return NULL;
187 :
188 318039 : entry = xa_head(xas->xa);
189 636098 : if (!xa_is_node(entry)) {
190 17889 : if (xas->xa_index)
191 1962 : return set_bounds(xas);
192 : } else {
193 300160 : if ((xas->xa_index >> xa_to_node(entry)->shift) > XA_CHUNK_MASK)
194 2660 : return set_bounds(xas);
195 : }
196 :
197 313427 : xas->xa_node = NULL;
198 313427 : return entry;
199 : }
200 :
201 590876 : static void *xas_descend(struct xa_state *xas, struct xa_node *node)
202 : {
203 590876 : unsigned int offset = get_offset(xas->xa_index, node);
204 590876 : void *entry = xa_entry(xas->xa, node, offset);
205 :
206 590886 : xas->xa_node = node;
207 883085 : if (xa_is_sibling(entry)) {
208 0 : offset = xa_to_sibling(entry);
209 0 : entry = xa_entry(xas->xa, node, offset);
210 : }
211 :
212 590886 : xas->xa_offset = offset;
213 590886 : return entry;
214 : }
215 :
216 : /**
217 : * xas_load() - Load an entry from the XArray (advanced).
218 : * @xas: XArray operation state.
219 : *
220 : * Usually walks the @xas to the appropriate state to load the entry
221 : * stored at xa_index. However, it will do nothing and return %NULL if
222 : * @xas is in an error state. xas_load() will never expand the tree.
223 : *
224 : * If the xa_state is set up to operate on a multi-index entry, xas_load()
225 : * may return %NULL or an internal entry, even if there are entries
226 : * present within the range specified by @xas.
227 : *
228 : * Context: Any context. The caller should hold the xa_lock or the RCU lock.
229 : * Return: Usually an entry in the XArray, but see description for exceptions.
230 : */
231 289080 : void *xas_load(struct xa_state *xas)
232 : {
233 289080 : void *entry = xas_start(xas);
234 :
235 1098219 : while (xa_is_node(entry)) {
236 528151 : struct xa_node *node = xa_to_node(entry);
237 :
238 528151 : if (xas->xa_shift > node->shift)
239 : break;
240 528151 : entry = xas_descend(xas, node);
241 528161 : if (node->shift == 0)
242 : break;
243 : }
244 289105 : return entry;
245 : }
246 : EXPORT_SYMBOL_GPL(xas_load);
247 :
248 : /* Move the radix tree node cache here */
249 : extern struct kmem_cache *radix_tree_node_cachep;
250 : extern void radix_tree_node_rcu_free(struct rcu_head *head);
251 :
252 : #define XA_RCU_FREE ((struct xarray *)1)
253 :
254 100 : static void xa_node_free(struct xa_node *node)
255 : {
256 100 : XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
257 100 : node->array = XA_RCU_FREE;
258 100 : call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
259 : }
260 :
261 : /*
262 : * xas_destroy() - Free any resources allocated during the XArray operation.
263 : * @xas: XArray operation state.
264 : *
265 : * This function is now internal-only.
266 : */
267 32118 : static void xas_destroy(struct xa_state *xas)
268 : {
269 32118 : struct xa_node *next, *node = xas->xa_alloc;
270 :
271 32118 : while (node) {
272 0 : XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
273 0 : next = rcu_dereference_raw(node->parent);
274 0 : radix_tree_node_rcu_free(&node->rcu_head);
275 0 : xas->xa_alloc = node = next;
276 : }
277 32118 : }
278 :
279 : /**
280 : * xas_nomem() - Allocate memory if needed.
281 : * @xas: XArray operation state.
282 : * @gfp: Memory allocation flags.
283 : *
284 : * If we need to add new nodes to the XArray, we try to allocate memory
285 : * with GFP_NOWAIT while holding the lock, which will usually succeed.
286 : * If it fails, @xas is flagged as needing memory to continue. The caller
287 : * should drop the lock and call xas_nomem(). If xas_nomem() succeeds,
288 : * the caller should retry the operation.
289 : *
290 : * Forward progress is guaranteed as one node is allocated here and
291 : * stored in the xa_state where it will be found by xas_alloc(). More
292 : * nodes will likely be found in the slab allocator, but we do not tie
293 : * them up here.
294 : *
295 : * Return: true if memory was needed, and was successfully allocated.
296 : */
297 32104 : bool xas_nomem(struct xa_state *xas, gfp_t gfp)
298 : {
299 32104 : if (xas->xa_node != XA_ERROR(-ENOMEM)) {
300 32104 : xas_destroy(xas);
301 32104 : return false;
302 : }
303 0 : if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
304 0 : gfp |= __GFP_ACCOUNT;
305 0 : xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
306 0 : if (!xas->xa_alloc)
307 : return false;
308 0 : xas->xa_alloc->parent = NULL;
309 0 : XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list));
310 0 : xas->xa_node = XAS_RESTART;
311 0 : return true;
312 : }
313 : EXPORT_SYMBOL_GPL(xas_nomem);
314 :
315 : /*
316 : * __xas_nomem() - Drop locks and allocate memory if needed.
317 : * @xas: XArray operation state.
318 : * @gfp: Memory allocation flags.
319 : *
320 : * Internal variant of xas_nomem().
321 : *
322 : * Return: true if memory was needed, and was successfully allocated.
323 : */
324 14 : static bool __xas_nomem(struct xa_state *xas, gfp_t gfp)
325 : __must_hold(xas->xa->xa_lock)
326 : {
327 14 : unsigned int lock_type = xa_lock_type(xas->xa);
328 :
329 14 : if (xas->xa_node != XA_ERROR(-ENOMEM)) {
330 14 : xas_destroy(xas);
331 14 : return false;
332 : }
333 0 : if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
334 0 : gfp |= __GFP_ACCOUNT;
335 0 : if (gfpflags_allow_blocking(gfp)) {
336 0 : xas_unlock_type(xas, lock_type);
337 0 : xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
338 0 : xas_lock_type(xas, lock_type);
339 : } else {
340 0 : xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
341 : }
342 0 : if (!xas->xa_alloc)
343 : return false;
344 0 : xas->xa_alloc->parent = NULL;
345 0 : XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list));
346 0 : xas->xa_node = XAS_RESTART;
347 0 : return true;
348 : }
349 :
350 31738 : static void xas_update(struct xa_state *xas, struct xa_node *node)
351 : {
352 31738 : if (xas->xa_update)
353 29266 : xas->xa_update(node);
354 : else
355 31166 : XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
356 : }
357 :
358 1206 : static void *xas_alloc(struct xa_state *xas, unsigned int shift)
359 : {
360 1206 : struct xa_node *parent = xas->xa_node;
361 1206 : struct xa_node *node = xas->xa_alloc;
362 :
363 1206 : if (xas_invalid(xas))
364 : return NULL;
365 :
366 1206 : if (node) {
367 0 : xas->xa_alloc = NULL;
368 : } else {
369 1206 : gfp_t gfp = GFP_NOWAIT | __GFP_NOWARN;
370 :
371 1206 : if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
372 1201 : gfp |= __GFP_ACCOUNT;
373 :
374 1206 : node = kmem_cache_alloc(radix_tree_node_cachep, gfp);
375 1206 : if (!node) {
376 0 : xas_set_err(xas, -ENOMEM);
377 0 : return NULL;
378 : }
379 : }
380 :
381 1206 : if (parent) {
382 548 : node->offset = xas->xa_offset;
383 548 : parent->count++;
384 548 : XA_NODE_BUG_ON(node, parent->count > XA_CHUNK_SIZE);
385 548 : xas_update(xas, parent);
386 : }
387 1206 : XA_NODE_BUG_ON(node, shift > BITS_PER_LONG);
388 1206 : XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
389 1206 : node->shift = shift;
390 1206 : node->count = 0;
391 1206 : node->nr_values = 0;
392 1206 : RCU_INIT_POINTER(node->parent, xas->xa_node);
393 1206 : node->array = xas->xa;
394 :
395 1206 : return node;
396 : }
397 :
398 : #ifdef CONFIG_XARRAY_MULTI
399 : /* Returns the number of indices covered by a given xa_state */
400 0 : static unsigned long xas_size(const struct xa_state *xas)
401 : {
402 0 : return (xas->xa_sibs + 1UL) << xas->xa_shift;
403 : }
404 : #endif
405 :
406 : /*
407 : * Use this to calculate the maximum index that will need to be created
408 : * in order to add the entry described by @xas. Because we cannot store a
409 : * multi-index entry at index 0, the calculation is a little more complex
410 : * than you might expect.
411 : */
412 2908 : static unsigned long xas_max(struct xa_state *xas)
413 : {
414 2908 : unsigned long max = xas->xa_index;
415 :
416 : #ifdef CONFIG_XARRAY_MULTI
417 2908 : if (xas->xa_shift || xas->xa_sibs) {
418 0 : unsigned long mask = xas_size(xas) - 1;
419 0 : max |= mask;
420 0 : if (mask == max)
421 0 : max++;
422 : }
423 : #endif
424 :
425 2908 : return max;
426 : }
427 :
428 : /* The maximum index that can be contained in the array without expanding it */
429 4749 : static unsigned long max_index(void *entry)
430 : {
431 9498 : if (!xa_is_node(entry))
432 : return 0;
433 1396 : return (XA_CHUNK_SIZE << xa_to_node(entry)->shift) - 1;
434 : }
435 :
436 487 : static void xas_shrink(struct xa_state *xas)
437 : {
438 487 : struct xarray *xa = xas->xa;
439 487 : struct xa_node *node = xas->xa_node;
440 :
441 487 : for (;;) {
442 487 : void *entry;
443 :
444 487 : XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
445 487 : if (node->count != 1)
446 : break;
447 76 : entry = xa_entry_locked(xa, node, 0);
448 76 : if (!entry)
449 : break;
450 0 : if (!xa_is_node(entry) && node->shift)
451 : break;
452 0 : if (xa_is_zero(entry) && xa_zero_busy(xa))
453 0 : entry = NULL;
454 0 : xas->xa_node = XAS_BOUNDS;
455 :
456 0 : RCU_INIT_POINTER(xa->xa_head, entry);
457 0 : if (xa_track_free(xa) && !node_get_mark(node, 0, XA_FREE_MARK))
458 0 : xa_mark_clear(xa, XA_FREE_MARK);
459 :
460 0 : node->count = 0;
461 0 : node->nr_values = 0;
462 0 : if (!xa_is_node(entry))
463 0 : RCU_INIT_POINTER(node->slots[0], XA_RETRY_ENTRY);
464 0 : xas_update(xas, node);
465 0 : xa_node_free(node);
466 0 : if (!xa_is_node(entry))
467 : break;
468 0 : node = xa_to_node(entry);
469 0 : node->parent = NULL;
470 : }
471 487 : }
472 :
473 : /*
474 : * xas_delete_node() - Attempt to delete an xa_node
475 : * @xas: Array operation state.
476 : *
477 : * Attempts to delete the @xas->xa_node. This will fail if xa->node has
478 : * a non-zero reference count.
479 : */
480 1876 : static void xas_delete_node(struct xa_state *xas)
481 : {
482 1876 : struct xa_node *node = xas->xa_node;
483 :
484 1900 : for (;;) {
485 1900 : struct xa_node *parent;
486 :
487 1900 : XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
488 1900 : if (node->count)
489 : break;
490 :
491 100 : parent = xa_parent_locked(xas->xa, node);
492 100 : xas->xa_node = parent;
493 100 : xas->xa_offset = node->offset;
494 100 : xa_node_free(node);
495 :
496 100 : if (!parent) {
497 76 : xas->xa->xa_head = NULL;
498 76 : xas->xa_node = XAS_BOUNDS;
499 76 : return;
500 : }
501 :
502 24 : parent->slots[xas->xa_offset] = NULL;
503 24 : parent->count--;
504 24 : XA_NODE_BUG_ON(parent, parent->count > XA_CHUNK_SIZE);
505 24 : node = parent;
506 1924 : xas_update(xas, node);
507 : }
508 :
509 1800 : if (!node->parent)
510 487 : xas_shrink(xas);
511 : }
512 :
513 : /**
514 : * xas_free_nodes() - Free this node and all nodes that it references
515 : * @xas: Array operation state.
516 : * @top: Node to free
517 : *
518 : * This node has been removed from the tree. We must now free it and all
519 : * of its subnodes. There may be RCU walkers with references into the tree,
520 : * so we must replace all entries with retry markers.
521 : */
522 0 : static void xas_free_nodes(struct xa_state *xas, struct xa_node *top)
523 : {
524 0 : unsigned int offset = 0;
525 0 : struct xa_node *node = top;
526 :
527 0 : for (;;) {
528 0 : void *entry = xa_entry_locked(xas->xa, node, offset);
529 :
530 0 : if (node->shift && xa_is_node(entry)) {
531 0 : node = xa_to_node(entry);
532 0 : offset = 0;
533 0 : continue;
534 : }
535 0 : if (entry)
536 0 : RCU_INIT_POINTER(node->slots[offset], XA_RETRY_ENTRY);
537 0 : offset++;
538 0 : while (offset == XA_CHUNK_SIZE) {
539 0 : struct xa_node *parent;
540 :
541 0 : parent = xa_parent_locked(xas->xa, node);
542 0 : offset = node->offset + 1;
543 0 : node->count = 0;
544 0 : node->nr_values = 0;
545 0 : xas_update(xas, node);
546 0 : xa_node_free(node);
547 0 : if (node == top)
548 0 : return;
549 : node = parent;
550 : }
551 : }
552 : }
553 :
554 : /*
555 : * xas_expand adds nodes to the head of the tree until it has reached
556 : * sufficient height to be able to contain @xas->xa_index
557 : */
558 2908 : static int xas_expand(struct xa_state *xas, void *head)
559 : {
560 2908 : struct xarray *xa = xas->xa;
561 2908 : struct xa_node *node = NULL;
562 2908 : unsigned int shift = 0;
563 2908 : unsigned long max = xas_max(xas);
564 :
565 2908 : if (!head) {
566 1815 : if (max == 0)
567 : return 0;
568 14 : while ((max >> shift) >= XA_CHUNK_SIZE)
569 5 : shift += XA_CHUNK_SHIFT;
570 9 : return shift + XA_CHUNK_SHIFT;
571 2186 : } else if (xa_is_node(head)) {
572 71 : node = xa_to_node(head);
573 71 : shift = node->shift + XA_CHUNK_SHIFT;
574 : }
575 1093 : xas->xa_node = NULL;
576 :
577 1742 : while (max > max_index(head)) {
578 649 : xa_mark_t mark = 0;
579 :
580 649 : XA_NODE_BUG_ON(node, shift > BITS_PER_LONG);
581 649 : node = xas_alloc(xas, shift);
582 649 : if (!node)
583 : return -ENOMEM;
584 :
585 649 : node->count = 1;
586 649 : if (xa_is_value(head))
587 0 : node->nr_values = 1;
588 649 : RCU_INIT_POINTER(node->slots[0], head);
589 :
590 : /* Propagate the aggregated mark info to the new child */
591 3245 : for (;;) {
592 1947 : if (xa_track_free(xa) && mark == XA_FREE_MARK) {
593 0 : node_mark_all(node, XA_FREE_MARK);
594 0 : if (!xa_marked(xa, XA_FREE_MARK)) {
595 0 : node_clear_mark(node, 0, XA_FREE_MARK);
596 0 : xa_mark_set(xa, XA_FREE_MARK);
597 : }
598 1947 : } else if (xa_marked(xa, mark)) {
599 305 : node_set_mark(node, 0, mark);
600 : }
601 1947 : if (mark == XA_MARK_MAX)
602 : break;
603 1298 : mark_inc(mark);
604 : }
605 :
606 : /*
607 : * Now that the new node is fully initialised, we can add
608 : * it to the tree
609 : */
610 1298 : if (xa_is_node(head)) {
611 68 : xa_to_node(head)->offset = 0;
612 68 : rcu_assign_pointer(xa_to_node(head)->parent, node);
613 : }
614 649 : head = xa_mk_node(node);
615 649 : rcu_assign_pointer(xa->xa_head, head);
616 649 : xas_update(xas, node);
617 :
618 649 : shift += XA_CHUNK_SHIFT;
619 : }
620 :
621 1093 : xas->xa_node = node;
622 1093 : return shift;
623 : }
624 :
625 : /*
626 : * xas_create() - Create a slot to store an entry in.
627 : * @xas: XArray operation state.
628 : * @allow_root: %true if we can store the entry in the root directly
629 : *
630 : * Most users will not need to call this function directly, as it is called
631 : * by xas_store(). It is useful for doing conditional store operations
632 : * (see the xa_cmpxchg() implementation for an example).
633 : *
634 : * Return: If the slot already existed, returns the contents of this slot.
635 : * If the slot was newly created, returns %NULL. If it failed to create the
636 : * slot, returns %NULL and indicates the error in @xas.
637 : */
638 32734 : static void *xas_create(struct xa_state *xas, bool allow_root)
639 : {
640 32734 : struct xarray *xa = xas->xa;
641 32734 : void *entry;
642 32734 : void __rcu **slot;
643 32734 : struct xa_node *node = xas->xa_node;
644 32734 : int shift;
645 32734 : unsigned int order = xas->xa_shift;
646 :
647 32734 : if (xas_top(node)) {
648 2908 : entry = xa_head_locked(xa);
649 2908 : xas->xa_node = NULL;
650 2908 : if (!entry && xa_zero_busy(xa))
651 0 : entry = XA_ZERO_ENTRY;
652 2908 : shift = xas_expand(xas, entry);
653 2908 : if (shift < 0)
654 : return NULL;
655 2908 : if (!shift && !allow_root)
656 0 : shift = XA_CHUNK_SHIFT;
657 2908 : entry = xa_head_locked(xa);
658 2908 : slot = &xa->xa_head;
659 29826 : } else if (xas_error(xas)) {
660 : return NULL;
661 29826 : } else if (node) {
662 29826 : unsigned int offset = xas->xa_offset;
663 :
664 29826 : shift = node->shift;
665 29826 : entry = xa_entry_locked(xa, node, offset);
666 29826 : slot = &node->slots[offset];
667 : } else {
668 0 : shift = 0;
669 0 : entry = xa_head_locked(xa);
670 0 : slot = &xa->xa_head;
671 : }
672 :
673 33944 : while (shift > order) {
674 1210 : shift -= XA_CHUNK_SHIFT;
675 1210 : if (!entry) {
676 557 : node = xas_alloc(xas, shift);
677 557 : if (!node)
678 : break;
679 557 : if (xa_track_free(xa))
680 0 : node_mark_all(node, XA_FREE_MARK);
681 557 : rcu_assign_pointer(*slot, xa_mk_node(node));
682 1306 : } else if (xa_is_node(entry)) {
683 653 : node = xa_to_node(entry);
684 : } else {
685 : break;
686 : }
687 1210 : entry = xas_descend(xas, node);
688 1210 : slot = &node->slots[xas->xa_offset];
689 : }
690 :
691 : return entry;
692 : }
693 :
694 : /**
695 : * xas_create_range() - Ensure that stores to this range will succeed
696 : * @xas: XArray operation state.
697 : *
698 : * Creates all of the slots in the range covered by @xas. Sets @xas to
699 : * create single-index entries and positions it at the beginning of the
700 : * range. This is for the benefit of users which have not yet been
701 : * converted to use multi-index entries.
702 : */
703 1986 : void xas_create_range(struct xa_state *xas)
704 : {
705 1986 : unsigned long index = xas->xa_index;
706 1986 : unsigned char shift = xas->xa_shift;
707 1986 : unsigned char sibs = xas->xa_sibs;
708 :
709 1986 : xas->xa_index |= ((sibs + 1UL) << shift) - 1;
710 3972 : if (xas_is_node(xas) && xas->xa_node->shift == xas->xa_shift)
711 1816 : xas->xa_offset |= sibs;
712 1986 : xas->xa_shift = 0;
713 1986 : xas->xa_sibs = 0;
714 :
715 1986 : for (;;) {
716 1986 : xas_create(xas, true);
717 1986 : if (xas_error(xas))
718 0 : goto restore;
719 1986 : if (xas->xa_index <= (index | XA_CHUNK_MASK))
720 1986 : goto success;
721 0 : xas->xa_index -= XA_CHUNK_SIZE;
722 :
723 0 : for (;;) {
724 0 : struct xa_node *node = xas->xa_node;
725 0 : xas->xa_node = xa_parent_locked(xas->xa, node);
726 0 : xas->xa_offset = node->offset - 1;
727 0 : if (node->offset != 0)
728 : break;
729 : }
730 : }
731 :
732 0 : restore:
733 0 : xas->xa_shift = shift;
734 0 : xas->xa_sibs = sibs;
735 0 : xas->xa_index = index;
736 0 : return;
737 1986 : success:
738 1986 : xas->xa_index = index;
739 1986 : if (xas->xa_node)
740 1845 : xas_set_offset(xas);
741 : }
742 : EXPORT_SYMBOL_GPL(xas_create_range);
743 :
744 32729 : static void update_node(struct xa_state *xas, struct xa_node *node,
745 : int count, int values)
746 : {
747 32729 : if (!node || (!count && !values))
748 : return;
749 :
750 30517 : node->count += count;
751 30517 : node->nr_values += values;
752 30517 : XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
753 30517 : XA_NODE_BUG_ON(node, node->nr_values > XA_CHUNK_SIZE);
754 30517 : xas_update(xas, node);
755 30517 : if (count < 0)
756 1876 : xas_delete_node(xas);
757 : }
758 :
759 : /**
760 : * xas_store() - Store this entry in the XArray.
761 : * @xas: XArray operation state.
762 : * @entry: New entry.
763 : *
764 : * If @xas is operating on a multi-index entry, the entry returned by this
765 : * function is essentially meaningless (it may be an internal entry or it
766 : * may be %NULL, even if there are non-NULL entries at some of the indices
767 : * covered by the range). This is not a problem for any current users,
768 : * and can be changed if needed.
769 : *
770 : * Return: The old entry at this index.
771 : */
772 32730 : void *xas_store(struct xa_state *xas, void *entry)
773 : {
774 32730 : struct xa_node *node;
775 32730 : void __rcu **slot = &xas->xa->xa_head;
776 32730 : unsigned int offset, max;
777 32730 : int count = 0;
778 32730 : int values = 0;
779 32730 : void *first, *next;
780 32730 : bool value = xa_is_value(entry);
781 :
782 32730 : if (entry) {
783 61496 : bool allow_root = !xa_is_node(entry) && !xa_is_zero(entry);
784 30748 : first = xas_create(xas, allow_root);
785 : } else {
786 1982 : first = xas_load(xas);
787 : }
788 :
789 32729 : if (xas_invalid(xas))
790 : return first;
791 32729 : node = xas->xa_node;
792 32729 : if (node && (xas->xa_shift < node->shift))
793 0 : xas->xa_sibs = 0;
794 32729 : if ((first == entry) && !xas->xa_sibs)
795 : return first;
796 :
797 32729 : next = first;
798 32729 : offset = xas->xa_offset;
799 32729 : max = xas->xa_offset + xas->xa_sibs;
800 32729 : if (node) {
801 30517 : slot = &node->slots[offset];
802 30517 : if (xas->xa_sibs)
803 0 : xas_squash_marks(xas);
804 : }
805 32729 : if (!entry)
806 1982 : xas_init_marks(xas);
807 :
808 32729 : for (;;) {
809 : /*
810 : * Must clear the marks before setting the entry to NULL,
811 : * otherwise xas_for_each_marked may find a NULL entry and
812 : * stop early. rcu_assign_pointer contains a release barrier
813 : * so the mark clearing will appear to happen before the
814 : * entry is set to NULL.
815 : */
816 32729 : rcu_assign_pointer(*slot, entry);
817 65458 : if (xa_is_node(next) && (!node || node->shift))
818 0 : xas_free_nodes(xas, xa_to_node(next));
819 32729 : if (!node)
820 : break;
821 30517 : count += !next - !entry;
822 30517 : values += !xa_is_value(first) - !value;
823 30517 : if (entry) {
824 28641 : if (offset == max)
825 : break;
826 0 : if (!xa_is_sibling(entry))
827 0 : entry = xa_mk_sibling(xas->xa_offset);
828 : } else {
829 1876 : if (offset == XA_CHUNK_MASK)
830 : break;
831 : }
832 1857 : next = xa_entry_locked(xas->xa, node, ++offset);
833 1857 : if (!xa_is_sibling(next)) {
834 1857 : if (!entry && (offset > max))
835 : break;
836 : first = next;
837 : }
838 0 : slot++;
839 : }
840 :
841 32729 : update_node(xas, node, count, values);
842 32729 : return first;
843 : }
844 : EXPORT_SYMBOL_GPL(xas_store);
845 :
846 : /**
847 : * xas_get_mark() - Returns the state of this mark.
848 : * @xas: XArray operation state.
849 : * @mark: Mark number.
850 : *
851 : * Return: true if the mark is set, false if the mark is clear or @xas
852 : * is in an error state.
853 : */
854 0 : bool xas_get_mark(const struct xa_state *xas, xa_mark_t mark)
855 : {
856 0 : if (xas_invalid(xas))
857 : return false;
858 0 : if (!xas->xa_node)
859 0 : return xa_marked(xas->xa, mark);
860 0 : return node_get_mark(xas->xa_node, xas->xa_offset, mark);
861 : }
862 : EXPORT_SYMBOL_GPL(xas_get_mark);
863 :
864 : /**
865 : * xas_set_mark() - Sets the mark on this entry and its parents.
866 : * @xas: XArray operation state.
867 : * @mark: Mark number.
868 : *
869 : * Sets the specified mark on this entry, and walks up the tree setting it
870 : * on all the ancestor entries. Does nothing if @xas has not been walked to
871 : * an entry, or is in an error state.
872 : */
873 7715 : void xas_set_mark(const struct xa_state *xas, xa_mark_t mark)
874 : {
875 7715 : struct xa_node *node = xas->xa_node;
876 7715 : unsigned int offset = xas->xa_offset;
877 :
878 7715 : if (xas_invalid(xas))
879 : return;
880 :
881 13341 : while (node) {
882 8496 : if (node_set_mark(node, offset, mark))
883 : return;
884 5626 : offset = node->offset;
885 5626 : node = xa_parent_locked(xas->xa, node);
886 : }
887 :
888 4845 : if (!xa_marked(xas->xa, mark))
889 1431 : xa_mark_set(xas->xa, mark);
890 : }
891 : EXPORT_SYMBOL_GPL(xas_set_mark);
892 :
893 : /**
894 : * xas_clear_mark() - Clears the mark on this entry and its parents.
895 : * @xas: XArray operation state.
896 : * @mark: Mark number.
897 : *
898 : * Clears the specified mark on this entry, and walks back to the head
899 : * attempting to clear it on all the ancestor entries. Does nothing if
900 : * @xas has not been walked to an entry, or is in an error state.
901 : */
902 15137 : void xas_clear_mark(const struct xa_state *xas, xa_mark_t mark)
903 : {
904 15137 : struct xa_node *node = xas->xa_node;
905 15137 : unsigned int offset = xas->xa_offset;
906 :
907 15137 : if (xas_invalid(xas))
908 : return;
909 :
910 15914 : while (node) {
911 14129 : if (!node_clear_mark(node, offset, mark))
912 : return;
913 5478 : if (node_any_mark(node, mark))
914 : return;
915 :
916 786 : offset = node->offset;
917 786 : node = xa_parent_locked(xas->xa, node);
918 : }
919 :
920 1785 : if (xa_marked(xas->xa, mark))
921 956 : xa_mark_clear(xas->xa, mark);
922 : }
923 : EXPORT_SYMBOL_GPL(xas_clear_mark);
924 :
925 : /**
926 : * xas_init_marks() - Initialise all marks for the entry
927 : * @xas: Array operations state.
928 : *
929 : * Initialise all marks for the entry specified by @xas. If we're tracking
930 : * free entries with a mark, we need to set it on all entries. All other
931 : * marks are cleared.
932 : *
933 : * This implementation is not as efficient as it could be; we may walk
934 : * up the tree multiple times.
935 : */
936 2652 : void xas_init_marks(const struct xa_state *xas)
937 : {
938 2652 : xa_mark_t mark = 0;
939 :
940 13260 : for (;;) {
941 7956 : if (xa_track_free(xas->xa) && mark == XA_FREE_MARK)
942 1 : xas_set_mark(xas, mark);
943 : else
944 7955 : xas_clear_mark(xas, mark);
945 7956 : if (mark == XA_MARK_MAX)
946 : break;
947 5304 : mark_inc(mark);
948 : }
949 2652 : }
950 : EXPORT_SYMBOL_GPL(xas_init_marks);
951 :
952 : #ifdef CONFIG_XARRAY_MULTI
953 0 : static unsigned int node_get_marks(struct xa_node *node, unsigned int offset)
954 : {
955 0 : unsigned int marks = 0;
956 0 : xa_mark_t mark = XA_MARK_0;
957 :
958 0 : for (;;) {
959 0 : if (node_get_mark(node, offset, mark))
960 0 : marks |= 1 << (__force unsigned int)mark;
961 0 : if (mark == XA_MARK_MAX)
962 : break;
963 0 : mark_inc(mark);
964 : }
965 :
966 0 : return marks;
967 : }
968 :
969 0 : static void node_set_marks(struct xa_node *node, unsigned int offset,
970 : struct xa_node *child, unsigned int marks)
971 : {
972 0 : xa_mark_t mark = XA_MARK_0;
973 :
974 0 : for (;;) {
975 0 : if (marks & (1 << (__force unsigned int)mark)) {
976 0 : node_set_mark(node, offset, mark);
977 0 : if (child)
978 0 : node_mark_all(child, mark);
979 : }
980 0 : if (mark == XA_MARK_MAX)
981 : break;
982 0 : mark_inc(mark);
983 : }
984 0 : }
985 :
986 : /**
987 : * xas_split_alloc() - Allocate memory for splitting an entry.
988 : * @xas: XArray operation state.
989 : * @entry: New entry which will be stored in the array.
990 : * @order: New entry order.
991 : * @gfp: Memory allocation flags.
992 : *
993 : * This function should be called before calling xas_split().
994 : * If necessary, it will allocate new nodes (and fill them with @entry)
995 : * to prepare for the upcoming split of an entry of @order size into
996 : * entries of the order stored in the @xas.
997 : *
998 : * Context: May sleep if @gfp flags permit.
999 : */
1000 0 : void xas_split_alloc(struct xa_state *xas, void *entry, unsigned int order,
1001 : gfp_t gfp)
1002 : {
1003 0 : unsigned int sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1;
1004 0 : unsigned int mask = xas->xa_sibs;
1005 :
1006 : /* XXX: no support for splitting really large entries yet */
1007 0 : if (WARN_ON(xas->xa_shift + 2 * XA_CHUNK_SHIFT < order))
1008 0 : goto nomem;
1009 0 : if (xas->xa_shift + XA_CHUNK_SHIFT > order)
1010 : return;
1011 :
1012 0 : do {
1013 0 : unsigned int i;
1014 0 : void *sibling;
1015 0 : struct xa_node *node;
1016 :
1017 0 : node = kmem_cache_alloc(radix_tree_node_cachep, gfp);
1018 0 : if (!node)
1019 0 : goto nomem;
1020 0 : node->array = xas->xa;
1021 0 : for (i = 0; i < XA_CHUNK_SIZE; i++) {
1022 0 : if ((i & mask) == 0) {
1023 0 : RCU_INIT_POINTER(node->slots[i], entry);
1024 0 : sibling = xa_mk_sibling(0);
1025 : } else {
1026 0 : RCU_INIT_POINTER(node->slots[i], sibling);
1027 : }
1028 : }
1029 0 : RCU_INIT_POINTER(node->parent, xas->xa_alloc);
1030 0 : xas->xa_alloc = node;
1031 0 : } while (sibs-- > 0);
1032 :
1033 : return;
1034 0 : nomem:
1035 0 : xas_destroy(xas);
1036 0 : xas_set_err(xas, -ENOMEM);
1037 : }
1038 : EXPORT_SYMBOL_GPL(xas_split_alloc);
1039 :
1040 : /**
1041 : * xas_split() - Split a multi-index entry into smaller entries.
1042 : * @xas: XArray operation state.
1043 : * @entry: New entry to store in the array.
1044 : * @order: New entry order.
1045 : *
1046 : * The value in the entry is copied to all the replacement entries.
1047 : *
1048 : * Context: Any context. The caller should hold the xa_lock.
1049 : */
1050 0 : void xas_split(struct xa_state *xas, void *entry, unsigned int order)
1051 : {
1052 0 : unsigned int sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1;
1053 0 : unsigned int offset, marks;
1054 0 : struct xa_node *node;
1055 0 : void *curr = xas_load(xas);
1056 0 : int values = 0;
1057 :
1058 0 : node = xas->xa_node;
1059 0 : if (xas_top(node))
1060 : return;
1061 :
1062 0 : marks = node_get_marks(node, xas->xa_offset);
1063 :
1064 0 : offset = xas->xa_offset + sibs;
1065 0 : do {
1066 0 : if (xas->xa_shift < node->shift) {
1067 0 : struct xa_node *child = xas->xa_alloc;
1068 :
1069 0 : xas->xa_alloc = rcu_dereference_raw(child->parent);
1070 0 : child->shift = node->shift - XA_CHUNK_SHIFT;
1071 0 : child->offset = offset;
1072 0 : child->count = XA_CHUNK_SIZE;
1073 0 : child->nr_values = xa_is_value(entry) ?
1074 : XA_CHUNK_SIZE : 0;
1075 0 : RCU_INIT_POINTER(child->parent, node);
1076 0 : node_set_marks(node, offset, child, marks);
1077 0 : rcu_assign_pointer(node->slots[offset],
1078 : xa_mk_node(child));
1079 0 : if (xa_is_value(curr))
1080 0 : values--;
1081 : } else {
1082 0 : unsigned int canon = offset - xas->xa_sibs;
1083 :
1084 0 : node_set_marks(node, canon, NULL, marks);
1085 0 : rcu_assign_pointer(node->slots[canon], entry);
1086 0 : while (offset > canon)
1087 0 : rcu_assign_pointer(node->slots[offset--],
1088 : xa_mk_sibling(canon));
1089 0 : values += (xa_is_value(entry) - xa_is_value(curr)) *
1090 0 : (xas->xa_sibs + 1);
1091 : }
1092 0 : } while (offset-- > xas->xa_offset);
1093 :
1094 0 : node->nr_values += values;
1095 : }
1096 : EXPORT_SYMBOL_GPL(xas_split);
1097 : #endif
1098 :
1099 : /**
1100 : * xas_pause() - Pause a walk to drop a lock.
1101 : * @xas: XArray operation state.
1102 : *
1103 : * Some users need to pause a walk and drop the lock they're holding in
1104 : * order to yield to a higher priority thread or carry out an operation
1105 : * on an entry. Those users should call this function before they drop
1106 : * the lock. It resets the @xas to be suitable for the next iteration
1107 : * of the loop after the user has reacquired the lock. If most entries
1108 : * found during a walk require you to call xas_pause(), the xa_for_each()
1109 : * iterator may be more appropriate.
1110 : *
1111 : * Note that xas_pause() only works for forward iteration. If a user needs
1112 : * to pause a reverse iteration, we will need a xas_pause_rev().
1113 : */
1114 0 : void xas_pause(struct xa_state *xas)
1115 : {
1116 0 : struct xa_node *node = xas->xa_node;
1117 :
1118 0 : if (xas_invalid(xas))
1119 : return;
1120 :
1121 0 : xas->xa_node = XAS_RESTART;
1122 0 : if (node) {
1123 0 : unsigned long offset = xas->xa_offset;
1124 0 : while (++offset < XA_CHUNK_SIZE) {
1125 0 : if (!xa_is_sibling(xa_entry(xas->xa, node, offset)))
1126 : break;
1127 : }
1128 0 : xas->xa_index += (offset - xas->xa_offset) << node->shift;
1129 0 : if (xas->xa_index == 0)
1130 0 : xas->xa_node = XAS_BOUNDS;
1131 : } else {
1132 0 : xas->xa_index++;
1133 : }
1134 : }
1135 : EXPORT_SYMBOL_GPL(xas_pause);
1136 :
1137 : /*
1138 : * __xas_prev() - Find the previous entry in the XArray.
1139 : * @xas: XArray operation state.
1140 : *
1141 : * Helper function for xas_prev() which handles all the complex cases
1142 : * out of line.
1143 : */
1144 1 : void *__xas_prev(struct xa_state *xas)
1145 : {
1146 1 : void *entry;
1147 :
1148 1 : if (!xas_frozen(xas->xa_node))
1149 0 : xas->xa_index--;
1150 1 : if (!xas->xa_node)
1151 0 : return set_bounds(xas);
1152 1 : if (xas_not_node(xas->xa_node))
1153 1 : return xas_load(xas);
1154 :
1155 0 : if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node))
1156 0 : xas->xa_offset--;
1157 :
1158 0 : while (xas->xa_offset == 255) {
1159 0 : xas->xa_offset = xas->xa_node->offset - 1;
1160 0 : xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1161 0 : if (!xas->xa_node)
1162 0 : return set_bounds(xas);
1163 : }
1164 :
1165 0 : for (;;) {
1166 0 : entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1167 0 : if (!xa_is_node(entry))
1168 0 : return entry;
1169 :
1170 0 : xas->xa_node = xa_to_node(entry);
1171 0 : xas_set_offset(xas);
1172 : }
1173 : }
1174 : EXPORT_SYMBOL_GPL(__xas_prev);
1175 :
1176 : /*
1177 : * __xas_next() - Find the next entry in the XArray.
1178 : * @xas: XArray operation state.
1179 : *
1180 : * Helper function for xas_next() which handles all the complex cases
1181 : * out of line.
1182 : */
1183 5276 : void *__xas_next(struct xa_state *xas)
1184 : {
1185 5276 : void *entry;
1186 :
1187 5276 : if (!xas_frozen(xas->xa_node))
1188 5020 : xas->xa_index++;
1189 5276 : if (!xas->xa_node)
1190 4920 : return set_bounds(xas);
1191 456 : if (xas_not_node(xas->xa_node))
1192 256 : return xas_load(xas);
1193 :
1194 100 : if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node))
1195 100 : xas->xa_offset++;
1196 :
1197 222 : while (xas->xa_offset == XA_CHUNK_SIZE) {
1198 122 : xas->xa_offset = xas->xa_node->offset + 1;
1199 122 : xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1200 122 : if (!xas->xa_node)
1201 0 : return set_bounds(xas);
1202 : }
1203 :
1204 171 : for (;;) {
1205 342 : entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1206 342 : if (!xa_is_node(entry))
1207 100 : return entry;
1208 :
1209 71 : xas->xa_node = xa_to_node(entry);
1210 171 : xas_set_offset(xas);
1211 : }
1212 : }
1213 : EXPORT_SYMBOL_GPL(__xas_next);
1214 :
1215 : /**
1216 : * xas_find() - Find the next present entry in the XArray.
1217 : * @xas: XArray operation state.
1218 : * @max: Highest index to return.
1219 : *
1220 : * If the @xas has not yet been walked to an entry, return the entry
1221 : * which has an index >= xas.xa_index. If it has been walked, the entry
1222 : * currently being pointed at has been processed, and so we move to the
1223 : * next entry.
1224 : *
1225 : * If no entry is found and the array is smaller than @max, the iterator
1226 : * is set to the smallest index not yet in the array. This allows @xas
1227 : * to be immediately passed to xas_store().
1228 : *
1229 : * Return: The entry, if found, otherwise %NULL.
1230 : */
1231 278605 : void *xas_find(struct xa_state *xas, unsigned long max)
1232 : {
1233 278605 : void *entry;
1234 :
1235 557210 : if (xas_error(xas) || xas->xa_node == XAS_BOUNDS)
1236 : return NULL;
1237 278532 : if (xas->xa_index > max)
1238 0 : return set_bounds(xas);
1239 :
1240 278532 : if (!xas->xa_node) {
1241 603 : xas->xa_index = 1;
1242 603 : return set_bounds(xas);
1243 277929 : } else if (xas->xa_node == XAS_RESTART) {
1244 130056 : entry = xas_load(xas);
1245 131663 : if (entry || xas_not_node(xas->xa_node))
1246 : return entry;
1247 147873 : } else if (!xas->xa_node->shift &&
1248 147864 : xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)) {
1249 0 : xas->xa_offset = ((xas->xa_index - 1) & XA_CHUNK_MASK) + 1;
1250 : }
1251 :
1252 148288 : xas_advance(xas);
1253 :
1254 198797 : while (xas->xa_node && (xas->xa_index <= max)) {
1255 73432 : if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
1256 19950 : xas->xa_offset = xas->xa_node->offset + 1;
1257 19950 : xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1258 19950 : continue;
1259 : }
1260 :
1261 53482 : entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1262 106964 : if (xa_is_node(entry)) {
1263 19701 : xas->xa_node = xa_to_node(entry);
1264 19701 : xas->xa_offset = 0;
1265 19701 : continue;
1266 : }
1267 56704 : if (entry && !xa_is_sibling(entry))
1268 22923 : return entry;
1269 :
1270 10858 : xas_advance(xas);
1271 : }
1272 :
1273 125365 : if (!xas->xa_node)
1274 160 : xas->xa_node = XAS_BOUNDS;
1275 : return NULL;
1276 : }
1277 : EXPORT_SYMBOL_GPL(xas_find);
1278 :
1279 : /**
1280 : * xas_find_marked() - Find the next marked entry in the XArray.
1281 : * @xas: XArray operation state.
1282 : * @max: Highest index to return.
1283 : * @mark: Mark number to search for.
1284 : *
1285 : * If the @xas has not yet been walked to an entry, return the marked entry
1286 : * which has an index >= xas.xa_index. If it has been walked, the entry
1287 : * currently being pointed at has been processed, and so we return the
1288 : * first marked entry with an index > xas.xa_index.
1289 : *
1290 : * If no marked entry is found and the array is smaller than @max, @xas is
1291 : * set to the bounds state and xas->xa_index is set to the smallest index
1292 : * not yet in the array. This allows @xas to be immediately passed to
1293 : * xas_store().
1294 : *
1295 : * If no entry is found before @max is reached, @xas is set to the restart
1296 : * state.
1297 : *
1298 : * Return: The entry, if found, otherwise %NULL.
1299 : */
1300 7090 : void *xas_find_marked(struct xa_state *xas, unsigned long max, xa_mark_t mark)
1301 : {
1302 7090 : bool advance = true;
1303 7090 : unsigned int offset;
1304 7090 : void *entry;
1305 :
1306 7090 : if (xas_error(xas))
1307 : return NULL;
1308 7090 : if (xas->xa_index > max)
1309 0 : goto max;
1310 :
1311 7090 : if (!xas->xa_node) {
1312 494 : xas->xa_index = 1;
1313 494 : goto out;
1314 6596 : } else if (xas_top(xas->xa_node)) {
1315 3007 : advance = false;
1316 3007 : entry = xa_head(xas->xa);
1317 3007 : xas->xa_node = NULL;
1318 3007 : if (xas->xa_index > max_index(entry))
1319 2 : goto out;
1320 6010 : if (!xa_is_node(entry)) {
1321 2331 : if (xa_marked(xas->xa, mark))
1322 : return entry;
1323 7 : xas->xa_index = 1;
1324 7 : goto out;
1325 : }
1326 674 : xas->xa_node = xa_to_node(entry);
1327 674 : xas->xa_offset = xas->xa_index >> xas->xa_node->shift;
1328 : }
1329 :
1330 5335 : while (xas->xa_index <= max) {
1331 5335 : if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
1332 521 : xas->xa_offset = xas->xa_node->offset + 1;
1333 521 : xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1334 521 : if (!xas->xa_node)
1335 : break;
1336 150 : advance = false;
1337 150 : continue;
1338 : }
1339 :
1340 4814 : if (!advance) {
1341 1258 : entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1342 1681 : if (xa_is_sibling(entry)) {
1343 0 : xas->xa_offset = xa_to_sibling(entry);
1344 0 : xas_move_index(xas, xas->xa_offset);
1345 : }
1346 : }
1347 :
1348 4814 : offset = xas_find_chunk(xas, advance, mark);
1349 4814 : if (offset > xas->xa_offset) {
1350 3897 : advance = false;
1351 3897 : xas_move_index(xas, offset);
1352 : /* Mind the wrap */
1353 3897 : if ((xas->xa_index - 1) >= max)
1354 128 : goto max;
1355 3769 : xas->xa_offset = offset;
1356 3769 : if (offset == XA_CHUNK_SIZE)
1357 488 : continue;
1358 : }
1359 :
1360 4198 : entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1361 4198 : if (!entry && !(xa_track_free(xas->xa) && mark == XA_FREE_MARK))
1362 0 : continue;
1363 8396 : if (!xa_is_node(entry))
1364 3764 : return entry;
1365 434 : xas->xa_node = xa_to_node(entry);
1366 5769 : xas_set_offset(xas);
1367 : }
1368 :
1369 371 : out:
1370 874 : if (xas->xa_index > max)
1371 3 : goto max;
1372 871 : return set_bounds(xas);
1373 131 : max:
1374 131 : xas->xa_node = XAS_RESTART;
1375 131 : return NULL;
1376 : }
1377 : EXPORT_SYMBOL_GPL(xas_find_marked);
1378 :
1379 : /**
1380 : * xas_find_conflict() - Find the next present entry in a range.
1381 : * @xas: XArray operation state.
1382 : *
1383 : * The @xas describes both a range and a position within that range.
1384 : *
1385 : * Context: Any context. Expects xa_lock to be held.
1386 : * Return: The next entry in the range covered by @xas or %NULL.
1387 : */
1388 30273 : void *xas_find_conflict(struct xa_state *xas)
1389 : {
1390 30273 : void *curr;
1391 :
1392 30273 : if (xas_error(xas))
1393 : return NULL;
1394 :
1395 30273 : if (!xas->xa_node)
1396 : return NULL;
1397 :
1398 30273 : if (xas_top(xas->xa_node)) {
1399 30273 : curr = xas_start(xas);
1400 30274 : if (!curr)
1401 : return NULL;
1402 179032 : while (xa_is_node(curr)) {
1403 61535 : struct xa_node *node = xa_to_node(curr);
1404 61535 : curr = xas_descend(xas, node);
1405 : }
1406 27981 : if (curr)
1407 : return curr;
1408 : }
1409 :
1410 27981 : if (xas->xa_node->shift > xas->xa_shift)
1411 : return NULL;
1412 :
1413 27527 : for (;;) {
1414 27527 : if (xas->xa_node->shift == xas->xa_shift) {
1415 27527 : if ((xas->xa_offset & xas->xa_sibs) == xas->xa_sibs)
1416 : break;
1417 0 : } else if (xas->xa_offset == XA_CHUNK_MASK) {
1418 0 : xas->xa_offset = xas->xa_node->offset;
1419 0 : xas->xa_node = xa_parent_locked(xas->xa, xas->xa_node);
1420 0 : if (!xas->xa_node)
1421 : break;
1422 0 : continue;
1423 : }
1424 0 : curr = xa_entry_locked(xas->xa, xas->xa_node, ++xas->xa_offset);
1425 0 : if (xa_is_sibling(curr))
1426 0 : continue;
1427 0 : while (xa_is_node(curr)) {
1428 0 : xas->xa_node = xa_to_node(curr);
1429 0 : xas->xa_offset = 0;
1430 0 : curr = xa_entry_locked(xas->xa, xas->xa_node, 0);
1431 : }
1432 0 : if (curr)
1433 0 : return curr;
1434 : }
1435 27527 : xas->xa_offset -= xas->xa_sibs;
1436 27527 : return NULL;
1437 : }
1438 : EXPORT_SYMBOL_GPL(xas_find_conflict);
1439 :
1440 : /**
1441 : * xa_load() - Load an entry from an XArray.
1442 : * @xa: XArray.
1443 : * @index: index into array.
1444 : *
1445 : * Context: Any context. Takes and releases the RCU lock.
1446 : * Return: The entry at @index in @xa.
1447 : */
1448 48409 : void *xa_load(struct xarray *xa, unsigned long index)
1449 : {
1450 48409 : XA_STATE(xas, xa, index);
1451 48409 : void *entry;
1452 :
1453 48409 : rcu_read_lock();
1454 48408 : do {
1455 96817 : entry = xas_load(&xas);
1456 48409 : if (xa_is_zero(entry))
1457 0 : entry = NULL;
1458 96817 : } while (xas_retry(&xas, entry));
1459 48409 : rcu_read_unlock();
1460 :
1461 48409 : return entry;
1462 : }
1463 : EXPORT_SYMBOL(xa_load);
1464 :
1465 4 : static void *xas_result(struct xa_state *xas, void *curr)
1466 : {
1467 4 : if (xa_is_zero(curr))
1468 : return NULL;
1469 4 : if (xas_error(xas))
1470 0 : curr = xas->xa_node;
1471 : return curr;
1472 : }
1473 :
1474 : /**
1475 : * __xa_erase() - Erase this entry from the XArray while locked.
1476 : * @xa: XArray.
1477 : * @index: Index into array.
1478 : *
1479 : * After this function returns, loading from @index will return %NULL.
1480 : * If the index is part of a multi-index entry, all indices will be erased
1481 : * and none of the entries will be part of a multi-index entry.
1482 : *
1483 : * Context: Any context. Expects xa_lock to be held on entry.
1484 : * Return: The entry which used to be at this index.
1485 : */
1486 0 : void *__xa_erase(struct xarray *xa, unsigned long index)
1487 : {
1488 0 : XA_STATE(xas, xa, index);
1489 0 : return xas_result(&xas, xas_store(&xas, NULL));
1490 : }
1491 : EXPORT_SYMBOL(__xa_erase);
1492 :
1493 : /**
1494 : * xa_erase() - Erase this entry from the XArray.
1495 : * @xa: XArray.
1496 : * @index: Index of entry.
1497 : *
1498 : * After this function returns, loading from @index will return %NULL.
1499 : * If the index is part of a multi-index entry, all indices will be erased
1500 : * and none of the entries will be part of a multi-index entry.
1501 : *
1502 : * Context: Any context. Takes and releases the xa_lock.
1503 : * Return: The entry which used to be at this index.
1504 : */
1505 0 : void *xa_erase(struct xarray *xa, unsigned long index)
1506 : {
1507 0 : void *entry;
1508 :
1509 0 : xa_lock(xa);
1510 0 : entry = __xa_erase(xa, index);
1511 0 : xa_unlock(xa);
1512 :
1513 0 : return entry;
1514 : }
1515 : EXPORT_SYMBOL(xa_erase);
1516 :
1517 : /**
1518 : * __xa_store() - Store this entry in the XArray.
1519 : * @xa: XArray.
1520 : * @index: Index into array.
1521 : * @entry: New entry.
1522 : * @gfp: Memory allocation flags.
1523 : *
1524 : * You must already be holding the xa_lock when calling this function.
1525 : * It will drop the lock if needed to allocate memory, and then reacquire
1526 : * it afterwards.
1527 : *
1528 : * Context: Any context. Expects xa_lock to be held on entry. May
1529 : * release and reacquire xa_lock if @gfp flags permit.
1530 : * Return: The old entry at this index or xa_err() if an error happened.
1531 : */
1532 4 : void *__xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1533 : {
1534 4 : XA_STATE(xas, xa, index);
1535 4 : void *curr;
1536 :
1537 4 : if (WARN_ON_ONCE(xa_is_advanced(entry)))
1538 : return XA_ERROR(-EINVAL);
1539 4 : if (xa_track_free(xa) && !entry)
1540 0 : entry = XA_ZERO_ENTRY;
1541 :
1542 4 : do {
1543 4 : curr = xas_store(&xas, entry);
1544 4 : if (xa_track_free(xa))
1545 0 : xas_clear_mark(&xas, XA_FREE_MARK);
1546 4 : } while (__xas_nomem(&xas, gfp));
1547 :
1548 4 : return xas_result(&xas, curr);
1549 : }
1550 : EXPORT_SYMBOL(__xa_store);
1551 :
1552 : /**
1553 : * xa_store() - Store this entry in the XArray.
1554 : * @xa: XArray.
1555 : * @index: Index into array.
1556 : * @entry: New entry.
1557 : * @gfp: Memory allocation flags.
1558 : *
1559 : * After this function returns, loads from this index will return @entry.
1560 : * Storing into an existing multi-index entry updates the entry of every index.
1561 : * The marks associated with @index are unaffected unless @entry is %NULL.
1562 : *
1563 : * Context: Any context. Takes and releases the xa_lock.
1564 : * May sleep if the @gfp flags permit.
1565 : * Return: The old entry at this index on success, xa_err(-EINVAL) if @entry
1566 : * cannot be stored in an XArray, or xa_err(-ENOMEM) if memory allocation
1567 : * failed.
1568 : */
1569 4 : void *xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1570 : {
1571 4 : void *curr;
1572 :
1573 4 : xa_lock(xa);
1574 4 : curr = __xa_store(xa, index, entry, gfp);
1575 4 : xa_unlock(xa);
1576 :
1577 4 : return curr;
1578 : }
1579 : EXPORT_SYMBOL(xa_store);
1580 :
1581 : /**
1582 : * __xa_cmpxchg() - Store this entry in the XArray.
1583 : * @xa: XArray.
1584 : * @index: Index into array.
1585 : * @old: Old value to test against.
1586 : * @entry: New entry.
1587 : * @gfp: Memory allocation flags.
1588 : *
1589 : * You must already be holding the xa_lock when calling this function.
1590 : * It will drop the lock if needed to allocate memory, and then reacquire
1591 : * it afterwards.
1592 : *
1593 : * Context: Any context. Expects xa_lock to be held on entry. May
1594 : * release and reacquire xa_lock if @gfp flags permit.
1595 : * Return: The old entry at this index or xa_err() if an error happened.
1596 : */
1597 0 : void *__xa_cmpxchg(struct xarray *xa, unsigned long index,
1598 : void *old, void *entry, gfp_t gfp)
1599 : {
1600 0 : XA_STATE(xas, xa, index);
1601 0 : void *curr;
1602 :
1603 0 : if (WARN_ON_ONCE(xa_is_advanced(entry)))
1604 : return XA_ERROR(-EINVAL);
1605 :
1606 0 : do {
1607 0 : curr = xas_load(&xas);
1608 0 : if (curr == old) {
1609 0 : xas_store(&xas, entry);
1610 0 : if (xa_track_free(xa) && entry && !curr)
1611 0 : xas_clear_mark(&xas, XA_FREE_MARK);
1612 : }
1613 0 : } while (__xas_nomem(&xas, gfp));
1614 :
1615 0 : return xas_result(&xas, curr);
1616 : }
1617 : EXPORT_SYMBOL(__xa_cmpxchg);
1618 :
1619 : /**
1620 : * __xa_insert() - Store this entry in the XArray if no entry is present.
1621 : * @xa: XArray.
1622 : * @index: Index into array.
1623 : * @entry: New entry.
1624 : * @gfp: Memory allocation flags.
1625 : *
1626 : * Inserting a NULL entry will store a reserved entry (like xa_reserve())
1627 : * if no entry is present. Inserting will fail if a reserved entry is
1628 : * present, even though loading from this index will return NULL.
1629 : *
1630 : * Context: Any context. Expects xa_lock to be held on entry. May
1631 : * release and reacquire xa_lock if @gfp flags permit.
1632 : * Return: 0 if the store succeeded. -EBUSY if another entry was present.
1633 : * -ENOMEM if memory could not be allocated.
1634 : */
1635 10 : int __xa_insert(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1636 : {
1637 10 : XA_STATE(xas, xa, index);
1638 10 : void *curr;
1639 :
1640 10 : if (WARN_ON_ONCE(xa_is_advanced(entry)))
1641 : return -EINVAL;
1642 10 : if (!entry)
1643 0 : entry = XA_ZERO_ENTRY;
1644 :
1645 10 : do {
1646 10 : curr = xas_load(&xas);
1647 10 : if (!curr) {
1648 10 : xas_store(&xas, entry);
1649 10 : if (xa_track_free(xa))
1650 0 : xas_clear_mark(&xas, XA_FREE_MARK);
1651 : } else {
1652 0 : xas_set_err(&xas, -EBUSY);
1653 : }
1654 10 : } while (__xas_nomem(&xas, gfp));
1655 :
1656 10 : return xas_error(&xas);
1657 : }
1658 : EXPORT_SYMBOL(__xa_insert);
1659 :
1660 : #ifdef CONFIG_XARRAY_MULTI
1661 0 : static void xas_set_range(struct xa_state *xas, unsigned long first,
1662 : unsigned long last)
1663 : {
1664 0 : unsigned int shift = 0;
1665 0 : unsigned long sibs = last - first;
1666 0 : unsigned int offset = XA_CHUNK_MASK;
1667 :
1668 0 : xas_set(xas, first);
1669 :
1670 0 : while ((first & XA_CHUNK_MASK) == 0) {
1671 0 : if (sibs < XA_CHUNK_MASK)
1672 : break;
1673 0 : if ((sibs == XA_CHUNK_MASK) && (offset < XA_CHUNK_MASK))
1674 : break;
1675 0 : shift += XA_CHUNK_SHIFT;
1676 0 : if (offset == XA_CHUNK_MASK)
1677 0 : offset = sibs & XA_CHUNK_MASK;
1678 0 : sibs >>= XA_CHUNK_SHIFT;
1679 0 : first >>= XA_CHUNK_SHIFT;
1680 : }
1681 :
1682 0 : offset = first & XA_CHUNK_MASK;
1683 0 : if (offset + sibs > XA_CHUNK_MASK)
1684 0 : sibs = XA_CHUNK_MASK - offset;
1685 0 : if ((((first + sibs + 1) << shift) - 1) > last)
1686 0 : sibs -= 1;
1687 :
1688 0 : xas->xa_shift = shift;
1689 0 : xas->xa_sibs = sibs;
1690 0 : }
1691 :
1692 : /**
1693 : * xa_store_range() - Store this entry at a range of indices in the XArray.
1694 : * @xa: XArray.
1695 : * @first: First index to affect.
1696 : * @last: Last index to affect.
1697 : * @entry: New entry.
1698 : * @gfp: Memory allocation flags.
1699 : *
1700 : * After this function returns, loads from any index between @first and @last,
1701 : * inclusive will return @entry.
1702 : * Storing into an existing multi-index entry updates the entry of every index.
1703 : * The marks associated with @index are unaffected unless @entry is %NULL.
1704 : *
1705 : * Context: Process context. Takes and releases the xa_lock. May sleep
1706 : * if the @gfp flags permit.
1707 : * Return: %NULL on success, xa_err(-EINVAL) if @entry cannot be stored in
1708 : * an XArray, or xa_err(-ENOMEM) if memory allocation failed.
1709 : */
1710 0 : void *xa_store_range(struct xarray *xa, unsigned long first,
1711 : unsigned long last, void *entry, gfp_t gfp)
1712 : {
1713 0 : XA_STATE(xas, xa, 0);
1714 :
1715 0 : if (WARN_ON_ONCE(xa_is_internal(entry)))
1716 : return XA_ERROR(-EINVAL);
1717 0 : if (last < first)
1718 : return XA_ERROR(-EINVAL);
1719 :
1720 0 : do {
1721 0 : xas_lock(&xas);
1722 0 : if (entry) {
1723 0 : unsigned int order = BITS_PER_LONG;
1724 0 : if (last + 1)
1725 0 : order = __ffs(last + 1);
1726 0 : xas_set_order(&xas, last, order);
1727 0 : xas_create(&xas, true);
1728 0 : if (xas_error(&xas))
1729 0 : goto unlock;
1730 : }
1731 0 : do {
1732 0 : xas_set_range(&xas, first, last);
1733 0 : xas_store(&xas, entry);
1734 0 : if (xas_error(&xas))
1735 0 : goto unlock;
1736 0 : first += xas_size(&xas);
1737 0 : } while (first <= last);
1738 0 : unlock:
1739 0 : xas_unlock(&xas);
1740 0 : } while (xas_nomem(&xas, gfp));
1741 :
1742 0 : return xas_result(&xas, NULL);
1743 : }
1744 : EXPORT_SYMBOL(xa_store_range);
1745 :
1746 : /**
1747 : * xa_get_order() - Get the order of an entry.
1748 : * @xa: XArray.
1749 : * @index: Index of the entry.
1750 : *
1751 : * Return: A number between 0 and 63 indicating the order of the entry.
1752 : */
1753 28288 : int xa_get_order(struct xarray *xa, unsigned long index)
1754 : {
1755 28288 : XA_STATE(xas, xa, index);
1756 28288 : void *entry;
1757 28288 : int order = 0;
1758 :
1759 28288 : rcu_read_lock();
1760 28288 : entry = xas_load(&xas);
1761 :
1762 28288 : if (!entry)
1763 28288 : goto unlock;
1764 :
1765 0 : if (!xas.xa_node)
1766 0 : goto unlock;
1767 :
1768 0 : for (;;) {
1769 0 : unsigned int slot = xas.xa_offset + (1 << order);
1770 :
1771 0 : if (slot >= XA_CHUNK_SIZE)
1772 : break;
1773 0 : if (!xa_is_sibling(xas.xa_node->slots[slot]))
1774 : break;
1775 0 : order++;
1776 : }
1777 :
1778 0 : order += xas.xa_node->shift;
1779 28288 : unlock:
1780 28288 : rcu_read_unlock();
1781 :
1782 28288 : return order;
1783 : }
1784 : EXPORT_SYMBOL(xa_get_order);
1785 : #endif /* CONFIG_XARRAY_MULTI */
1786 :
1787 : /**
1788 : * __xa_alloc() - Find somewhere to store this entry in the XArray.
1789 : * @xa: XArray.
1790 : * @id: Pointer to ID.
1791 : * @limit: Range for allocated ID.
1792 : * @entry: New entry.
1793 : * @gfp: Memory allocation flags.
1794 : *
1795 : * Finds an empty entry in @xa between @limit.min and @limit.max,
1796 : * stores the index into the @id pointer, then stores the entry at
1797 : * that index. A concurrent lookup will not see an uninitialised @id.
1798 : *
1799 : * Context: Any context. Expects xa_lock to be held on entry. May
1800 : * release and reacquire xa_lock if @gfp flags permit.
1801 : * Return: 0 on success, -ENOMEM if memory could not be allocated or
1802 : * -EBUSY if there are no free entries in @limit.
1803 : */
1804 0 : int __xa_alloc(struct xarray *xa, u32 *id, void *entry,
1805 : struct xa_limit limit, gfp_t gfp)
1806 : {
1807 0 : XA_STATE(xas, xa, 0);
1808 :
1809 0 : if (WARN_ON_ONCE(xa_is_advanced(entry)))
1810 : return -EINVAL;
1811 0 : if (WARN_ON_ONCE(!xa_track_free(xa)))
1812 : return -EINVAL;
1813 :
1814 0 : if (!entry)
1815 0 : entry = XA_ZERO_ENTRY;
1816 :
1817 0 : do {
1818 0 : xas.xa_index = limit.min;
1819 0 : xas_find_marked(&xas, limit.max, XA_FREE_MARK);
1820 0 : if (xas.xa_node == XAS_RESTART)
1821 0 : xas_set_err(&xas, -EBUSY);
1822 : else
1823 0 : *id = xas.xa_index;
1824 0 : xas_store(&xas, entry);
1825 0 : xas_clear_mark(&xas, XA_FREE_MARK);
1826 0 : } while (__xas_nomem(&xas, gfp));
1827 :
1828 0 : return xas_error(&xas);
1829 : }
1830 : EXPORT_SYMBOL(__xa_alloc);
1831 :
1832 : /**
1833 : * __xa_alloc_cyclic() - Find somewhere to store this entry in the XArray.
1834 : * @xa: XArray.
1835 : * @id: Pointer to ID.
1836 : * @entry: New entry.
1837 : * @limit: Range of allocated ID.
1838 : * @next: Pointer to next ID to allocate.
1839 : * @gfp: Memory allocation flags.
1840 : *
1841 : * Finds an empty entry in @xa between @limit.min and @limit.max,
1842 : * stores the index into the @id pointer, then stores the entry at
1843 : * that index. A concurrent lookup will not see an uninitialised @id.
1844 : * The search for an empty entry will start at @next and will wrap
1845 : * around if necessary.
1846 : *
1847 : * Context: Any context. Expects xa_lock to be held on entry. May
1848 : * release and reacquire xa_lock if @gfp flags permit.
1849 : * Return: 0 if the allocation succeeded without wrapping. 1 if the
1850 : * allocation succeeded after wrapping, -ENOMEM if memory could not be
1851 : * allocated or -EBUSY if there are no free entries in @limit.
1852 : */
1853 0 : int __xa_alloc_cyclic(struct xarray *xa, u32 *id, void *entry,
1854 : struct xa_limit limit, u32 *next, gfp_t gfp)
1855 : {
1856 0 : u32 min = limit.min;
1857 0 : int ret;
1858 :
1859 0 : limit.min = max(min, *next);
1860 0 : ret = __xa_alloc(xa, id, entry, limit, gfp);
1861 0 : if ((xa->xa_flags & XA_FLAGS_ALLOC_WRAPPED) && ret == 0) {
1862 0 : xa->xa_flags &= ~XA_FLAGS_ALLOC_WRAPPED;
1863 0 : ret = 1;
1864 : }
1865 :
1866 0 : if (ret < 0 && limit.min > min) {
1867 0 : limit.min = min;
1868 0 : ret = __xa_alloc(xa, id, entry, limit, gfp);
1869 0 : if (ret == 0)
1870 : ret = 1;
1871 : }
1872 :
1873 0 : if (ret >= 0) {
1874 0 : *next = *id + 1;
1875 0 : if (*next == 0)
1876 0 : xa->xa_flags |= XA_FLAGS_ALLOC_WRAPPED;
1877 : }
1878 0 : return ret;
1879 : }
1880 : EXPORT_SYMBOL(__xa_alloc_cyclic);
1881 :
1882 : /**
1883 : * __xa_set_mark() - Set this mark on this entry while locked.
1884 : * @xa: XArray.
1885 : * @index: Index of entry.
1886 : * @mark: Mark number.
1887 : *
1888 : * Attempting to set a mark on a %NULL entry does not succeed.
1889 : *
1890 : * Context: Any context. Expects xa_lock to be held on entry.
1891 : */
1892 3681 : void __xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1893 : {
1894 3681 : XA_STATE(xas, xa, index);
1895 3681 : void *entry = xas_load(&xas);
1896 :
1897 3681 : if (entry)
1898 3681 : xas_set_mark(&xas, mark);
1899 3681 : }
1900 : EXPORT_SYMBOL(__xa_set_mark);
1901 :
1902 : /**
1903 : * __xa_clear_mark() - Clear this mark on this entry while locked.
1904 : * @xa: XArray.
1905 : * @index: Index of entry.
1906 : * @mark: Mark number.
1907 : *
1908 : * Context: Any context. Expects xa_lock to be held on entry.
1909 : */
1910 2394 : void __xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1911 : {
1912 2394 : XA_STATE(xas, xa, index);
1913 2394 : void *entry = xas_load(&xas);
1914 :
1915 2394 : if (entry)
1916 2394 : xas_clear_mark(&xas, mark);
1917 2394 : }
1918 : EXPORT_SYMBOL(__xa_clear_mark);
1919 :
1920 : /**
1921 : * xa_get_mark() - Inquire whether this mark is set on this entry.
1922 : * @xa: XArray.
1923 : * @index: Index of entry.
1924 : * @mark: Mark number.
1925 : *
1926 : * This function uses the RCU read lock, so the result may be out of date
1927 : * by the time it returns. If you need the result to be stable, use a lock.
1928 : *
1929 : * Context: Any context. Takes and releases the RCU lock.
1930 : * Return: True if the entry at @index has this mark set, false if it doesn't.
1931 : */
1932 0 : bool xa_get_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1933 : {
1934 0 : XA_STATE(xas, xa, index);
1935 0 : void *entry;
1936 :
1937 0 : rcu_read_lock();
1938 0 : entry = xas_start(&xas);
1939 0 : while (xas_get_mark(&xas, mark)) {
1940 0 : if (!xa_is_node(entry))
1941 0 : goto found;
1942 0 : entry = xas_descend(&xas, xa_to_node(entry));
1943 : }
1944 0 : rcu_read_unlock();
1945 0 : return false;
1946 0 : found:
1947 0 : rcu_read_unlock();
1948 0 : return true;
1949 : }
1950 : EXPORT_SYMBOL(xa_get_mark);
1951 :
1952 : /**
1953 : * xa_set_mark() - Set this mark on this entry.
1954 : * @xa: XArray.
1955 : * @index: Index of entry.
1956 : * @mark: Mark number.
1957 : *
1958 : * Attempting to set a mark on a %NULL entry does not succeed.
1959 : *
1960 : * Context: Process context. Takes and releases the xa_lock.
1961 : */
1962 0 : void xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1963 : {
1964 0 : xa_lock(xa);
1965 0 : __xa_set_mark(xa, index, mark);
1966 0 : xa_unlock(xa);
1967 0 : }
1968 : EXPORT_SYMBOL(xa_set_mark);
1969 :
1970 : /**
1971 : * xa_clear_mark() - Clear this mark on this entry.
1972 : * @xa: XArray.
1973 : * @index: Index of entry.
1974 : * @mark: Mark number.
1975 : *
1976 : * Clearing a mark always succeeds.
1977 : *
1978 : * Context: Process context. Takes and releases the xa_lock.
1979 : */
1980 0 : void xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1981 : {
1982 0 : xa_lock(xa);
1983 0 : __xa_clear_mark(xa, index, mark);
1984 0 : xa_unlock(xa);
1985 0 : }
1986 : EXPORT_SYMBOL(xa_clear_mark);
1987 :
1988 : /**
1989 : * xa_find() - Search the XArray for an entry.
1990 : * @xa: XArray.
1991 : * @indexp: Pointer to an index.
1992 : * @max: Maximum index to search to.
1993 : * @filter: Selection criterion.
1994 : *
1995 : * Finds the entry in @xa which matches the @filter, and has the lowest
1996 : * index that is at least @indexp and no more than @max.
1997 : * If an entry is found, @indexp is updated to be the index of the entry.
1998 : * This function is protected by the RCU read lock, so it may not find
1999 : * entries which are being simultaneously added. It will not return an
2000 : * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
2001 : *
2002 : * Context: Any context. Takes and releases the RCU lock.
2003 : * Return: The entry, if found, otherwise %NULL.
2004 : */
2005 23 : void *xa_find(struct xarray *xa, unsigned long *indexp,
2006 : unsigned long max, xa_mark_t filter)
2007 : {
2008 23 : XA_STATE(xas, xa, *indexp);
2009 23 : void *entry;
2010 :
2011 23 : rcu_read_lock();
2012 23 : do {
2013 23 : if ((__force unsigned int)filter < XA_MAX_MARKS)
2014 0 : entry = xas_find_marked(&xas, max, filter);
2015 : else
2016 23 : entry = xas_find(&xas, max);
2017 46 : } while (xas_retry(&xas, entry));
2018 23 : rcu_read_unlock();
2019 :
2020 23 : if (entry)
2021 12 : *indexp = xas.xa_index;
2022 23 : return entry;
2023 : }
2024 : EXPORT_SYMBOL(xa_find);
2025 :
2026 0 : static bool xas_sibling(struct xa_state *xas)
2027 : {
2028 0 : struct xa_node *node = xas->xa_node;
2029 0 : unsigned long mask;
2030 :
2031 0 : if (!IS_ENABLED(CONFIG_XARRAY_MULTI) || !node)
2032 : return false;
2033 0 : mask = (XA_CHUNK_SIZE << node->shift) - 1;
2034 0 : return (xas->xa_index & mask) >
2035 0 : ((unsigned long)xas->xa_offset << node->shift);
2036 : }
2037 :
2038 : /**
2039 : * xa_find_after() - Search the XArray for a present entry.
2040 : * @xa: XArray.
2041 : * @indexp: Pointer to an index.
2042 : * @max: Maximum index to search to.
2043 : * @filter: Selection criterion.
2044 : *
2045 : * Finds the entry in @xa which matches the @filter and has the lowest
2046 : * index that is above @indexp and no more than @max.
2047 : * If an entry is found, @indexp is updated to be the index of the entry.
2048 : * This function is protected by the RCU read lock, so it may miss entries
2049 : * which are being simultaneously added. It will not return an
2050 : * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
2051 : *
2052 : * Context: Any context. Takes and releases the RCU lock.
2053 : * Return: The pointer, if found, otherwise %NULL.
2054 : */
2055 0 : void *xa_find_after(struct xarray *xa, unsigned long *indexp,
2056 : unsigned long max, xa_mark_t filter)
2057 : {
2058 0 : XA_STATE(xas, xa, *indexp + 1);
2059 0 : void *entry;
2060 :
2061 0 : if (xas.xa_index == 0)
2062 : return NULL;
2063 :
2064 0 : rcu_read_lock();
2065 0 : for (;;) {
2066 0 : if ((__force unsigned int)filter < XA_MAX_MARKS)
2067 0 : entry = xas_find_marked(&xas, max, filter);
2068 : else
2069 0 : entry = xas_find(&xas, max);
2070 :
2071 0 : if (xas_invalid(&xas))
2072 : break;
2073 0 : if (xas_sibling(&xas))
2074 0 : continue;
2075 0 : if (!xas_retry(&xas, entry))
2076 : break;
2077 : }
2078 0 : rcu_read_unlock();
2079 :
2080 0 : if (entry)
2081 0 : *indexp = xas.xa_index;
2082 : return entry;
2083 : }
2084 : EXPORT_SYMBOL(xa_find_after);
2085 :
2086 0 : static unsigned int xas_extract_present(struct xa_state *xas, void **dst,
2087 : unsigned long max, unsigned int n)
2088 : {
2089 0 : void *entry;
2090 0 : unsigned int i = 0;
2091 :
2092 0 : rcu_read_lock();
2093 0 : xas_for_each(xas, entry, max) {
2094 0 : if (xas_retry(xas, entry))
2095 0 : continue;
2096 0 : dst[i++] = entry;
2097 0 : if (i == n)
2098 : break;
2099 : }
2100 0 : rcu_read_unlock();
2101 :
2102 0 : return i;
2103 : }
2104 :
2105 0 : static unsigned int xas_extract_marked(struct xa_state *xas, void **dst,
2106 : unsigned long max, unsigned int n, xa_mark_t mark)
2107 : {
2108 0 : void *entry;
2109 0 : unsigned int i = 0;
2110 :
2111 0 : rcu_read_lock();
2112 0 : xas_for_each_marked(xas, entry, max, mark) {
2113 0 : if (xas_retry(xas, entry))
2114 0 : continue;
2115 0 : dst[i++] = entry;
2116 0 : if (i == n)
2117 : break;
2118 : }
2119 0 : rcu_read_unlock();
2120 :
2121 0 : return i;
2122 : }
2123 :
2124 : /**
2125 : * xa_extract() - Copy selected entries from the XArray into a normal array.
2126 : * @xa: The source XArray to copy from.
2127 : * @dst: The buffer to copy entries into.
2128 : * @start: The first index in the XArray eligible to be selected.
2129 : * @max: The last index in the XArray eligible to be selected.
2130 : * @n: The maximum number of entries to copy.
2131 : * @filter: Selection criterion.
2132 : *
2133 : * Copies up to @n entries that match @filter from the XArray. The
2134 : * copied entries will have indices between @start and @max, inclusive.
2135 : *
2136 : * The @filter may be an XArray mark value, in which case entries which are
2137 : * marked with that mark will be copied. It may also be %XA_PRESENT, in
2138 : * which case all entries which are not %NULL will be copied.
2139 : *
2140 : * The entries returned may not represent a snapshot of the XArray at a
2141 : * moment in time. For example, if another thread stores to index 5, then
2142 : * index 10, calling xa_extract() may return the old contents of index 5
2143 : * and the new contents of index 10. Indices not modified while this
2144 : * function is running will not be skipped.
2145 : *
2146 : * If you need stronger guarantees, holding the xa_lock across calls to this
2147 : * function will prevent concurrent modification.
2148 : *
2149 : * Context: Any context. Takes and releases the RCU lock.
2150 : * Return: The number of entries copied.
2151 : */
2152 0 : unsigned int xa_extract(struct xarray *xa, void **dst, unsigned long start,
2153 : unsigned long max, unsigned int n, xa_mark_t filter)
2154 : {
2155 0 : XA_STATE(xas, xa, start);
2156 :
2157 0 : if (!n)
2158 : return 0;
2159 :
2160 0 : if ((__force unsigned int)filter < XA_MAX_MARKS)
2161 0 : return xas_extract_marked(&xas, dst, max, n, filter);
2162 0 : return xas_extract_present(&xas, dst, max, n);
2163 : }
2164 : EXPORT_SYMBOL(xa_extract);
2165 :
2166 : /**
2167 : * xa_delete_node() - Private interface for workingset code.
2168 : * @node: Node to be removed from the tree.
2169 : * @update: Function to call to update ancestor nodes.
2170 : *
2171 : * Context: xa_lock must be held on entry and will not be released.
2172 : */
2173 0 : void xa_delete_node(struct xa_node *node, xa_update_node_t update)
2174 : {
2175 0 : struct xa_state xas = {
2176 0 : .xa = node->array,
2177 0 : .xa_index = (unsigned long)node->offset <<
2178 0 : (node->shift + XA_CHUNK_SHIFT),
2179 0 : .xa_shift = node->shift + XA_CHUNK_SHIFT,
2180 : .xa_offset = node->offset,
2181 0 : .xa_node = xa_parent_locked(node->array, node),
2182 : .xa_update = update,
2183 : };
2184 :
2185 0 : xas_store(&xas, NULL);
2186 0 : }
2187 : EXPORT_SYMBOL_GPL(xa_delete_node); /* For the benefit of the test suite */
2188 :
2189 : /**
2190 : * xa_destroy() - Free all internal data structures.
2191 : * @xa: XArray.
2192 : *
2193 : * After calling this function, the XArray is empty and has freed all memory
2194 : * allocated for its internal data structures. You are responsible for
2195 : * freeing the objects referenced by the XArray.
2196 : *
2197 : * Context: Any context. Takes and releases the xa_lock, interrupt-safe.
2198 : */
2199 0 : void xa_destroy(struct xarray *xa)
2200 : {
2201 0 : XA_STATE(xas, xa, 0);
2202 0 : unsigned long flags;
2203 0 : void *entry;
2204 :
2205 0 : xas.xa_node = NULL;
2206 0 : xas_lock_irqsave(&xas, flags);
2207 0 : entry = xa_head_locked(xa);
2208 0 : RCU_INIT_POINTER(xa->xa_head, NULL);
2209 0 : xas_init_marks(&xas);
2210 0 : if (xa_zero_busy(xa))
2211 0 : xa_mark_clear(xa, XA_FREE_MARK);
2212 : /* lockdep checks we're still holding the lock in xas_free_nodes() */
2213 0 : if (xa_is_node(entry))
2214 0 : xas_free_nodes(&xas, xa_to_node(entry));
2215 0 : xas_unlock_irqrestore(&xas, flags);
2216 0 : }
2217 : EXPORT_SYMBOL(xa_destroy);
2218 :
2219 : #ifdef XA_DEBUG
2220 : void xa_dump_node(const struct xa_node *node)
2221 : {
2222 : unsigned i, j;
2223 :
2224 : if (!node)
2225 : return;
2226 : if ((unsigned long)node & 3) {
2227 : pr_cont("node %px\n", node);
2228 : return;
2229 : }
2230 :
2231 : pr_cont("node %px %s %d parent %px shift %d count %d values %d "
2232 : "array %px list %px %px marks",
2233 : node, node->parent ? "offset" : "max", node->offset,
2234 : node->parent, node->shift, node->count, node->nr_values,
2235 : node->array, node->private_list.prev, node->private_list.next);
2236 : for (i = 0; i < XA_MAX_MARKS; i++)
2237 : for (j = 0; j < XA_MARK_LONGS; j++)
2238 : pr_cont(" %lx", node->marks[i][j]);
2239 : pr_cont("\n");
2240 : }
2241 :
2242 : void xa_dump_index(unsigned long index, unsigned int shift)
2243 : {
2244 : if (!shift)
2245 : pr_info("%lu: ", index);
2246 : else if (shift >= BITS_PER_LONG)
2247 : pr_info("0-%lu: ", ~0UL);
2248 : else
2249 : pr_info("%lu-%lu: ", index, index | ((1UL << shift) - 1));
2250 : }
2251 :
2252 : void xa_dump_entry(const void *entry, unsigned long index, unsigned long shift)
2253 : {
2254 : if (!entry)
2255 : return;
2256 :
2257 : xa_dump_index(index, shift);
2258 :
2259 : if (xa_is_node(entry)) {
2260 : if (shift == 0) {
2261 : pr_cont("%px\n", entry);
2262 : } else {
2263 : unsigned long i;
2264 : struct xa_node *node = xa_to_node(entry);
2265 : xa_dump_node(node);
2266 : for (i = 0; i < XA_CHUNK_SIZE; i++)
2267 : xa_dump_entry(node->slots[i],
2268 : index + (i << node->shift), node->shift);
2269 : }
2270 : } else if (xa_is_value(entry))
2271 : pr_cont("value %ld (0x%lx) [%px]\n", xa_to_value(entry),
2272 : xa_to_value(entry), entry);
2273 : else if (!xa_is_internal(entry))
2274 : pr_cont("%px\n", entry);
2275 : else if (xa_is_retry(entry))
2276 : pr_cont("retry (%ld)\n", xa_to_internal(entry));
2277 : else if (xa_is_sibling(entry))
2278 : pr_cont("sibling (slot %ld)\n", xa_to_sibling(entry));
2279 : else if (xa_is_zero(entry))
2280 : pr_cont("zero (%ld)\n", xa_to_internal(entry));
2281 : else
2282 : pr_cont("UNKNOWN ENTRY (%px)\n", entry);
2283 : }
2284 :
2285 : void xa_dump(const struct xarray *xa)
2286 : {
2287 : void *entry = xa->xa_head;
2288 : unsigned int shift = 0;
2289 :
2290 : pr_info("xarray: %px head %px flags %x marks %d %d %d\n", xa, entry,
2291 : xa->xa_flags, xa_marked(xa, XA_MARK_0),
2292 : xa_marked(xa, XA_MARK_1), xa_marked(xa, XA_MARK_2));
2293 : if (xa_is_node(entry))
2294 : shift = xa_to_node(entry)->shift + XA_CHUNK_SHIFT;
2295 : xa_dump_entry(entry, 0, shift);
2296 : }
2297 : #endif
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