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f8d5d0cc MW |
1 | // SPDX-License-Identifier: GPL-2.0+ |
2 | /* | |
3 | * XArray implementation | |
4 | * Copyright (c) 2017 Microsoft Corporation | |
5 | * Author: Matthew Wilcox <willy@infradead.org> | |
6 | */ | |
7 | ||
9b89a035 | 8 | #include <linux/bitmap.h> |
f8d5d0cc | 9 | #include <linux/export.h> |
58d6ea30 MW |
10 | #include <linux/list.h> |
11 | #include <linux/slab.h> | |
f8d5d0cc MW |
12 | #include <linux/xarray.h> |
13 | ||
14 | /* | |
15 | * Coding conventions in this file: | |
16 | * | |
17 | * @xa is used to refer to the entire xarray. | |
18 | * @xas is the 'xarray operation state'. It may be either a pointer to | |
19 | * an xa_state, or an xa_state stored on the stack. This is an unfortunate | |
20 | * ambiguity. | |
21 | * @index is the index of the entry being operated on | |
22 | * @mark is an xa_mark_t; a small number indicating one of the mark bits. | |
23 | * @node refers to an xa_node; usually the primary one being operated on by | |
24 | * this function. | |
25 | * @offset is the index into the slots array inside an xa_node. | |
26 | * @parent refers to the @xa_node closer to the head than @node. | |
27 | * @entry refers to something stored in a slot in the xarray | |
28 | */ | |
29 | ||
58d6ea30 MW |
30 | static inline unsigned int xa_lock_type(const struct xarray *xa) |
31 | { | |
32 | return (__force unsigned int)xa->xa_flags & 3; | |
33 | } | |
34 | ||
35 | static inline void xas_lock_type(struct xa_state *xas, unsigned int lock_type) | |
36 | { | |
37 | if (lock_type == XA_LOCK_IRQ) | |
38 | xas_lock_irq(xas); | |
39 | else if (lock_type == XA_LOCK_BH) | |
40 | xas_lock_bh(xas); | |
41 | else | |
42 | xas_lock(xas); | |
43 | } | |
44 | ||
45 | static inline void xas_unlock_type(struct xa_state *xas, unsigned int lock_type) | |
46 | { | |
47 | if (lock_type == XA_LOCK_IRQ) | |
48 | xas_unlock_irq(xas); | |
49 | else if (lock_type == XA_LOCK_BH) | |
50 | xas_unlock_bh(xas); | |
51 | else | |
52 | xas_unlock(xas); | |
53 | } | |
54 | ||
9b89a035 MW |
55 | static inline void xa_mark_set(struct xarray *xa, xa_mark_t mark) |
56 | { | |
57 | if (!(xa->xa_flags & XA_FLAGS_MARK(mark))) | |
58 | xa->xa_flags |= XA_FLAGS_MARK(mark); | |
59 | } | |
60 | ||
61 | static inline void xa_mark_clear(struct xarray *xa, xa_mark_t mark) | |
62 | { | |
63 | if (xa->xa_flags & XA_FLAGS_MARK(mark)) | |
64 | xa->xa_flags &= ~(XA_FLAGS_MARK(mark)); | |
65 | } | |
66 | ||
67 | static inline unsigned long *node_marks(struct xa_node *node, xa_mark_t mark) | |
68 | { | |
69 | return node->marks[(__force unsigned)mark]; | |
70 | } | |
71 | ||
72 | static inline bool node_get_mark(struct xa_node *node, | |
73 | unsigned int offset, xa_mark_t mark) | |
74 | { | |
75 | return test_bit(offset, node_marks(node, mark)); | |
76 | } | |
77 | ||
78 | /* returns true if the bit was set */ | |
79 | static inline bool node_set_mark(struct xa_node *node, unsigned int offset, | |
80 | xa_mark_t mark) | |
81 | { | |
82 | return __test_and_set_bit(offset, node_marks(node, mark)); | |
83 | } | |
84 | ||
85 | /* returns true if the bit was set */ | |
86 | static inline bool node_clear_mark(struct xa_node *node, unsigned int offset, | |
87 | xa_mark_t mark) | |
88 | { | |
89 | return __test_and_clear_bit(offset, node_marks(node, mark)); | |
90 | } | |
91 | ||
92 | static inline bool node_any_mark(struct xa_node *node, xa_mark_t mark) | |
93 | { | |
94 | return !bitmap_empty(node_marks(node, mark), XA_CHUNK_SIZE); | |
95 | } | |
96 | ||
58d6ea30 MW |
97 | #define mark_inc(mark) do { \ |
98 | mark = (__force xa_mark_t)((__force unsigned)(mark) + 1); \ | |
99 | } while (0) | |
100 | ||
101 | /* | |
102 | * xas_squash_marks() - Merge all marks to the first entry | |
103 | * @xas: Array operation state. | |
104 | * | |
105 | * Set a mark on the first entry if any entry has it set. Clear marks on | |
106 | * all sibling entries. | |
107 | */ | |
108 | static void xas_squash_marks(const struct xa_state *xas) | |
109 | { | |
110 | unsigned int mark = 0; | |
111 | unsigned int limit = xas->xa_offset + xas->xa_sibs + 1; | |
112 | ||
113 | if (!xas->xa_sibs) | |
114 | return; | |
115 | ||
116 | do { | |
117 | unsigned long *marks = xas->xa_node->marks[mark]; | |
118 | if (find_next_bit(marks, limit, xas->xa_offset + 1) == limit) | |
119 | continue; | |
120 | __set_bit(xas->xa_offset, marks); | |
121 | bitmap_clear(marks, xas->xa_offset + 1, xas->xa_sibs); | |
122 | } while (mark++ != (__force unsigned)XA_MARK_MAX); | |
123 | } | |
124 | ||
ad3d6c72 MW |
125 | /* extracts the offset within this node from the index */ |
126 | static unsigned int get_offset(unsigned long index, struct xa_node *node) | |
127 | { | |
128 | return (index >> node->shift) & XA_CHUNK_MASK; | |
129 | } | |
130 | ||
b803b428 MW |
131 | static void xas_set_offset(struct xa_state *xas) |
132 | { | |
133 | xas->xa_offset = get_offset(xas->xa_index, xas->xa_node); | |
134 | } | |
135 | ||
ad3d6c72 MW |
136 | /* move the index either forwards (find) or backwards (sibling slot) */ |
137 | static void xas_move_index(struct xa_state *xas, unsigned long offset) | |
138 | { | |
139 | unsigned int shift = xas->xa_node->shift; | |
140 | xas->xa_index &= ~XA_CHUNK_MASK << shift; | |
141 | xas->xa_index += offset << shift; | |
142 | } | |
143 | ||
b803b428 MW |
144 | static void xas_advance(struct xa_state *xas) |
145 | { | |
146 | xas->xa_offset++; | |
147 | xas_move_index(xas, xas->xa_offset); | |
148 | } | |
149 | ||
ad3d6c72 MW |
150 | static void *set_bounds(struct xa_state *xas) |
151 | { | |
152 | xas->xa_node = XAS_BOUNDS; | |
153 | return NULL; | |
154 | } | |
155 | ||
156 | /* | |
157 | * Starts a walk. If the @xas is already valid, we assume that it's on | |
158 | * the right path and just return where we've got to. If we're in an | |
159 | * error state, return NULL. If the index is outside the current scope | |
160 | * of the xarray, return NULL without changing @xas->xa_node. Otherwise | |
161 | * set @xas->xa_node to NULL and return the current head of the array. | |
162 | */ | |
163 | static void *xas_start(struct xa_state *xas) | |
164 | { | |
165 | void *entry; | |
166 | ||
167 | if (xas_valid(xas)) | |
168 | return xas_reload(xas); | |
169 | if (xas_error(xas)) | |
170 | return NULL; | |
171 | ||
172 | entry = xa_head(xas->xa); | |
173 | if (!xa_is_node(entry)) { | |
174 | if (xas->xa_index) | |
175 | return set_bounds(xas); | |
176 | } else { | |
177 | if ((xas->xa_index >> xa_to_node(entry)->shift) > XA_CHUNK_MASK) | |
178 | return set_bounds(xas); | |
179 | } | |
180 | ||
181 | xas->xa_node = NULL; | |
182 | return entry; | |
183 | } | |
184 | ||
185 | static void *xas_descend(struct xa_state *xas, struct xa_node *node) | |
186 | { | |
187 | unsigned int offset = get_offset(xas->xa_index, node); | |
188 | void *entry = xa_entry(xas->xa, node, offset); | |
189 | ||
190 | xas->xa_node = node; | |
191 | if (xa_is_sibling(entry)) { | |
192 | offset = xa_to_sibling(entry); | |
193 | entry = xa_entry(xas->xa, node, offset); | |
194 | } | |
195 | ||
196 | xas->xa_offset = offset; | |
197 | return entry; | |
198 | } | |
199 | ||
200 | /** | |
201 | * xas_load() - Load an entry from the XArray (advanced). | |
202 | * @xas: XArray operation state. | |
203 | * | |
204 | * Usually walks the @xas to the appropriate state to load the entry | |
205 | * stored at xa_index. However, it will do nothing and return %NULL if | |
206 | * @xas is in an error state. xas_load() will never expand the tree. | |
207 | * | |
208 | * If the xa_state is set up to operate on a multi-index entry, xas_load() | |
209 | * may return %NULL or an internal entry, even if there are entries | |
210 | * present within the range specified by @xas. | |
211 | * | |
212 | * Context: Any context. The caller should hold the xa_lock or the RCU lock. | |
213 | * Return: Usually an entry in the XArray, but see description for exceptions. | |
214 | */ | |
215 | void *xas_load(struct xa_state *xas) | |
216 | { | |
217 | void *entry = xas_start(xas); | |
218 | ||
219 | while (xa_is_node(entry)) { | |
220 | struct xa_node *node = xa_to_node(entry); | |
221 | ||
222 | if (xas->xa_shift > node->shift) | |
223 | break; | |
224 | entry = xas_descend(xas, node); | |
225 | } | |
226 | return entry; | |
227 | } | |
228 | EXPORT_SYMBOL_GPL(xas_load); | |
229 | ||
58d6ea30 MW |
230 | /* Move the radix tree node cache here */ |
231 | extern struct kmem_cache *radix_tree_node_cachep; | |
232 | extern void radix_tree_node_rcu_free(struct rcu_head *head); | |
233 | ||
234 | #define XA_RCU_FREE ((struct xarray *)1) | |
235 | ||
236 | static void xa_node_free(struct xa_node *node) | |
237 | { | |
238 | XA_NODE_BUG_ON(node, !list_empty(&node->private_list)); | |
239 | node->array = XA_RCU_FREE; | |
240 | call_rcu(&node->rcu_head, radix_tree_node_rcu_free); | |
241 | } | |
242 | ||
243 | /* | |
244 | * xas_destroy() - Free any resources allocated during the XArray operation. | |
245 | * @xas: XArray operation state. | |
246 | * | |
247 | * This function is now internal-only. | |
248 | */ | |
249 | static void xas_destroy(struct xa_state *xas) | |
250 | { | |
251 | struct xa_node *node = xas->xa_alloc; | |
252 | ||
253 | if (!node) | |
254 | return; | |
255 | XA_NODE_BUG_ON(node, !list_empty(&node->private_list)); | |
256 | kmem_cache_free(radix_tree_node_cachep, node); | |
257 | xas->xa_alloc = NULL; | |
258 | } | |
259 | ||
260 | /** | |
261 | * xas_nomem() - Allocate memory if needed. | |
262 | * @xas: XArray operation state. | |
263 | * @gfp: Memory allocation flags. | |
264 | * | |
265 | * If we need to add new nodes to the XArray, we try to allocate memory | |
266 | * with GFP_NOWAIT while holding the lock, which will usually succeed. | |
267 | * If it fails, @xas is flagged as needing memory to continue. The caller | |
268 | * should drop the lock and call xas_nomem(). If xas_nomem() succeeds, | |
269 | * the caller should retry the operation. | |
270 | * | |
271 | * Forward progress is guaranteed as one node is allocated here and | |
272 | * stored in the xa_state where it will be found by xas_alloc(). More | |
273 | * nodes will likely be found in the slab allocator, but we do not tie | |
274 | * them up here. | |
275 | * | |
276 | * Return: true if memory was needed, and was successfully allocated. | |
277 | */ | |
278 | bool xas_nomem(struct xa_state *xas, gfp_t gfp) | |
279 | { | |
280 | if (xas->xa_node != XA_ERROR(-ENOMEM)) { | |
281 | xas_destroy(xas); | |
282 | return false; | |
283 | } | |
284 | xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp); | |
285 | if (!xas->xa_alloc) | |
286 | return false; | |
287 | XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list)); | |
288 | xas->xa_node = XAS_RESTART; | |
289 | return true; | |
290 | } | |
291 | EXPORT_SYMBOL_GPL(xas_nomem); | |
292 | ||
293 | /* | |
294 | * __xas_nomem() - Drop locks and allocate memory if needed. | |
295 | * @xas: XArray operation state. | |
296 | * @gfp: Memory allocation flags. | |
297 | * | |
298 | * Internal variant of xas_nomem(). | |
299 | * | |
300 | * Return: true if memory was needed, and was successfully allocated. | |
301 | */ | |
302 | static bool __xas_nomem(struct xa_state *xas, gfp_t gfp) | |
303 | __must_hold(xas->xa->xa_lock) | |
304 | { | |
305 | unsigned int lock_type = xa_lock_type(xas->xa); | |
306 | ||
307 | if (xas->xa_node != XA_ERROR(-ENOMEM)) { | |
308 | xas_destroy(xas); | |
309 | return false; | |
310 | } | |
311 | if (gfpflags_allow_blocking(gfp)) { | |
312 | xas_unlock_type(xas, lock_type); | |
313 | xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp); | |
314 | xas_lock_type(xas, lock_type); | |
315 | } else { | |
316 | xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp); | |
317 | } | |
318 | if (!xas->xa_alloc) | |
319 | return false; | |
320 | XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list)); | |
321 | xas->xa_node = XAS_RESTART; | |
322 | return true; | |
323 | } | |
324 | ||
325 | static void xas_update(struct xa_state *xas, struct xa_node *node) | |
326 | { | |
327 | if (xas->xa_update) | |
328 | xas->xa_update(node); | |
329 | else | |
330 | XA_NODE_BUG_ON(node, !list_empty(&node->private_list)); | |
331 | } | |
332 | ||
333 | static void *xas_alloc(struct xa_state *xas, unsigned int shift) | |
334 | { | |
335 | struct xa_node *parent = xas->xa_node; | |
336 | struct xa_node *node = xas->xa_alloc; | |
337 | ||
338 | if (xas_invalid(xas)) | |
339 | return NULL; | |
340 | ||
341 | if (node) { | |
342 | xas->xa_alloc = NULL; | |
343 | } else { | |
344 | node = kmem_cache_alloc(radix_tree_node_cachep, | |
345 | GFP_NOWAIT | __GFP_NOWARN); | |
346 | if (!node) { | |
347 | xas_set_err(xas, -ENOMEM); | |
348 | return NULL; | |
349 | } | |
350 | } | |
351 | ||
352 | if (parent) { | |
353 | node->offset = xas->xa_offset; | |
354 | parent->count++; | |
355 | XA_NODE_BUG_ON(node, parent->count > XA_CHUNK_SIZE); | |
356 | xas_update(xas, parent); | |
357 | } | |
358 | XA_NODE_BUG_ON(node, shift > BITS_PER_LONG); | |
359 | XA_NODE_BUG_ON(node, !list_empty(&node->private_list)); | |
360 | node->shift = shift; | |
361 | node->count = 0; | |
362 | node->nr_values = 0; | |
363 | RCU_INIT_POINTER(node->parent, xas->xa_node); | |
364 | node->array = xas->xa; | |
365 | ||
366 | return node; | |
367 | } | |
368 | ||
369 | /* | |
370 | * Use this to calculate the maximum index that will need to be created | |
371 | * in order to add the entry described by @xas. Because we cannot store a | |
372 | * multiple-index entry at index 0, the calculation is a little more complex | |
373 | * than you might expect. | |
374 | */ | |
375 | static unsigned long xas_max(struct xa_state *xas) | |
376 | { | |
377 | unsigned long max = xas->xa_index; | |
378 | ||
379 | #ifdef CONFIG_XARRAY_MULTI | |
380 | if (xas->xa_shift || xas->xa_sibs) { | |
381 | unsigned long mask; | |
382 | mask = (((xas->xa_sibs + 1UL) << xas->xa_shift) - 1); | |
383 | max |= mask; | |
384 | if (mask == max) | |
385 | max++; | |
386 | } | |
387 | #endif | |
388 | ||
389 | return max; | |
390 | } | |
391 | ||
392 | /* The maximum index that can be contained in the array without expanding it */ | |
393 | static unsigned long max_index(void *entry) | |
394 | { | |
395 | if (!xa_is_node(entry)) | |
396 | return 0; | |
397 | return (XA_CHUNK_SIZE << xa_to_node(entry)->shift) - 1; | |
398 | } | |
399 | ||
400 | static void xas_shrink(struct xa_state *xas) | |
401 | { | |
402 | struct xarray *xa = xas->xa; | |
403 | struct xa_node *node = xas->xa_node; | |
404 | ||
405 | for (;;) { | |
406 | void *entry; | |
407 | ||
408 | XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE); | |
409 | if (node->count != 1) | |
410 | break; | |
411 | entry = xa_entry_locked(xa, node, 0); | |
412 | if (!entry) | |
413 | break; | |
414 | if (!xa_is_node(entry) && node->shift) | |
415 | break; | |
416 | xas->xa_node = XAS_BOUNDS; | |
417 | ||
418 | RCU_INIT_POINTER(xa->xa_head, entry); | |
419 | ||
420 | node->count = 0; | |
421 | node->nr_values = 0; | |
422 | if (!xa_is_node(entry)) | |
423 | RCU_INIT_POINTER(node->slots[0], XA_RETRY_ENTRY); | |
424 | xas_update(xas, node); | |
425 | xa_node_free(node); | |
426 | if (!xa_is_node(entry)) | |
427 | break; | |
428 | node = xa_to_node(entry); | |
429 | node->parent = NULL; | |
430 | } | |
431 | } | |
432 | ||
433 | /* | |
434 | * xas_delete_node() - Attempt to delete an xa_node | |
435 | * @xas: Array operation state. | |
436 | * | |
437 | * Attempts to delete the @xas->xa_node. This will fail if xa->node has | |
438 | * a non-zero reference count. | |
439 | */ | |
440 | static void xas_delete_node(struct xa_state *xas) | |
441 | { | |
442 | struct xa_node *node = xas->xa_node; | |
443 | ||
444 | for (;;) { | |
445 | struct xa_node *parent; | |
446 | ||
447 | XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE); | |
448 | if (node->count) | |
449 | break; | |
450 | ||
451 | parent = xa_parent_locked(xas->xa, node); | |
452 | xas->xa_node = parent; | |
453 | xas->xa_offset = node->offset; | |
454 | xa_node_free(node); | |
455 | ||
456 | if (!parent) { | |
457 | xas->xa->xa_head = NULL; | |
458 | xas->xa_node = XAS_BOUNDS; | |
459 | return; | |
460 | } | |
461 | ||
462 | parent->slots[xas->xa_offset] = NULL; | |
463 | parent->count--; | |
464 | XA_NODE_BUG_ON(parent, parent->count > XA_CHUNK_SIZE); | |
465 | node = parent; | |
466 | xas_update(xas, node); | |
467 | } | |
468 | ||
469 | if (!node->parent) | |
470 | xas_shrink(xas); | |
471 | } | |
472 | ||
473 | /** | |
474 | * xas_free_nodes() - Free this node and all nodes that it references | |
475 | * @xas: Array operation state. | |
476 | * @top: Node to free | |
477 | * | |
478 | * This node has been removed from the tree. We must now free it and all | |
479 | * of its subnodes. There may be RCU walkers with references into the tree, | |
480 | * so we must replace all entries with retry markers. | |
481 | */ | |
482 | static void xas_free_nodes(struct xa_state *xas, struct xa_node *top) | |
483 | { | |
484 | unsigned int offset = 0; | |
485 | struct xa_node *node = top; | |
486 | ||
487 | for (;;) { | |
488 | void *entry = xa_entry_locked(xas->xa, node, offset); | |
489 | ||
490 | if (xa_is_node(entry)) { | |
491 | node = xa_to_node(entry); | |
492 | offset = 0; | |
493 | continue; | |
494 | } | |
495 | if (entry) | |
496 | RCU_INIT_POINTER(node->slots[offset], XA_RETRY_ENTRY); | |
497 | offset++; | |
498 | while (offset == XA_CHUNK_SIZE) { | |
499 | struct xa_node *parent; | |
500 | ||
501 | parent = xa_parent_locked(xas->xa, node); | |
502 | offset = node->offset + 1; | |
503 | node->count = 0; | |
504 | node->nr_values = 0; | |
505 | xas_update(xas, node); | |
506 | xa_node_free(node); | |
507 | if (node == top) | |
508 | return; | |
509 | node = parent; | |
510 | } | |
511 | } | |
512 | } | |
513 | ||
514 | /* | |
515 | * xas_expand adds nodes to the head of the tree until it has reached | |
516 | * sufficient height to be able to contain @xas->xa_index | |
517 | */ | |
518 | static int xas_expand(struct xa_state *xas, void *head) | |
519 | { | |
520 | struct xarray *xa = xas->xa; | |
521 | struct xa_node *node = NULL; | |
522 | unsigned int shift = 0; | |
523 | unsigned long max = xas_max(xas); | |
524 | ||
525 | if (!head) { | |
526 | if (max == 0) | |
527 | return 0; | |
528 | while ((max >> shift) >= XA_CHUNK_SIZE) | |
529 | shift += XA_CHUNK_SHIFT; | |
530 | return shift + XA_CHUNK_SHIFT; | |
531 | } else if (xa_is_node(head)) { | |
532 | node = xa_to_node(head); | |
533 | shift = node->shift + XA_CHUNK_SHIFT; | |
534 | } | |
535 | xas->xa_node = NULL; | |
536 | ||
537 | while (max > max_index(head)) { | |
538 | xa_mark_t mark = 0; | |
539 | ||
540 | XA_NODE_BUG_ON(node, shift > BITS_PER_LONG); | |
541 | node = xas_alloc(xas, shift); | |
542 | if (!node) | |
543 | return -ENOMEM; | |
544 | ||
545 | node->count = 1; | |
546 | if (xa_is_value(head)) | |
547 | node->nr_values = 1; | |
548 | RCU_INIT_POINTER(node->slots[0], head); | |
549 | ||
550 | /* Propagate the aggregated mark info to the new child */ | |
551 | for (;;) { | |
552 | if (xa_marked(xa, mark)) | |
553 | node_set_mark(node, 0, mark); | |
554 | if (mark == XA_MARK_MAX) | |
555 | break; | |
556 | mark_inc(mark); | |
557 | } | |
558 | ||
559 | /* | |
560 | * Now that the new node is fully initialised, we can add | |
561 | * it to the tree | |
562 | */ | |
563 | if (xa_is_node(head)) { | |
564 | xa_to_node(head)->offset = 0; | |
565 | rcu_assign_pointer(xa_to_node(head)->parent, node); | |
566 | } | |
567 | head = xa_mk_node(node); | |
568 | rcu_assign_pointer(xa->xa_head, head); | |
569 | xas_update(xas, node); | |
570 | ||
571 | shift += XA_CHUNK_SHIFT; | |
572 | } | |
573 | ||
574 | xas->xa_node = node; | |
575 | return shift; | |
576 | } | |
577 | ||
578 | /* | |
579 | * xas_create() - Create a slot to store an entry in. | |
580 | * @xas: XArray operation state. | |
581 | * | |
582 | * Most users will not need to call this function directly, as it is called | |
583 | * by xas_store(). It is useful for doing conditional store operations | |
584 | * (see the xa_cmpxchg() implementation for an example). | |
585 | * | |
586 | * Return: If the slot already existed, returns the contents of this slot. | |
587 | * If the slot was newly created, returns NULL. If it failed to create the | |
588 | * slot, returns NULL and indicates the error in @xas. | |
589 | */ | |
590 | static void *xas_create(struct xa_state *xas) | |
591 | { | |
592 | struct xarray *xa = xas->xa; | |
593 | void *entry; | |
594 | void __rcu **slot; | |
595 | struct xa_node *node = xas->xa_node; | |
596 | int shift; | |
597 | unsigned int order = xas->xa_shift; | |
598 | ||
599 | if (xas_top(node)) { | |
600 | entry = xa_head_locked(xa); | |
601 | xas->xa_node = NULL; | |
602 | shift = xas_expand(xas, entry); | |
603 | if (shift < 0) | |
604 | return NULL; | |
605 | entry = xa_head_locked(xa); | |
606 | slot = &xa->xa_head; | |
607 | } else if (xas_error(xas)) { | |
608 | return NULL; | |
609 | } else if (node) { | |
610 | unsigned int offset = xas->xa_offset; | |
611 | ||
612 | shift = node->shift; | |
613 | entry = xa_entry_locked(xa, node, offset); | |
614 | slot = &node->slots[offset]; | |
615 | } else { | |
616 | shift = 0; | |
617 | entry = xa_head_locked(xa); | |
618 | slot = &xa->xa_head; | |
619 | } | |
620 | ||
621 | while (shift > order) { | |
622 | shift -= XA_CHUNK_SHIFT; | |
623 | if (!entry) { | |
624 | node = xas_alloc(xas, shift); | |
625 | if (!node) | |
626 | break; | |
627 | rcu_assign_pointer(*slot, xa_mk_node(node)); | |
628 | } else if (xa_is_node(entry)) { | |
629 | node = xa_to_node(entry); | |
630 | } else { | |
631 | break; | |
632 | } | |
633 | entry = xas_descend(xas, node); | |
634 | slot = &node->slots[xas->xa_offset]; | |
635 | } | |
636 | ||
637 | return entry; | |
638 | } | |
639 | ||
640 | static void update_node(struct xa_state *xas, struct xa_node *node, | |
641 | int count, int values) | |
642 | { | |
643 | if (!node || (!count && !values)) | |
644 | return; | |
645 | ||
646 | node->count += count; | |
647 | node->nr_values += values; | |
648 | XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE); | |
649 | XA_NODE_BUG_ON(node, node->nr_values > XA_CHUNK_SIZE); | |
650 | xas_update(xas, node); | |
651 | if (count < 0) | |
652 | xas_delete_node(xas); | |
653 | } | |
654 | ||
655 | /** | |
656 | * xas_store() - Store this entry in the XArray. | |
657 | * @xas: XArray operation state. | |
658 | * @entry: New entry. | |
659 | * | |
660 | * If @xas is operating on a multi-index entry, the entry returned by this | |
661 | * function is essentially meaningless (it may be an internal entry or it | |
662 | * may be %NULL, even if there are non-NULL entries at some of the indices | |
663 | * covered by the range). This is not a problem for any current users, | |
664 | * and can be changed if needed. | |
665 | * | |
666 | * Return: The old entry at this index. | |
667 | */ | |
668 | void *xas_store(struct xa_state *xas, void *entry) | |
669 | { | |
670 | struct xa_node *node; | |
671 | void __rcu **slot = &xas->xa->xa_head; | |
672 | unsigned int offset, max; | |
673 | int count = 0; | |
674 | int values = 0; | |
675 | void *first, *next; | |
676 | bool value = xa_is_value(entry); | |
677 | ||
678 | if (entry) | |
679 | first = xas_create(xas); | |
680 | else | |
681 | first = xas_load(xas); | |
682 | ||
683 | if (xas_invalid(xas)) | |
684 | return first; | |
685 | node = xas->xa_node; | |
686 | if (node && (xas->xa_shift < node->shift)) | |
687 | xas->xa_sibs = 0; | |
688 | if ((first == entry) && !xas->xa_sibs) | |
689 | return first; | |
690 | ||
691 | next = first; | |
692 | offset = xas->xa_offset; | |
693 | max = xas->xa_offset + xas->xa_sibs; | |
694 | if (node) { | |
695 | slot = &node->slots[offset]; | |
696 | if (xas->xa_sibs) | |
697 | xas_squash_marks(xas); | |
698 | } | |
699 | if (!entry) | |
700 | xas_init_marks(xas); | |
701 | ||
702 | for (;;) { | |
703 | /* | |
704 | * Must clear the marks before setting the entry to NULL, | |
705 | * otherwise xas_for_each_marked may find a NULL entry and | |
706 | * stop early. rcu_assign_pointer contains a release barrier | |
707 | * so the mark clearing will appear to happen before the | |
708 | * entry is set to NULL. | |
709 | */ | |
710 | rcu_assign_pointer(*slot, entry); | |
711 | if (xa_is_node(next)) | |
712 | xas_free_nodes(xas, xa_to_node(next)); | |
713 | if (!node) | |
714 | break; | |
715 | count += !next - !entry; | |
716 | values += !xa_is_value(first) - !value; | |
717 | if (entry) { | |
718 | if (offset == max) | |
719 | break; | |
720 | if (!xa_is_sibling(entry)) | |
721 | entry = xa_mk_sibling(xas->xa_offset); | |
722 | } else { | |
723 | if (offset == XA_CHUNK_MASK) | |
724 | break; | |
725 | } | |
726 | next = xa_entry_locked(xas->xa, node, ++offset); | |
727 | if (!xa_is_sibling(next)) { | |
728 | if (!entry && (offset > max)) | |
729 | break; | |
730 | first = next; | |
731 | } | |
732 | slot++; | |
733 | } | |
734 | ||
735 | update_node(xas, node, count, values); | |
736 | return first; | |
737 | } | |
738 | EXPORT_SYMBOL_GPL(xas_store); | |
739 | ||
9b89a035 MW |
740 | /** |
741 | * xas_get_mark() - Returns the state of this mark. | |
742 | * @xas: XArray operation state. | |
743 | * @mark: Mark number. | |
744 | * | |
745 | * Return: true if the mark is set, false if the mark is clear or @xas | |
746 | * is in an error state. | |
747 | */ | |
748 | bool xas_get_mark(const struct xa_state *xas, xa_mark_t mark) | |
749 | { | |
750 | if (xas_invalid(xas)) | |
751 | return false; | |
752 | if (!xas->xa_node) | |
753 | return xa_marked(xas->xa, mark); | |
754 | return node_get_mark(xas->xa_node, xas->xa_offset, mark); | |
755 | } | |
756 | EXPORT_SYMBOL_GPL(xas_get_mark); | |
757 | ||
758 | /** | |
759 | * xas_set_mark() - Sets the mark on this entry and its parents. | |
760 | * @xas: XArray operation state. | |
761 | * @mark: Mark number. | |
762 | * | |
763 | * Sets the specified mark on this entry, and walks up the tree setting it | |
764 | * on all the ancestor entries. Does nothing if @xas has not been walked to | |
765 | * an entry, or is in an error state. | |
766 | */ | |
767 | void xas_set_mark(const struct xa_state *xas, xa_mark_t mark) | |
768 | { | |
769 | struct xa_node *node = xas->xa_node; | |
770 | unsigned int offset = xas->xa_offset; | |
771 | ||
772 | if (xas_invalid(xas)) | |
773 | return; | |
774 | ||
775 | while (node) { | |
776 | if (node_set_mark(node, offset, mark)) | |
777 | return; | |
778 | offset = node->offset; | |
779 | node = xa_parent_locked(xas->xa, node); | |
780 | } | |
781 | ||
782 | if (!xa_marked(xas->xa, mark)) | |
783 | xa_mark_set(xas->xa, mark); | |
784 | } | |
785 | EXPORT_SYMBOL_GPL(xas_set_mark); | |
786 | ||
787 | /** | |
788 | * xas_clear_mark() - Clears the mark on this entry and its parents. | |
789 | * @xas: XArray operation state. | |
790 | * @mark: Mark number. | |
791 | * | |
792 | * Clears the specified mark on this entry, and walks back to the head | |
793 | * attempting to clear it on all the ancestor entries. Does nothing if | |
794 | * @xas has not been walked to an entry, or is in an error state. | |
795 | */ | |
796 | void xas_clear_mark(const struct xa_state *xas, xa_mark_t mark) | |
797 | { | |
798 | struct xa_node *node = xas->xa_node; | |
799 | unsigned int offset = xas->xa_offset; | |
800 | ||
801 | if (xas_invalid(xas)) | |
802 | return; | |
803 | ||
804 | while (node) { | |
805 | if (!node_clear_mark(node, offset, mark)) | |
806 | return; | |
807 | if (node_any_mark(node, mark)) | |
808 | return; | |
809 | ||
810 | offset = node->offset; | |
811 | node = xa_parent_locked(xas->xa, node); | |
812 | } | |
813 | ||
814 | if (xa_marked(xas->xa, mark)) | |
815 | xa_mark_clear(xas->xa, mark); | |
816 | } | |
817 | EXPORT_SYMBOL_GPL(xas_clear_mark); | |
818 | ||
58d6ea30 MW |
819 | /** |
820 | * xas_init_marks() - Initialise all marks for the entry | |
821 | * @xas: Array operations state. | |
822 | * | |
823 | * Initialise all marks for the entry specified by @xas. If we're tracking | |
824 | * free entries with a mark, we need to set it on all entries. All other | |
825 | * marks are cleared. | |
826 | * | |
827 | * This implementation is not as efficient as it could be; we may walk | |
828 | * up the tree multiple times. | |
829 | */ | |
830 | void xas_init_marks(const struct xa_state *xas) | |
831 | { | |
832 | xa_mark_t mark = 0; | |
833 | ||
834 | for (;;) { | |
835 | xas_clear_mark(xas, mark); | |
836 | if (mark == XA_MARK_MAX) | |
837 | break; | |
838 | mark_inc(mark); | |
839 | } | |
840 | } | |
841 | EXPORT_SYMBOL_GPL(xas_init_marks); | |
842 | ||
b803b428 MW |
843 | /** |
844 | * xas_pause() - Pause a walk to drop a lock. | |
845 | * @xas: XArray operation state. | |
846 | * | |
847 | * Some users need to pause a walk and drop the lock they're holding in | |
848 | * order to yield to a higher priority thread or carry out an operation | |
849 | * on an entry. Those users should call this function before they drop | |
850 | * the lock. It resets the @xas to be suitable for the next iteration | |
851 | * of the loop after the user has reacquired the lock. If most entries | |
852 | * found during a walk require you to call xas_pause(), the xa_for_each() | |
853 | * iterator may be more appropriate. | |
854 | * | |
855 | * Note that xas_pause() only works for forward iteration. If a user needs | |
856 | * to pause a reverse iteration, we will need a xas_pause_rev(). | |
857 | */ | |
858 | void xas_pause(struct xa_state *xas) | |
859 | { | |
860 | struct xa_node *node = xas->xa_node; | |
861 | ||
862 | if (xas_invalid(xas)) | |
863 | return; | |
864 | ||
865 | if (node) { | |
866 | unsigned int offset = xas->xa_offset; | |
867 | while (++offset < XA_CHUNK_SIZE) { | |
868 | if (!xa_is_sibling(xa_entry(xas->xa, node, offset))) | |
869 | break; | |
870 | } | |
871 | xas->xa_index += (offset - xas->xa_offset) << node->shift; | |
872 | } else { | |
873 | xas->xa_index++; | |
874 | } | |
875 | xas->xa_node = XAS_RESTART; | |
876 | } | |
877 | EXPORT_SYMBOL_GPL(xas_pause); | |
878 | ||
64d3e9a9 MW |
879 | /* |
880 | * __xas_prev() - Find the previous entry in the XArray. | |
881 | * @xas: XArray operation state. | |
882 | * | |
883 | * Helper function for xas_prev() which handles all the complex cases | |
884 | * out of line. | |
885 | */ | |
886 | void *__xas_prev(struct xa_state *xas) | |
887 | { | |
888 | void *entry; | |
889 | ||
890 | if (!xas_frozen(xas->xa_node)) | |
891 | xas->xa_index--; | |
892 | if (xas_not_node(xas->xa_node)) | |
893 | return xas_load(xas); | |
894 | ||
895 | if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node)) | |
896 | xas->xa_offset--; | |
897 | ||
898 | while (xas->xa_offset == 255) { | |
899 | xas->xa_offset = xas->xa_node->offset - 1; | |
900 | xas->xa_node = xa_parent(xas->xa, xas->xa_node); | |
901 | if (!xas->xa_node) | |
902 | return set_bounds(xas); | |
903 | } | |
904 | ||
905 | for (;;) { | |
906 | entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset); | |
907 | if (!xa_is_node(entry)) | |
908 | return entry; | |
909 | ||
910 | xas->xa_node = xa_to_node(entry); | |
911 | xas_set_offset(xas); | |
912 | } | |
913 | } | |
914 | EXPORT_SYMBOL_GPL(__xas_prev); | |
915 | ||
916 | /* | |
917 | * __xas_next() - Find the next entry in the XArray. | |
918 | * @xas: XArray operation state. | |
919 | * | |
920 | * Helper function for xas_next() which handles all the complex cases | |
921 | * out of line. | |
922 | */ | |
923 | void *__xas_next(struct xa_state *xas) | |
924 | { | |
925 | void *entry; | |
926 | ||
927 | if (!xas_frozen(xas->xa_node)) | |
928 | xas->xa_index++; | |
929 | if (xas_not_node(xas->xa_node)) | |
930 | return xas_load(xas); | |
931 | ||
932 | if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node)) | |
933 | xas->xa_offset++; | |
934 | ||
935 | while (xas->xa_offset == XA_CHUNK_SIZE) { | |
936 | xas->xa_offset = xas->xa_node->offset + 1; | |
937 | xas->xa_node = xa_parent(xas->xa, xas->xa_node); | |
938 | if (!xas->xa_node) | |
939 | return set_bounds(xas); | |
940 | } | |
941 | ||
942 | for (;;) { | |
943 | entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset); | |
944 | if (!xa_is_node(entry)) | |
945 | return entry; | |
946 | ||
947 | xas->xa_node = xa_to_node(entry); | |
948 | xas_set_offset(xas); | |
949 | } | |
950 | } | |
951 | EXPORT_SYMBOL_GPL(__xas_next); | |
952 | ||
b803b428 MW |
953 | /** |
954 | * xas_find() - Find the next present entry in the XArray. | |
955 | * @xas: XArray operation state. | |
956 | * @max: Highest index to return. | |
957 | * | |
958 | * If the @xas has not yet been walked to an entry, return the entry | |
959 | * which has an index >= xas.xa_index. If it has been walked, the entry | |
960 | * currently being pointed at has been processed, and so we move to the | |
961 | * next entry. | |
962 | * | |
963 | * If no entry is found and the array is smaller than @max, the iterator | |
964 | * is set to the smallest index not yet in the array. This allows @xas | |
965 | * to be immediately passed to xas_store(). | |
966 | * | |
967 | * Return: The entry, if found, otherwise %NULL. | |
968 | */ | |
969 | void *xas_find(struct xa_state *xas, unsigned long max) | |
970 | { | |
971 | void *entry; | |
972 | ||
973 | if (xas_error(xas)) | |
974 | return NULL; | |
975 | ||
976 | if (!xas->xa_node) { | |
977 | xas->xa_index = 1; | |
978 | return set_bounds(xas); | |
979 | } else if (xas_top(xas->xa_node)) { | |
980 | entry = xas_load(xas); | |
981 | if (entry || xas_not_node(xas->xa_node)) | |
982 | return entry; | |
983 | } else if (!xas->xa_node->shift && | |
984 | xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)) { | |
985 | xas->xa_offset = ((xas->xa_index - 1) & XA_CHUNK_MASK) + 1; | |
986 | } | |
987 | ||
988 | xas_advance(xas); | |
989 | ||
990 | while (xas->xa_node && (xas->xa_index <= max)) { | |
991 | if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) { | |
992 | xas->xa_offset = xas->xa_node->offset + 1; | |
993 | xas->xa_node = xa_parent(xas->xa, xas->xa_node); | |
994 | continue; | |
995 | } | |
996 | ||
997 | entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset); | |
998 | if (xa_is_node(entry)) { | |
999 | xas->xa_node = xa_to_node(entry); | |
1000 | xas->xa_offset = 0; | |
1001 | continue; | |
1002 | } | |
1003 | if (entry && !xa_is_sibling(entry)) | |
1004 | return entry; | |
1005 | ||
1006 | xas_advance(xas); | |
1007 | } | |
1008 | ||
1009 | if (!xas->xa_node) | |
1010 | xas->xa_node = XAS_BOUNDS; | |
1011 | return NULL; | |
1012 | } | |
1013 | EXPORT_SYMBOL_GPL(xas_find); | |
1014 | ||
1015 | /** | |
1016 | * xas_find_marked() - Find the next marked entry in the XArray. | |
1017 | * @xas: XArray operation state. | |
1018 | * @max: Highest index to return. | |
1019 | * @mark: Mark number to search for. | |
1020 | * | |
1021 | * If the @xas has not yet been walked to an entry, return the marked entry | |
1022 | * which has an index >= xas.xa_index. If it has been walked, the entry | |
1023 | * currently being pointed at has been processed, and so we return the | |
1024 | * first marked entry with an index > xas.xa_index. | |
1025 | * | |
1026 | * If no marked entry is found and the array is smaller than @max, @xas is | |
1027 | * set to the bounds state and xas->xa_index is set to the smallest index | |
1028 | * not yet in the array. This allows @xas to be immediately passed to | |
1029 | * xas_store(). | |
1030 | * | |
1031 | * If no entry is found before @max is reached, @xas is set to the restart | |
1032 | * state. | |
1033 | * | |
1034 | * Return: The entry, if found, otherwise %NULL. | |
1035 | */ | |
1036 | void *xas_find_marked(struct xa_state *xas, unsigned long max, xa_mark_t mark) | |
1037 | { | |
1038 | bool advance = true; | |
1039 | unsigned int offset; | |
1040 | void *entry; | |
1041 | ||
1042 | if (xas_error(xas)) | |
1043 | return NULL; | |
1044 | ||
1045 | if (!xas->xa_node) { | |
1046 | xas->xa_index = 1; | |
1047 | goto out; | |
1048 | } else if (xas_top(xas->xa_node)) { | |
1049 | advance = false; | |
1050 | entry = xa_head(xas->xa); | |
1051 | xas->xa_node = NULL; | |
1052 | if (xas->xa_index > max_index(entry)) | |
1053 | goto bounds; | |
1054 | if (!xa_is_node(entry)) { | |
1055 | if (xa_marked(xas->xa, mark)) | |
1056 | return entry; | |
1057 | xas->xa_index = 1; | |
1058 | goto out; | |
1059 | } | |
1060 | xas->xa_node = xa_to_node(entry); | |
1061 | xas->xa_offset = xas->xa_index >> xas->xa_node->shift; | |
1062 | } | |
1063 | ||
1064 | while (xas->xa_index <= max) { | |
1065 | if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) { | |
1066 | xas->xa_offset = xas->xa_node->offset + 1; | |
1067 | xas->xa_node = xa_parent(xas->xa, xas->xa_node); | |
1068 | if (!xas->xa_node) | |
1069 | break; | |
1070 | advance = false; | |
1071 | continue; | |
1072 | } | |
1073 | ||
1074 | if (!advance) { | |
1075 | entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset); | |
1076 | if (xa_is_sibling(entry)) { | |
1077 | xas->xa_offset = xa_to_sibling(entry); | |
1078 | xas_move_index(xas, xas->xa_offset); | |
1079 | } | |
1080 | } | |
1081 | ||
1082 | offset = xas_find_chunk(xas, advance, mark); | |
1083 | if (offset > xas->xa_offset) { | |
1084 | advance = false; | |
1085 | xas_move_index(xas, offset); | |
1086 | /* Mind the wrap */ | |
1087 | if ((xas->xa_index - 1) >= max) | |
1088 | goto max; | |
1089 | xas->xa_offset = offset; | |
1090 | if (offset == XA_CHUNK_SIZE) | |
1091 | continue; | |
1092 | } | |
1093 | ||
1094 | entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset); | |
1095 | if (!xa_is_node(entry)) | |
1096 | return entry; | |
1097 | xas->xa_node = xa_to_node(entry); | |
1098 | xas_set_offset(xas); | |
1099 | } | |
1100 | ||
1101 | out: | |
1102 | if (!max) | |
1103 | goto max; | |
1104 | bounds: | |
1105 | xas->xa_node = XAS_BOUNDS; | |
1106 | return NULL; | |
1107 | max: | |
1108 | xas->xa_node = XAS_RESTART; | |
1109 | return NULL; | |
1110 | } | |
1111 | EXPORT_SYMBOL_GPL(xas_find_marked); | |
1112 | ||
f8d5d0cc MW |
1113 | /** |
1114 | * xa_init_flags() - Initialise an empty XArray with flags. | |
1115 | * @xa: XArray. | |
1116 | * @flags: XA_FLAG values. | |
1117 | * | |
1118 | * If you need to initialise an XArray with special flags (eg you need | |
1119 | * to take the lock from interrupt context), use this function instead | |
1120 | * of xa_init(). | |
1121 | * | |
1122 | * Context: Any context. | |
1123 | */ | |
1124 | void xa_init_flags(struct xarray *xa, gfp_t flags) | |
1125 | { | |
58d6ea30 MW |
1126 | unsigned int lock_type; |
1127 | static struct lock_class_key xa_lock_irq; | |
1128 | static struct lock_class_key xa_lock_bh; | |
1129 | ||
f8d5d0cc MW |
1130 | spin_lock_init(&xa->xa_lock); |
1131 | xa->xa_flags = flags; | |
1132 | xa->xa_head = NULL; | |
58d6ea30 MW |
1133 | |
1134 | lock_type = xa_lock_type(xa); | |
1135 | if (lock_type == XA_LOCK_IRQ) | |
1136 | lockdep_set_class(&xa->xa_lock, &xa_lock_irq); | |
1137 | else if (lock_type == XA_LOCK_BH) | |
1138 | lockdep_set_class(&xa->xa_lock, &xa_lock_bh); | |
f8d5d0cc MW |
1139 | } |
1140 | EXPORT_SYMBOL(xa_init_flags); | |
ad3d6c72 MW |
1141 | |
1142 | /** | |
1143 | * xa_load() - Load an entry from an XArray. | |
1144 | * @xa: XArray. | |
1145 | * @index: index into array. | |
1146 | * | |
1147 | * Context: Any context. Takes and releases the RCU lock. | |
1148 | * Return: The entry at @index in @xa. | |
1149 | */ | |
1150 | void *xa_load(struct xarray *xa, unsigned long index) | |
1151 | { | |
1152 | XA_STATE(xas, xa, index); | |
1153 | void *entry; | |
1154 | ||
1155 | rcu_read_lock(); | |
1156 | do { | |
1157 | entry = xas_load(&xas); | |
1158 | } while (xas_retry(&xas, entry)); | |
1159 | rcu_read_unlock(); | |
1160 | ||
1161 | return entry; | |
1162 | } | |
1163 | EXPORT_SYMBOL(xa_load); | |
1164 | ||
58d6ea30 MW |
1165 | static void *xas_result(struct xa_state *xas, void *curr) |
1166 | { | |
1167 | XA_NODE_BUG_ON(xas->xa_node, xa_is_internal(curr)); | |
1168 | if (xas_error(xas)) | |
1169 | curr = xas->xa_node; | |
1170 | return curr; | |
1171 | } | |
1172 | ||
1173 | /** | |
1174 | * __xa_erase() - Erase this entry from the XArray while locked. | |
1175 | * @xa: XArray. | |
1176 | * @index: Index into array. | |
1177 | * | |
1178 | * If the entry at this index is a multi-index entry then all indices will | |
1179 | * be erased, and the entry will no longer be a multi-index entry. | |
1180 | * This function expects the xa_lock to be held on entry. | |
1181 | * | |
1182 | * Context: Any context. Expects xa_lock to be held on entry. May | |
1183 | * release and reacquire xa_lock if @gfp flags permit. | |
1184 | * Return: The old entry at this index. | |
1185 | */ | |
1186 | void *__xa_erase(struct xarray *xa, unsigned long index) | |
1187 | { | |
1188 | XA_STATE(xas, xa, index); | |
1189 | return xas_result(&xas, xas_store(&xas, NULL)); | |
1190 | } | |
1191 | EXPORT_SYMBOL_GPL(__xa_erase); | |
1192 | ||
1193 | /** | |
1194 | * xa_store() - Store this entry in the XArray. | |
1195 | * @xa: XArray. | |
1196 | * @index: Index into array. | |
1197 | * @entry: New entry. | |
1198 | * @gfp: Memory allocation flags. | |
1199 | * | |
1200 | * After this function returns, loads from this index will return @entry. | |
1201 | * Storing into an existing multislot entry updates the entry of every index. | |
1202 | * The marks associated with @index are unaffected unless @entry is %NULL. | |
1203 | * | |
1204 | * Context: Process context. Takes and releases the xa_lock. May sleep | |
1205 | * if the @gfp flags permit. | |
1206 | * Return: The old entry at this index on success, xa_err(-EINVAL) if @entry | |
1207 | * cannot be stored in an XArray, or xa_err(-ENOMEM) if memory allocation | |
1208 | * failed. | |
1209 | */ | |
1210 | void *xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp) | |
1211 | { | |
1212 | XA_STATE(xas, xa, index); | |
1213 | void *curr; | |
1214 | ||
1215 | if (WARN_ON_ONCE(xa_is_internal(entry))) | |
1216 | return XA_ERROR(-EINVAL); | |
1217 | ||
1218 | do { | |
1219 | xas_lock(&xas); | |
1220 | curr = xas_store(&xas, entry); | |
1221 | xas_unlock(&xas); | |
1222 | } while (xas_nomem(&xas, gfp)); | |
1223 | ||
1224 | return xas_result(&xas, curr); | |
1225 | } | |
1226 | EXPORT_SYMBOL(xa_store); | |
1227 | ||
1228 | /** | |
1229 | * __xa_store() - Store this entry in the XArray. | |
1230 | * @xa: XArray. | |
1231 | * @index: Index into array. | |
1232 | * @entry: New entry. | |
1233 | * @gfp: Memory allocation flags. | |
1234 | * | |
1235 | * You must already be holding the xa_lock when calling this function. | |
1236 | * It will drop the lock if needed to allocate memory, and then reacquire | |
1237 | * it afterwards. | |
1238 | * | |
1239 | * Context: Any context. Expects xa_lock to be held on entry. May | |
1240 | * release and reacquire xa_lock if @gfp flags permit. | |
1241 | * Return: The old entry at this index or xa_err() if an error happened. | |
1242 | */ | |
1243 | void *__xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp) | |
1244 | { | |
1245 | XA_STATE(xas, xa, index); | |
1246 | void *curr; | |
1247 | ||
1248 | if (WARN_ON_ONCE(xa_is_internal(entry))) | |
1249 | return XA_ERROR(-EINVAL); | |
1250 | ||
1251 | do { | |
1252 | curr = xas_store(&xas, entry); | |
1253 | } while (__xas_nomem(&xas, gfp)); | |
1254 | ||
1255 | return xas_result(&xas, curr); | |
1256 | } | |
1257 | EXPORT_SYMBOL(__xa_store); | |
1258 | ||
41aec91f MW |
1259 | /** |
1260 | * xa_cmpxchg() - Conditionally replace an entry in the XArray. | |
1261 | * @xa: XArray. | |
1262 | * @index: Index into array. | |
1263 | * @old: Old value to test against. | |
1264 | * @entry: New value to place in array. | |
1265 | * @gfp: Memory allocation flags. | |
1266 | * | |
1267 | * If the entry at @index is the same as @old, replace it with @entry. | |
1268 | * If the return value is equal to @old, then the exchange was successful. | |
1269 | * | |
1270 | * Context: Process context. Takes and releases the xa_lock. May sleep | |
1271 | * if the @gfp flags permit. | |
1272 | * Return: The old value at this index or xa_err() if an error happened. | |
1273 | */ | |
1274 | void *xa_cmpxchg(struct xarray *xa, unsigned long index, | |
1275 | void *old, void *entry, gfp_t gfp) | |
1276 | { | |
1277 | XA_STATE(xas, xa, index); | |
1278 | void *curr; | |
1279 | ||
1280 | if (WARN_ON_ONCE(xa_is_internal(entry))) | |
1281 | return XA_ERROR(-EINVAL); | |
1282 | ||
1283 | do { | |
1284 | xas_lock(&xas); | |
1285 | curr = xas_load(&xas); | |
1286 | if (curr == old) | |
1287 | xas_store(&xas, entry); | |
1288 | xas_unlock(&xas); | |
1289 | } while (xas_nomem(&xas, gfp)); | |
1290 | ||
1291 | return xas_result(&xas, curr); | |
1292 | } | |
1293 | EXPORT_SYMBOL(xa_cmpxchg); | |
1294 | ||
1295 | /** | |
1296 | * __xa_cmpxchg() - Store this entry in the XArray. | |
1297 | * @xa: XArray. | |
1298 | * @index: Index into array. | |
1299 | * @old: Old value to test against. | |
1300 | * @entry: New entry. | |
1301 | * @gfp: Memory allocation flags. | |
1302 | * | |
1303 | * You must already be holding the xa_lock when calling this function. | |
1304 | * It will drop the lock if needed to allocate memory, and then reacquire | |
1305 | * it afterwards. | |
1306 | * | |
1307 | * Context: Any context. Expects xa_lock to be held on entry. May | |
1308 | * release and reacquire xa_lock if @gfp flags permit. | |
1309 | * Return: The old entry at this index or xa_err() if an error happened. | |
1310 | */ | |
1311 | void *__xa_cmpxchg(struct xarray *xa, unsigned long index, | |
1312 | void *old, void *entry, gfp_t gfp) | |
1313 | { | |
1314 | XA_STATE(xas, xa, index); | |
1315 | void *curr; | |
1316 | ||
1317 | if (WARN_ON_ONCE(xa_is_internal(entry))) | |
1318 | return XA_ERROR(-EINVAL); | |
1319 | ||
1320 | do { | |
1321 | curr = xas_load(&xas); | |
1322 | if (curr == old) | |
1323 | xas_store(&xas, entry); | |
1324 | } while (__xas_nomem(&xas, gfp)); | |
1325 | ||
1326 | return xas_result(&xas, curr); | |
1327 | } | |
1328 | EXPORT_SYMBOL(__xa_cmpxchg); | |
1329 | ||
9b89a035 MW |
1330 | /** |
1331 | * __xa_set_mark() - Set this mark on this entry while locked. | |
1332 | * @xa: XArray. | |
1333 | * @index: Index of entry. | |
1334 | * @mark: Mark number. | |
1335 | * | |
1336 | * Attempting to set a mark on a NULL entry does not succeed. | |
1337 | * | |
1338 | * Context: Any context. Expects xa_lock to be held on entry. | |
1339 | */ | |
1340 | void __xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark) | |
1341 | { | |
1342 | XA_STATE(xas, xa, index); | |
1343 | void *entry = xas_load(&xas); | |
1344 | ||
1345 | if (entry) | |
1346 | xas_set_mark(&xas, mark); | |
1347 | } | |
1348 | EXPORT_SYMBOL_GPL(__xa_set_mark); | |
1349 | ||
1350 | /** | |
1351 | * __xa_clear_mark() - Clear this mark on this entry while locked. | |
1352 | * @xa: XArray. | |
1353 | * @index: Index of entry. | |
1354 | * @mark: Mark number. | |
1355 | * | |
1356 | * Context: Any context. Expects xa_lock to be held on entry. | |
1357 | */ | |
1358 | void __xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark) | |
1359 | { | |
1360 | XA_STATE(xas, xa, index); | |
1361 | void *entry = xas_load(&xas); | |
1362 | ||
1363 | if (entry) | |
1364 | xas_clear_mark(&xas, mark); | |
1365 | } | |
1366 | EXPORT_SYMBOL_GPL(__xa_clear_mark); | |
1367 | ||
1368 | /** | |
1369 | * xa_get_mark() - Inquire whether this mark is set on this entry. | |
1370 | * @xa: XArray. | |
1371 | * @index: Index of entry. | |
1372 | * @mark: Mark number. | |
1373 | * | |
1374 | * This function uses the RCU read lock, so the result may be out of date | |
1375 | * by the time it returns. If you need the result to be stable, use a lock. | |
1376 | * | |
1377 | * Context: Any context. Takes and releases the RCU lock. | |
1378 | * Return: True if the entry at @index has this mark set, false if it doesn't. | |
1379 | */ | |
1380 | bool xa_get_mark(struct xarray *xa, unsigned long index, xa_mark_t mark) | |
1381 | { | |
1382 | XA_STATE(xas, xa, index); | |
1383 | void *entry; | |
1384 | ||
1385 | rcu_read_lock(); | |
1386 | entry = xas_start(&xas); | |
1387 | while (xas_get_mark(&xas, mark)) { | |
1388 | if (!xa_is_node(entry)) | |
1389 | goto found; | |
1390 | entry = xas_descend(&xas, xa_to_node(entry)); | |
1391 | } | |
1392 | rcu_read_unlock(); | |
1393 | return false; | |
1394 | found: | |
1395 | rcu_read_unlock(); | |
1396 | return true; | |
1397 | } | |
1398 | EXPORT_SYMBOL(xa_get_mark); | |
1399 | ||
1400 | /** | |
1401 | * xa_set_mark() - Set this mark on this entry. | |
1402 | * @xa: XArray. | |
1403 | * @index: Index of entry. | |
1404 | * @mark: Mark number. | |
1405 | * | |
1406 | * Attempting to set a mark on a NULL entry does not succeed. | |
1407 | * | |
1408 | * Context: Process context. Takes and releases the xa_lock. | |
1409 | */ | |
1410 | void xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark) | |
1411 | { | |
1412 | xa_lock(xa); | |
1413 | __xa_set_mark(xa, index, mark); | |
1414 | xa_unlock(xa); | |
1415 | } | |
1416 | EXPORT_SYMBOL(xa_set_mark); | |
1417 | ||
1418 | /** | |
1419 | * xa_clear_mark() - Clear this mark on this entry. | |
1420 | * @xa: XArray. | |
1421 | * @index: Index of entry. | |
1422 | * @mark: Mark number. | |
1423 | * | |
1424 | * Clearing a mark always succeeds. | |
1425 | * | |
1426 | * Context: Process context. Takes and releases the xa_lock. | |
1427 | */ | |
1428 | void xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark) | |
1429 | { | |
1430 | xa_lock(xa); | |
1431 | __xa_clear_mark(xa, index, mark); | |
1432 | xa_unlock(xa); | |
1433 | } | |
1434 | EXPORT_SYMBOL(xa_clear_mark); | |
1435 | ||
b803b428 MW |
1436 | /** |
1437 | * xa_find() - Search the XArray for an entry. | |
1438 | * @xa: XArray. | |
1439 | * @indexp: Pointer to an index. | |
1440 | * @max: Maximum index to search to. | |
1441 | * @filter: Selection criterion. | |
1442 | * | |
1443 | * Finds the entry in @xa which matches the @filter, and has the lowest | |
1444 | * index that is at least @indexp and no more than @max. | |
1445 | * If an entry is found, @indexp is updated to be the index of the entry. | |
1446 | * This function is protected by the RCU read lock, so it may not find | |
1447 | * entries which are being simultaneously added. It will not return an | |
1448 | * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find(). | |
1449 | * | |
1450 | * Context: Any context. Takes and releases the RCU lock. | |
1451 | * Return: The entry, if found, otherwise %NULL. | |
1452 | */ | |
1453 | void *xa_find(struct xarray *xa, unsigned long *indexp, | |
1454 | unsigned long max, xa_mark_t filter) | |
1455 | { | |
1456 | XA_STATE(xas, xa, *indexp); | |
1457 | void *entry; | |
1458 | ||
1459 | rcu_read_lock(); | |
1460 | do { | |
1461 | if ((__force unsigned int)filter < XA_MAX_MARKS) | |
1462 | entry = xas_find_marked(&xas, max, filter); | |
1463 | else | |
1464 | entry = xas_find(&xas, max); | |
1465 | } while (xas_retry(&xas, entry)); | |
1466 | rcu_read_unlock(); | |
1467 | ||
1468 | if (entry) | |
1469 | *indexp = xas.xa_index; | |
1470 | return entry; | |
1471 | } | |
1472 | EXPORT_SYMBOL(xa_find); | |
1473 | ||
1474 | /** | |
1475 | * xa_find_after() - Search the XArray for a present entry. | |
1476 | * @xa: XArray. | |
1477 | * @indexp: Pointer to an index. | |
1478 | * @max: Maximum index to search to. | |
1479 | * @filter: Selection criterion. | |
1480 | * | |
1481 | * Finds the entry in @xa which matches the @filter and has the lowest | |
1482 | * index that is above @indexp and no more than @max. | |
1483 | * If an entry is found, @indexp is updated to be the index of the entry. | |
1484 | * This function is protected by the RCU read lock, so it may miss entries | |
1485 | * which are being simultaneously added. It will not return an | |
1486 | * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find(). | |
1487 | * | |
1488 | * Context: Any context. Takes and releases the RCU lock. | |
1489 | * Return: The pointer, if found, otherwise %NULL. | |
1490 | */ | |
1491 | void *xa_find_after(struct xarray *xa, unsigned long *indexp, | |
1492 | unsigned long max, xa_mark_t filter) | |
1493 | { | |
1494 | XA_STATE(xas, xa, *indexp + 1); | |
1495 | void *entry; | |
1496 | ||
1497 | rcu_read_lock(); | |
1498 | for (;;) { | |
1499 | if ((__force unsigned int)filter < XA_MAX_MARKS) | |
1500 | entry = xas_find_marked(&xas, max, filter); | |
1501 | else | |
1502 | entry = xas_find(&xas, max); | |
1503 | if (xas.xa_shift) { | |
1504 | if (xas.xa_index & ((1UL << xas.xa_shift) - 1)) | |
1505 | continue; | |
1506 | } else { | |
1507 | if (xas.xa_offset < (xas.xa_index & XA_CHUNK_MASK)) | |
1508 | continue; | |
1509 | } | |
1510 | if (!xas_retry(&xas, entry)) | |
1511 | break; | |
1512 | } | |
1513 | rcu_read_unlock(); | |
1514 | ||
1515 | if (entry) | |
1516 | *indexp = xas.xa_index; | |
1517 | return entry; | |
1518 | } | |
1519 | EXPORT_SYMBOL(xa_find_after); | |
1520 | ||
80a0a1a9 MW |
1521 | static unsigned int xas_extract_present(struct xa_state *xas, void **dst, |
1522 | unsigned long max, unsigned int n) | |
1523 | { | |
1524 | void *entry; | |
1525 | unsigned int i = 0; | |
1526 | ||
1527 | rcu_read_lock(); | |
1528 | xas_for_each(xas, entry, max) { | |
1529 | if (xas_retry(xas, entry)) | |
1530 | continue; | |
1531 | dst[i++] = entry; | |
1532 | if (i == n) | |
1533 | break; | |
1534 | } | |
1535 | rcu_read_unlock(); | |
1536 | ||
1537 | return i; | |
1538 | } | |
1539 | ||
1540 | static unsigned int xas_extract_marked(struct xa_state *xas, void **dst, | |
1541 | unsigned long max, unsigned int n, xa_mark_t mark) | |
1542 | { | |
1543 | void *entry; | |
1544 | unsigned int i = 0; | |
1545 | ||
1546 | rcu_read_lock(); | |
1547 | xas_for_each_marked(xas, entry, max, mark) { | |
1548 | if (xas_retry(xas, entry)) | |
1549 | continue; | |
1550 | dst[i++] = entry; | |
1551 | if (i == n) | |
1552 | break; | |
1553 | } | |
1554 | rcu_read_unlock(); | |
1555 | ||
1556 | return i; | |
1557 | } | |
1558 | ||
1559 | /** | |
1560 | * xa_extract() - Copy selected entries from the XArray into a normal array. | |
1561 | * @xa: The source XArray to copy from. | |
1562 | * @dst: The buffer to copy entries into. | |
1563 | * @start: The first index in the XArray eligible to be selected. | |
1564 | * @max: The last index in the XArray eligible to be selected. | |
1565 | * @n: The maximum number of entries to copy. | |
1566 | * @filter: Selection criterion. | |
1567 | * | |
1568 | * Copies up to @n entries that match @filter from the XArray. The | |
1569 | * copied entries will have indices between @start and @max, inclusive. | |
1570 | * | |
1571 | * The @filter may be an XArray mark value, in which case entries which are | |
1572 | * marked with that mark will be copied. It may also be %XA_PRESENT, in | |
1573 | * which case all entries which are not NULL will be copied. | |
1574 | * | |
1575 | * The entries returned may not represent a snapshot of the XArray at a | |
1576 | * moment in time. For example, if another thread stores to index 5, then | |
1577 | * index 10, calling xa_extract() may return the old contents of index 5 | |
1578 | * and the new contents of index 10. Indices not modified while this | |
1579 | * function is running will not be skipped. | |
1580 | * | |
1581 | * If you need stronger guarantees, holding the xa_lock across calls to this | |
1582 | * function will prevent concurrent modification. | |
1583 | * | |
1584 | * Context: Any context. Takes and releases the RCU lock. | |
1585 | * Return: The number of entries copied. | |
1586 | */ | |
1587 | unsigned int xa_extract(struct xarray *xa, void **dst, unsigned long start, | |
1588 | unsigned long max, unsigned int n, xa_mark_t filter) | |
1589 | { | |
1590 | XA_STATE(xas, xa, start); | |
1591 | ||
1592 | if (!n) | |
1593 | return 0; | |
1594 | ||
1595 | if ((__force unsigned int)filter < XA_MAX_MARKS) | |
1596 | return xas_extract_marked(&xas, dst, max, n, filter); | |
1597 | return xas_extract_present(&xas, dst, max, n); | |
1598 | } | |
1599 | EXPORT_SYMBOL(xa_extract); | |
1600 | ||
687149fc MW |
1601 | /** |
1602 | * xa_destroy() - Free all internal data structures. | |
1603 | * @xa: XArray. | |
1604 | * | |
1605 | * After calling this function, the XArray is empty and has freed all memory | |
1606 | * allocated for its internal data structures. You are responsible for | |
1607 | * freeing the objects referenced by the XArray. | |
1608 | * | |
1609 | * Context: Any context. Takes and releases the xa_lock, interrupt-safe. | |
1610 | */ | |
1611 | void xa_destroy(struct xarray *xa) | |
1612 | { | |
1613 | XA_STATE(xas, xa, 0); | |
1614 | unsigned long flags; | |
1615 | void *entry; | |
1616 | ||
1617 | xas.xa_node = NULL; | |
1618 | xas_lock_irqsave(&xas, flags); | |
1619 | entry = xa_head_locked(xa); | |
1620 | RCU_INIT_POINTER(xa->xa_head, NULL); | |
1621 | xas_init_marks(&xas); | |
1622 | /* lockdep checks we're still holding the lock in xas_free_nodes() */ | |
1623 | if (xa_is_node(entry)) | |
1624 | xas_free_nodes(&xas, xa_to_node(entry)); | |
1625 | xas_unlock_irqrestore(&xas, flags); | |
1626 | } | |
1627 | EXPORT_SYMBOL(xa_destroy); | |
1628 | ||
ad3d6c72 MW |
1629 | #ifdef XA_DEBUG |
1630 | void xa_dump_node(const struct xa_node *node) | |
1631 | { | |
1632 | unsigned i, j; | |
1633 | ||
1634 | if (!node) | |
1635 | return; | |
1636 | if ((unsigned long)node & 3) { | |
1637 | pr_cont("node %px\n", node); | |
1638 | return; | |
1639 | } | |
1640 | ||
1641 | pr_cont("node %px %s %d parent %px shift %d count %d values %d " | |
1642 | "array %px list %px %px marks", | |
1643 | node, node->parent ? "offset" : "max", node->offset, | |
1644 | node->parent, node->shift, node->count, node->nr_values, | |
1645 | node->array, node->private_list.prev, node->private_list.next); | |
1646 | for (i = 0; i < XA_MAX_MARKS; i++) | |
1647 | for (j = 0; j < XA_MARK_LONGS; j++) | |
1648 | pr_cont(" %lx", node->marks[i][j]); | |
1649 | pr_cont("\n"); | |
1650 | } | |
1651 | ||
1652 | void xa_dump_index(unsigned long index, unsigned int shift) | |
1653 | { | |
1654 | if (!shift) | |
1655 | pr_info("%lu: ", index); | |
1656 | else if (shift >= BITS_PER_LONG) | |
1657 | pr_info("0-%lu: ", ~0UL); | |
1658 | else | |
1659 | pr_info("%lu-%lu: ", index, index | ((1UL << shift) - 1)); | |
1660 | } | |
1661 | ||
1662 | void xa_dump_entry(const void *entry, unsigned long index, unsigned long shift) | |
1663 | { | |
1664 | if (!entry) | |
1665 | return; | |
1666 | ||
1667 | xa_dump_index(index, shift); | |
1668 | ||
1669 | if (xa_is_node(entry)) { | |
1670 | if (shift == 0) { | |
1671 | pr_cont("%px\n", entry); | |
1672 | } else { | |
1673 | unsigned long i; | |
1674 | struct xa_node *node = xa_to_node(entry); | |
1675 | xa_dump_node(node); | |
1676 | for (i = 0; i < XA_CHUNK_SIZE; i++) | |
1677 | xa_dump_entry(node->slots[i], | |
1678 | index + (i << node->shift), node->shift); | |
1679 | } | |
1680 | } else if (xa_is_value(entry)) | |
1681 | pr_cont("value %ld (0x%lx) [%px]\n", xa_to_value(entry), | |
1682 | xa_to_value(entry), entry); | |
1683 | else if (!xa_is_internal(entry)) | |
1684 | pr_cont("%px\n", entry); | |
1685 | else if (xa_is_retry(entry)) | |
1686 | pr_cont("retry (%ld)\n", xa_to_internal(entry)); | |
1687 | else if (xa_is_sibling(entry)) | |
1688 | pr_cont("sibling (slot %ld)\n", xa_to_sibling(entry)); | |
1689 | else | |
1690 | pr_cont("UNKNOWN ENTRY (%px)\n", entry); | |
1691 | } | |
1692 | ||
1693 | void xa_dump(const struct xarray *xa) | |
1694 | { | |
1695 | void *entry = xa->xa_head; | |
1696 | unsigned int shift = 0; | |
1697 | ||
1698 | pr_info("xarray: %px head %px flags %x marks %d %d %d\n", xa, entry, | |
9b89a035 MW |
1699 | xa->xa_flags, xa_marked(xa, XA_MARK_0), |
1700 | xa_marked(xa, XA_MARK_1), xa_marked(xa, XA_MARK_2)); | |
ad3d6c72 MW |
1701 | if (xa_is_node(entry)) |
1702 | shift = xa_to_node(entry)->shift + XA_CHUNK_SHIFT; | |
1703 | xa_dump_entry(entry, 0, shift); | |
1704 | } | |
1705 | #endif |