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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 | ||
371c752d MW |
55 | static inline bool xa_track_free(const struct xarray *xa) |
56 | { | |
57 | return xa->xa_flags & XA_FLAGS_TRACK_FREE; | |
58 | } | |
59 | ||
3ccaf57a MW |
60 | static inline bool xa_zero_busy(const struct xarray *xa) |
61 | { | |
62 | return xa->xa_flags & XA_FLAGS_ZERO_BUSY; | |
63 | } | |
64 | ||
9b89a035 MW |
65 | static inline void xa_mark_set(struct xarray *xa, xa_mark_t mark) |
66 | { | |
67 | if (!(xa->xa_flags & XA_FLAGS_MARK(mark))) | |
68 | xa->xa_flags |= XA_FLAGS_MARK(mark); | |
69 | } | |
70 | ||
71 | static inline void xa_mark_clear(struct xarray *xa, xa_mark_t mark) | |
72 | { | |
73 | if (xa->xa_flags & XA_FLAGS_MARK(mark)) | |
74 | xa->xa_flags &= ~(XA_FLAGS_MARK(mark)); | |
75 | } | |
76 | ||
77 | static inline unsigned long *node_marks(struct xa_node *node, xa_mark_t mark) | |
78 | { | |
79 | return node->marks[(__force unsigned)mark]; | |
80 | } | |
81 | ||
82 | static inline bool node_get_mark(struct xa_node *node, | |
83 | unsigned int offset, xa_mark_t mark) | |
84 | { | |
85 | return test_bit(offset, node_marks(node, mark)); | |
86 | } | |
87 | ||
88 | /* returns true if the bit was set */ | |
89 | static inline bool node_set_mark(struct xa_node *node, unsigned int offset, | |
90 | xa_mark_t mark) | |
91 | { | |
92 | return __test_and_set_bit(offset, node_marks(node, mark)); | |
93 | } | |
94 | ||
95 | /* returns true if the bit was set */ | |
96 | static inline bool node_clear_mark(struct xa_node *node, unsigned int offset, | |
97 | xa_mark_t mark) | |
98 | { | |
99 | return __test_and_clear_bit(offset, node_marks(node, mark)); | |
100 | } | |
101 | ||
102 | static inline bool node_any_mark(struct xa_node *node, xa_mark_t mark) | |
103 | { | |
104 | return !bitmap_empty(node_marks(node, mark), XA_CHUNK_SIZE); | |
105 | } | |
106 | ||
371c752d MW |
107 | static inline void node_mark_all(struct xa_node *node, xa_mark_t mark) |
108 | { | |
109 | bitmap_fill(node_marks(node, mark), XA_CHUNK_SIZE); | |
110 | } | |
111 | ||
58d6ea30 MW |
112 | #define mark_inc(mark) do { \ |
113 | mark = (__force xa_mark_t)((__force unsigned)(mark) + 1); \ | |
114 | } while (0) | |
115 | ||
116 | /* | |
117 | * xas_squash_marks() - Merge all marks to the first entry | |
118 | * @xas: Array operation state. | |
119 | * | |
120 | * Set a mark on the first entry if any entry has it set. Clear marks on | |
121 | * all sibling entries. | |
122 | */ | |
123 | static void xas_squash_marks(const struct xa_state *xas) | |
124 | { | |
125 | unsigned int mark = 0; | |
126 | unsigned int limit = xas->xa_offset + xas->xa_sibs + 1; | |
127 | ||
128 | if (!xas->xa_sibs) | |
129 | return; | |
130 | ||
131 | do { | |
132 | unsigned long *marks = xas->xa_node->marks[mark]; | |
133 | if (find_next_bit(marks, limit, xas->xa_offset + 1) == limit) | |
134 | continue; | |
135 | __set_bit(xas->xa_offset, marks); | |
136 | bitmap_clear(marks, xas->xa_offset + 1, xas->xa_sibs); | |
137 | } while (mark++ != (__force unsigned)XA_MARK_MAX); | |
138 | } | |
139 | ||
ad3d6c72 MW |
140 | /* extracts the offset within this node from the index */ |
141 | static unsigned int get_offset(unsigned long index, struct xa_node *node) | |
142 | { | |
143 | return (index >> node->shift) & XA_CHUNK_MASK; | |
144 | } | |
145 | ||
b803b428 MW |
146 | static void xas_set_offset(struct xa_state *xas) |
147 | { | |
148 | xas->xa_offset = get_offset(xas->xa_index, xas->xa_node); | |
149 | } | |
150 | ||
ad3d6c72 MW |
151 | /* move the index either forwards (find) or backwards (sibling slot) */ |
152 | static void xas_move_index(struct xa_state *xas, unsigned long offset) | |
153 | { | |
154 | unsigned int shift = xas->xa_node->shift; | |
155 | xas->xa_index &= ~XA_CHUNK_MASK << shift; | |
156 | xas->xa_index += offset << shift; | |
157 | } | |
158 | ||
b803b428 MW |
159 | static void xas_advance(struct xa_state *xas) |
160 | { | |
161 | xas->xa_offset++; | |
162 | xas_move_index(xas, xas->xa_offset); | |
163 | } | |
164 | ||
ad3d6c72 MW |
165 | static void *set_bounds(struct xa_state *xas) |
166 | { | |
167 | xas->xa_node = XAS_BOUNDS; | |
168 | return NULL; | |
169 | } | |
170 | ||
171 | /* | |
172 | * Starts a walk. If the @xas is already valid, we assume that it's on | |
173 | * the right path and just return where we've got to. If we're in an | |
174 | * error state, return NULL. If the index is outside the current scope | |
175 | * of the xarray, return NULL without changing @xas->xa_node. Otherwise | |
176 | * set @xas->xa_node to NULL and return the current head of the array. | |
177 | */ | |
178 | static void *xas_start(struct xa_state *xas) | |
179 | { | |
180 | void *entry; | |
181 | ||
182 | if (xas_valid(xas)) | |
183 | return xas_reload(xas); | |
184 | if (xas_error(xas)) | |
185 | return NULL; | |
186 | ||
187 | entry = xa_head(xas->xa); | |
188 | if (!xa_is_node(entry)) { | |
189 | if (xas->xa_index) | |
190 | return set_bounds(xas); | |
191 | } else { | |
192 | if ((xas->xa_index >> xa_to_node(entry)->shift) > XA_CHUNK_MASK) | |
193 | return set_bounds(xas); | |
194 | } | |
195 | ||
196 | xas->xa_node = NULL; | |
197 | return entry; | |
198 | } | |
199 | ||
200 | static void *xas_descend(struct xa_state *xas, struct xa_node *node) | |
201 | { | |
202 | unsigned int offset = get_offset(xas->xa_index, node); | |
203 | void *entry = xa_entry(xas->xa, node, offset); | |
204 | ||
205 | xas->xa_node = node; | |
206 | if (xa_is_sibling(entry)) { | |
207 | offset = xa_to_sibling(entry); | |
208 | entry = xa_entry(xas->xa, node, offset); | |
209 | } | |
210 | ||
211 | xas->xa_offset = offset; | |
212 | return entry; | |
213 | } | |
214 | ||
215 | /** | |
216 | * xas_load() - Load an entry from the XArray (advanced). | |
217 | * @xas: XArray operation state. | |
218 | * | |
219 | * Usually walks the @xas to the appropriate state to load the entry | |
220 | * stored at xa_index. However, it will do nothing and return %NULL if | |
221 | * @xas is in an error state. xas_load() will never expand the tree. | |
222 | * | |
223 | * If the xa_state is set up to operate on a multi-index entry, xas_load() | |
224 | * may return %NULL or an internal entry, even if there are entries | |
225 | * present within the range specified by @xas. | |
226 | * | |
227 | * Context: Any context. The caller should hold the xa_lock or the RCU lock. | |
228 | * Return: Usually an entry in the XArray, but see description for exceptions. | |
229 | */ | |
230 | void *xas_load(struct xa_state *xas) | |
231 | { | |
232 | void *entry = xas_start(xas); | |
233 | ||
234 | while (xa_is_node(entry)) { | |
235 | struct xa_node *node = xa_to_node(entry); | |
236 | ||
237 | if (xas->xa_shift > node->shift) | |
238 | break; | |
239 | entry = xas_descend(xas, node); | |
76b4e529 MW |
240 | if (node->shift == 0) |
241 | break; | |
ad3d6c72 MW |
242 | } |
243 | return entry; | |
244 | } | |
245 | EXPORT_SYMBOL_GPL(xas_load); | |
246 | ||
58d6ea30 MW |
247 | /* Move the radix tree node cache here */ |
248 | extern struct kmem_cache *radix_tree_node_cachep; | |
249 | extern void radix_tree_node_rcu_free(struct rcu_head *head); | |
250 | ||
251 | #define XA_RCU_FREE ((struct xarray *)1) | |
252 | ||
253 | static void xa_node_free(struct xa_node *node) | |
254 | { | |
255 | XA_NODE_BUG_ON(node, !list_empty(&node->private_list)); | |
256 | node->array = XA_RCU_FREE; | |
257 | call_rcu(&node->rcu_head, radix_tree_node_rcu_free); | |
258 | } | |
259 | ||
260 | /* | |
261 | * xas_destroy() - Free any resources allocated during the XArray operation. | |
262 | * @xas: XArray operation state. | |
263 | * | |
264 | * This function is now internal-only. | |
265 | */ | |
266 | static void xas_destroy(struct xa_state *xas) | |
267 | { | |
268 | struct xa_node *node = xas->xa_alloc; | |
269 | ||
270 | if (!node) | |
271 | return; | |
272 | XA_NODE_BUG_ON(node, !list_empty(&node->private_list)); | |
273 | kmem_cache_free(radix_tree_node_cachep, node); | |
274 | xas->xa_alloc = NULL; | |
275 | } | |
276 | ||
277 | /** | |
278 | * xas_nomem() - Allocate memory if needed. | |
279 | * @xas: XArray operation state. | |
280 | * @gfp: Memory allocation flags. | |
281 | * | |
282 | * If we need to add new nodes to the XArray, we try to allocate memory | |
283 | * with GFP_NOWAIT while holding the lock, which will usually succeed. | |
284 | * If it fails, @xas is flagged as needing memory to continue. The caller | |
285 | * should drop the lock and call xas_nomem(). If xas_nomem() succeeds, | |
286 | * the caller should retry the operation. | |
287 | * | |
288 | * Forward progress is guaranteed as one node is allocated here and | |
289 | * stored in the xa_state where it will be found by xas_alloc(). More | |
290 | * nodes will likely be found in the slab allocator, but we do not tie | |
291 | * them up here. | |
292 | * | |
293 | * Return: true if memory was needed, and was successfully allocated. | |
294 | */ | |
295 | bool xas_nomem(struct xa_state *xas, gfp_t gfp) | |
296 | { | |
297 | if (xas->xa_node != XA_ERROR(-ENOMEM)) { | |
298 | xas_destroy(xas); | |
299 | return false; | |
300 | } | |
301 | xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp); | |
302 | if (!xas->xa_alloc) | |
303 | return false; | |
304 | XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list)); | |
305 | xas->xa_node = XAS_RESTART; | |
306 | return true; | |
307 | } | |
308 | EXPORT_SYMBOL_GPL(xas_nomem); | |
309 | ||
310 | /* | |
311 | * __xas_nomem() - Drop locks and allocate memory if needed. | |
312 | * @xas: XArray operation state. | |
313 | * @gfp: Memory allocation flags. | |
314 | * | |
315 | * Internal variant of xas_nomem(). | |
316 | * | |
317 | * Return: true if memory was needed, and was successfully allocated. | |
318 | */ | |
319 | static bool __xas_nomem(struct xa_state *xas, gfp_t gfp) | |
320 | __must_hold(xas->xa->xa_lock) | |
321 | { | |
322 | unsigned int lock_type = xa_lock_type(xas->xa); | |
323 | ||
324 | if (xas->xa_node != XA_ERROR(-ENOMEM)) { | |
325 | xas_destroy(xas); | |
326 | return false; | |
327 | } | |
328 | if (gfpflags_allow_blocking(gfp)) { | |
329 | xas_unlock_type(xas, lock_type); | |
330 | xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp); | |
331 | xas_lock_type(xas, lock_type); | |
332 | } else { | |
333 | xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp); | |
334 | } | |
335 | if (!xas->xa_alloc) | |
336 | return false; | |
337 | XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list)); | |
338 | xas->xa_node = XAS_RESTART; | |
339 | return true; | |
340 | } | |
341 | ||
342 | static void xas_update(struct xa_state *xas, struct xa_node *node) | |
343 | { | |
344 | if (xas->xa_update) | |
345 | xas->xa_update(node); | |
346 | else | |
347 | XA_NODE_BUG_ON(node, !list_empty(&node->private_list)); | |
348 | } | |
349 | ||
350 | static void *xas_alloc(struct xa_state *xas, unsigned int shift) | |
351 | { | |
352 | struct xa_node *parent = xas->xa_node; | |
353 | struct xa_node *node = xas->xa_alloc; | |
354 | ||
355 | if (xas_invalid(xas)) | |
356 | return NULL; | |
357 | ||
358 | if (node) { | |
359 | xas->xa_alloc = NULL; | |
360 | } else { | |
361 | node = kmem_cache_alloc(radix_tree_node_cachep, | |
362 | GFP_NOWAIT | __GFP_NOWARN); | |
363 | if (!node) { | |
364 | xas_set_err(xas, -ENOMEM); | |
365 | return NULL; | |
366 | } | |
367 | } | |
368 | ||
369 | if (parent) { | |
370 | node->offset = xas->xa_offset; | |
371 | parent->count++; | |
372 | XA_NODE_BUG_ON(node, parent->count > XA_CHUNK_SIZE); | |
373 | xas_update(xas, parent); | |
374 | } | |
375 | XA_NODE_BUG_ON(node, shift > BITS_PER_LONG); | |
376 | XA_NODE_BUG_ON(node, !list_empty(&node->private_list)); | |
377 | node->shift = shift; | |
378 | node->count = 0; | |
379 | node->nr_values = 0; | |
380 | RCU_INIT_POINTER(node->parent, xas->xa_node); | |
381 | node->array = xas->xa; | |
382 | ||
383 | return node; | |
384 | } | |
385 | ||
0e9446c3 MW |
386 | #ifdef CONFIG_XARRAY_MULTI |
387 | /* Returns the number of indices covered by a given xa_state */ | |
388 | static unsigned long xas_size(const struct xa_state *xas) | |
389 | { | |
390 | return (xas->xa_sibs + 1UL) << xas->xa_shift; | |
391 | } | |
392 | #endif | |
393 | ||
58d6ea30 MW |
394 | /* |
395 | * Use this to calculate the maximum index that will need to be created | |
396 | * in order to add the entry described by @xas. Because we cannot store a | |
397 | * multiple-index entry at index 0, the calculation is a little more complex | |
398 | * than you might expect. | |
399 | */ | |
400 | static unsigned long xas_max(struct xa_state *xas) | |
401 | { | |
402 | unsigned long max = xas->xa_index; | |
403 | ||
404 | #ifdef CONFIG_XARRAY_MULTI | |
405 | if (xas->xa_shift || xas->xa_sibs) { | |
0e9446c3 | 406 | unsigned long mask = xas_size(xas) - 1; |
58d6ea30 MW |
407 | max |= mask; |
408 | if (mask == max) | |
409 | max++; | |
410 | } | |
411 | #endif | |
412 | ||
413 | return max; | |
414 | } | |
415 | ||
416 | /* The maximum index that can be contained in the array without expanding it */ | |
417 | static unsigned long max_index(void *entry) | |
418 | { | |
419 | if (!xa_is_node(entry)) | |
420 | return 0; | |
421 | return (XA_CHUNK_SIZE << xa_to_node(entry)->shift) - 1; | |
422 | } | |
423 | ||
424 | static void xas_shrink(struct xa_state *xas) | |
425 | { | |
426 | struct xarray *xa = xas->xa; | |
427 | struct xa_node *node = xas->xa_node; | |
428 | ||
429 | for (;;) { | |
430 | void *entry; | |
431 | ||
432 | XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE); | |
433 | if (node->count != 1) | |
434 | break; | |
435 | entry = xa_entry_locked(xa, node, 0); | |
436 | if (!entry) | |
437 | break; | |
438 | if (!xa_is_node(entry) && node->shift) | |
439 | break; | |
3ccaf57a MW |
440 | if (xa_is_zero(entry) && xa_zero_busy(xa)) |
441 | entry = NULL; | |
58d6ea30 MW |
442 | xas->xa_node = XAS_BOUNDS; |
443 | ||
444 | RCU_INIT_POINTER(xa->xa_head, entry); | |
371c752d MW |
445 | if (xa_track_free(xa) && !node_get_mark(node, 0, XA_FREE_MARK)) |
446 | xa_mark_clear(xa, XA_FREE_MARK); | |
58d6ea30 MW |
447 | |
448 | node->count = 0; | |
449 | node->nr_values = 0; | |
450 | if (!xa_is_node(entry)) | |
451 | RCU_INIT_POINTER(node->slots[0], XA_RETRY_ENTRY); | |
452 | xas_update(xas, node); | |
453 | xa_node_free(node); | |
454 | if (!xa_is_node(entry)) | |
455 | break; | |
456 | node = xa_to_node(entry); | |
457 | node->parent = NULL; | |
458 | } | |
459 | } | |
460 | ||
461 | /* | |
462 | * xas_delete_node() - Attempt to delete an xa_node | |
463 | * @xas: Array operation state. | |
464 | * | |
465 | * Attempts to delete the @xas->xa_node. This will fail if xa->node has | |
466 | * a non-zero reference count. | |
467 | */ | |
468 | static void xas_delete_node(struct xa_state *xas) | |
469 | { | |
470 | struct xa_node *node = xas->xa_node; | |
471 | ||
472 | for (;;) { | |
473 | struct xa_node *parent; | |
474 | ||
475 | XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE); | |
476 | if (node->count) | |
477 | break; | |
478 | ||
479 | parent = xa_parent_locked(xas->xa, node); | |
480 | xas->xa_node = parent; | |
481 | xas->xa_offset = node->offset; | |
482 | xa_node_free(node); | |
483 | ||
484 | if (!parent) { | |
485 | xas->xa->xa_head = NULL; | |
486 | xas->xa_node = XAS_BOUNDS; | |
487 | return; | |
488 | } | |
489 | ||
490 | parent->slots[xas->xa_offset] = NULL; | |
491 | parent->count--; | |
492 | XA_NODE_BUG_ON(parent, parent->count > XA_CHUNK_SIZE); | |
493 | node = parent; | |
494 | xas_update(xas, node); | |
495 | } | |
496 | ||
497 | if (!node->parent) | |
498 | xas_shrink(xas); | |
499 | } | |
500 | ||
501 | /** | |
502 | * xas_free_nodes() - Free this node and all nodes that it references | |
503 | * @xas: Array operation state. | |
504 | * @top: Node to free | |
505 | * | |
506 | * This node has been removed from the tree. We must now free it and all | |
507 | * of its subnodes. There may be RCU walkers with references into the tree, | |
508 | * so we must replace all entries with retry markers. | |
509 | */ | |
510 | static void xas_free_nodes(struct xa_state *xas, struct xa_node *top) | |
511 | { | |
512 | unsigned int offset = 0; | |
513 | struct xa_node *node = top; | |
514 | ||
515 | for (;;) { | |
516 | void *entry = xa_entry_locked(xas->xa, node, offset); | |
517 | ||
76b4e529 | 518 | if (node->shift && xa_is_node(entry)) { |
58d6ea30 MW |
519 | node = xa_to_node(entry); |
520 | offset = 0; | |
521 | continue; | |
522 | } | |
523 | if (entry) | |
524 | RCU_INIT_POINTER(node->slots[offset], XA_RETRY_ENTRY); | |
525 | offset++; | |
526 | while (offset == XA_CHUNK_SIZE) { | |
527 | struct xa_node *parent; | |
528 | ||
529 | parent = xa_parent_locked(xas->xa, node); | |
530 | offset = node->offset + 1; | |
531 | node->count = 0; | |
532 | node->nr_values = 0; | |
533 | xas_update(xas, node); | |
534 | xa_node_free(node); | |
535 | if (node == top) | |
536 | return; | |
537 | node = parent; | |
538 | } | |
539 | } | |
540 | } | |
541 | ||
542 | /* | |
543 | * xas_expand adds nodes to the head of the tree until it has reached | |
544 | * sufficient height to be able to contain @xas->xa_index | |
545 | */ | |
546 | static int xas_expand(struct xa_state *xas, void *head) | |
547 | { | |
548 | struct xarray *xa = xas->xa; | |
549 | struct xa_node *node = NULL; | |
550 | unsigned int shift = 0; | |
551 | unsigned long max = xas_max(xas); | |
552 | ||
553 | if (!head) { | |
554 | if (max == 0) | |
555 | return 0; | |
556 | while ((max >> shift) >= XA_CHUNK_SIZE) | |
557 | shift += XA_CHUNK_SHIFT; | |
558 | return shift + XA_CHUNK_SHIFT; | |
559 | } else if (xa_is_node(head)) { | |
560 | node = xa_to_node(head); | |
561 | shift = node->shift + XA_CHUNK_SHIFT; | |
562 | } | |
563 | xas->xa_node = NULL; | |
564 | ||
565 | while (max > max_index(head)) { | |
566 | xa_mark_t mark = 0; | |
567 | ||
568 | XA_NODE_BUG_ON(node, shift > BITS_PER_LONG); | |
569 | node = xas_alloc(xas, shift); | |
570 | if (!node) | |
571 | return -ENOMEM; | |
572 | ||
573 | node->count = 1; | |
574 | if (xa_is_value(head)) | |
575 | node->nr_values = 1; | |
576 | RCU_INIT_POINTER(node->slots[0], head); | |
577 | ||
578 | /* Propagate the aggregated mark info to the new child */ | |
579 | for (;;) { | |
371c752d MW |
580 | if (xa_track_free(xa) && mark == XA_FREE_MARK) { |
581 | node_mark_all(node, XA_FREE_MARK); | |
582 | if (!xa_marked(xa, XA_FREE_MARK)) { | |
583 | node_clear_mark(node, 0, XA_FREE_MARK); | |
584 | xa_mark_set(xa, XA_FREE_MARK); | |
585 | } | |
586 | } else if (xa_marked(xa, mark)) { | |
58d6ea30 | 587 | node_set_mark(node, 0, mark); |
371c752d | 588 | } |
58d6ea30 MW |
589 | if (mark == XA_MARK_MAX) |
590 | break; | |
591 | mark_inc(mark); | |
592 | } | |
593 | ||
594 | /* | |
595 | * Now that the new node is fully initialised, we can add | |
596 | * it to the tree | |
597 | */ | |
598 | if (xa_is_node(head)) { | |
599 | xa_to_node(head)->offset = 0; | |
600 | rcu_assign_pointer(xa_to_node(head)->parent, node); | |
601 | } | |
602 | head = xa_mk_node(node); | |
603 | rcu_assign_pointer(xa->xa_head, head); | |
604 | xas_update(xas, node); | |
605 | ||
606 | shift += XA_CHUNK_SHIFT; | |
607 | } | |
608 | ||
609 | xas->xa_node = node; | |
610 | return shift; | |
611 | } | |
612 | ||
613 | /* | |
614 | * xas_create() - Create a slot to store an entry in. | |
615 | * @xas: XArray operation state. | |
76b4e529 | 616 | * @allow_root: %true if we can store the entry in the root directly |
58d6ea30 MW |
617 | * |
618 | * Most users will not need to call this function directly, as it is called | |
619 | * by xas_store(). It is useful for doing conditional store operations | |
620 | * (see the xa_cmpxchg() implementation for an example). | |
621 | * | |
622 | * Return: If the slot already existed, returns the contents of this slot. | |
804dfaf0 MW |
623 | * If the slot was newly created, returns %NULL. If it failed to create the |
624 | * slot, returns %NULL and indicates the error in @xas. | |
58d6ea30 | 625 | */ |
76b4e529 | 626 | static void *xas_create(struct xa_state *xas, bool allow_root) |
58d6ea30 MW |
627 | { |
628 | struct xarray *xa = xas->xa; | |
629 | void *entry; | |
630 | void __rcu **slot; | |
631 | struct xa_node *node = xas->xa_node; | |
632 | int shift; | |
633 | unsigned int order = xas->xa_shift; | |
634 | ||
635 | if (xas_top(node)) { | |
636 | entry = xa_head_locked(xa); | |
637 | xas->xa_node = NULL; | |
3ccaf57a MW |
638 | if (!entry && xa_zero_busy(xa)) |
639 | entry = XA_ZERO_ENTRY; | |
58d6ea30 MW |
640 | shift = xas_expand(xas, entry); |
641 | if (shift < 0) | |
642 | return NULL; | |
76b4e529 MW |
643 | if (!shift && !allow_root) |
644 | shift = XA_CHUNK_SHIFT; | |
58d6ea30 MW |
645 | entry = xa_head_locked(xa); |
646 | slot = &xa->xa_head; | |
647 | } else if (xas_error(xas)) { | |
648 | return NULL; | |
649 | } else if (node) { | |
650 | unsigned int offset = xas->xa_offset; | |
651 | ||
652 | shift = node->shift; | |
653 | entry = xa_entry_locked(xa, node, offset); | |
654 | slot = &node->slots[offset]; | |
655 | } else { | |
656 | shift = 0; | |
657 | entry = xa_head_locked(xa); | |
658 | slot = &xa->xa_head; | |
659 | } | |
660 | ||
661 | while (shift > order) { | |
662 | shift -= XA_CHUNK_SHIFT; | |
663 | if (!entry) { | |
664 | node = xas_alloc(xas, shift); | |
665 | if (!node) | |
666 | break; | |
371c752d MW |
667 | if (xa_track_free(xa)) |
668 | node_mark_all(node, XA_FREE_MARK); | |
58d6ea30 MW |
669 | rcu_assign_pointer(*slot, xa_mk_node(node)); |
670 | } else if (xa_is_node(entry)) { | |
671 | node = xa_to_node(entry); | |
672 | } else { | |
673 | break; | |
674 | } | |
675 | entry = xas_descend(xas, node); | |
676 | slot = &node->slots[xas->xa_offset]; | |
677 | } | |
678 | ||
679 | return entry; | |
680 | } | |
681 | ||
2264f513 MW |
682 | /** |
683 | * xas_create_range() - Ensure that stores to this range will succeed | |
684 | * @xas: XArray operation state. | |
685 | * | |
686 | * Creates all of the slots in the range covered by @xas. Sets @xas to | |
687 | * create single-index entries and positions it at the beginning of the | |
688 | * range. This is for the benefit of users which have not yet been | |
689 | * converted to use multi-index entries. | |
690 | */ | |
691 | void xas_create_range(struct xa_state *xas) | |
692 | { | |
693 | unsigned long index = xas->xa_index; | |
694 | unsigned char shift = xas->xa_shift; | |
695 | unsigned char sibs = xas->xa_sibs; | |
696 | ||
697 | xas->xa_index |= ((sibs + 1) << shift) - 1; | |
698 | if (xas_is_node(xas) && xas->xa_node->shift == xas->xa_shift) | |
699 | xas->xa_offset |= sibs; | |
700 | xas->xa_shift = 0; | |
701 | xas->xa_sibs = 0; | |
702 | ||
703 | for (;;) { | |
76b4e529 | 704 | xas_create(xas, true); |
2264f513 MW |
705 | if (xas_error(xas)) |
706 | goto restore; | |
707 | if (xas->xa_index <= (index | XA_CHUNK_MASK)) | |
708 | goto success; | |
709 | xas->xa_index -= XA_CHUNK_SIZE; | |
710 | ||
711 | for (;;) { | |
712 | struct xa_node *node = xas->xa_node; | |
713 | xas->xa_node = xa_parent_locked(xas->xa, node); | |
714 | xas->xa_offset = node->offset - 1; | |
715 | if (node->offset != 0) | |
716 | break; | |
717 | } | |
718 | } | |
719 | ||
720 | restore: | |
721 | xas->xa_shift = shift; | |
722 | xas->xa_sibs = sibs; | |
723 | xas->xa_index = index; | |
724 | return; | |
725 | success: | |
726 | xas->xa_index = index; | |
727 | if (xas->xa_node) | |
728 | xas_set_offset(xas); | |
729 | } | |
730 | EXPORT_SYMBOL_GPL(xas_create_range); | |
731 | ||
58d6ea30 MW |
732 | static void update_node(struct xa_state *xas, struct xa_node *node, |
733 | int count, int values) | |
734 | { | |
735 | if (!node || (!count && !values)) | |
736 | return; | |
737 | ||
738 | node->count += count; | |
739 | node->nr_values += values; | |
740 | XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE); | |
741 | XA_NODE_BUG_ON(node, node->nr_values > XA_CHUNK_SIZE); | |
742 | xas_update(xas, node); | |
743 | if (count < 0) | |
744 | xas_delete_node(xas); | |
745 | } | |
746 | ||
747 | /** | |
748 | * xas_store() - Store this entry in the XArray. | |
749 | * @xas: XArray operation state. | |
750 | * @entry: New entry. | |
751 | * | |
752 | * If @xas is operating on a multi-index entry, the entry returned by this | |
753 | * function is essentially meaningless (it may be an internal entry or it | |
754 | * may be %NULL, even if there are non-NULL entries at some of the indices | |
755 | * covered by the range). This is not a problem for any current users, | |
756 | * and can be changed if needed. | |
757 | * | |
758 | * Return: The old entry at this index. | |
759 | */ | |
760 | void *xas_store(struct xa_state *xas, void *entry) | |
761 | { | |
762 | struct xa_node *node; | |
763 | void __rcu **slot = &xas->xa->xa_head; | |
764 | unsigned int offset, max; | |
765 | int count = 0; | |
766 | int values = 0; | |
767 | void *first, *next; | |
768 | bool value = xa_is_value(entry); | |
769 | ||
770 | if (entry) | |
76b4e529 | 771 | first = xas_create(xas, !xa_is_node(entry)); |
58d6ea30 MW |
772 | else |
773 | first = xas_load(xas); | |
774 | ||
775 | if (xas_invalid(xas)) | |
776 | return first; | |
777 | node = xas->xa_node; | |
778 | if (node && (xas->xa_shift < node->shift)) | |
779 | xas->xa_sibs = 0; | |
780 | if ((first == entry) && !xas->xa_sibs) | |
781 | return first; | |
782 | ||
783 | next = first; | |
784 | offset = xas->xa_offset; | |
785 | max = xas->xa_offset + xas->xa_sibs; | |
786 | if (node) { | |
787 | slot = &node->slots[offset]; | |
788 | if (xas->xa_sibs) | |
789 | xas_squash_marks(xas); | |
790 | } | |
791 | if (!entry) | |
792 | xas_init_marks(xas); | |
793 | ||
794 | for (;;) { | |
795 | /* | |
796 | * Must clear the marks before setting the entry to NULL, | |
797 | * otherwise xas_for_each_marked may find a NULL entry and | |
798 | * stop early. rcu_assign_pointer contains a release barrier | |
799 | * so the mark clearing will appear to happen before the | |
800 | * entry is set to NULL. | |
801 | */ | |
802 | rcu_assign_pointer(*slot, entry); | |
803 | if (xa_is_node(next)) | |
804 | xas_free_nodes(xas, xa_to_node(next)); | |
805 | if (!node) | |
806 | break; | |
807 | count += !next - !entry; | |
808 | values += !xa_is_value(first) - !value; | |
809 | if (entry) { | |
810 | if (offset == max) | |
811 | break; | |
812 | if (!xa_is_sibling(entry)) | |
813 | entry = xa_mk_sibling(xas->xa_offset); | |
814 | } else { | |
815 | if (offset == XA_CHUNK_MASK) | |
816 | break; | |
817 | } | |
818 | next = xa_entry_locked(xas->xa, node, ++offset); | |
819 | if (!xa_is_sibling(next)) { | |
820 | if (!entry && (offset > max)) | |
821 | break; | |
822 | first = next; | |
823 | } | |
824 | slot++; | |
825 | } | |
826 | ||
827 | update_node(xas, node, count, values); | |
828 | return first; | |
829 | } | |
830 | EXPORT_SYMBOL_GPL(xas_store); | |
831 | ||
9b89a035 MW |
832 | /** |
833 | * xas_get_mark() - Returns the state of this mark. | |
834 | * @xas: XArray operation state. | |
835 | * @mark: Mark number. | |
836 | * | |
837 | * Return: true if the mark is set, false if the mark is clear or @xas | |
838 | * is in an error state. | |
839 | */ | |
840 | bool xas_get_mark(const struct xa_state *xas, xa_mark_t mark) | |
841 | { | |
842 | if (xas_invalid(xas)) | |
843 | return false; | |
844 | if (!xas->xa_node) | |
845 | return xa_marked(xas->xa, mark); | |
846 | return node_get_mark(xas->xa_node, xas->xa_offset, mark); | |
847 | } | |
848 | EXPORT_SYMBOL_GPL(xas_get_mark); | |
849 | ||
850 | /** | |
851 | * xas_set_mark() - Sets the mark on this entry and its parents. | |
852 | * @xas: XArray operation state. | |
853 | * @mark: Mark number. | |
854 | * | |
855 | * Sets the specified mark on this entry, and walks up the tree setting it | |
856 | * on all the ancestor entries. Does nothing if @xas has not been walked to | |
857 | * an entry, or is in an error state. | |
858 | */ | |
859 | void xas_set_mark(const struct xa_state *xas, xa_mark_t mark) | |
860 | { | |
861 | struct xa_node *node = xas->xa_node; | |
862 | unsigned int offset = xas->xa_offset; | |
863 | ||
864 | if (xas_invalid(xas)) | |
865 | return; | |
866 | ||
867 | while (node) { | |
868 | if (node_set_mark(node, offset, mark)) | |
869 | return; | |
870 | offset = node->offset; | |
871 | node = xa_parent_locked(xas->xa, node); | |
872 | } | |
873 | ||
874 | if (!xa_marked(xas->xa, mark)) | |
875 | xa_mark_set(xas->xa, mark); | |
876 | } | |
877 | EXPORT_SYMBOL_GPL(xas_set_mark); | |
878 | ||
879 | /** | |
880 | * xas_clear_mark() - Clears the mark on this entry and its parents. | |
881 | * @xas: XArray operation state. | |
882 | * @mark: Mark number. | |
883 | * | |
884 | * Clears the specified mark on this entry, and walks back to the head | |
885 | * attempting to clear it on all the ancestor entries. Does nothing if | |
886 | * @xas has not been walked to an entry, or is in an error state. | |
887 | */ | |
888 | void xas_clear_mark(const struct xa_state *xas, xa_mark_t mark) | |
889 | { | |
890 | struct xa_node *node = xas->xa_node; | |
891 | unsigned int offset = xas->xa_offset; | |
892 | ||
893 | if (xas_invalid(xas)) | |
894 | return; | |
895 | ||
896 | while (node) { | |
897 | if (!node_clear_mark(node, offset, mark)) | |
898 | return; | |
899 | if (node_any_mark(node, mark)) | |
900 | return; | |
901 | ||
902 | offset = node->offset; | |
903 | node = xa_parent_locked(xas->xa, node); | |
904 | } | |
905 | ||
906 | if (xa_marked(xas->xa, mark)) | |
907 | xa_mark_clear(xas->xa, mark); | |
908 | } | |
909 | EXPORT_SYMBOL_GPL(xas_clear_mark); | |
910 | ||
58d6ea30 MW |
911 | /** |
912 | * xas_init_marks() - Initialise all marks for the entry | |
913 | * @xas: Array operations state. | |
914 | * | |
915 | * Initialise all marks for the entry specified by @xas. If we're tracking | |
916 | * free entries with a mark, we need to set it on all entries. All other | |
917 | * marks are cleared. | |
918 | * | |
919 | * This implementation is not as efficient as it could be; we may walk | |
920 | * up the tree multiple times. | |
921 | */ | |
922 | void xas_init_marks(const struct xa_state *xas) | |
923 | { | |
924 | xa_mark_t mark = 0; | |
925 | ||
926 | for (;;) { | |
371c752d MW |
927 | if (xa_track_free(xas->xa) && mark == XA_FREE_MARK) |
928 | xas_set_mark(xas, mark); | |
929 | else | |
930 | xas_clear_mark(xas, mark); | |
58d6ea30 MW |
931 | if (mark == XA_MARK_MAX) |
932 | break; | |
933 | mark_inc(mark); | |
934 | } | |
935 | } | |
936 | EXPORT_SYMBOL_GPL(xas_init_marks); | |
937 | ||
b803b428 MW |
938 | /** |
939 | * xas_pause() - Pause a walk to drop a lock. | |
940 | * @xas: XArray operation state. | |
941 | * | |
942 | * Some users need to pause a walk and drop the lock they're holding in | |
943 | * order to yield to a higher priority thread or carry out an operation | |
944 | * on an entry. Those users should call this function before they drop | |
945 | * the lock. It resets the @xas to be suitable for the next iteration | |
946 | * of the loop after the user has reacquired the lock. If most entries | |
947 | * found during a walk require you to call xas_pause(), the xa_for_each() | |
948 | * iterator may be more appropriate. | |
949 | * | |
950 | * Note that xas_pause() only works for forward iteration. If a user needs | |
951 | * to pause a reverse iteration, we will need a xas_pause_rev(). | |
952 | */ | |
953 | void xas_pause(struct xa_state *xas) | |
954 | { | |
955 | struct xa_node *node = xas->xa_node; | |
956 | ||
957 | if (xas_invalid(xas)) | |
958 | return; | |
959 | ||
960 | if (node) { | |
961 | unsigned int offset = xas->xa_offset; | |
962 | while (++offset < XA_CHUNK_SIZE) { | |
963 | if (!xa_is_sibling(xa_entry(xas->xa, node, offset))) | |
964 | break; | |
965 | } | |
966 | xas->xa_index += (offset - xas->xa_offset) << node->shift; | |
967 | } else { | |
968 | xas->xa_index++; | |
969 | } | |
970 | xas->xa_node = XAS_RESTART; | |
971 | } | |
972 | EXPORT_SYMBOL_GPL(xas_pause); | |
973 | ||
64d3e9a9 MW |
974 | /* |
975 | * __xas_prev() - Find the previous entry in the XArray. | |
976 | * @xas: XArray operation state. | |
977 | * | |
978 | * Helper function for xas_prev() which handles all the complex cases | |
979 | * out of line. | |
980 | */ | |
981 | void *__xas_prev(struct xa_state *xas) | |
982 | { | |
983 | void *entry; | |
984 | ||
985 | if (!xas_frozen(xas->xa_node)) | |
986 | xas->xa_index--; | |
987 | if (xas_not_node(xas->xa_node)) | |
988 | return xas_load(xas); | |
989 | ||
990 | if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node)) | |
991 | xas->xa_offset--; | |
992 | ||
993 | while (xas->xa_offset == 255) { | |
994 | xas->xa_offset = xas->xa_node->offset - 1; | |
995 | xas->xa_node = xa_parent(xas->xa, xas->xa_node); | |
996 | if (!xas->xa_node) | |
997 | return set_bounds(xas); | |
998 | } | |
999 | ||
1000 | for (;;) { | |
1001 | entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset); | |
1002 | if (!xa_is_node(entry)) | |
1003 | return entry; | |
1004 | ||
1005 | xas->xa_node = xa_to_node(entry); | |
1006 | xas_set_offset(xas); | |
1007 | } | |
1008 | } | |
1009 | EXPORT_SYMBOL_GPL(__xas_prev); | |
1010 | ||
1011 | /* | |
1012 | * __xas_next() - Find the next entry in the XArray. | |
1013 | * @xas: XArray operation state. | |
1014 | * | |
1015 | * Helper function for xas_next() which handles all the complex cases | |
1016 | * out of line. | |
1017 | */ | |
1018 | void *__xas_next(struct xa_state *xas) | |
1019 | { | |
1020 | void *entry; | |
1021 | ||
1022 | if (!xas_frozen(xas->xa_node)) | |
1023 | xas->xa_index++; | |
1024 | if (xas_not_node(xas->xa_node)) | |
1025 | return xas_load(xas); | |
1026 | ||
1027 | if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node)) | |
1028 | xas->xa_offset++; | |
1029 | ||
1030 | while (xas->xa_offset == XA_CHUNK_SIZE) { | |
1031 | xas->xa_offset = xas->xa_node->offset + 1; | |
1032 | xas->xa_node = xa_parent(xas->xa, xas->xa_node); | |
1033 | if (!xas->xa_node) | |
1034 | return set_bounds(xas); | |
1035 | } | |
1036 | ||
1037 | for (;;) { | |
1038 | entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset); | |
1039 | if (!xa_is_node(entry)) | |
1040 | return entry; | |
1041 | ||
1042 | xas->xa_node = xa_to_node(entry); | |
1043 | xas_set_offset(xas); | |
1044 | } | |
1045 | } | |
1046 | EXPORT_SYMBOL_GPL(__xas_next); | |
1047 | ||
b803b428 MW |
1048 | /** |
1049 | * xas_find() - Find the next present entry in the XArray. | |
1050 | * @xas: XArray operation state. | |
1051 | * @max: Highest index to return. | |
1052 | * | |
1053 | * If the @xas has not yet been walked to an entry, return the entry | |
1054 | * which has an index >= xas.xa_index. If it has been walked, the entry | |
1055 | * currently being pointed at has been processed, and so we move to the | |
1056 | * next entry. | |
1057 | * | |
1058 | * If no entry is found and the array is smaller than @max, the iterator | |
1059 | * is set to the smallest index not yet in the array. This allows @xas | |
1060 | * to be immediately passed to xas_store(). | |
1061 | * | |
1062 | * Return: The entry, if found, otherwise %NULL. | |
1063 | */ | |
1064 | void *xas_find(struct xa_state *xas, unsigned long max) | |
1065 | { | |
1066 | void *entry; | |
1067 | ||
1068 | if (xas_error(xas)) | |
1069 | return NULL; | |
1070 | ||
1071 | if (!xas->xa_node) { | |
1072 | xas->xa_index = 1; | |
1073 | return set_bounds(xas); | |
1074 | } else if (xas_top(xas->xa_node)) { | |
1075 | entry = xas_load(xas); | |
1076 | if (entry || xas_not_node(xas->xa_node)) | |
1077 | return entry; | |
1078 | } else if (!xas->xa_node->shift && | |
1079 | xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)) { | |
1080 | xas->xa_offset = ((xas->xa_index - 1) & XA_CHUNK_MASK) + 1; | |
1081 | } | |
1082 | ||
1083 | xas_advance(xas); | |
1084 | ||
1085 | while (xas->xa_node && (xas->xa_index <= max)) { | |
1086 | if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) { | |
1087 | xas->xa_offset = xas->xa_node->offset + 1; | |
1088 | xas->xa_node = xa_parent(xas->xa, xas->xa_node); | |
1089 | continue; | |
1090 | } | |
1091 | ||
1092 | entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset); | |
1093 | if (xa_is_node(entry)) { | |
1094 | xas->xa_node = xa_to_node(entry); | |
1095 | xas->xa_offset = 0; | |
1096 | continue; | |
1097 | } | |
1098 | if (entry && !xa_is_sibling(entry)) | |
1099 | return entry; | |
1100 | ||
1101 | xas_advance(xas); | |
1102 | } | |
1103 | ||
1104 | if (!xas->xa_node) | |
1105 | xas->xa_node = XAS_BOUNDS; | |
1106 | return NULL; | |
1107 | } | |
1108 | EXPORT_SYMBOL_GPL(xas_find); | |
1109 | ||
1110 | /** | |
1111 | * xas_find_marked() - Find the next marked entry in the XArray. | |
1112 | * @xas: XArray operation state. | |
1113 | * @max: Highest index to return. | |
1114 | * @mark: Mark number to search for. | |
1115 | * | |
1116 | * If the @xas has not yet been walked to an entry, return the marked entry | |
1117 | * which has an index >= xas.xa_index. If it has been walked, the entry | |
1118 | * currently being pointed at has been processed, and so we return the | |
1119 | * first marked entry with an index > xas.xa_index. | |
1120 | * | |
1121 | * If no marked entry is found and the array is smaller than @max, @xas is | |
1122 | * set to the bounds state and xas->xa_index is set to the smallest index | |
1123 | * not yet in the array. This allows @xas to be immediately passed to | |
1124 | * xas_store(). | |
1125 | * | |
1126 | * If no entry is found before @max is reached, @xas is set to the restart | |
1127 | * state. | |
1128 | * | |
1129 | * Return: The entry, if found, otherwise %NULL. | |
1130 | */ | |
1131 | void *xas_find_marked(struct xa_state *xas, unsigned long max, xa_mark_t mark) | |
1132 | { | |
1133 | bool advance = true; | |
1134 | unsigned int offset; | |
1135 | void *entry; | |
1136 | ||
1137 | if (xas_error(xas)) | |
1138 | return NULL; | |
1139 | ||
1140 | if (!xas->xa_node) { | |
1141 | xas->xa_index = 1; | |
1142 | goto out; | |
1143 | } else if (xas_top(xas->xa_node)) { | |
1144 | advance = false; | |
1145 | entry = xa_head(xas->xa); | |
1146 | xas->xa_node = NULL; | |
1147 | if (xas->xa_index > max_index(entry)) | |
48483614 | 1148 | goto out; |
b803b428 MW |
1149 | if (!xa_is_node(entry)) { |
1150 | if (xa_marked(xas->xa, mark)) | |
1151 | return entry; | |
1152 | xas->xa_index = 1; | |
1153 | goto out; | |
1154 | } | |
1155 | xas->xa_node = xa_to_node(entry); | |
1156 | xas->xa_offset = xas->xa_index >> xas->xa_node->shift; | |
1157 | } | |
1158 | ||
1159 | while (xas->xa_index <= max) { | |
1160 | if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) { | |
1161 | xas->xa_offset = xas->xa_node->offset + 1; | |
1162 | xas->xa_node = xa_parent(xas->xa, xas->xa_node); | |
1163 | if (!xas->xa_node) | |
1164 | break; | |
1165 | advance = false; | |
1166 | continue; | |
1167 | } | |
1168 | ||
1169 | if (!advance) { | |
1170 | entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset); | |
1171 | if (xa_is_sibling(entry)) { | |
1172 | xas->xa_offset = xa_to_sibling(entry); | |
1173 | xas_move_index(xas, xas->xa_offset); | |
1174 | } | |
1175 | } | |
1176 | ||
1177 | offset = xas_find_chunk(xas, advance, mark); | |
1178 | if (offset > xas->xa_offset) { | |
1179 | advance = false; | |
1180 | xas_move_index(xas, offset); | |
1181 | /* Mind the wrap */ | |
1182 | if ((xas->xa_index - 1) >= max) | |
1183 | goto max; | |
1184 | xas->xa_offset = offset; | |
1185 | if (offset == XA_CHUNK_SIZE) | |
1186 | continue; | |
1187 | } | |
1188 | ||
1189 | entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset); | |
1190 | if (!xa_is_node(entry)) | |
1191 | return entry; | |
1192 | xas->xa_node = xa_to_node(entry); | |
1193 | xas_set_offset(xas); | |
1194 | } | |
1195 | ||
1196 | out: | |
48483614 | 1197 | if (xas->xa_index > max) |
b803b428 | 1198 | goto max; |
48483614 | 1199 | return set_bounds(xas); |
b803b428 MW |
1200 | max: |
1201 | xas->xa_node = XAS_RESTART; | |
1202 | return NULL; | |
1203 | } | |
1204 | EXPORT_SYMBOL_GPL(xas_find_marked); | |
1205 | ||
4e99d4e9 MW |
1206 | /** |
1207 | * xas_find_conflict() - Find the next present entry in a range. | |
1208 | * @xas: XArray operation state. | |
1209 | * | |
1210 | * The @xas describes both a range and a position within that range. | |
1211 | * | |
1212 | * Context: Any context. Expects xa_lock to be held. | |
1213 | * Return: The next entry in the range covered by @xas or %NULL. | |
1214 | */ | |
1215 | void *xas_find_conflict(struct xa_state *xas) | |
1216 | { | |
1217 | void *curr; | |
1218 | ||
1219 | if (xas_error(xas)) | |
1220 | return NULL; | |
1221 | ||
1222 | if (!xas->xa_node) | |
1223 | return NULL; | |
1224 | ||
1225 | if (xas_top(xas->xa_node)) { | |
1226 | curr = xas_start(xas); | |
1227 | if (!curr) | |
1228 | return NULL; | |
1229 | while (xa_is_node(curr)) { | |
1230 | struct xa_node *node = xa_to_node(curr); | |
1231 | curr = xas_descend(xas, node); | |
1232 | } | |
1233 | if (curr) | |
1234 | return curr; | |
1235 | } | |
1236 | ||
1237 | if (xas->xa_node->shift > xas->xa_shift) | |
1238 | return NULL; | |
1239 | ||
1240 | for (;;) { | |
1241 | if (xas->xa_node->shift == xas->xa_shift) { | |
1242 | if ((xas->xa_offset & xas->xa_sibs) == xas->xa_sibs) | |
1243 | break; | |
1244 | } else if (xas->xa_offset == XA_CHUNK_MASK) { | |
1245 | xas->xa_offset = xas->xa_node->offset; | |
1246 | xas->xa_node = xa_parent_locked(xas->xa, xas->xa_node); | |
1247 | if (!xas->xa_node) | |
1248 | break; | |
1249 | continue; | |
1250 | } | |
1251 | curr = xa_entry_locked(xas->xa, xas->xa_node, ++xas->xa_offset); | |
1252 | if (xa_is_sibling(curr)) | |
1253 | continue; | |
1254 | while (xa_is_node(curr)) { | |
1255 | xas->xa_node = xa_to_node(curr); | |
1256 | xas->xa_offset = 0; | |
1257 | curr = xa_entry_locked(xas->xa, xas->xa_node, 0); | |
1258 | } | |
1259 | if (curr) | |
1260 | return curr; | |
1261 | } | |
1262 | xas->xa_offset -= xas->xa_sibs; | |
1263 | return NULL; | |
1264 | } | |
1265 | EXPORT_SYMBOL_GPL(xas_find_conflict); | |
1266 | ||
ad3d6c72 MW |
1267 | /** |
1268 | * xa_load() - Load an entry from an XArray. | |
1269 | * @xa: XArray. | |
1270 | * @index: index into array. | |
1271 | * | |
1272 | * Context: Any context. Takes and releases the RCU lock. | |
1273 | * Return: The entry at @index in @xa. | |
1274 | */ | |
1275 | void *xa_load(struct xarray *xa, unsigned long index) | |
1276 | { | |
1277 | XA_STATE(xas, xa, index); | |
1278 | void *entry; | |
1279 | ||
1280 | rcu_read_lock(); | |
1281 | do { | |
1282 | entry = xas_load(&xas); | |
9f14d4f1 MW |
1283 | if (xa_is_zero(entry)) |
1284 | entry = NULL; | |
ad3d6c72 MW |
1285 | } while (xas_retry(&xas, entry)); |
1286 | rcu_read_unlock(); | |
1287 | ||
1288 | return entry; | |
1289 | } | |
1290 | EXPORT_SYMBOL(xa_load); | |
1291 | ||
58d6ea30 MW |
1292 | static void *xas_result(struct xa_state *xas, void *curr) |
1293 | { | |
9f14d4f1 MW |
1294 | if (xa_is_zero(curr)) |
1295 | return NULL; | |
58d6ea30 MW |
1296 | if (xas_error(xas)) |
1297 | curr = xas->xa_node; | |
1298 | return curr; | |
1299 | } | |
1300 | ||
1301 | /** | |
1302 | * __xa_erase() - Erase this entry from the XArray while locked. | |
1303 | * @xa: XArray. | |
1304 | * @index: Index into array. | |
1305 | * | |
809ab937 MW |
1306 | * After this function returns, loading from @index will return %NULL. |
1307 | * If the index is part of a multi-index entry, all indices will be erased | |
1308 | * and none of the entries will be part of a multi-index entry. | |
58d6ea30 | 1309 | * |
809ab937 MW |
1310 | * Context: Any context. Expects xa_lock to be held on entry. |
1311 | * Return: The entry which used to be at this index. | |
58d6ea30 MW |
1312 | */ |
1313 | void *__xa_erase(struct xarray *xa, unsigned long index) | |
1314 | { | |
1315 | XA_STATE(xas, xa, index); | |
1316 | return xas_result(&xas, xas_store(&xas, NULL)); | |
1317 | } | |
9ee5a3b7 | 1318 | EXPORT_SYMBOL(__xa_erase); |
58d6ea30 | 1319 | |
9c16bb88 MW |
1320 | /** |
1321 | * xa_erase() - Erase this entry from the XArray. | |
1322 | * @xa: XArray. | |
1323 | * @index: Index of entry. | |
1324 | * | |
809ab937 MW |
1325 | * After this function returns, loading from @index will return %NULL. |
1326 | * If the index is part of a multi-index entry, all indices will be erased | |
1327 | * and none of the entries will be part of a multi-index entry. | |
9c16bb88 MW |
1328 | * |
1329 | * Context: Any context. Takes and releases the xa_lock. | |
1330 | * Return: The entry which used to be at this index. | |
1331 | */ | |
1332 | void *xa_erase(struct xarray *xa, unsigned long index) | |
1333 | { | |
1334 | void *entry; | |
1335 | ||
1336 | xa_lock(xa); | |
1337 | entry = __xa_erase(xa, index); | |
1338 | xa_unlock(xa); | |
1339 | ||
1340 | return entry; | |
1341 | } | |
1342 | EXPORT_SYMBOL(xa_erase); | |
1343 | ||
58d6ea30 | 1344 | /** |
611f3186 | 1345 | * __xa_store() - Store this entry in the XArray. |
58d6ea30 MW |
1346 | * @xa: XArray. |
1347 | * @index: Index into array. | |
1348 | * @entry: New entry. | |
1349 | * @gfp: Memory allocation flags. | |
1350 | * | |
611f3186 MW |
1351 | * You must already be holding the xa_lock when calling this function. |
1352 | * It will drop the lock if needed to allocate memory, and then reacquire | |
1353 | * it afterwards. | |
58d6ea30 | 1354 | * |
611f3186 MW |
1355 | * Context: Any context. Expects xa_lock to be held on entry. May |
1356 | * release and reacquire xa_lock if @gfp flags permit. | |
1357 | * Return: The old entry at this index or xa_err() if an error happened. | |
58d6ea30 | 1358 | */ |
611f3186 | 1359 | void *__xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp) |
58d6ea30 MW |
1360 | { |
1361 | XA_STATE(xas, xa, index); | |
1362 | void *curr; | |
1363 | ||
76b4e529 | 1364 | if (WARN_ON_ONCE(xa_is_advanced(entry))) |
58d6ea30 | 1365 | return XA_ERROR(-EINVAL); |
d9c48043 MW |
1366 | if (xa_track_free(xa) && !entry) |
1367 | entry = XA_ZERO_ENTRY; | |
58d6ea30 MW |
1368 | |
1369 | do { | |
58d6ea30 | 1370 | curr = xas_store(&xas, entry); |
d9c48043 | 1371 | if (xa_track_free(xa)) |
371c752d | 1372 | xas_clear_mark(&xas, XA_FREE_MARK); |
611f3186 | 1373 | } while (__xas_nomem(&xas, gfp)); |
58d6ea30 MW |
1374 | |
1375 | return xas_result(&xas, curr); | |
1376 | } | |
611f3186 | 1377 | EXPORT_SYMBOL(__xa_store); |
58d6ea30 MW |
1378 | |
1379 | /** | |
611f3186 | 1380 | * xa_store() - Store this entry in the XArray. |
58d6ea30 MW |
1381 | * @xa: XArray. |
1382 | * @index: Index into array. | |
1383 | * @entry: New entry. | |
1384 | * @gfp: Memory allocation flags. | |
1385 | * | |
611f3186 MW |
1386 | * After this function returns, loads from this index will return @entry. |
1387 | * Storing into an existing multislot entry updates the entry of every index. | |
1388 | * The marks associated with @index are unaffected unless @entry is %NULL. | |
58d6ea30 | 1389 | * |
611f3186 MW |
1390 | * Context: Any context. Takes and releases the xa_lock. |
1391 | * May sleep if the @gfp flags permit. | |
1392 | * Return: The old entry at this index on success, xa_err(-EINVAL) if @entry | |
1393 | * cannot be stored in an XArray, or xa_err(-ENOMEM) if memory allocation | |
1394 | * failed. | |
58d6ea30 | 1395 | */ |
611f3186 | 1396 | void *xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp) |
58d6ea30 | 1397 | { |
58d6ea30 MW |
1398 | void *curr; |
1399 | ||
611f3186 MW |
1400 | xa_lock(xa); |
1401 | curr = __xa_store(xa, index, entry, gfp); | |
1402 | xa_unlock(xa); | |
58d6ea30 | 1403 | |
611f3186 | 1404 | return curr; |
58d6ea30 | 1405 | } |
611f3186 | 1406 | EXPORT_SYMBOL(xa_store); |
58d6ea30 | 1407 | |
41aec91f MW |
1408 | /** |
1409 | * __xa_cmpxchg() - Store this entry in the XArray. | |
1410 | * @xa: XArray. | |
1411 | * @index: Index into array. | |
1412 | * @old: Old value to test against. | |
1413 | * @entry: New entry. | |
1414 | * @gfp: Memory allocation flags. | |
1415 | * | |
1416 | * You must already be holding the xa_lock when calling this function. | |
1417 | * It will drop the lock if needed to allocate memory, and then reacquire | |
1418 | * it afterwards. | |
1419 | * | |
1420 | * Context: Any context. Expects xa_lock to be held on entry. May | |
1421 | * release and reacquire xa_lock if @gfp flags permit. | |
1422 | * Return: The old entry at this index or xa_err() if an error happened. | |
1423 | */ | |
1424 | void *__xa_cmpxchg(struct xarray *xa, unsigned long index, | |
1425 | void *old, void *entry, gfp_t gfp) | |
1426 | { | |
1427 | XA_STATE(xas, xa, index); | |
1428 | void *curr; | |
1429 | ||
76b4e529 | 1430 | if (WARN_ON_ONCE(xa_is_advanced(entry))) |
41aec91f | 1431 | return XA_ERROR(-EINVAL); |
d9c48043 MW |
1432 | if (xa_track_free(xa) && !entry) |
1433 | entry = XA_ZERO_ENTRY; | |
41aec91f MW |
1434 | |
1435 | do { | |
1436 | curr = xas_load(&xas); | |
9f14d4f1 MW |
1437 | if (curr == XA_ZERO_ENTRY) |
1438 | curr = NULL; | |
371c752d | 1439 | if (curr == old) { |
41aec91f | 1440 | xas_store(&xas, entry); |
d9c48043 | 1441 | if (xa_track_free(xa)) |
371c752d MW |
1442 | xas_clear_mark(&xas, XA_FREE_MARK); |
1443 | } | |
41aec91f MW |
1444 | } while (__xas_nomem(&xas, gfp)); |
1445 | ||
1446 | return xas_result(&xas, curr); | |
1447 | } | |
1448 | EXPORT_SYMBOL(__xa_cmpxchg); | |
1449 | ||
b0606fed MW |
1450 | /** |
1451 | * __xa_insert() - Store this entry in the XArray if no entry is present. | |
1452 | * @xa: XArray. | |
1453 | * @index: Index into array. | |
1454 | * @entry: New entry. | |
1455 | * @gfp: Memory allocation flags. | |
1456 | * | |
1457 | * Inserting a NULL entry will store a reserved entry (like xa_reserve()) | |
1458 | * if no entry is present. Inserting will fail if a reserved entry is | |
1459 | * present, even though loading from this index will return NULL. | |
1460 | * | |
1461 | * Context: Any context. Expects xa_lock to be held on entry. May | |
1462 | * release and reacquire xa_lock if @gfp flags permit. | |
fd9dc93e | 1463 | * Return: 0 if the store succeeded. -EBUSY if another entry was present. |
b0606fed MW |
1464 | * -ENOMEM if memory could not be allocated. |
1465 | */ | |
1466 | int __xa_insert(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp) | |
1467 | { | |
1468 | XA_STATE(xas, xa, index); | |
1469 | void *curr; | |
1470 | ||
1471 | if (WARN_ON_ONCE(xa_is_advanced(entry))) | |
1472 | return -EINVAL; | |
1473 | if (!entry) | |
1474 | entry = XA_ZERO_ENTRY; | |
1475 | ||
1476 | do { | |
1477 | curr = xas_load(&xas); | |
1478 | if (!curr) { | |
1479 | xas_store(&xas, entry); | |
1480 | if (xa_track_free(xa)) | |
1481 | xas_clear_mark(&xas, XA_FREE_MARK); | |
1482 | } else { | |
fd9dc93e | 1483 | xas_set_err(&xas, -EBUSY); |
b0606fed MW |
1484 | } |
1485 | } while (__xas_nomem(&xas, gfp)); | |
1486 | ||
1487 | return xas_error(&xas); | |
1488 | } | |
1489 | EXPORT_SYMBOL(__xa_insert); | |
1490 | ||
9f14d4f1 | 1491 | /** |
4c0608f4 | 1492 | * __xa_reserve() - Reserve this index in the XArray. |
9f14d4f1 MW |
1493 | * @xa: XArray. |
1494 | * @index: Index into array. | |
1495 | * @gfp: Memory allocation flags. | |
1496 | * | |
1497 | * Ensures there is somewhere to store an entry at @index in the array. | |
1498 | * If there is already something stored at @index, this function does | |
1499 | * nothing. If there was nothing there, the entry is marked as reserved. | |
4c0608f4 | 1500 | * Loading from a reserved entry returns a %NULL pointer. |
9f14d4f1 MW |
1501 | * |
1502 | * If you do not use the entry that you have reserved, call xa_release() | |
1503 | * or xa_erase() to free any unnecessary memory. | |
1504 | * | |
4c0608f4 MW |
1505 | * Context: Any context. Expects the xa_lock to be held on entry. May |
1506 | * release the lock, sleep and reacquire the lock if the @gfp flags permit. | |
9f14d4f1 MW |
1507 | * Return: 0 if the reservation succeeded or -ENOMEM if it failed. |
1508 | */ | |
4c0608f4 | 1509 | int __xa_reserve(struct xarray *xa, unsigned long index, gfp_t gfp) |
9f14d4f1 MW |
1510 | { |
1511 | XA_STATE(xas, xa, index); | |
9f14d4f1 MW |
1512 | void *curr; |
1513 | ||
1514 | do { | |
9f14d4f1 | 1515 | curr = xas_load(&xas); |
d9c48043 | 1516 | if (!curr) { |
9f14d4f1 | 1517 | xas_store(&xas, XA_ZERO_ENTRY); |
d9c48043 MW |
1518 | if (xa_track_free(xa)) |
1519 | xas_clear_mark(&xas, XA_FREE_MARK); | |
1520 | } | |
4c0608f4 | 1521 | } while (__xas_nomem(&xas, gfp)); |
9f14d4f1 MW |
1522 | |
1523 | return xas_error(&xas); | |
1524 | } | |
4c0608f4 | 1525 | EXPORT_SYMBOL(__xa_reserve); |
9f14d4f1 | 1526 | |
0e9446c3 MW |
1527 | #ifdef CONFIG_XARRAY_MULTI |
1528 | static void xas_set_range(struct xa_state *xas, unsigned long first, | |
1529 | unsigned long last) | |
1530 | { | |
1531 | unsigned int shift = 0; | |
1532 | unsigned long sibs = last - first; | |
1533 | unsigned int offset = XA_CHUNK_MASK; | |
1534 | ||
1535 | xas_set(xas, first); | |
1536 | ||
1537 | while ((first & XA_CHUNK_MASK) == 0) { | |
1538 | if (sibs < XA_CHUNK_MASK) | |
1539 | break; | |
1540 | if ((sibs == XA_CHUNK_MASK) && (offset < XA_CHUNK_MASK)) | |
1541 | break; | |
1542 | shift += XA_CHUNK_SHIFT; | |
1543 | if (offset == XA_CHUNK_MASK) | |
1544 | offset = sibs & XA_CHUNK_MASK; | |
1545 | sibs >>= XA_CHUNK_SHIFT; | |
1546 | first >>= XA_CHUNK_SHIFT; | |
1547 | } | |
1548 | ||
1549 | offset = first & XA_CHUNK_MASK; | |
1550 | if (offset + sibs > XA_CHUNK_MASK) | |
1551 | sibs = XA_CHUNK_MASK - offset; | |
1552 | if ((((first + sibs + 1) << shift) - 1) > last) | |
1553 | sibs -= 1; | |
1554 | ||
1555 | xas->xa_shift = shift; | |
1556 | xas->xa_sibs = sibs; | |
1557 | } | |
1558 | ||
1559 | /** | |
1560 | * xa_store_range() - Store this entry at a range of indices in the XArray. | |
1561 | * @xa: XArray. | |
1562 | * @first: First index to affect. | |
1563 | * @last: Last index to affect. | |
1564 | * @entry: New entry. | |
1565 | * @gfp: Memory allocation flags. | |
1566 | * | |
1567 | * After this function returns, loads from any index between @first and @last, | |
1568 | * inclusive will return @entry. | |
1569 | * Storing into an existing multislot entry updates the entry of every index. | |
1570 | * The marks associated with @index are unaffected unless @entry is %NULL. | |
1571 | * | |
1572 | * Context: Process context. Takes and releases the xa_lock. May sleep | |
1573 | * if the @gfp flags permit. | |
1574 | * Return: %NULL on success, xa_err(-EINVAL) if @entry cannot be stored in | |
1575 | * an XArray, or xa_err(-ENOMEM) if memory allocation failed. | |
1576 | */ | |
1577 | void *xa_store_range(struct xarray *xa, unsigned long first, | |
1578 | unsigned long last, void *entry, gfp_t gfp) | |
1579 | { | |
1580 | XA_STATE(xas, xa, 0); | |
1581 | ||
1582 | if (WARN_ON_ONCE(xa_is_internal(entry))) | |
1583 | return XA_ERROR(-EINVAL); | |
1584 | if (last < first) | |
1585 | return XA_ERROR(-EINVAL); | |
1586 | ||
1587 | do { | |
1588 | xas_lock(&xas); | |
1589 | if (entry) { | |
44a4a66b MW |
1590 | unsigned int order = BITS_PER_LONG; |
1591 | if (last + 1) | |
1592 | order = __ffs(last + 1); | |
0e9446c3 | 1593 | xas_set_order(&xas, last, order); |
76b4e529 | 1594 | xas_create(&xas, true); |
0e9446c3 MW |
1595 | if (xas_error(&xas)) |
1596 | goto unlock; | |
1597 | } | |
1598 | do { | |
1599 | xas_set_range(&xas, first, last); | |
1600 | xas_store(&xas, entry); | |
1601 | if (xas_error(&xas)) | |
1602 | goto unlock; | |
1603 | first += xas_size(&xas); | |
1604 | } while (first <= last); | |
1605 | unlock: | |
1606 | xas_unlock(&xas); | |
1607 | } while (xas_nomem(&xas, gfp)); | |
1608 | ||
1609 | return xas_result(&xas, NULL); | |
1610 | } | |
1611 | EXPORT_SYMBOL(xa_store_range); | |
1612 | #endif /* CONFIG_XARRAY_MULTI */ | |
1613 | ||
371c752d MW |
1614 | /** |
1615 | * __xa_alloc() - Find somewhere to store this entry in the XArray. | |
1616 | * @xa: XArray. | |
1617 | * @id: Pointer to ID. | |
a3e4d3f9 | 1618 | * @limit: Range for allocated ID. |
371c752d MW |
1619 | * @entry: New entry. |
1620 | * @gfp: Memory allocation flags. | |
1621 | * | |
a3e4d3f9 MW |
1622 | * Finds an empty entry in @xa between @limit.min and @limit.max, |
1623 | * stores the index into the @id pointer, then stores the entry at | |
1624 | * that index. A concurrent lookup will not see an uninitialised @id. | |
371c752d MW |
1625 | * |
1626 | * Context: Any context. Expects xa_lock to be held on entry. May | |
1627 | * release and reacquire xa_lock if @gfp flags permit. | |
a3e4d3f9 MW |
1628 | * Return: 0 on success, -ENOMEM if memory could not be allocated or |
1629 | * -EBUSY if there are no free entries in @limit. | |
371c752d | 1630 | */ |
a3e4d3f9 MW |
1631 | int __xa_alloc(struct xarray *xa, u32 *id, void *entry, |
1632 | struct xa_limit limit, gfp_t gfp) | |
371c752d MW |
1633 | { |
1634 | XA_STATE(xas, xa, 0); | |
371c752d | 1635 | |
76b4e529 | 1636 | if (WARN_ON_ONCE(xa_is_advanced(entry))) |
371c752d MW |
1637 | return -EINVAL; |
1638 | if (WARN_ON_ONCE(!xa_track_free(xa))) | |
1639 | return -EINVAL; | |
1640 | ||
1641 | if (!entry) | |
1642 | entry = XA_ZERO_ENTRY; | |
1643 | ||
1644 | do { | |
a3e4d3f9 MW |
1645 | xas.xa_index = limit.min; |
1646 | xas_find_marked(&xas, limit.max, XA_FREE_MARK); | |
371c752d | 1647 | if (xas.xa_node == XAS_RESTART) |
a3e4d3f9 MW |
1648 | xas_set_err(&xas, -EBUSY); |
1649 | else | |
1650 | *id = xas.xa_index; | |
371c752d MW |
1651 | xas_store(&xas, entry); |
1652 | xas_clear_mark(&xas, XA_FREE_MARK); | |
1653 | } while (__xas_nomem(&xas, gfp)); | |
1654 | ||
a3e4d3f9 | 1655 | return xas_error(&xas); |
371c752d MW |
1656 | } |
1657 | EXPORT_SYMBOL(__xa_alloc); | |
1658 | ||
9b89a035 MW |
1659 | /** |
1660 | * __xa_set_mark() - Set this mark on this entry while locked. | |
1661 | * @xa: XArray. | |
1662 | * @index: Index of entry. | |
1663 | * @mark: Mark number. | |
1664 | * | |
804dfaf0 | 1665 | * Attempting to set a mark on a %NULL entry does not succeed. |
9b89a035 MW |
1666 | * |
1667 | * Context: Any context. Expects xa_lock to be held on entry. | |
1668 | */ | |
1669 | void __xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark) | |
1670 | { | |
1671 | XA_STATE(xas, xa, index); | |
1672 | void *entry = xas_load(&xas); | |
1673 | ||
1674 | if (entry) | |
1675 | xas_set_mark(&xas, mark); | |
1676 | } | |
9ee5a3b7 | 1677 | EXPORT_SYMBOL(__xa_set_mark); |
9b89a035 MW |
1678 | |
1679 | /** | |
1680 | * __xa_clear_mark() - Clear this mark on this entry while locked. | |
1681 | * @xa: XArray. | |
1682 | * @index: Index of entry. | |
1683 | * @mark: Mark number. | |
1684 | * | |
1685 | * Context: Any context. Expects xa_lock to be held on entry. | |
1686 | */ | |
1687 | void __xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark) | |
1688 | { | |
1689 | XA_STATE(xas, xa, index); | |
1690 | void *entry = xas_load(&xas); | |
1691 | ||
1692 | if (entry) | |
1693 | xas_clear_mark(&xas, mark); | |
1694 | } | |
9ee5a3b7 | 1695 | EXPORT_SYMBOL(__xa_clear_mark); |
9b89a035 MW |
1696 | |
1697 | /** | |
1698 | * xa_get_mark() - Inquire whether this mark is set on this entry. | |
1699 | * @xa: XArray. | |
1700 | * @index: Index of entry. | |
1701 | * @mark: Mark number. | |
1702 | * | |
1703 | * This function uses the RCU read lock, so the result may be out of date | |
1704 | * by the time it returns. If you need the result to be stable, use a lock. | |
1705 | * | |
1706 | * Context: Any context. Takes and releases the RCU lock. | |
1707 | * Return: True if the entry at @index has this mark set, false if it doesn't. | |
1708 | */ | |
1709 | bool xa_get_mark(struct xarray *xa, unsigned long index, xa_mark_t mark) | |
1710 | { | |
1711 | XA_STATE(xas, xa, index); | |
1712 | void *entry; | |
1713 | ||
1714 | rcu_read_lock(); | |
1715 | entry = xas_start(&xas); | |
1716 | while (xas_get_mark(&xas, mark)) { | |
1717 | if (!xa_is_node(entry)) | |
1718 | goto found; | |
1719 | entry = xas_descend(&xas, xa_to_node(entry)); | |
1720 | } | |
1721 | rcu_read_unlock(); | |
1722 | return false; | |
1723 | found: | |
1724 | rcu_read_unlock(); | |
1725 | return true; | |
1726 | } | |
1727 | EXPORT_SYMBOL(xa_get_mark); | |
1728 | ||
1729 | /** | |
1730 | * xa_set_mark() - Set this mark on this entry. | |
1731 | * @xa: XArray. | |
1732 | * @index: Index of entry. | |
1733 | * @mark: Mark number. | |
1734 | * | |
804dfaf0 | 1735 | * Attempting to set a mark on a %NULL entry does not succeed. |
9b89a035 MW |
1736 | * |
1737 | * Context: Process context. Takes and releases the xa_lock. | |
1738 | */ | |
1739 | void xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark) | |
1740 | { | |
1741 | xa_lock(xa); | |
1742 | __xa_set_mark(xa, index, mark); | |
1743 | xa_unlock(xa); | |
1744 | } | |
1745 | EXPORT_SYMBOL(xa_set_mark); | |
1746 | ||
1747 | /** | |
1748 | * xa_clear_mark() - Clear this mark on this entry. | |
1749 | * @xa: XArray. | |
1750 | * @index: Index of entry. | |
1751 | * @mark: Mark number. | |
1752 | * | |
1753 | * Clearing a mark always succeeds. | |
1754 | * | |
1755 | * Context: Process context. Takes and releases the xa_lock. | |
1756 | */ | |
1757 | void xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark) | |
1758 | { | |
1759 | xa_lock(xa); | |
1760 | __xa_clear_mark(xa, index, mark); | |
1761 | xa_unlock(xa); | |
1762 | } | |
1763 | EXPORT_SYMBOL(xa_clear_mark); | |
1764 | ||
b803b428 MW |
1765 | /** |
1766 | * xa_find() - Search the XArray for an entry. | |
1767 | * @xa: XArray. | |
1768 | * @indexp: Pointer to an index. | |
1769 | * @max: Maximum index to search to. | |
1770 | * @filter: Selection criterion. | |
1771 | * | |
1772 | * Finds the entry in @xa which matches the @filter, and has the lowest | |
1773 | * index that is at least @indexp and no more than @max. | |
1774 | * If an entry is found, @indexp is updated to be the index of the entry. | |
1775 | * This function is protected by the RCU read lock, so it may not find | |
1776 | * entries which are being simultaneously added. It will not return an | |
1777 | * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find(). | |
1778 | * | |
1779 | * Context: Any context. Takes and releases the RCU lock. | |
1780 | * Return: The entry, if found, otherwise %NULL. | |
1781 | */ | |
1782 | void *xa_find(struct xarray *xa, unsigned long *indexp, | |
1783 | unsigned long max, xa_mark_t filter) | |
1784 | { | |
1785 | XA_STATE(xas, xa, *indexp); | |
1786 | void *entry; | |
1787 | ||
1788 | rcu_read_lock(); | |
1789 | do { | |
1790 | if ((__force unsigned int)filter < XA_MAX_MARKS) | |
1791 | entry = xas_find_marked(&xas, max, filter); | |
1792 | else | |
1793 | entry = xas_find(&xas, max); | |
1794 | } while (xas_retry(&xas, entry)); | |
1795 | rcu_read_unlock(); | |
1796 | ||
1797 | if (entry) | |
1798 | *indexp = xas.xa_index; | |
1799 | return entry; | |
1800 | } | |
1801 | EXPORT_SYMBOL(xa_find); | |
1802 | ||
1803 | /** | |
1804 | * xa_find_after() - Search the XArray for a present entry. | |
1805 | * @xa: XArray. | |
1806 | * @indexp: Pointer to an index. | |
1807 | * @max: Maximum index to search to. | |
1808 | * @filter: Selection criterion. | |
1809 | * | |
1810 | * Finds the entry in @xa which matches the @filter and has the lowest | |
1811 | * index that is above @indexp and no more than @max. | |
1812 | * If an entry is found, @indexp is updated to be the index of the entry. | |
1813 | * This function is protected by the RCU read lock, so it may miss entries | |
1814 | * which are being simultaneously added. It will not return an | |
1815 | * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find(). | |
1816 | * | |
1817 | * Context: Any context. Takes and releases the RCU lock. | |
1818 | * Return: The pointer, if found, otherwise %NULL. | |
1819 | */ | |
1820 | void *xa_find_after(struct xarray *xa, unsigned long *indexp, | |
1821 | unsigned long max, xa_mark_t filter) | |
1822 | { | |
1823 | XA_STATE(xas, xa, *indexp + 1); | |
1824 | void *entry; | |
1825 | ||
1826 | rcu_read_lock(); | |
1827 | for (;;) { | |
1828 | if ((__force unsigned int)filter < XA_MAX_MARKS) | |
1829 | entry = xas_find_marked(&xas, max, filter); | |
1830 | else | |
1831 | entry = xas_find(&xas, max); | |
8229706e MW |
1832 | if (xas.xa_node == XAS_BOUNDS) |
1833 | break; | |
b803b428 MW |
1834 | if (xas.xa_shift) { |
1835 | if (xas.xa_index & ((1UL << xas.xa_shift) - 1)) | |
1836 | continue; | |
1837 | } else { | |
1838 | if (xas.xa_offset < (xas.xa_index & XA_CHUNK_MASK)) | |
1839 | continue; | |
1840 | } | |
1841 | if (!xas_retry(&xas, entry)) | |
1842 | break; | |
1843 | } | |
1844 | rcu_read_unlock(); | |
1845 | ||
1846 | if (entry) | |
1847 | *indexp = xas.xa_index; | |
1848 | return entry; | |
1849 | } | |
1850 | EXPORT_SYMBOL(xa_find_after); | |
1851 | ||
80a0a1a9 MW |
1852 | static unsigned int xas_extract_present(struct xa_state *xas, void **dst, |
1853 | unsigned long max, unsigned int n) | |
1854 | { | |
1855 | void *entry; | |
1856 | unsigned int i = 0; | |
1857 | ||
1858 | rcu_read_lock(); | |
1859 | xas_for_each(xas, entry, max) { | |
1860 | if (xas_retry(xas, entry)) | |
1861 | continue; | |
1862 | dst[i++] = entry; | |
1863 | if (i == n) | |
1864 | break; | |
1865 | } | |
1866 | rcu_read_unlock(); | |
1867 | ||
1868 | return i; | |
1869 | } | |
1870 | ||
1871 | static unsigned int xas_extract_marked(struct xa_state *xas, void **dst, | |
1872 | unsigned long max, unsigned int n, xa_mark_t mark) | |
1873 | { | |
1874 | void *entry; | |
1875 | unsigned int i = 0; | |
1876 | ||
1877 | rcu_read_lock(); | |
1878 | xas_for_each_marked(xas, entry, max, mark) { | |
1879 | if (xas_retry(xas, entry)) | |
1880 | continue; | |
1881 | dst[i++] = entry; | |
1882 | if (i == n) | |
1883 | break; | |
1884 | } | |
1885 | rcu_read_unlock(); | |
1886 | ||
1887 | return i; | |
1888 | } | |
1889 | ||
1890 | /** | |
1891 | * xa_extract() - Copy selected entries from the XArray into a normal array. | |
1892 | * @xa: The source XArray to copy from. | |
1893 | * @dst: The buffer to copy entries into. | |
1894 | * @start: The first index in the XArray eligible to be selected. | |
1895 | * @max: The last index in the XArray eligible to be selected. | |
1896 | * @n: The maximum number of entries to copy. | |
1897 | * @filter: Selection criterion. | |
1898 | * | |
1899 | * Copies up to @n entries that match @filter from the XArray. The | |
1900 | * copied entries will have indices between @start and @max, inclusive. | |
1901 | * | |
1902 | * The @filter may be an XArray mark value, in which case entries which are | |
1903 | * marked with that mark will be copied. It may also be %XA_PRESENT, in | |
804dfaf0 | 1904 | * which case all entries which are not %NULL will be copied. |
80a0a1a9 MW |
1905 | * |
1906 | * The entries returned may not represent a snapshot of the XArray at a | |
1907 | * moment in time. For example, if another thread stores to index 5, then | |
1908 | * index 10, calling xa_extract() may return the old contents of index 5 | |
1909 | * and the new contents of index 10. Indices not modified while this | |
1910 | * function is running will not be skipped. | |
1911 | * | |
1912 | * If you need stronger guarantees, holding the xa_lock across calls to this | |
1913 | * function will prevent concurrent modification. | |
1914 | * | |
1915 | * Context: Any context. Takes and releases the RCU lock. | |
1916 | * Return: The number of entries copied. | |
1917 | */ | |
1918 | unsigned int xa_extract(struct xarray *xa, void **dst, unsigned long start, | |
1919 | unsigned long max, unsigned int n, xa_mark_t filter) | |
1920 | { | |
1921 | XA_STATE(xas, xa, start); | |
1922 | ||
1923 | if (!n) | |
1924 | return 0; | |
1925 | ||
1926 | if ((__force unsigned int)filter < XA_MAX_MARKS) | |
1927 | return xas_extract_marked(&xas, dst, max, n, filter); | |
1928 | return xas_extract_present(&xas, dst, max, n); | |
1929 | } | |
1930 | EXPORT_SYMBOL(xa_extract); | |
1931 | ||
687149fc MW |
1932 | /** |
1933 | * xa_destroy() - Free all internal data structures. | |
1934 | * @xa: XArray. | |
1935 | * | |
1936 | * After calling this function, the XArray is empty and has freed all memory | |
1937 | * allocated for its internal data structures. You are responsible for | |
1938 | * freeing the objects referenced by the XArray. | |
1939 | * | |
1940 | * Context: Any context. Takes and releases the xa_lock, interrupt-safe. | |
1941 | */ | |
1942 | void xa_destroy(struct xarray *xa) | |
1943 | { | |
1944 | XA_STATE(xas, xa, 0); | |
1945 | unsigned long flags; | |
1946 | void *entry; | |
1947 | ||
1948 | xas.xa_node = NULL; | |
1949 | xas_lock_irqsave(&xas, flags); | |
1950 | entry = xa_head_locked(xa); | |
1951 | RCU_INIT_POINTER(xa->xa_head, NULL); | |
1952 | xas_init_marks(&xas); | |
3ccaf57a MW |
1953 | if (xa_zero_busy(xa)) |
1954 | xa_mark_clear(xa, XA_FREE_MARK); | |
687149fc MW |
1955 | /* lockdep checks we're still holding the lock in xas_free_nodes() */ |
1956 | if (xa_is_node(entry)) | |
1957 | xas_free_nodes(&xas, xa_to_node(entry)); | |
1958 | xas_unlock_irqrestore(&xas, flags); | |
1959 | } | |
1960 | EXPORT_SYMBOL(xa_destroy); | |
1961 | ||
ad3d6c72 MW |
1962 | #ifdef XA_DEBUG |
1963 | void xa_dump_node(const struct xa_node *node) | |
1964 | { | |
1965 | unsigned i, j; | |
1966 | ||
1967 | if (!node) | |
1968 | return; | |
1969 | if ((unsigned long)node & 3) { | |
1970 | pr_cont("node %px\n", node); | |
1971 | return; | |
1972 | } | |
1973 | ||
1974 | pr_cont("node %px %s %d parent %px shift %d count %d values %d " | |
1975 | "array %px list %px %px marks", | |
1976 | node, node->parent ? "offset" : "max", node->offset, | |
1977 | node->parent, node->shift, node->count, node->nr_values, | |
1978 | node->array, node->private_list.prev, node->private_list.next); | |
1979 | for (i = 0; i < XA_MAX_MARKS; i++) | |
1980 | for (j = 0; j < XA_MARK_LONGS; j++) | |
1981 | pr_cont(" %lx", node->marks[i][j]); | |
1982 | pr_cont("\n"); | |
1983 | } | |
1984 | ||
1985 | void xa_dump_index(unsigned long index, unsigned int shift) | |
1986 | { | |
1987 | if (!shift) | |
1988 | pr_info("%lu: ", index); | |
1989 | else if (shift >= BITS_PER_LONG) | |
1990 | pr_info("0-%lu: ", ~0UL); | |
1991 | else | |
1992 | pr_info("%lu-%lu: ", index, index | ((1UL << shift) - 1)); | |
1993 | } | |
1994 | ||
1995 | void xa_dump_entry(const void *entry, unsigned long index, unsigned long shift) | |
1996 | { | |
1997 | if (!entry) | |
1998 | return; | |
1999 | ||
2000 | xa_dump_index(index, shift); | |
2001 | ||
2002 | if (xa_is_node(entry)) { | |
2003 | if (shift == 0) { | |
2004 | pr_cont("%px\n", entry); | |
2005 | } else { | |
2006 | unsigned long i; | |
2007 | struct xa_node *node = xa_to_node(entry); | |
2008 | xa_dump_node(node); | |
2009 | for (i = 0; i < XA_CHUNK_SIZE; i++) | |
2010 | xa_dump_entry(node->slots[i], | |
2011 | index + (i << node->shift), node->shift); | |
2012 | } | |
2013 | } else if (xa_is_value(entry)) | |
2014 | pr_cont("value %ld (0x%lx) [%px]\n", xa_to_value(entry), | |
2015 | xa_to_value(entry), entry); | |
2016 | else if (!xa_is_internal(entry)) | |
2017 | pr_cont("%px\n", entry); | |
2018 | else if (xa_is_retry(entry)) | |
2019 | pr_cont("retry (%ld)\n", xa_to_internal(entry)); | |
2020 | else if (xa_is_sibling(entry)) | |
2021 | pr_cont("sibling (slot %ld)\n", xa_to_sibling(entry)); | |
9f14d4f1 MW |
2022 | else if (xa_is_zero(entry)) |
2023 | pr_cont("zero (%ld)\n", xa_to_internal(entry)); | |
ad3d6c72 MW |
2024 | else |
2025 | pr_cont("UNKNOWN ENTRY (%px)\n", entry); | |
2026 | } | |
2027 | ||
2028 | void xa_dump(const struct xarray *xa) | |
2029 | { | |
2030 | void *entry = xa->xa_head; | |
2031 | unsigned int shift = 0; | |
2032 | ||
2033 | pr_info("xarray: %px head %px flags %x marks %d %d %d\n", xa, entry, | |
9b89a035 MW |
2034 | xa->xa_flags, xa_marked(xa, XA_MARK_0), |
2035 | xa_marked(xa, XA_MARK_1), xa_marked(xa, XA_MARK_2)); | |
ad3d6c72 MW |
2036 | if (xa_is_node(entry)) |
2037 | shift = xa_to_node(entry)->shift + XA_CHUNK_SHIFT; | |
2038 | xa_dump_entry(entry, 0, shift); | |
2039 | } | |
2040 | #endif |