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f8d5d0cc MW |
1 | // SPDX-License-Identifier: GPL-2.0+ |
2 | /* | |
3 | * XArray implementation | |
c44aa5e8 MWO |
4 | * Copyright (c) 2017-2018 Microsoft Corporation |
5 | * Copyright (c) 2018-2020 Oracle | |
f8d5d0cc MW |
6 | * Author: Matthew Wilcox <willy@infradead.org> |
7 | */ | |
8 | ||
9b89a035 | 9 | #include <linux/bitmap.h> |
f8d5d0cc | 10 | #include <linux/export.h> |
58d6ea30 MW |
11 | #include <linux/list.h> |
12 | #include <linux/slab.h> | |
f8d5d0cc MW |
13 | #include <linux/xarray.h> |
14 | ||
bde1597d AB |
15 | #include "radix-tree.h" |
16 | ||
f8d5d0cc MW |
17 | /* |
18 | * Coding conventions in this file: | |
19 | * | |
20 | * @xa is used to refer to the entire xarray. | |
21 | * @xas is the 'xarray operation state'. It may be either a pointer to | |
22 | * an xa_state, or an xa_state stored on the stack. This is an unfortunate | |
23 | * ambiguity. | |
24 | * @index is the index of the entry being operated on | |
25 | * @mark is an xa_mark_t; a small number indicating one of the mark bits. | |
26 | * @node refers to an xa_node; usually the primary one being operated on by | |
27 | * this function. | |
28 | * @offset is the index into the slots array inside an xa_node. | |
29 | * @parent refers to the @xa_node closer to the head than @node. | |
30 | * @entry refers to something stored in a slot in the xarray | |
31 | */ | |
32 | ||
58d6ea30 MW |
33 | static inline unsigned int xa_lock_type(const struct xarray *xa) |
34 | { | |
35 | return (__force unsigned int)xa->xa_flags & 3; | |
36 | } | |
37 | ||
38 | static inline void xas_lock_type(struct xa_state *xas, unsigned int lock_type) | |
39 | { | |
40 | if (lock_type == XA_LOCK_IRQ) | |
41 | xas_lock_irq(xas); | |
42 | else if (lock_type == XA_LOCK_BH) | |
43 | xas_lock_bh(xas); | |
44 | else | |
45 | xas_lock(xas); | |
46 | } | |
47 | ||
48 | static inline void xas_unlock_type(struct xa_state *xas, unsigned int lock_type) | |
49 | { | |
50 | if (lock_type == XA_LOCK_IRQ) | |
51 | xas_unlock_irq(xas); | |
52 | else if (lock_type == XA_LOCK_BH) | |
53 | xas_unlock_bh(xas); | |
54 | else | |
55 | xas_unlock(xas); | |
56 | } | |
57 | ||
371c752d MW |
58 | static inline bool xa_track_free(const struct xarray *xa) |
59 | { | |
60 | return xa->xa_flags & XA_FLAGS_TRACK_FREE; | |
61 | } | |
62 | ||
3ccaf57a MW |
63 | static inline bool xa_zero_busy(const struct xarray *xa) |
64 | { | |
65 | return xa->xa_flags & XA_FLAGS_ZERO_BUSY; | |
66 | } | |
67 | ||
9b89a035 MW |
68 | static inline void xa_mark_set(struct xarray *xa, xa_mark_t mark) |
69 | { | |
70 | if (!(xa->xa_flags & XA_FLAGS_MARK(mark))) | |
71 | xa->xa_flags |= XA_FLAGS_MARK(mark); | |
72 | } | |
73 | ||
74 | static inline void xa_mark_clear(struct xarray *xa, xa_mark_t mark) | |
75 | { | |
76 | if (xa->xa_flags & XA_FLAGS_MARK(mark)) | |
77 | xa->xa_flags &= ~(XA_FLAGS_MARK(mark)); | |
78 | } | |
79 | ||
80 | static inline unsigned long *node_marks(struct xa_node *node, xa_mark_t mark) | |
81 | { | |
82 | return node->marks[(__force unsigned)mark]; | |
83 | } | |
84 | ||
85 | static inline bool node_get_mark(struct xa_node *node, | |
86 | unsigned int offset, xa_mark_t mark) | |
87 | { | |
88 | return test_bit(offset, node_marks(node, mark)); | |
89 | } | |
90 | ||
91 | /* returns true if the bit was set */ | |
92 | static inline bool node_set_mark(struct xa_node *node, unsigned int offset, | |
93 | xa_mark_t mark) | |
94 | { | |
95 | return __test_and_set_bit(offset, node_marks(node, mark)); | |
96 | } | |
97 | ||
98 | /* returns true if the bit was set */ | |
99 | static inline bool node_clear_mark(struct xa_node *node, unsigned int offset, | |
100 | xa_mark_t mark) | |
101 | { | |
102 | return __test_and_clear_bit(offset, node_marks(node, mark)); | |
103 | } | |
104 | ||
105 | static inline bool node_any_mark(struct xa_node *node, xa_mark_t mark) | |
106 | { | |
107 | return !bitmap_empty(node_marks(node, mark), XA_CHUNK_SIZE); | |
108 | } | |
109 | ||
371c752d MW |
110 | static inline void node_mark_all(struct xa_node *node, xa_mark_t mark) |
111 | { | |
112 | bitmap_fill(node_marks(node, mark), XA_CHUNK_SIZE); | |
113 | } | |
114 | ||
58d6ea30 MW |
115 | #define mark_inc(mark) do { \ |
116 | mark = (__force xa_mark_t)((__force unsigned)(mark) + 1); \ | |
117 | } while (0) | |
118 | ||
119 | /* | |
120 | * xas_squash_marks() - Merge all marks to the first entry | |
121 | * @xas: Array operation state. | |
122 | * | |
123 | * Set a mark on the first entry if any entry has it set. Clear marks on | |
124 | * all sibling entries. | |
125 | */ | |
126 | static void xas_squash_marks(const struct xa_state *xas) | |
127 | { | |
128 | unsigned int mark = 0; | |
129 | unsigned int limit = xas->xa_offset + xas->xa_sibs + 1; | |
130 | ||
131 | if (!xas->xa_sibs) | |
132 | return; | |
133 | ||
134 | do { | |
135 | unsigned long *marks = xas->xa_node->marks[mark]; | |
136 | if (find_next_bit(marks, limit, xas->xa_offset + 1) == limit) | |
137 | continue; | |
138 | __set_bit(xas->xa_offset, marks); | |
139 | bitmap_clear(marks, xas->xa_offset + 1, xas->xa_sibs); | |
140 | } while (mark++ != (__force unsigned)XA_MARK_MAX); | |
141 | } | |
142 | ||
ad3d6c72 MW |
143 | /* extracts the offset within this node from the index */ |
144 | static unsigned int get_offset(unsigned long index, struct xa_node *node) | |
145 | { | |
146 | return (index >> node->shift) & XA_CHUNK_MASK; | |
147 | } | |
148 | ||
b803b428 MW |
149 | static void xas_set_offset(struct xa_state *xas) |
150 | { | |
151 | xas->xa_offset = get_offset(xas->xa_index, xas->xa_node); | |
152 | } | |
153 | ||
ad3d6c72 MW |
154 | /* move the index either forwards (find) or backwards (sibling slot) */ |
155 | static void xas_move_index(struct xa_state *xas, unsigned long offset) | |
156 | { | |
157 | unsigned int shift = xas->xa_node->shift; | |
158 | xas->xa_index &= ~XA_CHUNK_MASK << shift; | |
159 | xas->xa_index += offset << shift; | |
160 | } | |
161 | ||
25a8de7f | 162 | static void xas_next_offset(struct xa_state *xas) |
b803b428 MW |
163 | { |
164 | xas->xa_offset++; | |
165 | xas_move_index(xas, xas->xa_offset); | |
166 | } | |
167 | ||
ad3d6c72 MW |
168 | static void *set_bounds(struct xa_state *xas) |
169 | { | |
170 | xas->xa_node = XAS_BOUNDS; | |
171 | return NULL; | |
172 | } | |
173 | ||
174 | /* | |
175 | * Starts a walk. If the @xas is already valid, we assume that it's on | |
176 | * the right path and just return where we've got to. If we're in an | |
177 | * error state, return NULL. If the index is outside the current scope | |
178 | * of the xarray, return NULL without changing @xas->xa_node. Otherwise | |
179 | * set @xas->xa_node to NULL and return the current head of the array. | |
180 | */ | |
181 | static void *xas_start(struct xa_state *xas) | |
182 | { | |
183 | void *entry; | |
184 | ||
185 | if (xas_valid(xas)) | |
186 | return xas_reload(xas); | |
187 | if (xas_error(xas)) | |
188 | return NULL; | |
189 | ||
190 | entry = xa_head(xas->xa); | |
191 | if (!xa_is_node(entry)) { | |
192 | if (xas->xa_index) | |
193 | return set_bounds(xas); | |
194 | } else { | |
195 | if ((xas->xa_index >> xa_to_node(entry)->shift) > XA_CHUNK_MASK) | |
196 | return set_bounds(xas); | |
197 | } | |
198 | ||
199 | xas->xa_node = NULL; | |
200 | return entry; | |
201 | } | |
202 | ||
ba591801 LL |
203 | static __always_inline void *xas_descend(struct xa_state *xas, |
204 | struct xa_node *node) | |
ad3d6c72 MW |
205 | { |
206 | unsigned int offset = get_offset(xas->xa_index, node); | |
207 | void *entry = xa_entry(xas->xa, node, offset); | |
208 | ||
209 | xas->xa_node = node; | |
cbc02854 | 210 | while (xa_is_sibling(entry)) { |
ad3d6c72 MW |
211 | offset = xa_to_sibling(entry); |
212 | entry = xa_entry(xas->xa, node, offset); | |
63b1898f MWO |
213 | if (node->shift && xa_is_node(entry)) |
214 | entry = XA_RETRY_ENTRY; | |
ad3d6c72 MW |
215 | } |
216 | ||
217 | xas->xa_offset = offset; | |
218 | return entry; | |
219 | } | |
220 | ||
221 | /** | |
222 | * xas_load() - Load an entry from the XArray (advanced). | |
223 | * @xas: XArray operation state. | |
224 | * | |
225 | * Usually walks the @xas to the appropriate state to load the entry | |
226 | * stored at xa_index. However, it will do nothing and return %NULL if | |
227 | * @xas is in an error state. xas_load() will never expand the tree. | |
228 | * | |
229 | * If the xa_state is set up to operate on a multi-index entry, xas_load() | |
230 | * may return %NULL or an internal entry, even if there are entries | |
231 | * present within the range specified by @xas. | |
232 | * | |
233 | * Context: Any context. The caller should hold the xa_lock or the RCU lock. | |
234 | * Return: Usually an entry in the XArray, but see description for exceptions. | |
235 | */ | |
236 | void *xas_load(struct xa_state *xas) | |
237 | { | |
238 | void *entry = xas_start(xas); | |
239 | ||
240 | while (xa_is_node(entry)) { | |
241 | struct xa_node *node = xa_to_node(entry); | |
242 | ||
243 | if (xas->xa_shift > node->shift) | |
244 | break; | |
245 | entry = xas_descend(xas, node); | |
76b4e529 MW |
246 | if (node->shift == 0) |
247 | break; | |
ad3d6c72 MW |
248 | } |
249 | return entry; | |
250 | } | |
251 | EXPORT_SYMBOL_GPL(xas_load); | |
252 | ||
58d6ea30 MW |
253 | #define XA_RCU_FREE ((struct xarray *)1) |
254 | ||
255 | static void xa_node_free(struct xa_node *node) | |
256 | { | |
257 | XA_NODE_BUG_ON(node, !list_empty(&node->private_list)); | |
258 | node->array = XA_RCU_FREE; | |
259 | call_rcu(&node->rcu_head, radix_tree_node_rcu_free); | |
260 | } | |
261 | ||
262 | /* | |
263 | * xas_destroy() - Free any resources allocated during the XArray operation. | |
264 | * @xas: XArray operation state. | |
265 | * | |
69a37a8b MWO |
266 | * Most users will not need to call this function; it is called for you |
267 | * by xas_nomem(). | |
58d6ea30 | 268 | */ |
69a37a8b | 269 | void xas_destroy(struct xa_state *xas) |
58d6ea30 | 270 | { |
8fc75643 | 271 | struct xa_node *next, *node = xas->xa_alloc; |
58d6ea30 | 272 | |
8fc75643 MWO |
273 | while (node) { |
274 | XA_NODE_BUG_ON(node, !list_empty(&node->private_list)); | |
275 | next = rcu_dereference_raw(node->parent); | |
276 | radix_tree_node_rcu_free(&node->rcu_head); | |
277 | xas->xa_alloc = node = next; | |
278 | } | |
58d6ea30 MW |
279 | } |
280 | ||
281 | /** | |
282 | * xas_nomem() - Allocate memory if needed. | |
283 | * @xas: XArray operation state. | |
284 | * @gfp: Memory allocation flags. | |
285 | * | |
286 | * If we need to add new nodes to the XArray, we try to allocate memory | |
287 | * with GFP_NOWAIT while holding the lock, which will usually succeed. | |
288 | * If it fails, @xas is flagged as needing memory to continue. The caller | |
289 | * should drop the lock and call xas_nomem(). If xas_nomem() succeeds, | |
290 | * the caller should retry the operation. | |
291 | * | |
292 | * Forward progress is guaranteed as one node is allocated here and | |
293 | * stored in the xa_state where it will be found by xas_alloc(). More | |
294 | * nodes will likely be found in the slab allocator, but we do not tie | |
295 | * them up here. | |
296 | * | |
297 | * Return: true if memory was needed, and was successfully allocated. | |
298 | */ | |
299 | bool xas_nomem(struct xa_state *xas, gfp_t gfp) | |
300 | { | |
301 | if (xas->xa_node != XA_ERROR(-ENOMEM)) { | |
302 | xas_destroy(xas); | |
303 | return false; | |
304 | } | |
7b785645 JW |
305 | if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT) |
306 | gfp |= __GFP_ACCOUNT; | |
9bbdc0f3 | 307 | xas->xa_alloc = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp); |
58d6ea30 MW |
308 | if (!xas->xa_alloc) |
309 | return false; | |
8fc75643 | 310 | xas->xa_alloc->parent = NULL; |
58d6ea30 MW |
311 | XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list)); |
312 | xas->xa_node = XAS_RESTART; | |
313 | return true; | |
314 | } | |
315 | EXPORT_SYMBOL_GPL(xas_nomem); | |
316 | ||
317 | /* | |
318 | * __xas_nomem() - Drop locks and allocate memory if needed. | |
319 | * @xas: XArray operation state. | |
320 | * @gfp: Memory allocation flags. | |
321 | * | |
322 | * Internal variant of xas_nomem(). | |
323 | * | |
324 | * Return: true if memory was needed, and was successfully allocated. | |
325 | */ | |
326 | static bool __xas_nomem(struct xa_state *xas, gfp_t gfp) | |
327 | __must_hold(xas->xa->xa_lock) | |
328 | { | |
329 | unsigned int lock_type = xa_lock_type(xas->xa); | |
330 | ||
331 | if (xas->xa_node != XA_ERROR(-ENOMEM)) { | |
332 | xas_destroy(xas); | |
333 | return false; | |
334 | } | |
7b785645 JW |
335 | if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT) |
336 | gfp |= __GFP_ACCOUNT; | |
58d6ea30 MW |
337 | if (gfpflags_allow_blocking(gfp)) { |
338 | xas_unlock_type(xas, lock_type); | |
9bbdc0f3 | 339 | xas->xa_alloc = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp); |
58d6ea30 MW |
340 | xas_lock_type(xas, lock_type); |
341 | } else { | |
9bbdc0f3 | 342 | xas->xa_alloc = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp); |
58d6ea30 MW |
343 | } |
344 | if (!xas->xa_alloc) | |
345 | return false; | |
8fc75643 | 346 | xas->xa_alloc->parent = NULL; |
58d6ea30 MW |
347 | XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list)); |
348 | xas->xa_node = XAS_RESTART; | |
349 | return true; | |
350 | } | |
351 | ||
352 | static void xas_update(struct xa_state *xas, struct xa_node *node) | |
353 | { | |
354 | if (xas->xa_update) | |
355 | xas->xa_update(node); | |
356 | else | |
357 | XA_NODE_BUG_ON(node, !list_empty(&node->private_list)); | |
358 | } | |
359 | ||
360 | static void *xas_alloc(struct xa_state *xas, unsigned int shift) | |
361 | { | |
362 | struct xa_node *parent = xas->xa_node; | |
363 | struct xa_node *node = xas->xa_alloc; | |
364 | ||
365 | if (xas_invalid(xas)) | |
366 | return NULL; | |
367 | ||
368 | if (node) { | |
369 | xas->xa_alloc = NULL; | |
370 | } else { | |
7b785645 JW |
371 | gfp_t gfp = GFP_NOWAIT | __GFP_NOWARN; |
372 | ||
373 | if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT) | |
374 | gfp |= __GFP_ACCOUNT; | |
375 | ||
9bbdc0f3 | 376 | node = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp); |
58d6ea30 MW |
377 | if (!node) { |
378 | xas_set_err(xas, -ENOMEM); | |
379 | return NULL; | |
380 | } | |
381 | } | |
382 | ||
383 | if (parent) { | |
384 | node->offset = xas->xa_offset; | |
385 | parent->count++; | |
386 | XA_NODE_BUG_ON(node, parent->count > XA_CHUNK_SIZE); | |
387 | xas_update(xas, parent); | |
388 | } | |
389 | XA_NODE_BUG_ON(node, shift > BITS_PER_LONG); | |
390 | XA_NODE_BUG_ON(node, !list_empty(&node->private_list)); | |
391 | node->shift = shift; | |
392 | node->count = 0; | |
393 | node->nr_values = 0; | |
394 | RCU_INIT_POINTER(node->parent, xas->xa_node); | |
395 | node->array = xas->xa; | |
396 | ||
397 | return node; | |
398 | } | |
399 | ||
0e9446c3 MW |
400 | #ifdef CONFIG_XARRAY_MULTI |
401 | /* Returns the number of indices covered by a given xa_state */ | |
402 | static unsigned long xas_size(const struct xa_state *xas) | |
403 | { | |
404 | return (xas->xa_sibs + 1UL) << xas->xa_shift; | |
405 | } | |
406 | #endif | |
407 | ||
58d6ea30 MW |
408 | /* |
409 | * Use this to calculate the maximum index that will need to be created | |
410 | * in order to add the entry described by @xas. Because we cannot store a | |
8fc75643 | 411 | * multi-index entry at index 0, the calculation is a little more complex |
58d6ea30 MW |
412 | * than you might expect. |
413 | */ | |
414 | static unsigned long xas_max(struct xa_state *xas) | |
415 | { | |
416 | unsigned long max = xas->xa_index; | |
417 | ||
418 | #ifdef CONFIG_XARRAY_MULTI | |
419 | if (xas->xa_shift || xas->xa_sibs) { | |
0e9446c3 | 420 | unsigned long mask = xas_size(xas) - 1; |
58d6ea30 MW |
421 | max |= mask; |
422 | if (mask == max) | |
423 | max++; | |
424 | } | |
425 | #endif | |
426 | ||
427 | return max; | |
428 | } | |
429 | ||
430 | /* The maximum index that can be contained in the array without expanding it */ | |
431 | static unsigned long max_index(void *entry) | |
432 | { | |
433 | if (!xa_is_node(entry)) | |
434 | return 0; | |
435 | return (XA_CHUNK_SIZE << xa_to_node(entry)->shift) - 1; | |
436 | } | |
437 | ||
438 | static void xas_shrink(struct xa_state *xas) | |
439 | { | |
440 | struct xarray *xa = xas->xa; | |
441 | struct xa_node *node = xas->xa_node; | |
442 | ||
443 | for (;;) { | |
444 | void *entry; | |
445 | ||
446 | XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE); | |
447 | if (node->count != 1) | |
448 | break; | |
449 | entry = xa_entry_locked(xa, node, 0); | |
450 | if (!entry) | |
451 | break; | |
452 | if (!xa_is_node(entry) && node->shift) | |
453 | break; | |
3ccaf57a MW |
454 | if (xa_is_zero(entry) && xa_zero_busy(xa)) |
455 | entry = NULL; | |
58d6ea30 MW |
456 | xas->xa_node = XAS_BOUNDS; |
457 | ||
458 | RCU_INIT_POINTER(xa->xa_head, entry); | |
371c752d MW |
459 | if (xa_track_free(xa) && !node_get_mark(node, 0, XA_FREE_MARK)) |
460 | xa_mark_clear(xa, XA_FREE_MARK); | |
58d6ea30 MW |
461 | |
462 | node->count = 0; | |
463 | node->nr_values = 0; | |
464 | if (!xa_is_node(entry)) | |
465 | RCU_INIT_POINTER(node->slots[0], XA_RETRY_ENTRY); | |
466 | xas_update(xas, node); | |
467 | xa_node_free(node); | |
468 | if (!xa_is_node(entry)) | |
469 | break; | |
470 | node = xa_to_node(entry); | |
471 | node->parent = NULL; | |
472 | } | |
473 | } | |
474 | ||
475 | /* | |
476 | * xas_delete_node() - Attempt to delete an xa_node | |
477 | * @xas: Array operation state. | |
478 | * | |
479 | * Attempts to delete the @xas->xa_node. This will fail if xa->node has | |
480 | * a non-zero reference count. | |
481 | */ | |
482 | static void xas_delete_node(struct xa_state *xas) | |
483 | { | |
484 | struct xa_node *node = xas->xa_node; | |
485 | ||
486 | for (;;) { | |
487 | struct xa_node *parent; | |
488 | ||
489 | XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE); | |
490 | if (node->count) | |
491 | break; | |
492 | ||
493 | parent = xa_parent_locked(xas->xa, node); | |
494 | xas->xa_node = parent; | |
495 | xas->xa_offset = node->offset; | |
496 | xa_node_free(node); | |
497 | ||
498 | if (!parent) { | |
499 | xas->xa->xa_head = NULL; | |
500 | xas->xa_node = XAS_BOUNDS; | |
501 | return; | |
502 | } | |
503 | ||
504 | parent->slots[xas->xa_offset] = NULL; | |
505 | parent->count--; | |
506 | XA_NODE_BUG_ON(parent, parent->count > XA_CHUNK_SIZE); | |
507 | node = parent; | |
508 | xas_update(xas, node); | |
509 | } | |
510 | ||
511 | if (!node->parent) | |
512 | xas_shrink(xas); | |
513 | } | |
514 | ||
515 | /** | |
516 | * xas_free_nodes() - Free this node and all nodes that it references | |
517 | * @xas: Array operation state. | |
518 | * @top: Node to free | |
519 | * | |
520 | * This node has been removed from the tree. We must now free it and all | |
521 | * of its subnodes. There may be RCU walkers with references into the tree, | |
522 | * so we must replace all entries with retry markers. | |
523 | */ | |
524 | static void xas_free_nodes(struct xa_state *xas, struct xa_node *top) | |
525 | { | |
526 | unsigned int offset = 0; | |
527 | struct xa_node *node = top; | |
528 | ||
529 | for (;;) { | |
530 | void *entry = xa_entry_locked(xas->xa, node, offset); | |
531 | ||
76b4e529 | 532 | if (node->shift && xa_is_node(entry)) { |
58d6ea30 MW |
533 | node = xa_to_node(entry); |
534 | offset = 0; | |
535 | continue; | |
536 | } | |
537 | if (entry) | |
538 | RCU_INIT_POINTER(node->slots[offset], XA_RETRY_ENTRY); | |
539 | offset++; | |
540 | while (offset == XA_CHUNK_SIZE) { | |
541 | struct xa_node *parent; | |
542 | ||
543 | parent = xa_parent_locked(xas->xa, node); | |
544 | offset = node->offset + 1; | |
545 | node->count = 0; | |
546 | node->nr_values = 0; | |
547 | xas_update(xas, node); | |
548 | xa_node_free(node); | |
549 | if (node == top) | |
550 | return; | |
551 | node = parent; | |
552 | } | |
553 | } | |
554 | } | |
555 | ||
556 | /* | |
557 | * xas_expand adds nodes to the head of the tree until it has reached | |
558 | * sufficient height to be able to contain @xas->xa_index | |
559 | */ | |
560 | static int xas_expand(struct xa_state *xas, void *head) | |
561 | { | |
562 | struct xarray *xa = xas->xa; | |
563 | struct xa_node *node = NULL; | |
564 | unsigned int shift = 0; | |
565 | unsigned long max = xas_max(xas); | |
566 | ||
567 | if (!head) { | |
568 | if (max == 0) | |
569 | return 0; | |
570 | while ((max >> shift) >= XA_CHUNK_SIZE) | |
571 | shift += XA_CHUNK_SHIFT; | |
572 | return shift + XA_CHUNK_SHIFT; | |
573 | } else if (xa_is_node(head)) { | |
574 | node = xa_to_node(head); | |
575 | shift = node->shift + XA_CHUNK_SHIFT; | |
576 | } | |
577 | xas->xa_node = NULL; | |
578 | ||
579 | while (max > max_index(head)) { | |
580 | xa_mark_t mark = 0; | |
581 | ||
582 | XA_NODE_BUG_ON(node, shift > BITS_PER_LONG); | |
583 | node = xas_alloc(xas, shift); | |
584 | if (!node) | |
585 | return -ENOMEM; | |
586 | ||
587 | node->count = 1; | |
588 | if (xa_is_value(head)) | |
589 | node->nr_values = 1; | |
590 | RCU_INIT_POINTER(node->slots[0], head); | |
591 | ||
592 | /* Propagate the aggregated mark info to the new child */ | |
593 | for (;;) { | |
371c752d MW |
594 | if (xa_track_free(xa) && mark == XA_FREE_MARK) { |
595 | node_mark_all(node, XA_FREE_MARK); | |
596 | if (!xa_marked(xa, XA_FREE_MARK)) { | |
597 | node_clear_mark(node, 0, XA_FREE_MARK); | |
598 | xa_mark_set(xa, XA_FREE_MARK); | |
599 | } | |
600 | } else if (xa_marked(xa, mark)) { | |
58d6ea30 | 601 | node_set_mark(node, 0, mark); |
371c752d | 602 | } |
58d6ea30 MW |
603 | if (mark == XA_MARK_MAX) |
604 | break; | |
605 | mark_inc(mark); | |
606 | } | |
607 | ||
608 | /* | |
609 | * Now that the new node is fully initialised, we can add | |
610 | * it to the tree | |
611 | */ | |
612 | if (xa_is_node(head)) { | |
613 | xa_to_node(head)->offset = 0; | |
614 | rcu_assign_pointer(xa_to_node(head)->parent, node); | |
615 | } | |
616 | head = xa_mk_node(node); | |
617 | rcu_assign_pointer(xa->xa_head, head); | |
618 | xas_update(xas, node); | |
619 | ||
620 | shift += XA_CHUNK_SHIFT; | |
621 | } | |
622 | ||
623 | xas->xa_node = node; | |
624 | return shift; | |
625 | } | |
626 | ||
627 | /* | |
628 | * xas_create() - Create a slot to store an entry in. | |
629 | * @xas: XArray operation state. | |
76b4e529 | 630 | * @allow_root: %true if we can store the entry in the root directly |
58d6ea30 MW |
631 | * |
632 | * Most users will not need to call this function directly, as it is called | |
633 | * by xas_store(). It is useful for doing conditional store operations | |
634 | * (see the xa_cmpxchg() implementation for an example). | |
635 | * | |
636 | * Return: If the slot already existed, returns the contents of this slot. | |
804dfaf0 MW |
637 | * If the slot was newly created, returns %NULL. If it failed to create the |
638 | * slot, returns %NULL and indicates the error in @xas. | |
58d6ea30 | 639 | */ |
76b4e529 | 640 | static void *xas_create(struct xa_state *xas, bool allow_root) |
58d6ea30 MW |
641 | { |
642 | struct xarray *xa = xas->xa; | |
643 | void *entry; | |
644 | void __rcu **slot; | |
645 | struct xa_node *node = xas->xa_node; | |
646 | int shift; | |
647 | unsigned int order = xas->xa_shift; | |
648 | ||
649 | if (xas_top(node)) { | |
650 | entry = xa_head_locked(xa); | |
651 | xas->xa_node = NULL; | |
3ccaf57a MW |
652 | if (!entry && xa_zero_busy(xa)) |
653 | entry = XA_ZERO_ENTRY; | |
58d6ea30 MW |
654 | shift = xas_expand(xas, entry); |
655 | if (shift < 0) | |
656 | return NULL; | |
76b4e529 MW |
657 | if (!shift && !allow_root) |
658 | shift = XA_CHUNK_SHIFT; | |
58d6ea30 MW |
659 | entry = xa_head_locked(xa); |
660 | slot = &xa->xa_head; | |
661 | } else if (xas_error(xas)) { | |
662 | return NULL; | |
663 | } else if (node) { | |
664 | unsigned int offset = xas->xa_offset; | |
665 | ||
666 | shift = node->shift; | |
667 | entry = xa_entry_locked(xa, node, offset); | |
668 | slot = &node->slots[offset]; | |
669 | } else { | |
670 | shift = 0; | |
671 | entry = xa_head_locked(xa); | |
672 | slot = &xa->xa_head; | |
673 | } | |
674 | ||
675 | while (shift > order) { | |
676 | shift -= XA_CHUNK_SHIFT; | |
677 | if (!entry) { | |
678 | node = xas_alloc(xas, shift); | |
679 | if (!node) | |
680 | break; | |
371c752d MW |
681 | if (xa_track_free(xa)) |
682 | node_mark_all(node, XA_FREE_MARK); | |
58d6ea30 MW |
683 | rcu_assign_pointer(*slot, xa_mk_node(node)); |
684 | } else if (xa_is_node(entry)) { | |
685 | node = xa_to_node(entry); | |
686 | } else { | |
687 | break; | |
688 | } | |
689 | entry = xas_descend(xas, node); | |
690 | slot = &node->slots[xas->xa_offset]; | |
691 | } | |
692 | ||
693 | return entry; | |
694 | } | |
695 | ||
2264f513 MW |
696 | /** |
697 | * xas_create_range() - Ensure that stores to this range will succeed | |
698 | * @xas: XArray operation state. | |
699 | * | |
700 | * Creates all of the slots in the range covered by @xas. Sets @xas to | |
701 | * create single-index entries and positions it at the beginning of the | |
702 | * range. This is for the benefit of users which have not yet been | |
703 | * converted to use multi-index entries. | |
704 | */ | |
705 | void xas_create_range(struct xa_state *xas) | |
706 | { | |
707 | unsigned long index = xas->xa_index; | |
708 | unsigned char shift = xas->xa_shift; | |
709 | unsigned char sibs = xas->xa_sibs; | |
710 | ||
84c34df1 | 711 | xas->xa_index |= ((sibs + 1UL) << shift) - 1; |
2264f513 MW |
712 | if (xas_is_node(xas) && xas->xa_node->shift == xas->xa_shift) |
713 | xas->xa_offset |= sibs; | |
714 | xas->xa_shift = 0; | |
715 | xas->xa_sibs = 0; | |
716 | ||
717 | for (;;) { | |
76b4e529 | 718 | xas_create(xas, true); |
2264f513 MW |
719 | if (xas_error(xas)) |
720 | goto restore; | |
721 | if (xas->xa_index <= (index | XA_CHUNK_MASK)) | |
722 | goto success; | |
723 | xas->xa_index -= XA_CHUNK_SIZE; | |
724 | ||
725 | for (;;) { | |
726 | struct xa_node *node = xas->xa_node; | |
3e3c6580 MWO |
727 | if (node->shift >= shift) |
728 | break; | |
2264f513 MW |
729 | xas->xa_node = xa_parent_locked(xas->xa, node); |
730 | xas->xa_offset = node->offset - 1; | |
731 | if (node->offset != 0) | |
732 | break; | |
733 | } | |
734 | } | |
735 | ||
736 | restore: | |
737 | xas->xa_shift = shift; | |
738 | xas->xa_sibs = sibs; | |
739 | xas->xa_index = index; | |
740 | return; | |
741 | success: | |
742 | xas->xa_index = index; | |
743 | if (xas->xa_node) | |
744 | xas_set_offset(xas); | |
745 | } | |
746 | EXPORT_SYMBOL_GPL(xas_create_range); | |
747 | ||
58d6ea30 MW |
748 | static void update_node(struct xa_state *xas, struct xa_node *node, |
749 | int count, int values) | |
750 | { | |
751 | if (!node || (!count && !values)) | |
752 | return; | |
753 | ||
754 | node->count += count; | |
755 | node->nr_values += values; | |
756 | XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE); | |
757 | XA_NODE_BUG_ON(node, node->nr_values > XA_CHUNK_SIZE); | |
758 | xas_update(xas, node); | |
759 | if (count < 0) | |
760 | xas_delete_node(xas); | |
761 | } | |
762 | ||
763 | /** | |
764 | * xas_store() - Store this entry in the XArray. | |
765 | * @xas: XArray operation state. | |
766 | * @entry: New entry. | |
767 | * | |
768 | * If @xas is operating on a multi-index entry, the entry returned by this | |
769 | * function is essentially meaningless (it may be an internal entry or it | |
770 | * may be %NULL, even if there are non-NULL entries at some of the indices | |
771 | * covered by the range). This is not a problem for any current users, | |
772 | * and can be changed if needed. | |
773 | * | |
774 | * Return: The old entry at this index. | |
775 | */ | |
776 | void *xas_store(struct xa_state *xas, void *entry) | |
777 | { | |
778 | struct xa_node *node; | |
779 | void __rcu **slot = &xas->xa->xa_head; | |
780 | unsigned int offset, max; | |
781 | int count = 0; | |
782 | int values = 0; | |
783 | void *first, *next; | |
784 | bool value = xa_is_value(entry); | |
785 | ||
4a5c8d89 MW |
786 | if (entry) { |
787 | bool allow_root = !xa_is_node(entry) && !xa_is_zero(entry); | |
788 | first = xas_create(xas, allow_root); | |
789 | } else { | |
58d6ea30 | 790 | first = xas_load(xas); |
4a5c8d89 | 791 | } |
58d6ea30 MW |
792 | |
793 | if (xas_invalid(xas)) | |
794 | return first; | |
795 | node = xas->xa_node; | |
796 | if (node && (xas->xa_shift < node->shift)) | |
797 | xas->xa_sibs = 0; | |
798 | if ((first == entry) && !xas->xa_sibs) | |
799 | return first; | |
800 | ||
801 | next = first; | |
802 | offset = xas->xa_offset; | |
803 | max = xas->xa_offset + xas->xa_sibs; | |
804 | if (node) { | |
805 | slot = &node->slots[offset]; | |
806 | if (xas->xa_sibs) | |
807 | xas_squash_marks(xas); | |
808 | } | |
809 | if (!entry) | |
810 | xas_init_marks(xas); | |
811 | ||
812 | for (;;) { | |
813 | /* | |
814 | * Must clear the marks before setting the entry to NULL, | |
815 | * otherwise xas_for_each_marked may find a NULL entry and | |
816 | * stop early. rcu_assign_pointer contains a release barrier | |
817 | * so the mark clearing will appear to happen before the | |
818 | * entry is set to NULL. | |
819 | */ | |
820 | rcu_assign_pointer(*slot, entry); | |
2fbe967b | 821 | if (xa_is_node(next) && (!node || node->shift)) |
58d6ea30 MW |
822 | xas_free_nodes(xas, xa_to_node(next)); |
823 | if (!node) | |
824 | break; | |
825 | count += !next - !entry; | |
826 | values += !xa_is_value(first) - !value; | |
827 | if (entry) { | |
828 | if (offset == max) | |
829 | break; | |
830 | if (!xa_is_sibling(entry)) | |
831 | entry = xa_mk_sibling(xas->xa_offset); | |
832 | } else { | |
833 | if (offset == XA_CHUNK_MASK) | |
834 | break; | |
835 | } | |
836 | next = xa_entry_locked(xas->xa, node, ++offset); | |
837 | if (!xa_is_sibling(next)) { | |
838 | if (!entry && (offset > max)) | |
839 | break; | |
840 | first = next; | |
841 | } | |
842 | slot++; | |
843 | } | |
844 | ||
845 | update_node(xas, node, count, values); | |
846 | return first; | |
847 | } | |
848 | EXPORT_SYMBOL_GPL(xas_store); | |
849 | ||
9b89a035 MW |
850 | /** |
851 | * xas_get_mark() - Returns the state of this mark. | |
852 | * @xas: XArray operation state. | |
853 | * @mark: Mark number. | |
854 | * | |
855 | * Return: true if the mark is set, false if the mark is clear or @xas | |
856 | * is in an error state. | |
857 | */ | |
858 | bool xas_get_mark(const struct xa_state *xas, xa_mark_t mark) | |
859 | { | |
860 | if (xas_invalid(xas)) | |
861 | return false; | |
862 | if (!xas->xa_node) | |
863 | return xa_marked(xas->xa, mark); | |
864 | return node_get_mark(xas->xa_node, xas->xa_offset, mark); | |
865 | } | |
866 | EXPORT_SYMBOL_GPL(xas_get_mark); | |
867 | ||
868 | /** | |
869 | * xas_set_mark() - Sets the mark on this entry and its parents. | |
870 | * @xas: XArray operation state. | |
871 | * @mark: Mark number. | |
872 | * | |
873 | * Sets the specified mark on this entry, and walks up the tree setting it | |
874 | * on all the ancestor entries. Does nothing if @xas has not been walked to | |
875 | * an entry, or is in an error state. | |
876 | */ | |
877 | void xas_set_mark(const struct xa_state *xas, xa_mark_t mark) | |
878 | { | |
879 | struct xa_node *node = xas->xa_node; | |
880 | unsigned int offset = xas->xa_offset; | |
881 | ||
882 | if (xas_invalid(xas)) | |
883 | return; | |
884 | ||
885 | while (node) { | |
886 | if (node_set_mark(node, offset, mark)) | |
887 | return; | |
888 | offset = node->offset; | |
889 | node = xa_parent_locked(xas->xa, node); | |
890 | } | |
891 | ||
892 | if (!xa_marked(xas->xa, mark)) | |
893 | xa_mark_set(xas->xa, mark); | |
894 | } | |
895 | EXPORT_SYMBOL_GPL(xas_set_mark); | |
896 | ||
897 | /** | |
898 | * xas_clear_mark() - Clears the mark on this entry and its parents. | |
899 | * @xas: XArray operation state. | |
900 | * @mark: Mark number. | |
901 | * | |
902 | * Clears the specified mark on this entry, and walks back to the head | |
903 | * attempting to clear it on all the ancestor entries. Does nothing if | |
904 | * @xas has not been walked to an entry, or is in an error state. | |
905 | */ | |
906 | void xas_clear_mark(const struct xa_state *xas, xa_mark_t mark) | |
907 | { | |
908 | struct xa_node *node = xas->xa_node; | |
909 | unsigned int offset = xas->xa_offset; | |
910 | ||
911 | if (xas_invalid(xas)) | |
912 | return; | |
913 | ||
914 | while (node) { | |
915 | if (!node_clear_mark(node, offset, mark)) | |
916 | return; | |
917 | if (node_any_mark(node, mark)) | |
918 | return; | |
919 | ||
920 | offset = node->offset; | |
921 | node = xa_parent_locked(xas->xa, node); | |
922 | } | |
923 | ||
924 | if (xa_marked(xas->xa, mark)) | |
925 | xa_mark_clear(xas->xa, mark); | |
926 | } | |
927 | EXPORT_SYMBOL_GPL(xas_clear_mark); | |
928 | ||
58d6ea30 MW |
929 | /** |
930 | * xas_init_marks() - Initialise all marks for the entry | |
931 | * @xas: Array operations state. | |
932 | * | |
933 | * Initialise all marks for the entry specified by @xas. If we're tracking | |
934 | * free entries with a mark, we need to set it on all entries. All other | |
935 | * marks are cleared. | |
936 | * | |
937 | * This implementation is not as efficient as it could be; we may walk | |
938 | * up the tree multiple times. | |
939 | */ | |
940 | void xas_init_marks(const struct xa_state *xas) | |
941 | { | |
942 | xa_mark_t mark = 0; | |
943 | ||
944 | for (;;) { | |
371c752d MW |
945 | if (xa_track_free(xas->xa) && mark == XA_FREE_MARK) |
946 | xas_set_mark(xas, mark); | |
947 | else | |
948 | xas_clear_mark(xas, mark); | |
58d6ea30 MW |
949 | if (mark == XA_MARK_MAX) |
950 | break; | |
951 | mark_inc(mark); | |
952 | } | |
953 | } | |
954 | EXPORT_SYMBOL_GPL(xas_init_marks); | |
955 | ||
8fc75643 MWO |
956 | #ifdef CONFIG_XARRAY_MULTI |
957 | static unsigned int node_get_marks(struct xa_node *node, unsigned int offset) | |
958 | { | |
959 | unsigned int marks = 0; | |
960 | xa_mark_t mark = XA_MARK_0; | |
961 | ||
962 | for (;;) { | |
963 | if (node_get_mark(node, offset, mark)) | |
964 | marks |= 1 << (__force unsigned int)mark; | |
965 | if (mark == XA_MARK_MAX) | |
966 | break; | |
967 | mark_inc(mark); | |
968 | } | |
969 | ||
970 | return marks; | |
971 | } | |
972 | ||
2a0774c2 MWO |
973 | static inline void node_mark_slots(struct xa_node *node, unsigned int sibs, |
974 | xa_mark_t mark) | |
975 | { | |
976 | int i; | |
977 | ||
978 | if (sibs == 0) | |
979 | node_mark_all(node, mark); | |
980 | else { | |
981 | for (i = 0; i < XA_CHUNK_SIZE; i += sibs + 1) | |
982 | node_set_mark(node, i, mark); | |
983 | } | |
984 | } | |
985 | ||
8fc75643 | 986 | static void node_set_marks(struct xa_node *node, unsigned int offset, |
2a0774c2 MWO |
987 | struct xa_node *child, unsigned int sibs, |
988 | unsigned int marks) | |
8fc75643 MWO |
989 | { |
990 | xa_mark_t mark = XA_MARK_0; | |
991 | ||
992 | for (;;) { | |
993 | if (marks & (1 << (__force unsigned int)mark)) { | |
994 | node_set_mark(node, offset, mark); | |
995 | if (child) | |
2a0774c2 | 996 | node_mark_slots(child, sibs, mark); |
8fc75643 MWO |
997 | } |
998 | if (mark == XA_MARK_MAX) | |
999 | break; | |
1000 | mark_inc(mark); | |
1001 | } | |
1002 | } | |
1003 | ||
1004 | /** | |
1005 | * xas_split_alloc() - Allocate memory for splitting an entry. | |
1006 | * @xas: XArray operation state. | |
1007 | * @entry: New entry which will be stored in the array. | |
12efebab | 1008 | * @order: Current entry order. |
8fc75643 MWO |
1009 | * @gfp: Memory allocation flags. |
1010 | * | |
1011 | * This function should be called before calling xas_split(). | |
1012 | * If necessary, it will allocate new nodes (and fill them with @entry) | |
1013 | * to prepare for the upcoming split of an entry of @order size into | |
1014 | * entries of the order stored in the @xas. | |
1015 | * | |
1016 | * Context: May sleep if @gfp flags permit. | |
1017 | */ | |
1018 | void xas_split_alloc(struct xa_state *xas, void *entry, unsigned int order, | |
1019 | gfp_t gfp) | |
1020 | { | |
1021 | unsigned int sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1; | |
1022 | unsigned int mask = xas->xa_sibs; | |
1023 | ||
1024 | /* XXX: no support for splitting really large entries yet */ | |
1025 | if (WARN_ON(xas->xa_shift + 2 * XA_CHUNK_SHIFT < order)) | |
1026 | goto nomem; | |
1027 | if (xas->xa_shift + XA_CHUNK_SHIFT > order) | |
1028 | return; | |
1029 | ||
1030 | do { | |
1031 | unsigned int i; | |
3012110d | 1032 | void *sibling = NULL; |
8fc75643 MWO |
1033 | struct xa_node *node; |
1034 | ||
9bbdc0f3 | 1035 | node = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp); |
8fc75643 MWO |
1036 | if (!node) |
1037 | goto nomem; | |
1038 | node->array = xas->xa; | |
1039 | for (i = 0; i < XA_CHUNK_SIZE; i++) { | |
1040 | if ((i & mask) == 0) { | |
1041 | RCU_INIT_POINTER(node->slots[i], entry); | |
3012110d | 1042 | sibling = xa_mk_sibling(i); |
8fc75643 MWO |
1043 | } else { |
1044 | RCU_INIT_POINTER(node->slots[i], sibling); | |
1045 | } | |
1046 | } | |
1047 | RCU_INIT_POINTER(node->parent, xas->xa_alloc); | |
1048 | xas->xa_alloc = node; | |
1049 | } while (sibs-- > 0); | |
1050 | ||
1051 | return; | |
1052 | nomem: | |
1053 | xas_destroy(xas); | |
1054 | xas_set_err(xas, -ENOMEM); | |
1055 | } | |
1056 | EXPORT_SYMBOL_GPL(xas_split_alloc); | |
1057 | ||
1058 | /** | |
1059 | * xas_split() - Split a multi-index entry into smaller entries. | |
1060 | * @xas: XArray operation state. | |
1061 | * @entry: New entry to store in the array. | |
12efebab | 1062 | * @order: Current entry order. |
8fc75643 | 1063 | * |
12efebab MWO |
1064 | * The size of the new entries is set in @xas. The value in @entry is |
1065 | * copied to all the replacement entries. | |
8fc75643 MWO |
1066 | * |
1067 | * Context: Any context. The caller should hold the xa_lock. | |
1068 | */ | |
1069 | void xas_split(struct xa_state *xas, void *entry, unsigned int order) | |
1070 | { | |
1071 | unsigned int sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1; | |
1072 | unsigned int offset, marks; | |
1073 | struct xa_node *node; | |
1074 | void *curr = xas_load(xas); | |
1075 | int values = 0; | |
1076 | ||
1077 | node = xas->xa_node; | |
1078 | if (xas_top(node)) | |
1079 | return; | |
1080 | ||
1081 | marks = node_get_marks(node, xas->xa_offset); | |
1082 | ||
1083 | offset = xas->xa_offset + sibs; | |
1084 | do { | |
1085 | if (xas->xa_shift < node->shift) { | |
1086 | struct xa_node *child = xas->xa_alloc; | |
1087 | ||
1088 | xas->xa_alloc = rcu_dereference_raw(child->parent); | |
1089 | child->shift = node->shift - XA_CHUNK_SHIFT; | |
1090 | child->offset = offset; | |
1091 | child->count = XA_CHUNK_SIZE; | |
1092 | child->nr_values = xa_is_value(entry) ? | |
1093 | XA_CHUNK_SIZE : 0; | |
1094 | RCU_INIT_POINTER(child->parent, node); | |
2a0774c2 MWO |
1095 | node_set_marks(node, offset, child, xas->xa_sibs, |
1096 | marks); | |
8fc75643 MWO |
1097 | rcu_assign_pointer(node->slots[offset], |
1098 | xa_mk_node(child)); | |
1099 | if (xa_is_value(curr)) | |
1100 | values--; | |
3ed4bb77 | 1101 | xas_update(xas, child); |
8fc75643 MWO |
1102 | } else { |
1103 | unsigned int canon = offset - xas->xa_sibs; | |
1104 | ||
2a0774c2 | 1105 | node_set_marks(node, canon, NULL, 0, marks); |
8fc75643 MWO |
1106 | rcu_assign_pointer(node->slots[canon], entry); |
1107 | while (offset > canon) | |
1108 | rcu_assign_pointer(node->slots[offset--], | |
1109 | xa_mk_sibling(canon)); | |
1110 | values += (xa_is_value(entry) - xa_is_value(curr)) * | |
1111 | (xas->xa_sibs + 1); | |
1112 | } | |
1113 | } while (offset-- > xas->xa_offset); | |
1114 | ||
1115 | node->nr_values += values; | |
3ed4bb77 | 1116 | xas_update(xas, node); |
8fc75643 MWO |
1117 | } |
1118 | EXPORT_SYMBOL_GPL(xas_split); | |
1119 | #endif | |
1120 | ||
b803b428 MW |
1121 | /** |
1122 | * xas_pause() - Pause a walk to drop a lock. | |
1123 | * @xas: XArray operation state. | |
1124 | * | |
1125 | * Some users need to pause a walk and drop the lock they're holding in | |
1126 | * order to yield to a higher priority thread or carry out an operation | |
1127 | * on an entry. Those users should call this function before they drop | |
1128 | * the lock. It resets the @xas to be suitable for the next iteration | |
1129 | * of the loop after the user has reacquired the lock. If most entries | |
1130 | * found during a walk require you to call xas_pause(), the xa_for_each() | |
1131 | * iterator may be more appropriate. | |
1132 | * | |
1133 | * Note that xas_pause() only works for forward iteration. If a user needs | |
1134 | * to pause a reverse iteration, we will need a xas_pause_rev(). | |
1135 | */ | |
1136 | void xas_pause(struct xa_state *xas) | |
1137 | { | |
1138 | struct xa_node *node = xas->xa_node; | |
1139 | ||
1140 | if (xas_invalid(xas)) | |
1141 | return; | |
1142 | ||
82a22311 | 1143 | xas->xa_node = XAS_RESTART; |
b803b428 | 1144 | if (node) { |
c36d451a | 1145 | unsigned long offset = xas->xa_offset; |
b803b428 MW |
1146 | while (++offset < XA_CHUNK_SIZE) { |
1147 | if (!xa_is_sibling(xa_entry(xas->xa, node, offset))) | |
1148 | break; | |
1149 | } | |
1150 | xas->xa_index += (offset - xas->xa_offset) << node->shift; | |
82a22311 MWO |
1151 | if (xas->xa_index == 0) |
1152 | xas->xa_node = XAS_BOUNDS; | |
b803b428 MW |
1153 | } else { |
1154 | xas->xa_index++; | |
1155 | } | |
b803b428 MW |
1156 | } |
1157 | EXPORT_SYMBOL_GPL(xas_pause); | |
1158 | ||
64d3e9a9 MW |
1159 | /* |
1160 | * __xas_prev() - Find the previous entry in the XArray. | |
1161 | * @xas: XArray operation state. | |
1162 | * | |
1163 | * Helper function for xas_prev() which handles all the complex cases | |
1164 | * out of line. | |
1165 | */ | |
1166 | void *__xas_prev(struct xa_state *xas) | |
1167 | { | |
1168 | void *entry; | |
1169 | ||
1170 | if (!xas_frozen(xas->xa_node)) | |
1171 | xas->xa_index--; | |
91abab83 MWO |
1172 | if (!xas->xa_node) |
1173 | return set_bounds(xas); | |
64d3e9a9 MW |
1174 | if (xas_not_node(xas->xa_node)) |
1175 | return xas_load(xas); | |
1176 | ||
1177 | if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node)) | |
1178 | xas->xa_offset--; | |
1179 | ||
1180 | while (xas->xa_offset == 255) { | |
1181 | xas->xa_offset = xas->xa_node->offset - 1; | |
1182 | xas->xa_node = xa_parent(xas->xa, xas->xa_node); | |
1183 | if (!xas->xa_node) | |
1184 | return set_bounds(xas); | |
1185 | } | |
1186 | ||
1187 | for (;;) { | |
1188 | entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset); | |
1189 | if (!xa_is_node(entry)) | |
1190 | return entry; | |
1191 | ||
1192 | xas->xa_node = xa_to_node(entry); | |
1193 | xas_set_offset(xas); | |
1194 | } | |
1195 | } | |
1196 | EXPORT_SYMBOL_GPL(__xas_prev); | |
1197 | ||
1198 | /* | |
1199 | * __xas_next() - Find the next entry in the XArray. | |
1200 | * @xas: XArray operation state. | |
1201 | * | |
1202 | * Helper function for xas_next() which handles all the complex cases | |
1203 | * out of line. | |
1204 | */ | |
1205 | void *__xas_next(struct xa_state *xas) | |
1206 | { | |
1207 | void *entry; | |
1208 | ||
1209 | if (!xas_frozen(xas->xa_node)) | |
1210 | xas->xa_index++; | |
91abab83 MWO |
1211 | if (!xas->xa_node) |
1212 | return set_bounds(xas); | |
64d3e9a9 MW |
1213 | if (xas_not_node(xas->xa_node)) |
1214 | return xas_load(xas); | |
1215 | ||
1216 | if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node)) | |
1217 | xas->xa_offset++; | |
1218 | ||
1219 | while (xas->xa_offset == XA_CHUNK_SIZE) { | |
1220 | xas->xa_offset = xas->xa_node->offset + 1; | |
1221 | xas->xa_node = xa_parent(xas->xa, xas->xa_node); | |
1222 | if (!xas->xa_node) | |
1223 | return set_bounds(xas); | |
1224 | } | |
1225 | ||
1226 | for (;;) { | |
1227 | entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset); | |
1228 | if (!xa_is_node(entry)) | |
1229 | return entry; | |
1230 | ||
1231 | xas->xa_node = xa_to_node(entry); | |
1232 | xas_set_offset(xas); | |
1233 | } | |
1234 | } | |
1235 | EXPORT_SYMBOL_GPL(__xas_next); | |
1236 | ||
b803b428 MW |
1237 | /** |
1238 | * xas_find() - Find the next present entry in the XArray. | |
1239 | * @xas: XArray operation state. | |
1240 | * @max: Highest index to return. | |
1241 | * | |
1242 | * If the @xas has not yet been walked to an entry, return the entry | |
1243 | * which has an index >= xas.xa_index. If it has been walked, the entry | |
1244 | * currently being pointed at has been processed, and so we move to the | |
1245 | * next entry. | |
1246 | * | |
1247 | * If no entry is found and the array is smaller than @max, the iterator | |
1248 | * is set to the smallest index not yet in the array. This allows @xas | |
1249 | * to be immediately passed to xas_store(). | |
1250 | * | |
1251 | * Return: The entry, if found, otherwise %NULL. | |
1252 | */ | |
1253 | void *xas_find(struct xa_state *xas, unsigned long max) | |
1254 | { | |
1255 | void *entry; | |
1256 | ||
82a22311 | 1257 | if (xas_error(xas) || xas->xa_node == XAS_BOUNDS) |
b803b428 | 1258 | return NULL; |
c44aa5e8 MWO |
1259 | if (xas->xa_index > max) |
1260 | return set_bounds(xas); | |
b803b428 MW |
1261 | |
1262 | if (!xas->xa_node) { | |
1263 | xas->xa_index = 1; | |
1264 | return set_bounds(xas); | |
82a22311 | 1265 | } else if (xas->xa_node == XAS_RESTART) { |
b803b428 MW |
1266 | entry = xas_load(xas); |
1267 | if (entry || xas_not_node(xas->xa_node)) | |
1268 | return entry; | |
1269 | } else if (!xas->xa_node->shift && | |
1270 | xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)) { | |
1271 | xas->xa_offset = ((xas->xa_index - 1) & XA_CHUNK_MASK) + 1; | |
1272 | } | |
1273 | ||
25a8de7f | 1274 | xas_next_offset(xas); |
b803b428 MW |
1275 | |
1276 | while (xas->xa_node && (xas->xa_index <= max)) { | |
1277 | if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) { | |
1278 | xas->xa_offset = xas->xa_node->offset + 1; | |
1279 | xas->xa_node = xa_parent(xas->xa, xas->xa_node); | |
1280 | continue; | |
1281 | } | |
1282 | ||
1283 | entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset); | |
1284 | if (xa_is_node(entry)) { | |
1285 | xas->xa_node = xa_to_node(entry); | |
1286 | xas->xa_offset = 0; | |
1287 | continue; | |
1288 | } | |
1289 | if (entry && !xa_is_sibling(entry)) | |
1290 | return entry; | |
1291 | ||
25a8de7f | 1292 | xas_next_offset(xas); |
b803b428 MW |
1293 | } |
1294 | ||
1295 | if (!xas->xa_node) | |
1296 | xas->xa_node = XAS_BOUNDS; | |
1297 | return NULL; | |
1298 | } | |
1299 | EXPORT_SYMBOL_GPL(xas_find); | |
1300 | ||
1301 | /** | |
1302 | * xas_find_marked() - Find the next marked entry in the XArray. | |
1303 | * @xas: XArray operation state. | |
1304 | * @max: Highest index to return. | |
1305 | * @mark: Mark number to search for. | |
1306 | * | |
1307 | * If the @xas has not yet been walked to an entry, return the marked entry | |
1308 | * which has an index >= xas.xa_index. If it has been walked, the entry | |
1309 | * currently being pointed at has been processed, and so we return the | |
1310 | * first marked entry with an index > xas.xa_index. | |
1311 | * | |
1312 | * If no marked entry is found and the array is smaller than @max, @xas is | |
1313 | * set to the bounds state and xas->xa_index is set to the smallest index | |
1314 | * not yet in the array. This allows @xas to be immediately passed to | |
1315 | * xas_store(). | |
1316 | * | |
1317 | * If no entry is found before @max is reached, @xas is set to the restart | |
1318 | * state. | |
1319 | * | |
1320 | * Return: The entry, if found, otherwise %NULL. | |
1321 | */ | |
1322 | void *xas_find_marked(struct xa_state *xas, unsigned long max, xa_mark_t mark) | |
1323 | { | |
1324 | bool advance = true; | |
1325 | unsigned int offset; | |
1326 | void *entry; | |
1327 | ||
1328 | if (xas_error(xas)) | |
1329 | return NULL; | |
c44aa5e8 MWO |
1330 | if (xas->xa_index > max) |
1331 | goto max; | |
b803b428 MW |
1332 | |
1333 | if (!xas->xa_node) { | |
1334 | xas->xa_index = 1; | |
1335 | goto out; | |
1336 | } else if (xas_top(xas->xa_node)) { | |
1337 | advance = false; | |
1338 | entry = xa_head(xas->xa); | |
1339 | xas->xa_node = NULL; | |
1340 | if (xas->xa_index > max_index(entry)) | |
48483614 | 1341 | goto out; |
b803b428 MW |
1342 | if (!xa_is_node(entry)) { |
1343 | if (xa_marked(xas->xa, mark)) | |
1344 | return entry; | |
1345 | xas->xa_index = 1; | |
1346 | goto out; | |
1347 | } | |
1348 | xas->xa_node = xa_to_node(entry); | |
1349 | xas->xa_offset = xas->xa_index >> xas->xa_node->shift; | |
1350 | } | |
1351 | ||
1352 | while (xas->xa_index <= max) { | |
1353 | if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) { | |
1354 | xas->xa_offset = xas->xa_node->offset + 1; | |
1355 | xas->xa_node = xa_parent(xas->xa, xas->xa_node); | |
1356 | if (!xas->xa_node) | |
1357 | break; | |
1358 | advance = false; | |
1359 | continue; | |
1360 | } | |
1361 | ||
1362 | if (!advance) { | |
1363 | entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset); | |
1364 | if (xa_is_sibling(entry)) { | |
1365 | xas->xa_offset = xa_to_sibling(entry); | |
1366 | xas_move_index(xas, xas->xa_offset); | |
1367 | } | |
1368 | } | |
1369 | ||
1370 | offset = xas_find_chunk(xas, advance, mark); | |
1371 | if (offset > xas->xa_offset) { | |
1372 | advance = false; | |
1373 | xas_move_index(xas, offset); | |
1374 | /* Mind the wrap */ | |
1375 | if ((xas->xa_index - 1) >= max) | |
1376 | goto max; | |
1377 | xas->xa_offset = offset; | |
1378 | if (offset == XA_CHUNK_SIZE) | |
1379 | continue; | |
1380 | } | |
1381 | ||
1382 | entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset); | |
7e934cf5 MWO |
1383 | if (!entry && !(xa_track_free(xas->xa) && mark == XA_FREE_MARK)) |
1384 | continue; | |
b803b428 MW |
1385 | if (!xa_is_node(entry)) |
1386 | return entry; | |
1387 | xas->xa_node = xa_to_node(entry); | |
1388 | xas_set_offset(xas); | |
1389 | } | |
1390 | ||
1391 | out: | |
48483614 | 1392 | if (xas->xa_index > max) |
b803b428 | 1393 | goto max; |
48483614 | 1394 | return set_bounds(xas); |
b803b428 MW |
1395 | max: |
1396 | xas->xa_node = XAS_RESTART; | |
1397 | return NULL; | |
1398 | } | |
1399 | EXPORT_SYMBOL_GPL(xas_find_marked); | |
1400 | ||
4e99d4e9 MW |
1401 | /** |
1402 | * xas_find_conflict() - Find the next present entry in a range. | |
1403 | * @xas: XArray operation state. | |
1404 | * | |
1405 | * The @xas describes both a range and a position within that range. | |
1406 | * | |
1407 | * Context: Any context. Expects xa_lock to be held. | |
1408 | * Return: The next entry in the range covered by @xas or %NULL. | |
1409 | */ | |
1410 | void *xas_find_conflict(struct xa_state *xas) | |
1411 | { | |
1412 | void *curr; | |
1413 | ||
1414 | if (xas_error(xas)) | |
1415 | return NULL; | |
1416 | ||
1417 | if (!xas->xa_node) | |
1418 | return NULL; | |
1419 | ||
1420 | if (xas_top(xas->xa_node)) { | |
1421 | curr = xas_start(xas); | |
1422 | if (!curr) | |
1423 | return NULL; | |
1424 | while (xa_is_node(curr)) { | |
1425 | struct xa_node *node = xa_to_node(curr); | |
1426 | curr = xas_descend(xas, node); | |
1427 | } | |
1428 | if (curr) | |
1429 | return curr; | |
1430 | } | |
1431 | ||
1432 | if (xas->xa_node->shift > xas->xa_shift) | |
1433 | return NULL; | |
1434 | ||
1435 | for (;;) { | |
1436 | if (xas->xa_node->shift == xas->xa_shift) { | |
1437 | if ((xas->xa_offset & xas->xa_sibs) == xas->xa_sibs) | |
1438 | break; | |
1439 | } else if (xas->xa_offset == XA_CHUNK_MASK) { | |
1440 | xas->xa_offset = xas->xa_node->offset; | |
1441 | xas->xa_node = xa_parent_locked(xas->xa, xas->xa_node); | |
1442 | if (!xas->xa_node) | |
1443 | break; | |
1444 | continue; | |
1445 | } | |
1446 | curr = xa_entry_locked(xas->xa, xas->xa_node, ++xas->xa_offset); | |
1447 | if (xa_is_sibling(curr)) | |
1448 | continue; | |
1449 | while (xa_is_node(curr)) { | |
1450 | xas->xa_node = xa_to_node(curr); | |
1451 | xas->xa_offset = 0; | |
1452 | curr = xa_entry_locked(xas->xa, xas->xa_node, 0); | |
1453 | } | |
1454 | if (curr) | |
1455 | return curr; | |
1456 | } | |
1457 | xas->xa_offset -= xas->xa_sibs; | |
1458 | return NULL; | |
1459 | } | |
1460 | EXPORT_SYMBOL_GPL(xas_find_conflict); | |
1461 | ||
ad3d6c72 MW |
1462 | /** |
1463 | * xa_load() - Load an entry from an XArray. | |
1464 | * @xa: XArray. | |
1465 | * @index: index into array. | |
1466 | * | |
1467 | * Context: Any context. Takes and releases the RCU lock. | |
1468 | * Return: The entry at @index in @xa. | |
1469 | */ | |
1470 | void *xa_load(struct xarray *xa, unsigned long index) | |
1471 | { | |
1472 | XA_STATE(xas, xa, index); | |
1473 | void *entry; | |
1474 | ||
1475 | rcu_read_lock(); | |
1476 | do { | |
1477 | entry = xas_load(&xas); | |
9f14d4f1 MW |
1478 | if (xa_is_zero(entry)) |
1479 | entry = NULL; | |
ad3d6c72 MW |
1480 | } while (xas_retry(&xas, entry)); |
1481 | rcu_read_unlock(); | |
1482 | ||
1483 | return entry; | |
1484 | } | |
1485 | EXPORT_SYMBOL(xa_load); | |
1486 | ||
58d6ea30 MW |
1487 | static void *xas_result(struct xa_state *xas, void *curr) |
1488 | { | |
9f14d4f1 MW |
1489 | if (xa_is_zero(curr)) |
1490 | return NULL; | |
58d6ea30 MW |
1491 | if (xas_error(xas)) |
1492 | curr = xas->xa_node; | |
1493 | return curr; | |
1494 | } | |
1495 | ||
1496 | /** | |
1497 | * __xa_erase() - Erase this entry from the XArray while locked. | |
1498 | * @xa: XArray. | |
1499 | * @index: Index into array. | |
1500 | * | |
809ab937 MW |
1501 | * After this function returns, loading from @index will return %NULL. |
1502 | * If the index is part of a multi-index entry, all indices will be erased | |
1503 | * and none of the entries will be part of a multi-index entry. | |
58d6ea30 | 1504 | * |
809ab937 MW |
1505 | * Context: Any context. Expects xa_lock to be held on entry. |
1506 | * Return: The entry which used to be at this index. | |
58d6ea30 MW |
1507 | */ |
1508 | void *__xa_erase(struct xarray *xa, unsigned long index) | |
1509 | { | |
1510 | XA_STATE(xas, xa, index); | |
1511 | return xas_result(&xas, xas_store(&xas, NULL)); | |
1512 | } | |
9ee5a3b7 | 1513 | EXPORT_SYMBOL(__xa_erase); |
58d6ea30 | 1514 | |
9c16bb88 MW |
1515 | /** |
1516 | * xa_erase() - Erase this entry from the XArray. | |
1517 | * @xa: XArray. | |
1518 | * @index: Index of entry. | |
1519 | * | |
809ab937 MW |
1520 | * After this function returns, loading from @index will return %NULL. |
1521 | * If the index is part of a multi-index entry, all indices will be erased | |
1522 | * and none of the entries will be part of a multi-index entry. | |
9c16bb88 MW |
1523 | * |
1524 | * Context: Any context. Takes and releases the xa_lock. | |
1525 | * Return: The entry which used to be at this index. | |
1526 | */ | |
1527 | void *xa_erase(struct xarray *xa, unsigned long index) | |
1528 | { | |
1529 | void *entry; | |
1530 | ||
1531 | xa_lock(xa); | |
1532 | entry = __xa_erase(xa, index); | |
1533 | xa_unlock(xa); | |
1534 | ||
1535 | return entry; | |
1536 | } | |
1537 | EXPORT_SYMBOL(xa_erase); | |
1538 | ||
58d6ea30 | 1539 | /** |
611f3186 | 1540 | * __xa_store() - Store this entry in the XArray. |
58d6ea30 MW |
1541 | * @xa: XArray. |
1542 | * @index: Index into array. | |
1543 | * @entry: New entry. | |
1544 | * @gfp: Memory allocation flags. | |
1545 | * | |
611f3186 MW |
1546 | * You must already be holding the xa_lock when calling this function. |
1547 | * It will drop the lock if needed to allocate memory, and then reacquire | |
1548 | * it afterwards. | |
58d6ea30 | 1549 | * |
611f3186 MW |
1550 | * Context: Any context. Expects xa_lock to be held on entry. May |
1551 | * release and reacquire xa_lock if @gfp flags permit. | |
1552 | * Return: The old entry at this index or xa_err() if an error happened. | |
58d6ea30 | 1553 | */ |
611f3186 | 1554 | void *__xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp) |
58d6ea30 MW |
1555 | { |
1556 | XA_STATE(xas, xa, index); | |
1557 | void *curr; | |
1558 | ||
76b4e529 | 1559 | if (WARN_ON_ONCE(xa_is_advanced(entry))) |
58d6ea30 | 1560 | return XA_ERROR(-EINVAL); |
d9c48043 MW |
1561 | if (xa_track_free(xa) && !entry) |
1562 | entry = XA_ZERO_ENTRY; | |
58d6ea30 MW |
1563 | |
1564 | do { | |
58d6ea30 | 1565 | curr = xas_store(&xas, entry); |
d9c48043 | 1566 | if (xa_track_free(xa)) |
371c752d | 1567 | xas_clear_mark(&xas, XA_FREE_MARK); |
611f3186 | 1568 | } while (__xas_nomem(&xas, gfp)); |
58d6ea30 MW |
1569 | |
1570 | return xas_result(&xas, curr); | |
1571 | } | |
611f3186 | 1572 | EXPORT_SYMBOL(__xa_store); |
58d6ea30 MW |
1573 | |
1574 | /** | |
611f3186 | 1575 | * xa_store() - Store this entry in the XArray. |
58d6ea30 MW |
1576 | * @xa: XArray. |
1577 | * @index: Index into array. | |
1578 | * @entry: New entry. | |
1579 | * @gfp: Memory allocation flags. | |
1580 | * | |
611f3186 | 1581 | * After this function returns, loads from this index will return @entry. |
8fc75643 | 1582 | * Storing into an existing multi-index entry updates the entry of every index. |
611f3186 | 1583 | * The marks associated with @index are unaffected unless @entry is %NULL. |
58d6ea30 | 1584 | * |
611f3186 MW |
1585 | * Context: Any context. Takes and releases the xa_lock. |
1586 | * May sleep if the @gfp flags permit. | |
1587 | * Return: The old entry at this index on success, xa_err(-EINVAL) if @entry | |
1588 | * cannot be stored in an XArray, or xa_err(-ENOMEM) if memory allocation | |
1589 | * failed. | |
58d6ea30 | 1590 | */ |
611f3186 | 1591 | void *xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp) |
58d6ea30 | 1592 | { |
58d6ea30 MW |
1593 | void *curr; |
1594 | ||
611f3186 MW |
1595 | xa_lock(xa); |
1596 | curr = __xa_store(xa, index, entry, gfp); | |
1597 | xa_unlock(xa); | |
58d6ea30 | 1598 | |
611f3186 | 1599 | return curr; |
58d6ea30 | 1600 | } |
611f3186 | 1601 | EXPORT_SYMBOL(xa_store); |
58d6ea30 | 1602 | |
41aec91f MW |
1603 | /** |
1604 | * __xa_cmpxchg() - Store this entry in the XArray. | |
1605 | * @xa: XArray. | |
1606 | * @index: Index into array. | |
1607 | * @old: Old value to test against. | |
1608 | * @entry: New entry. | |
1609 | * @gfp: Memory allocation flags. | |
1610 | * | |
1611 | * You must already be holding the xa_lock when calling this function. | |
1612 | * It will drop the lock if needed to allocate memory, and then reacquire | |
1613 | * it afterwards. | |
1614 | * | |
1615 | * Context: Any context. Expects xa_lock to be held on entry. May | |
1616 | * release and reacquire xa_lock if @gfp flags permit. | |
1617 | * Return: The old entry at this index or xa_err() if an error happened. | |
1618 | */ | |
1619 | void *__xa_cmpxchg(struct xarray *xa, unsigned long index, | |
1620 | void *old, void *entry, gfp_t gfp) | |
1621 | { | |
1622 | XA_STATE(xas, xa, index); | |
1623 | void *curr; | |
1624 | ||
76b4e529 | 1625 | if (WARN_ON_ONCE(xa_is_advanced(entry))) |
41aec91f MW |
1626 | return XA_ERROR(-EINVAL); |
1627 | ||
1628 | do { | |
1629 | curr = xas_load(&xas); | |
371c752d | 1630 | if (curr == old) { |
41aec91f | 1631 | xas_store(&xas, entry); |
b38f6c50 | 1632 | if (xa_track_free(xa) && entry && !curr) |
371c752d MW |
1633 | xas_clear_mark(&xas, XA_FREE_MARK); |
1634 | } | |
41aec91f MW |
1635 | } while (__xas_nomem(&xas, gfp)); |
1636 | ||
1637 | return xas_result(&xas, curr); | |
1638 | } | |
1639 | EXPORT_SYMBOL(__xa_cmpxchg); | |
1640 | ||
b0606fed MW |
1641 | /** |
1642 | * __xa_insert() - Store this entry in the XArray if no entry is present. | |
1643 | * @xa: XArray. | |
1644 | * @index: Index into array. | |
1645 | * @entry: New entry. | |
1646 | * @gfp: Memory allocation flags. | |
1647 | * | |
1648 | * Inserting a NULL entry will store a reserved entry (like xa_reserve()) | |
1649 | * if no entry is present. Inserting will fail if a reserved entry is | |
1650 | * present, even though loading from this index will return NULL. | |
1651 | * | |
1652 | * Context: Any context. Expects xa_lock to be held on entry. May | |
1653 | * release and reacquire xa_lock if @gfp flags permit. | |
fd9dc93e | 1654 | * Return: 0 if the store succeeded. -EBUSY if another entry was present. |
b0606fed MW |
1655 | * -ENOMEM if memory could not be allocated. |
1656 | */ | |
1657 | int __xa_insert(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp) | |
1658 | { | |
1659 | XA_STATE(xas, xa, index); | |
1660 | void *curr; | |
1661 | ||
1662 | if (WARN_ON_ONCE(xa_is_advanced(entry))) | |
1663 | return -EINVAL; | |
1664 | if (!entry) | |
1665 | entry = XA_ZERO_ENTRY; | |
1666 | ||
1667 | do { | |
1668 | curr = xas_load(&xas); | |
1669 | if (!curr) { | |
1670 | xas_store(&xas, entry); | |
1671 | if (xa_track_free(xa)) | |
1672 | xas_clear_mark(&xas, XA_FREE_MARK); | |
1673 | } else { | |
fd9dc93e | 1674 | xas_set_err(&xas, -EBUSY); |
b0606fed MW |
1675 | } |
1676 | } while (__xas_nomem(&xas, gfp)); | |
1677 | ||
1678 | return xas_error(&xas); | |
1679 | } | |
1680 | EXPORT_SYMBOL(__xa_insert); | |
1681 | ||
0e9446c3 MW |
1682 | #ifdef CONFIG_XARRAY_MULTI |
1683 | static void xas_set_range(struct xa_state *xas, unsigned long first, | |
1684 | unsigned long last) | |
1685 | { | |
1686 | unsigned int shift = 0; | |
1687 | unsigned long sibs = last - first; | |
1688 | unsigned int offset = XA_CHUNK_MASK; | |
1689 | ||
1690 | xas_set(xas, first); | |
1691 | ||
1692 | while ((first & XA_CHUNK_MASK) == 0) { | |
1693 | if (sibs < XA_CHUNK_MASK) | |
1694 | break; | |
1695 | if ((sibs == XA_CHUNK_MASK) && (offset < XA_CHUNK_MASK)) | |
1696 | break; | |
1697 | shift += XA_CHUNK_SHIFT; | |
1698 | if (offset == XA_CHUNK_MASK) | |
1699 | offset = sibs & XA_CHUNK_MASK; | |
1700 | sibs >>= XA_CHUNK_SHIFT; | |
1701 | first >>= XA_CHUNK_SHIFT; | |
1702 | } | |
1703 | ||
1704 | offset = first & XA_CHUNK_MASK; | |
1705 | if (offset + sibs > XA_CHUNK_MASK) | |
1706 | sibs = XA_CHUNK_MASK - offset; | |
1707 | if ((((first + sibs + 1) << shift) - 1) > last) | |
1708 | sibs -= 1; | |
1709 | ||
1710 | xas->xa_shift = shift; | |
1711 | xas->xa_sibs = sibs; | |
1712 | } | |
1713 | ||
1714 | /** | |
1715 | * xa_store_range() - Store this entry at a range of indices in the XArray. | |
1716 | * @xa: XArray. | |
1717 | * @first: First index to affect. | |
1718 | * @last: Last index to affect. | |
1719 | * @entry: New entry. | |
1720 | * @gfp: Memory allocation flags. | |
1721 | * | |
1722 | * After this function returns, loads from any index between @first and @last, | |
1723 | * inclusive will return @entry. | |
8fc75643 | 1724 | * Storing into an existing multi-index entry updates the entry of every index. |
0e9446c3 MW |
1725 | * The marks associated with @index are unaffected unless @entry is %NULL. |
1726 | * | |
1727 | * Context: Process context. Takes and releases the xa_lock. May sleep | |
1728 | * if the @gfp flags permit. | |
1729 | * Return: %NULL on success, xa_err(-EINVAL) if @entry cannot be stored in | |
1730 | * an XArray, or xa_err(-ENOMEM) if memory allocation failed. | |
1731 | */ | |
1732 | void *xa_store_range(struct xarray *xa, unsigned long first, | |
1733 | unsigned long last, void *entry, gfp_t gfp) | |
1734 | { | |
1735 | XA_STATE(xas, xa, 0); | |
1736 | ||
1737 | if (WARN_ON_ONCE(xa_is_internal(entry))) | |
1738 | return XA_ERROR(-EINVAL); | |
1739 | if (last < first) | |
1740 | return XA_ERROR(-EINVAL); | |
1741 | ||
1742 | do { | |
1743 | xas_lock(&xas); | |
1744 | if (entry) { | |
44a4a66b MW |
1745 | unsigned int order = BITS_PER_LONG; |
1746 | if (last + 1) | |
1747 | order = __ffs(last + 1); | |
0e9446c3 | 1748 | xas_set_order(&xas, last, order); |
76b4e529 | 1749 | xas_create(&xas, true); |
0e9446c3 MW |
1750 | if (xas_error(&xas)) |
1751 | goto unlock; | |
1752 | } | |
1753 | do { | |
1754 | xas_set_range(&xas, first, last); | |
1755 | xas_store(&xas, entry); | |
1756 | if (xas_error(&xas)) | |
1757 | goto unlock; | |
1758 | first += xas_size(&xas); | |
1759 | } while (first <= last); | |
1760 | unlock: | |
1761 | xas_unlock(&xas); | |
1762 | } while (xas_nomem(&xas, gfp)); | |
1763 | ||
1764 | return xas_result(&xas, NULL); | |
1765 | } | |
1766 | EXPORT_SYMBOL(xa_store_range); | |
57417ceb MWO |
1767 | |
1768 | /** | |
a4864671 KS |
1769 | * xas_get_order() - Get the order of an entry. |
1770 | * @xas: XArray operation state. | |
1771 | * | |
1772 | * Called after xas_load, the xas should not be in an error state. | |
57417ceb MWO |
1773 | * |
1774 | * Return: A number between 0 and 63 indicating the order of the entry. | |
1775 | */ | |
a4864671 | 1776 | int xas_get_order(struct xa_state *xas) |
57417ceb | 1777 | { |
57417ceb MWO |
1778 | int order = 0; |
1779 | ||
a4864671 KS |
1780 | if (!xas->xa_node) |
1781 | return 0; | |
57417ceb MWO |
1782 | |
1783 | for (;;) { | |
a4864671 | 1784 | unsigned int slot = xas->xa_offset + (1 << order); |
57417ceb MWO |
1785 | |
1786 | if (slot >= XA_CHUNK_SIZE) | |
1787 | break; | |
a4864671 | 1788 | if (!xa_is_sibling(xa_entry(xas->xa, xas->xa_node, slot))) |
57417ceb MWO |
1789 | break; |
1790 | order++; | |
1791 | } | |
1792 | ||
a4864671 KS |
1793 | order += xas->xa_node->shift; |
1794 | return order; | |
1795 | } | |
1796 | EXPORT_SYMBOL_GPL(xas_get_order); | |
1797 | ||
1798 | /** | |
1799 | * xa_get_order() - Get the order of an entry. | |
1800 | * @xa: XArray. | |
1801 | * @index: Index of the entry. | |
1802 | * | |
1803 | * Return: A number between 0 and 63 indicating the order of the entry. | |
1804 | */ | |
1805 | int xa_get_order(struct xarray *xa, unsigned long index) | |
1806 | { | |
1807 | XA_STATE(xas, xa, index); | |
1808 | int order = 0; | |
1809 | void *entry; | |
1810 | ||
1811 | rcu_read_lock(); | |
1812 | entry = xas_load(&xas); | |
1813 | if (entry) | |
1814 | order = xas_get_order(&xas); | |
57417ceb MWO |
1815 | rcu_read_unlock(); |
1816 | ||
1817 | return order; | |
1818 | } | |
1819 | EXPORT_SYMBOL(xa_get_order); | |
0e9446c3 MW |
1820 | #endif /* CONFIG_XARRAY_MULTI */ |
1821 | ||
371c752d MW |
1822 | /** |
1823 | * __xa_alloc() - Find somewhere to store this entry in the XArray. | |
1824 | * @xa: XArray. | |
1825 | * @id: Pointer to ID. | |
a3e4d3f9 | 1826 | * @limit: Range for allocated ID. |
371c752d MW |
1827 | * @entry: New entry. |
1828 | * @gfp: Memory allocation flags. | |
1829 | * | |
a3e4d3f9 MW |
1830 | * Finds an empty entry in @xa between @limit.min and @limit.max, |
1831 | * stores the index into the @id pointer, then stores the entry at | |
1832 | * that index. A concurrent lookup will not see an uninitialised @id. | |
371c752d | 1833 | * |
e7716c74 PS |
1834 | * Must only be operated on an xarray initialized with flag XA_FLAGS_ALLOC set |
1835 | * in xa_init_flags(). | |
1836 | * | |
371c752d MW |
1837 | * Context: Any context. Expects xa_lock to be held on entry. May |
1838 | * release and reacquire xa_lock if @gfp flags permit. | |
a3e4d3f9 MW |
1839 | * Return: 0 on success, -ENOMEM if memory could not be allocated or |
1840 | * -EBUSY if there are no free entries in @limit. | |
371c752d | 1841 | */ |
a3e4d3f9 MW |
1842 | int __xa_alloc(struct xarray *xa, u32 *id, void *entry, |
1843 | struct xa_limit limit, gfp_t gfp) | |
371c752d MW |
1844 | { |
1845 | XA_STATE(xas, xa, 0); | |
371c752d | 1846 | |
76b4e529 | 1847 | if (WARN_ON_ONCE(xa_is_advanced(entry))) |
371c752d MW |
1848 | return -EINVAL; |
1849 | if (WARN_ON_ONCE(!xa_track_free(xa))) | |
1850 | return -EINVAL; | |
1851 | ||
1852 | if (!entry) | |
1853 | entry = XA_ZERO_ENTRY; | |
1854 | ||
1855 | do { | |
a3e4d3f9 MW |
1856 | xas.xa_index = limit.min; |
1857 | xas_find_marked(&xas, limit.max, XA_FREE_MARK); | |
371c752d | 1858 | if (xas.xa_node == XAS_RESTART) |
a3e4d3f9 MW |
1859 | xas_set_err(&xas, -EBUSY); |
1860 | else | |
1861 | *id = xas.xa_index; | |
371c752d MW |
1862 | xas_store(&xas, entry); |
1863 | xas_clear_mark(&xas, XA_FREE_MARK); | |
1864 | } while (__xas_nomem(&xas, gfp)); | |
1865 | ||
a3e4d3f9 | 1866 | return xas_error(&xas); |
371c752d MW |
1867 | } |
1868 | EXPORT_SYMBOL(__xa_alloc); | |
1869 | ||
2fa044e5 MW |
1870 | /** |
1871 | * __xa_alloc_cyclic() - Find somewhere to store this entry in the XArray. | |
1872 | * @xa: XArray. | |
1873 | * @id: Pointer to ID. | |
1874 | * @entry: New entry. | |
1875 | * @limit: Range of allocated ID. | |
1876 | * @next: Pointer to next ID to allocate. | |
1877 | * @gfp: Memory allocation flags. | |
1878 | * | |
1879 | * Finds an empty entry in @xa between @limit.min and @limit.max, | |
1880 | * stores the index into the @id pointer, then stores the entry at | |
1881 | * that index. A concurrent lookup will not see an uninitialised @id. | |
1882 | * The search for an empty entry will start at @next and will wrap | |
1883 | * around if necessary. | |
1884 | * | |
e7716c74 PS |
1885 | * Must only be operated on an xarray initialized with flag XA_FLAGS_ALLOC set |
1886 | * in xa_init_flags(). | |
1887 | * | |
2fa044e5 MW |
1888 | * Context: Any context. Expects xa_lock to be held on entry. May |
1889 | * release and reacquire xa_lock if @gfp flags permit. | |
1890 | * Return: 0 if the allocation succeeded without wrapping. 1 if the | |
1891 | * allocation succeeded after wrapping, -ENOMEM if memory could not be | |
1892 | * allocated or -EBUSY if there are no free entries in @limit. | |
1893 | */ | |
1894 | int __xa_alloc_cyclic(struct xarray *xa, u32 *id, void *entry, | |
1895 | struct xa_limit limit, u32 *next, gfp_t gfp) | |
1896 | { | |
1897 | u32 min = limit.min; | |
1898 | int ret; | |
1899 | ||
1900 | limit.min = max(min, *next); | |
1901 | ret = __xa_alloc(xa, id, entry, limit, gfp); | |
1902 | if ((xa->xa_flags & XA_FLAGS_ALLOC_WRAPPED) && ret == 0) { | |
1903 | xa->xa_flags &= ~XA_FLAGS_ALLOC_WRAPPED; | |
1904 | ret = 1; | |
1905 | } | |
1906 | ||
1907 | if (ret < 0 && limit.min > min) { | |
1908 | limit.min = min; | |
1909 | ret = __xa_alloc(xa, id, entry, limit, gfp); | |
1910 | if (ret == 0) | |
1911 | ret = 1; | |
1912 | } | |
1913 | ||
1914 | if (ret >= 0) { | |
1915 | *next = *id + 1; | |
1916 | if (*next == 0) | |
1917 | xa->xa_flags |= XA_FLAGS_ALLOC_WRAPPED; | |
1918 | } | |
1919 | return ret; | |
1920 | } | |
1921 | EXPORT_SYMBOL(__xa_alloc_cyclic); | |
1922 | ||
9b89a035 MW |
1923 | /** |
1924 | * __xa_set_mark() - Set this mark on this entry while locked. | |
1925 | * @xa: XArray. | |
1926 | * @index: Index of entry. | |
1927 | * @mark: Mark number. | |
1928 | * | |
804dfaf0 | 1929 | * Attempting to set a mark on a %NULL entry does not succeed. |
9b89a035 MW |
1930 | * |
1931 | * Context: Any context. Expects xa_lock to be held on entry. | |
1932 | */ | |
1933 | void __xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark) | |
1934 | { | |
1935 | XA_STATE(xas, xa, index); | |
1936 | void *entry = xas_load(&xas); | |
1937 | ||
1938 | if (entry) | |
1939 | xas_set_mark(&xas, mark); | |
1940 | } | |
9ee5a3b7 | 1941 | EXPORT_SYMBOL(__xa_set_mark); |
9b89a035 MW |
1942 | |
1943 | /** | |
1944 | * __xa_clear_mark() - Clear this mark on this entry while locked. | |
1945 | * @xa: XArray. | |
1946 | * @index: Index of entry. | |
1947 | * @mark: Mark number. | |
1948 | * | |
1949 | * Context: Any context. Expects xa_lock to be held on entry. | |
1950 | */ | |
1951 | void __xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark) | |
1952 | { | |
1953 | XA_STATE(xas, xa, index); | |
1954 | void *entry = xas_load(&xas); | |
1955 | ||
1956 | if (entry) | |
1957 | xas_clear_mark(&xas, mark); | |
1958 | } | |
9ee5a3b7 | 1959 | EXPORT_SYMBOL(__xa_clear_mark); |
9b89a035 MW |
1960 | |
1961 | /** | |
1962 | * xa_get_mark() - Inquire whether this mark is set on this entry. | |
1963 | * @xa: XArray. | |
1964 | * @index: Index of entry. | |
1965 | * @mark: Mark number. | |
1966 | * | |
1967 | * This function uses the RCU read lock, so the result may be out of date | |
1968 | * by the time it returns. If you need the result to be stable, use a lock. | |
1969 | * | |
1970 | * Context: Any context. Takes and releases the RCU lock. | |
1971 | * Return: True if the entry at @index has this mark set, false if it doesn't. | |
1972 | */ | |
1973 | bool xa_get_mark(struct xarray *xa, unsigned long index, xa_mark_t mark) | |
1974 | { | |
1975 | XA_STATE(xas, xa, index); | |
1976 | void *entry; | |
1977 | ||
1978 | rcu_read_lock(); | |
1979 | entry = xas_start(&xas); | |
1980 | while (xas_get_mark(&xas, mark)) { | |
1981 | if (!xa_is_node(entry)) | |
1982 | goto found; | |
1983 | entry = xas_descend(&xas, xa_to_node(entry)); | |
1984 | } | |
1985 | rcu_read_unlock(); | |
1986 | return false; | |
1987 | found: | |
1988 | rcu_read_unlock(); | |
1989 | return true; | |
1990 | } | |
1991 | EXPORT_SYMBOL(xa_get_mark); | |
1992 | ||
1993 | /** | |
1994 | * xa_set_mark() - Set this mark on this entry. | |
1995 | * @xa: XArray. | |
1996 | * @index: Index of entry. | |
1997 | * @mark: Mark number. | |
1998 | * | |
804dfaf0 | 1999 | * Attempting to set a mark on a %NULL entry does not succeed. |
9b89a035 MW |
2000 | * |
2001 | * Context: Process context. Takes and releases the xa_lock. | |
2002 | */ | |
2003 | void xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark) | |
2004 | { | |
2005 | xa_lock(xa); | |
2006 | __xa_set_mark(xa, index, mark); | |
2007 | xa_unlock(xa); | |
2008 | } | |
2009 | EXPORT_SYMBOL(xa_set_mark); | |
2010 | ||
2011 | /** | |
2012 | * xa_clear_mark() - Clear this mark on this entry. | |
2013 | * @xa: XArray. | |
2014 | * @index: Index of entry. | |
2015 | * @mark: Mark number. | |
2016 | * | |
2017 | * Clearing a mark always succeeds. | |
2018 | * | |
2019 | * Context: Process context. Takes and releases the xa_lock. | |
2020 | */ | |
2021 | void xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark) | |
2022 | { | |
2023 | xa_lock(xa); | |
2024 | __xa_clear_mark(xa, index, mark); | |
2025 | xa_unlock(xa); | |
2026 | } | |
2027 | EXPORT_SYMBOL(xa_clear_mark); | |
2028 | ||
b803b428 MW |
2029 | /** |
2030 | * xa_find() - Search the XArray for an entry. | |
2031 | * @xa: XArray. | |
2032 | * @indexp: Pointer to an index. | |
2033 | * @max: Maximum index to search to. | |
2034 | * @filter: Selection criterion. | |
2035 | * | |
2036 | * Finds the entry in @xa which matches the @filter, and has the lowest | |
2037 | * index that is at least @indexp and no more than @max. | |
2038 | * If an entry is found, @indexp is updated to be the index of the entry. | |
2039 | * This function is protected by the RCU read lock, so it may not find | |
2040 | * entries which are being simultaneously added. It will not return an | |
2041 | * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find(). | |
2042 | * | |
2043 | * Context: Any context. Takes and releases the RCU lock. | |
2044 | * Return: The entry, if found, otherwise %NULL. | |
2045 | */ | |
2046 | void *xa_find(struct xarray *xa, unsigned long *indexp, | |
2047 | unsigned long max, xa_mark_t filter) | |
2048 | { | |
2049 | XA_STATE(xas, xa, *indexp); | |
2050 | void *entry; | |
2051 | ||
2052 | rcu_read_lock(); | |
2053 | do { | |
2054 | if ((__force unsigned int)filter < XA_MAX_MARKS) | |
2055 | entry = xas_find_marked(&xas, max, filter); | |
2056 | else | |
2057 | entry = xas_find(&xas, max); | |
2058 | } while (xas_retry(&xas, entry)); | |
2059 | rcu_read_unlock(); | |
2060 | ||
2061 | if (entry) | |
2062 | *indexp = xas.xa_index; | |
2063 | return entry; | |
2064 | } | |
2065 | EXPORT_SYMBOL(xa_find); | |
2066 | ||
19c30f4d MWO |
2067 | static bool xas_sibling(struct xa_state *xas) |
2068 | { | |
2069 | struct xa_node *node = xas->xa_node; | |
2070 | unsigned long mask; | |
2071 | ||
d8e93e3f | 2072 | if (!IS_ENABLED(CONFIG_XARRAY_MULTI) || !node) |
19c30f4d MWO |
2073 | return false; |
2074 | mask = (XA_CHUNK_SIZE << node->shift) - 1; | |
bd40b17c MWO |
2075 | return (xas->xa_index & mask) > |
2076 | ((unsigned long)xas->xa_offset << node->shift); | |
19c30f4d MWO |
2077 | } |
2078 | ||
b803b428 MW |
2079 | /** |
2080 | * xa_find_after() - Search the XArray for a present entry. | |
2081 | * @xa: XArray. | |
2082 | * @indexp: Pointer to an index. | |
2083 | * @max: Maximum index to search to. | |
2084 | * @filter: Selection criterion. | |
2085 | * | |
2086 | * Finds the entry in @xa which matches the @filter and has the lowest | |
2087 | * index that is above @indexp and no more than @max. | |
2088 | * If an entry is found, @indexp is updated to be the index of the entry. | |
2089 | * This function is protected by the RCU read lock, so it may miss entries | |
2090 | * which are being simultaneously added. It will not return an | |
2091 | * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find(). | |
2092 | * | |
2093 | * Context: Any context. Takes and releases the RCU lock. | |
2094 | * Return: The pointer, if found, otherwise %NULL. | |
2095 | */ | |
2096 | void *xa_find_after(struct xarray *xa, unsigned long *indexp, | |
2097 | unsigned long max, xa_mark_t filter) | |
2098 | { | |
2099 | XA_STATE(xas, xa, *indexp + 1); | |
2100 | void *entry; | |
2101 | ||
430f24f9 MWO |
2102 | if (xas.xa_index == 0) |
2103 | return NULL; | |
2104 | ||
b803b428 MW |
2105 | rcu_read_lock(); |
2106 | for (;;) { | |
2107 | if ((__force unsigned int)filter < XA_MAX_MARKS) | |
2108 | entry = xas_find_marked(&xas, max, filter); | |
2109 | else | |
2110 | entry = xas_find(&xas, max); | |
c44aa5e8 MWO |
2111 | |
2112 | if (xas_invalid(&xas)) | |
8229706e | 2113 | break; |
19c30f4d MWO |
2114 | if (xas_sibling(&xas)) |
2115 | continue; | |
b803b428 MW |
2116 | if (!xas_retry(&xas, entry)) |
2117 | break; | |
2118 | } | |
2119 | rcu_read_unlock(); | |
2120 | ||
2121 | if (entry) | |
2122 | *indexp = xas.xa_index; | |
2123 | return entry; | |
2124 | } | |
2125 | EXPORT_SYMBOL(xa_find_after); | |
2126 | ||
80a0a1a9 MW |
2127 | static unsigned int xas_extract_present(struct xa_state *xas, void **dst, |
2128 | unsigned long max, unsigned int n) | |
2129 | { | |
2130 | void *entry; | |
2131 | unsigned int i = 0; | |
2132 | ||
2133 | rcu_read_lock(); | |
2134 | xas_for_each(xas, entry, max) { | |
2135 | if (xas_retry(xas, entry)) | |
2136 | continue; | |
2137 | dst[i++] = entry; | |
2138 | if (i == n) | |
2139 | break; | |
2140 | } | |
2141 | rcu_read_unlock(); | |
2142 | ||
2143 | return i; | |
2144 | } | |
2145 | ||
2146 | static unsigned int xas_extract_marked(struct xa_state *xas, void **dst, | |
2147 | unsigned long max, unsigned int n, xa_mark_t mark) | |
2148 | { | |
2149 | void *entry; | |
2150 | unsigned int i = 0; | |
2151 | ||
2152 | rcu_read_lock(); | |
2153 | xas_for_each_marked(xas, entry, max, mark) { | |
2154 | if (xas_retry(xas, entry)) | |
2155 | continue; | |
2156 | dst[i++] = entry; | |
2157 | if (i == n) | |
2158 | break; | |
2159 | } | |
2160 | rcu_read_unlock(); | |
2161 | ||
2162 | return i; | |
2163 | } | |
2164 | ||
2165 | /** | |
2166 | * xa_extract() - Copy selected entries from the XArray into a normal array. | |
2167 | * @xa: The source XArray to copy from. | |
2168 | * @dst: The buffer to copy entries into. | |
2169 | * @start: The first index in the XArray eligible to be selected. | |
2170 | * @max: The last index in the XArray eligible to be selected. | |
2171 | * @n: The maximum number of entries to copy. | |
2172 | * @filter: Selection criterion. | |
2173 | * | |
2174 | * Copies up to @n entries that match @filter from the XArray. The | |
2175 | * copied entries will have indices between @start and @max, inclusive. | |
2176 | * | |
2177 | * The @filter may be an XArray mark value, in which case entries which are | |
2178 | * marked with that mark will be copied. It may also be %XA_PRESENT, in | |
804dfaf0 | 2179 | * which case all entries which are not %NULL will be copied. |
80a0a1a9 MW |
2180 | * |
2181 | * The entries returned may not represent a snapshot of the XArray at a | |
2182 | * moment in time. For example, if another thread stores to index 5, then | |
2183 | * index 10, calling xa_extract() may return the old contents of index 5 | |
2184 | * and the new contents of index 10. Indices not modified while this | |
2185 | * function is running will not be skipped. | |
2186 | * | |
2187 | * If you need stronger guarantees, holding the xa_lock across calls to this | |
2188 | * function will prevent concurrent modification. | |
2189 | * | |
2190 | * Context: Any context. Takes and releases the RCU lock. | |
2191 | * Return: The number of entries copied. | |
2192 | */ | |
2193 | unsigned int xa_extract(struct xarray *xa, void **dst, unsigned long start, | |
2194 | unsigned long max, unsigned int n, xa_mark_t filter) | |
2195 | { | |
2196 | XA_STATE(xas, xa, start); | |
2197 | ||
2198 | if (!n) | |
2199 | return 0; | |
2200 | ||
2201 | if ((__force unsigned int)filter < XA_MAX_MARKS) | |
2202 | return xas_extract_marked(&xas, dst, max, n, filter); | |
2203 | return xas_extract_present(&xas, dst, max, n); | |
2204 | } | |
2205 | EXPORT_SYMBOL(xa_extract); | |
2206 | ||
f82cd2f0 MWO |
2207 | /** |
2208 | * xa_delete_node() - Private interface for workingset code. | |
2209 | * @node: Node to be removed from the tree. | |
2210 | * @update: Function to call to update ancestor nodes. | |
2211 | * | |
2212 | * Context: xa_lock must be held on entry and will not be released. | |
2213 | */ | |
2214 | void xa_delete_node(struct xa_node *node, xa_update_node_t update) | |
2215 | { | |
2216 | struct xa_state xas = { | |
2217 | .xa = node->array, | |
2218 | .xa_index = (unsigned long)node->offset << | |
2219 | (node->shift + XA_CHUNK_SHIFT), | |
2220 | .xa_shift = node->shift + XA_CHUNK_SHIFT, | |
2221 | .xa_offset = node->offset, | |
2222 | .xa_node = xa_parent_locked(node->array, node), | |
2223 | .xa_update = update, | |
2224 | }; | |
2225 | ||
2226 | xas_store(&xas, NULL); | |
2227 | } | |
2228 | EXPORT_SYMBOL_GPL(xa_delete_node); /* For the benefit of the test suite */ | |
2229 | ||
687149fc MW |
2230 | /** |
2231 | * xa_destroy() - Free all internal data structures. | |
2232 | * @xa: XArray. | |
2233 | * | |
2234 | * After calling this function, the XArray is empty and has freed all memory | |
2235 | * allocated for its internal data structures. You are responsible for | |
2236 | * freeing the objects referenced by the XArray. | |
2237 | * | |
2238 | * Context: Any context. Takes and releases the xa_lock, interrupt-safe. | |
2239 | */ | |
2240 | void xa_destroy(struct xarray *xa) | |
2241 | { | |
2242 | XA_STATE(xas, xa, 0); | |
2243 | unsigned long flags; | |
2244 | void *entry; | |
2245 | ||
2246 | xas.xa_node = NULL; | |
2247 | xas_lock_irqsave(&xas, flags); | |
2248 | entry = xa_head_locked(xa); | |
2249 | RCU_INIT_POINTER(xa->xa_head, NULL); | |
2250 | xas_init_marks(&xas); | |
3ccaf57a MW |
2251 | if (xa_zero_busy(xa)) |
2252 | xa_mark_clear(xa, XA_FREE_MARK); | |
687149fc MW |
2253 | /* lockdep checks we're still holding the lock in xas_free_nodes() */ |
2254 | if (xa_is_node(entry)) | |
2255 | xas_free_nodes(&xas, xa_to_node(entry)); | |
2256 | xas_unlock_irqrestore(&xas, flags); | |
2257 | } | |
2258 | EXPORT_SYMBOL(xa_destroy); | |
2259 | ||
ad3d6c72 MW |
2260 | #ifdef XA_DEBUG |
2261 | void xa_dump_node(const struct xa_node *node) | |
2262 | { | |
2263 | unsigned i, j; | |
2264 | ||
2265 | if (!node) | |
2266 | return; | |
2267 | if ((unsigned long)node & 3) { | |
2268 | pr_cont("node %px\n", node); | |
2269 | return; | |
2270 | } | |
2271 | ||
2272 | pr_cont("node %px %s %d parent %px shift %d count %d values %d " | |
2273 | "array %px list %px %px marks", | |
2274 | node, node->parent ? "offset" : "max", node->offset, | |
2275 | node->parent, node->shift, node->count, node->nr_values, | |
2276 | node->array, node->private_list.prev, node->private_list.next); | |
2277 | for (i = 0; i < XA_MAX_MARKS; i++) | |
2278 | for (j = 0; j < XA_MARK_LONGS; j++) | |
2279 | pr_cont(" %lx", node->marks[i][j]); | |
2280 | pr_cont("\n"); | |
2281 | } | |
2282 | ||
2283 | void xa_dump_index(unsigned long index, unsigned int shift) | |
2284 | { | |
2285 | if (!shift) | |
2286 | pr_info("%lu: ", index); | |
2287 | else if (shift >= BITS_PER_LONG) | |
2288 | pr_info("0-%lu: ", ~0UL); | |
2289 | else | |
2290 | pr_info("%lu-%lu: ", index, index | ((1UL << shift) - 1)); | |
2291 | } | |
2292 | ||
2293 | void xa_dump_entry(const void *entry, unsigned long index, unsigned long shift) | |
2294 | { | |
2295 | if (!entry) | |
2296 | return; | |
2297 | ||
2298 | xa_dump_index(index, shift); | |
2299 | ||
2300 | if (xa_is_node(entry)) { | |
2301 | if (shift == 0) { | |
2302 | pr_cont("%px\n", entry); | |
2303 | } else { | |
2304 | unsigned long i; | |
2305 | struct xa_node *node = xa_to_node(entry); | |
2306 | xa_dump_node(node); | |
2307 | for (i = 0; i < XA_CHUNK_SIZE; i++) | |
2308 | xa_dump_entry(node->slots[i], | |
2309 | index + (i << node->shift), node->shift); | |
2310 | } | |
2311 | } else if (xa_is_value(entry)) | |
2312 | pr_cont("value %ld (0x%lx) [%px]\n", xa_to_value(entry), | |
2313 | xa_to_value(entry), entry); | |
2314 | else if (!xa_is_internal(entry)) | |
2315 | pr_cont("%px\n", entry); | |
2316 | else if (xa_is_retry(entry)) | |
2317 | pr_cont("retry (%ld)\n", xa_to_internal(entry)); | |
2318 | else if (xa_is_sibling(entry)) | |
2319 | pr_cont("sibling (slot %ld)\n", xa_to_sibling(entry)); | |
9f14d4f1 MW |
2320 | else if (xa_is_zero(entry)) |
2321 | pr_cont("zero (%ld)\n", xa_to_internal(entry)); | |
ad3d6c72 MW |
2322 | else |
2323 | pr_cont("UNKNOWN ENTRY (%px)\n", entry); | |
2324 | } | |
2325 | ||
2326 | void xa_dump(const struct xarray *xa) | |
2327 | { | |
2328 | void *entry = xa->xa_head; | |
2329 | unsigned int shift = 0; | |
2330 | ||
2331 | pr_info("xarray: %px head %px flags %x marks %d %d %d\n", xa, entry, | |
9b89a035 MW |
2332 | xa->xa_flags, xa_marked(xa, XA_MARK_0), |
2333 | xa_marked(xa, XA_MARK_1), xa_marked(xa, XA_MARK_2)); | |
ad3d6c72 MW |
2334 | if (xa_is_node(entry)) |
2335 | shift = xa_to_node(entry)->shift + XA_CHUNK_SHIFT; | |
2336 | xa_dump_entry(entry, 0, shift); | |
2337 | } | |
2338 | #endif |