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