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1 | /* | |
2 | * Copyright (C) 2001 Momchil Velikov | |
3 | * Portions Copyright (C) 2001 Christoph Hellwig | |
4 | * Copyright (C) 2005 SGI, Christoph Lameter | |
5 | * Copyright (C) 2006 Nick Piggin | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or | |
8 | * modify it under the terms of the GNU General Public License as | |
9 | * published by the Free Software Foundation; either version 2, or (at | |
10 | * your option) any later version. | |
11 | * | |
12 | * This program is distributed in the hope that it will be useful, but | |
13 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
15 | * General Public License for more details. | |
16 | * | |
17 | * You should have received a copy of the GNU General Public License | |
18 | * along with this program; if not, write to the Free Software | |
19 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
20 | */ | |
21 | ||
22 | #include <linux/errno.h> | |
23 | #include <linux/init.h> | |
24 | #include <linux/kernel.h> | |
25 | #include <linux/module.h> | |
26 | #include <linux/radix-tree.h> | |
27 | #include <linux/percpu.h> | |
28 | #include <linux/slab.h> | |
29 | #include <linux/notifier.h> | |
30 | #include <linux/cpu.h> | |
31 | #include <linux/string.h> | |
32 | #include <linux/bitops.h> | |
33 | #include <linux/rcupdate.h> | |
34 | ||
35 | ||
36 | #ifdef __KERNEL__ | |
37 | #define RADIX_TREE_MAP_SHIFT (CONFIG_BASE_SMALL ? 4 : 6) | |
38 | #else | |
39 | #define RADIX_TREE_MAP_SHIFT 3 /* For more stressful testing */ | |
40 | #endif | |
41 | ||
42 | #define RADIX_TREE_MAP_SIZE (1UL << RADIX_TREE_MAP_SHIFT) | |
43 | #define RADIX_TREE_MAP_MASK (RADIX_TREE_MAP_SIZE-1) | |
44 | ||
45 | #define RADIX_TREE_TAG_LONGS \ | |
46 | ((RADIX_TREE_MAP_SIZE + BITS_PER_LONG - 1) / BITS_PER_LONG) | |
47 | ||
48 | struct radix_tree_node { | |
49 | unsigned int height; /* Height from the bottom */ | |
50 | unsigned int count; | |
51 | struct rcu_head rcu_head; | |
52 | void *slots[RADIX_TREE_MAP_SIZE]; | |
53 | unsigned long tags[RADIX_TREE_MAX_TAGS][RADIX_TREE_TAG_LONGS]; | |
54 | }; | |
55 | ||
56 | struct radix_tree_path { | |
57 | struct radix_tree_node *node; | |
58 | int offset; | |
59 | }; | |
60 | ||
61 | #define RADIX_TREE_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(unsigned long)) | |
62 | #define RADIX_TREE_MAX_PATH (DIV_ROUND_UP(RADIX_TREE_INDEX_BITS, \ | |
63 | RADIX_TREE_MAP_SHIFT)) | |
64 | ||
65 | /* | |
66 | * The height_to_maxindex array needs to be one deeper than the maximum | |
67 | * path as height 0 holds only 1 entry. | |
68 | */ | |
69 | static unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH + 1] __read_mostly; | |
70 | ||
71 | /* | |
72 | * Radix tree node cache. | |
73 | */ | |
74 | static struct kmem_cache *radix_tree_node_cachep; | |
75 | ||
76 | /* | |
77 | * Per-cpu pool of preloaded nodes | |
78 | */ | |
79 | struct radix_tree_preload { | |
80 | int nr; | |
81 | struct radix_tree_node *nodes[RADIX_TREE_MAX_PATH]; | |
82 | }; | |
83 | static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, }; | |
84 | ||
85 | static inline gfp_t root_gfp_mask(struct radix_tree_root *root) | |
86 | { | |
87 | return root->gfp_mask & __GFP_BITS_MASK; | |
88 | } | |
89 | ||
90 | static inline void tag_set(struct radix_tree_node *node, unsigned int tag, | |
91 | int offset) | |
92 | { | |
93 | __set_bit(offset, node->tags[tag]); | |
94 | } | |
95 | ||
96 | static inline void tag_clear(struct radix_tree_node *node, unsigned int tag, | |
97 | int offset) | |
98 | { | |
99 | __clear_bit(offset, node->tags[tag]); | |
100 | } | |
101 | ||
102 | static inline int tag_get(struct radix_tree_node *node, unsigned int tag, | |
103 | int offset) | |
104 | { | |
105 | return test_bit(offset, node->tags[tag]); | |
106 | } | |
107 | ||
108 | static inline void root_tag_set(struct radix_tree_root *root, unsigned int tag) | |
109 | { | |
110 | root->gfp_mask |= (__force gfp_t)(1 << (tag + __GFP_BITS_SHIFT)); | |
111 | } | |
112 | ||
113 | static inline void root_tag_clear(struct radix_tree_root *root, unsigned int tag) | |
114 | { | |
115 | root->gfp_mask &= (__force gfp_t)~(1 << (tag + __GFP_BITS_SHIFT)); | |
116 | } | |
117 | ||
118 | static inline void root_tag_clear_all(struct radix_tree_root *root) | |
119 | { | |
120 | root->gfp_mask &= __GFP_BITS_MASK; | |
121 | } | |
122 | ||
123 | static inline int root_tag_get(struct radix_tree_root *root, unsigned int tag) | |
124 | { | |
125 | return (__force unsigned)root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT)); | |
126 | } | |
127 | ||
128 | /* | |
129 | * Returns 1 if any slot in the node has this tag set. | |
130 | * Otherwise returns 0. | |
131 | */ | |
132 | static inline int any_tag_set(struct radix_tree_node *node, unsigned int tag) | |
133 | { | |
134 | int idx; | |
135 | for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) { | |
136 | if (node->tags[tag][idx]) | |
137 | return 1; | |
138 | } | |
139 | return 0; | |
140 | } | |
141 | /* | |
142 | * This assumes that the caller has performed appropriate preallocation, and | |
143 | * that the caller has pinned this thread of control to the current CPU. | |
144 | */ | |
145 | static struct radix_tree_node * | |
146 | radix_tree_node_alloc(struct radix_tree_root *root) | |
147 | { | |
148 | struct radix_tree_node *ret = NULL; | |
149 | gfp_t gfp_mask = root_gfp_mask(root); | |
150 | ||
151 | if (!(gfp_mask & __GFP_WAIT)) { | |
152 | struct radix_tree_preload *rtp; | |
153 | ||
154 | /* | |
155 | * Provided the caller has preloaded here, we will always | |
156 | * succeed in getting a node here (and never reach | |
157 | * kmem_cache_alloc) | |
158 | */ | |
159 | rtp = &__get_cpu_var(radix_tree_preloads); | |
160 | if (rtp->nr) { | |
161 | ret = rtp->nodes[rtp->nr - 1]; | |
162 | rtp->nodes[rtp->nr - 1] = NULL; | |
163 | rtp->nr--; | |
164 | } | |
165 | } | |
166 | if (ret == NULL) | |
167 | ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask); | |
168 | ||
169 | BUG_ON(radix_tree_is_indirect_ptr(ret)); | |
170 | return ret; | |
171 | } | |
172 | ||
173 | static void radix_tree_node_rcu_free(struct rcu_head *head) | |
174 | { | |
175 | struct radix_tree_node *node = | |
176 | container_of(head, struct radix_tree_node, rcu_head); | |
177 | int i; | |
178 | ||
179 | /* | |
180 | * must only free zeroed nodes into the slab. radix_tree_shrink | |
181 | * can leave us with a non-NULL entry in the first slot, so clear | |
182 | * that here to make sure. | |
183 | */ | |
184 | for (i = 0; i < RADIX_TREE_MAX_TAGS; i++) | |
185 | tag_clear(node, i, 0); | |
186 | ||
187 | node->slots[0] = NULL; | |
188 | node->count = 0; | |
189 | ||
190 | kmem_cache_free(radix_tree_node_cachep, node); | |
191 | } | |
192 | ||
193 | static inline void | |
194 | radix_tree_node_free(struct radix_tree_node *node) | |
195 | { | |
196 | call_rcu(&node->rcu_head, radix_tree_node_rcu_free); | |
197 | } | |
198 | ||
199 | /* | |
200 | * Load up this CPU's radix_tree_node buffer with sufficient objects to | |
201 | * ensure that the addition of a single element in the tree cannot fail. On | |
202 | * success, return zero, with preemption disabled. On error, return -ENOMEM | |
203 | * with preemption not disabled. | |
204 | * | |
205 | * To make use of this facility, the radix tree must be initialised without | |
206 | * __GFP_WAIT being passed to INIT_RADIX_TREE(). | |
207 | */ | |
208 | int radix_tree_preload(gfp_t gfp_mask) | |
209 | { | |
210 | struct radix_tree_preload *rtp; | |
211 | struct radix_tree_node *node; | |
212 | int ret = -ENOMEM; | |
213 | ||
214 | preempt_disable(); | |
215 | rtp = &__get_cpu_var(radix_tree_preloads); | |
216 | while (rtp->nr < ARRAY_SIZE(rtp->nodes)) { | |
217 | preempt_enable(); | |
218 | node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask); | |
219 | if (node == NULL) | |
220 | goto out; | |
221 | preempt_disable(); | |
222 | rtp = &__get_cpu_var(radix_tree_preloads); | |
223 | if (rtp->nr < ARRAY_SIZE(rtp->nodes)) | |
224 | rtp->nodes[rtp->nr++] = node; | |
225 | else | |
226 | kmem_cache_free(radix_tree_node_cachep, node); | |
227 | } | |
228 | ret = 0; | |
229 | out: | |
230 | return ret; | |
231 | } | |
232 | EXPORT_SYMBOL(radix_tree_preload); | |
233 | ||
234 | /* | |
235 | * Return the maximum key which can be store into a | |
236 | * radix tree with height HEIGHT. | |
237 | */ | |
238 | static inline unsigned long radix_tree_maxindex(unsigned int height) | |
239 | { | |
240 | return height_to_maxindex[height]; | |
241 | } | |
242 | ||
243 | /* | |
244 | * Extend a radix tree so it can store key @index. | |
245 | */ | |
246 | static int radix_tree_extend(struct radix_tree_root *root, unsigned long index) | |
247 | { | |
248 | struct radix_tree_node *node; | |
249 | unsigned int height; | |
250 | int tag; | |
251 | ||
252 | /* Figure out what the height should be. */ | |
253 | height = root->height + 1; | |
254 | while (index > radix_tree_maxindex(height)) | |
255 | height++; | |
256 | ||
257 | if (root->rnode == NULL) { | |
258 | root->height = height; | |
259 | goto out; | |
260 | } | |
261 | ||
262 | do { | |
263 | unsigned int newheight; | |
264 | if (!(node = radix_tree_node_alloc(root))) | |
265 | return -ENOMEM; | |
266 | ||
267 | /* Increase the height. */ | |
268 | node->slots[0] = radix_tree_indirect_to_ptr(root->rnode); | |
269 | ||
270 | /* Propagate the aggregated tag info into the new root */ | |
271 | for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) { | |
272 | if (root_tag_get(root, tag)) | |
273 | tag_set(node, tag, 0); | |
274 | } | |
275 | ||
276 | newheight = root->height+1; | |
277 | node->height = newheight; | |
278 | node->count = 1; | |
279 | node = radix_tree_ptr_to_indirect(node); | |
280 | rcu_assign_pointer(root->rnode, node); | |
281 | root->height = newheight; | |
282 | } while (height > root->height); | |
283 | out: | |
284 | return 0; | |
285 | } | |
286 | ||
287 | /** | |
288 | * radix_tree_insert - insert into a radix tree | |
289 | * @root: radix tree root | |
290 | * @index: index key | |
291 | * @item: item to insert | |
292 | * | |
293 | * Insert an item into the radix tree at position @index. | |
294 | */ | |
295 | int radix_tree_insert(struct radix_tree_root *root, | |
296 | unsigned long index, void *item) | |
297 | { | |
298 | struct radix_tree_node *node = NULL, *slot; | |
299 | unsigned int height, shift; | |
300 | int offset; | |
301 | int error; | |
302 | ||
303 | BUG_ON(radix_tree_is_indirect_ptr(item)); | |
304 | ||
305 | /* Make sure the tree is high enough. */ | |
306 | if (index > radix_tree_maxindex(root->height)) { | |
307 | error = radix_tree_extend(root, index); | |
308 | if (error) | |
309 | return error; | |
310 | } | |
311 | ||
312 | slot = radix_tree_indirect_to_ptr(root->rnode); | |
313 | ||
314 | height = root->height; | |
315 | shift = (height-1) * RADIX_TREE_MAP_SHIFT; | |
316 | ||
317 | offset = 0; /* uninitialised var warning */ | |
318 | while (height > 0) { | |
319 | if (slot == NULL) { | |
320 | /* Have to add a child node. */ | |
321 | if (!(slot = radix_tree_node_alloc(root))) | |
322 | return -ENOMEM; | |
323 | slot->height = height; | |
324 | if (node) { | |
325 | rcu_assign_pointer(node->slots[offset], slot); | |
326 | node->count++; | |
327 | } else | |
328 | rcu_assign_pointer(root->rnode, | |
329 | radix_tree_ptr_to_indirect(slot)); | |
330 | } | |
331 | ||
332 | /* Go a level down */ | |
333 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; | |
334 | node = slot; | |
335 | slot = node->slots[offset]; | |
336 | shift -= RADIX_TREE_MAP_SHIFT; | |
337 | height--; | |
338 | } | |
339 | ||
340 | if (slot != NULL) | |
341 | return -EEXIST; | |
342 | ||
343 | if (node) { | |
344 | node->count++; | |
345 | rcu_assign_pointer(node->slots[offset], item); | |
346 | BUG_ON(tag_get(node, 0, offset)); | |
347 | BUG_ON(tag_get(node, 1, offset)); | |
348 | } else { | |
349 | rcu_assign_pointer(root->rnode, item); | |
350 | BUG_ON(root_tag_get(root, 0)); | |
351 | BUG_ON(root_tag_get(root, 1)); | |
352 | } | |
353 | ||
354 | return 0; | |
355 | } | |
356 | EXPORT_SYMBOL(radix_tree_insert); | |
357 | ||
358 | /* | |
359 | * is_slot == 1 : search for the slot. | |
360 | * is_slot == 0 : search for the node. | |
361 | */ | |
362 | static void *radix_tree_lookup_element(struct radix_tree_root *root, | |
363 | unsigned long index, int is_slot) | |
364 | { | |
365 | unsigned int height, shift; | |
366 | struct radix_tree_node *node, **slot; | |
367 | ||
368 | node = rcu_dereference_raw(root->rnode); | |
369 | if (node == NULL) | |
370 | return NULL; | |
371 | ||
372 | if (!radix_tree_is_indirect_ptr(node)) { | |
373 | if (index > 0) | |
374 | return NULL; | |
375 | return is_slot ? (void *)&root->rnode : node; | |
376 | } | |
377 | node = radix_tree_indirect_to_ptr(node); | |
378 | ||
379 | height = node->height; | |
380 | if (index > radix_tree_maxindex(height)) | |
381 | return NULL; | |
382 | ||
383 | shift = (height-1) * RADIX_TREE_MAP_SHIFT; | |
384 | ||
385 | do { | |
386 | slot = (struct radix_tree_node **) | |
387 | (node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK)); | |
388 | node = rcu_dereference_raw(*slot); | |
389 | if (node == NULL) | |
390 | return NULL; | |
391 | ||
392 | shift -= RADIX_TREE_MAP_SHIFT; | |
393 | height--; | |
394 | } while (height > 0); | |
395 | ||
396 | return is_slot ? (void *)slot:node; | |
397 | } | |
398 | ||
399 | /** | |
400 | * radix_tree_lookup_slot - lookup a slot in a radix tree | |
401 | * @root: radix tree root | |
402 | * @index: index key | |
403 | * | |
404 | * Returns: the slot corresponding to the position @index in the | |
405 | * radix tree @root. This is useful for update-if-exists operations. | |
406 | * | |
407 | * This function can be called under rcu_read_lock iff the slot is not | |
408 | * modified by radix_tree_replace_slot, otherwise it must be called | |
409 | * exclusive from other writers. Any dereference of the slot must be done | |
410 | * using radix_tree_deref_slot. | |
411 | */ | |
412 | void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index) | |
413 | { | |
414 | return (void **)radix_tree_lookup_element(root, index, 1); | |
415 | } | |
416 | EXPORT_SYMBOL(radix_tree_lookup_slot); | |
417 | ||
418 | /** | |
419 | * radix_tree_lookup - perform lookup operation on a radix tree | |
420 | * @root: radix tree root | |
421 | * @index: index key | |
422 | * | |
423 | * Lookup the item at the position @index in the radix tree @root. | |
424 | * | |
425 | * This function can be called under rcu_read_lock, however the caller | |
426 | * must manage lifetimes of leaf nodes (eg. RCU may also be used to free | |
427 | * them safely). No RCU barriers are required to access or modify the | |
428 | * returned item, however. | |
429 | */ | |
430 | void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index) | |
431 | { | |
432 | return radix_tree_lookup_element(root, index, 0); | |
433 | } | |
434 | EXPORT_SYMBOL(radix_tree_lookup); | |
435 | ||
436 | /** | |
437 | * radix_tree_tag_set - set a tag on a radix tree node | |
438 | * @root: radix tree root | |
439 | * @index: index key | |
440 | * @tag: tag index | |
441 | * | |
442 | * Set the search tag (which must be < RADIX_TREE_MAX_TAGS) | |
443 | * corresponding to @index in the radix tree. From | |
444 | * the root all the way down to the leaf node. | |
445 | * | |
446 | * Returns the address of the tagged item. Setting a tag on a not-present | |
447 | * item is a bug. | |
448 | */ | |
449 | void *radix_tree_tag_set(struct radix_tree_root *root, | |
450 | unsigned long index, unsigned int tag) | |
451 | { | |
452 | unsigned int height, shift; | |
453 | struct radix_tree_node *slot; | |
454 | ||
455 | height = root->height; | |
456 | BUG_ON(index > radix_tree_maxindex(height)); | |
457 | ||
458 | slot = radix_tree_indirect_to_ptr(root->rnode); | |
459 | shift = (height - 1) * RADIX_TREE_MAP_SHIFT; | |
460 | ||
461 | while (height > 0) { | |
462 | int offset; | |
463 | ||
464 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; | |
465 | if (!tag_get(slot, tag, offset)) | |
466 | tag_set(slot, tag, offset); | |
467 | slot = slot->slots[offset]; | |
468 | BUG_ON(slot == NULL); | |
469 | shift -= RADIX_TREE_MAP_SHIFT; | |
470 | height--; | |
471 | } | |
472 | ||
473 | /* set the root's tag bit */ | |
474 | if (slot && !root_tag_get(root, tag)) | |
475 | root_tag_set(root, tag); | |
476 | ||
477 | return slot; | |
478 | } | |
479 | EXPORT_SYMBOL(radix_tree_tag_set); | |
480 | ||
481 | /** | |
482 | * radix_tree_tag_clear - clear a tag on a radix tree node | |
483 | * @root: radix tree root | |
484 | * @index: index key | |
485 | * @tag: tag index | |
486 | * | |
487 | * Clear the search tag (which must be < RADIX_TREE_MAX_TAGS) | |
488 | * corresponding to @index in the radix tree. If | |
489 | * this causes the leaf node to have no tags set then clear the tag in the | |
490 | * next-to-leaf node, etc. | |
491 | * | |
492 | * Returns the address of the tagged item on success, else NULL. ie: | |
493 | * has the same return value and semantics as radix_tree_lookup(). | |
494 | */ | |
495 | void *radix_tree_tag_clear(struct radix_tree_root *root, | |
496 | unsigned long index, unsigned int tag) | |
497 | { | |
498 | /* | |
499 | * The radix tree path needs to be one longer than the maximum path | |
500 | * since the "list" is null terminated. | |
501 | */ | |
502 | struct radix_tree_path path[RADIX_TREE_MAX_PATH + 1], *pathp = path; | |
503 | struct radix_tree_node *slot = NULL; | |
504 | unsigned int height, shift; | |
505 | ||
506 | height = root->height; | |
507 | if (index > radix_tree_maxindex(height)) | |
508 | goto out; | |
509 | ||
510 | shift = (height - 1) * RADIX_TREE_MAP_SHIFT; | |
511 | pathp->node = NULL; | |
512 | slot = radix_tree_indirect_to_ptr(root->rnode); | |
513 | ||
514 | while (height > 0) { | |
515 | int offset; | |
516 | ||
517 | if (slot == NULL) | |
518 | goto out; | |
519 | ||
520 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; | |
521 | pathp[1].offset = offset; | |
522 | pathp[1].node = slot; | |
523 | slot = slot->slots[offset]; | |
524 | pathp++; | |
525 | shift -= RADIX_TREE_MAP_SHIFT; | |
526 | height--; | |
527 | } | |
528 | ||
529 | if (slot == NULL) | |
530 | goto out; | |
531 | ||
532 | while (pathp->node) { | |
533 | if (!tag_get(pathp->node, tag, pathp->offset)) | |
534 | goto out; | |
535 | tag_clear(pathp->node, tag, pathp->offset); | |
536 | if (any_tag_set(pathp->node, tag)) | |
537 | goto out; | |
538 | pathp--; | |
539 | } | |
540 | ||
541 | /* clear the root's tag bit */ | |
542 | if (root_tag_get(root, tag)) | |
543 | root_tag_clear(root, tag); | |
544 | ||
545 | out: | |
546 | return slot; | |
547 | } | |
548 | EXPORT_SYMBOL(radix_tree_tag_clear); | |
549 | ||
550 | /** | |
551 | * radix_tree_tag_get - get a tag on a radix tree node | |
552 | * @root: radix tree root | |
553 | * @index: index key | |
554 | * @tag: tag index (< RADIX_TREE_MAX_TAGS) | |
555 | * | |
556 | * Return values: | |
557 | * | |
558 | * 0: tag not present or not set | |
559 | * 1: tag set | |
560 | * | |
561 | * Note that the return value of this function may not be relied on, even if | |
562 | * the RCU lock is held, unless tag modification and node deletion are excluded | |
563 | * from concurrency. | |
564 | */ | |
565 | int radix_tree_tag_get(struct radix_tree_root *root, | |
566 | unsigned long index, unsigned int tag) | |
567 | { | |
568 | unsigned int height, shift; | |
569 | struct radix_tree_node *node; | |
570 | int saw_unset_tag = 0; | |
571 | ||
572 | /* check the root's tag bit */ | |
573 | if (!root_tag_get(root, tag)) | |
574 | return 0; | |
575 | ||
576 | node = rcu_dereference_raw(root->rnode); | |
577 | if (node == NULL) | |
578 | return 0; | |
579 | ||
580 | if (!radix_tree_is_indirect_ptr(node)) | |
581 | return (index == 0); | |
582 | node = radix_tree_indirect_to_ptr(node); | |
583 | ||
584 | height = node->height; | |
585 | if (index > radix_tree_maxindex(height)) | |
586 | return 0; | |
587 | ||
588 | shift = (height - 1) * RADIX_TREE_MAP_SHIFT; | |
589 | ||
590 | for ( ; ; ) { | |
591 | int offset; | |
592 | ||
593 | if (node == NULL) | |
594 | return 0; | |
595 | ||
596 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; | |
597 | ||
598 | /* | |
599 | * This is just a debug check. Later, we can bale as soon as | |
600 | * we see an unset tag. | |
601 | */ | |
602 | if (!tag_get(node, tag, offset)) | |
603 | saw_unset_tag = 1; | |
604 | if (height == 1) | |
605 | return !!tag_get(node, tag, offset); | |
606 | node = rcu_dereference_raw(node->slots[offset]); | |
607 | shift -= RADIX_TREE_MAP_SHIFT; | |
608 | height--; | |
609 | } | |
610 | } | |
611 | EXPORT_SYMBOL(radix_tree_tag_get); | |
612 | ||
613 | /** | |
614 | * radix_tree_range_tag_if_tagged - for each item in given range set given | |
615 | * tag if item has another tag set | |
616 | * @root: radix tree root | |
617 | * @first_indexp: pointer to a starting index of a range to scan | |
618 | * @last_index: last index of a range to scan | |
619 | * @nr_to_tag: maximum number items to tag | |
620 | * @iftag: tag index to test | |
621 | * @settag: tag index to set if tested tag is set | |
622 | * | |
623 | * This function scans range of radix tree from first_index to last_index | |
624 | * (inclusive). For each item in the range if iftag is set, the function sets | |
625 | * also settag. The function stops either after tagging nr_to_tag items or | |
626 | * after reaching last_index. | |
627 | * | |
628 | * The tags must be set from the leaf level only and propagated back up the | |
629 | * path to the root. We must do this so that we resolve the full path before | |
630 | * setting any tags on intermediate nodes. If we set tags as we descend, then | |
631 | * we can get to the leaf node and find that the index that has the iftag | |
632 | * set is outside the range we are scanning. This reults in dangling tags and | |
633 | * can lead to problems with later tag operations (e.g. livelocks on lookups). | |
634 | * | |
635 | * The function returns number of leaves where the tag was set and sets | |
636 | * *first_indexp to the first unscanned index. | |
637 | * WARNING! *first_indexp can wrap if last_index is ULONG_MAX. Caller must | |
638 | * be prepared to handle that. | |
639 | */ | |
640 | unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root, | |
641 | unsigned long *first_indexp, unsigned long last_index, | |
642 | unsigned long nr_to_tag, | |
643 | unsigned int iftag, unsigned int settag) | |
644 | { | |
645 | unsigned int height = root->height; | |
646 | struct radix_tree_path path[height]; | |
647 | struct radix_tree_path *pathp = path; | |
648 | struct radix_tree_node *slot; | |
649 | unsigned int shift; | |
650 | unsigned long tagged = 0; | |
651 | unsigned long index = *first_indexp; | |
652 | ||
653 | last_index = min(last_index, radix_tree_maxindex(height)); | |
654 | if (index > last_index) | |
655 | return 0; | |
656 | if (!nr_to_tag) | |
657 | return 0; | |
658 | if (!root_tag_get(root, iftag)) { | |
659 | *first_indexp = last_index + 1; | |
660 | return 0; | |
661 | } | |
662 | if (height == 0) { | |
663 | *first_indexp = last_index + 1; | |
664 | root_tag_set(root, settag); | |
665 | return 1; | |
666 | } | |
667 | ||
668 | shift = (height - 1) * RADIX_TREE_MAP_SHIFT; | |
669 | slot = radix_tree_indirect_to_ptr(root->rnode); | |
670 | ||
671 | /* | |
672 | * we fill the path from (root->height - 2) to 0, leaving the index at | |
673 | * (root->height - 1) as a terminator. Zero the node in the terminator | |
674 | * so that we can use this to end walk loops back up the path. | |
675 | */ | |
676 | path[height - 1].node = NULL; | |
677 | ||
678 | for (;;) { | |
679 | int offset; | |
680 | ||
681 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; | |
682 | if (!slot->slots[offset]) | |
683 | goto next; | |
684 | if (!tag_get(slot, iftag, offset)) | |
685 | goto next; | |
686 | if (height > 1) { | |
687 | /* Go down one level */ | |
688 | height--; | |
689 | shift -= RADIX_TREE_MAP_SHIFT; | |
690 | path[height - 1].node = slot; | |
691 | path[height - 1].offset = offset; | |
692 | slot = slot->slots[offset]; | |
693 | continue; | |
694 | } | |
695 | ||
696 | /* tag the leaf */ | |
697 | tagged++; | |
698 | tag_set(slot, settag, offset); | |
699 | ||
700 | /* walk back up the path tagging interior nodes */ | |
701 | pathp = &path[0]; | |
702 | while (pathp->node) { | |
703 | /* stop if we find a node with the tag already set */ | |
704 | if (tag_get(pathp->node, settag, pathp->offset)) | |
705 | break; | |
706 | tag_set(pathp->node, settag, pathp->offset); | |
707 | pathp++; | |
708 | } | |
709 | ||
710 | next: | |
711 | /* Go to next item at level determined by 'shift' */ | |
712 | index = ((index >> shift) + 1) << shift; | |
713 | /* Overflow can happen when last_index is ~0UL... */ | |
714 | if (index > last_index || !index) | |
715 | break; | |
716 | if (tagged >= nr_to_tag) | |
717 | break; | |
718 | while (((index >> shift) & RADIX_TREE_MAP_MASK) == 0) { | |
719 | /* | |
720 | * We've fully scanned this node. Go up. Because | |
721 | * last_index is guaranteed to be in the tree, what | |
722 | * we do below cannot wander astray. | |
723 | */ | |
724 | slot = path[height - 1].node; | |
725 | height++; | |
726 | shift += RADIX_TREE_MAP_SHIFT; | |
727 | } | |
728 | } | |
729 | /* | |
730 | * The iftag must have been set somewhere because otherwise | |
731 | * we would return immediated at the beginning of the function | |
732 | */ | |
733 | root_tag_set(root, settag); | |
734 | *first_indexp = index; | |
735 | ||
736 | return tagged; | |
737 | } | |
738 | EXPORT_SYMBOL(radix_tree_range_tag_if_tagged); | |
739 | ||
740 | ||
741 | /** | |
742 | * radix_tree_next_hole - find the next hole (not-present entry) | |
743 | * @root: tree root | |
744 | * @index: index key | |
745 | * @max_scan: maximum range to search | |
746 | * | |
747 | * Search the set [index, min(index+max_scan-1, MAX_INDEX)] for the lowest | |
748 | * indexed hole. | |
749 | * | |
750 | * Returns: the index of the hole if found, otherwise returns an index | |
751 | * outside of the set specified (in which case 'return - index >= max_scan' | |
752 | * will be true). In rare cases of index wrap-around, 0 will be returned. | |
753 | * | |
754 | * radix_tree_next_hole may be called under rcu_read_lock. However, like | |
755 | * radix_tree_gang_lookup, this will not atomically search a snapshot of | |
756 | * the tree at a single point in time. For example, if a hole is created | |
757 | * at index 5, then subsequently a hole is created at index 10, | |
758 | * radix_tree_next_hole covering both indexes may return 10 if called | |
759 | * under rcu_read_lock. | |
760 | */ | |
761 | unsigned long radix_tree_next_hole(struct radix_tree_root *root, | |
762 | unsigned long index, unsigned long max_scan) | |
763 | { | |
764 | unsigned long i; | |
765 | ||
766 | for (i = 0; i < max_scan; i++) { | |
767 | if (!radix_tree_lookup(root, index)) | |
768 | break; | |
769 | index++; | |
770 | if (index == 0) | |
771 | break; | |
772 | } | |
773 | ||
774 | return index; | |
775 | } | |
776 | EXPORT_SYMBOL(radix_tree_next_hole); | |
777 | ||
778 | /** | |
779 | * radix_tree_prev_hole - find the prev hole (not-present entry) | |
780 | * @root: tree root | |
781 | * @index: index key | |
782 | * @max_scan: maximum range to search | |
783 | * | |
784 | * Search backwards in the range [max(index-max_scan+1, 0), index] | |
785 | * for the first hole. | |
786 | * | |
787 | * Returns: the index of the hole if found, otherwise returns an index | |
788 | * outside of the set specified (in which case 'index - return >= max_scan' | |
789 | * will be true). In rare cases of wrap-around, ULONG_MAX will be returned. | |
790 | * | |
791 | * radix_tree_next_hole may be called under rcu_read_lock. However, like | |
792 | * radix_tree_gang_lookup, this will not atomically search a snapshot of | |
793 | * the tree at a single point in time. For example, if a hole is created | |
794 | * at index 10, then subsequently a hole is created at index 5, | |
795 | * radix_tree_prev_hole covering both indexes may return 5 if called under | |
796 | * rcu_read_lock. | |
797 | */ | |
798 | unsigned long radix_tree_prev_hole(struct radix_tree_root *root, | |
799 | unsigned long index, unsigned long max_scan) | |
800 | { | |
801 | unsigned long i; | |
802 | ||
803 | for (i = 0; i < max_scan; i++) { | |
804 | if (!radix_tree_lookup(root, index)) | |
805 | break; | |
806 | index--; | |
807 | if (index == ULONG_MAX) | |
808 | break; | |
809 | } | |
810 | ||
811 | return index; | |
812 | } | |
813 | EXPORT_SYMBOL(radix_tree_prev_hole); | |
814 | ||
815 | static unsigned int | |
816 | __lookup(struct radix_tree_node *slot, void ***results, unsigned long index, | |
817 | unsigned int max_items, unsigned long *next_index) | |
818 | { | |
819 | unsigned int nr_found = 0; | |
820 | unsigned int shift, height; | |
821 | unsigned long i; | |
822 | ||
823 | height = slot->height; | |
824 | if (height == 0) | |
825 | goto out; | |
826 | shift = (height-1) * RADIX_TREE_MAP_SHIFT; | |
827 | ||
828 | for ( ; height > 1; height--) { | |
829 | i = (index >> shift) & RADIX_TREE_MAP_MASK; | |
830 | for (;;) { | |
831 | if (slot->slots[i] != NULL) | |
832 | break; | |
833 | index &= ~((1UL << shift) - 1); | |
834 | index += 1UL << shift; | |
835 | if (index == 0) | |
836 | goto out; /* 32-bit wraparound */ | |
837 | i++; | |
838 | if (i == RADIX_TREE_MAP_SIZE) | |
839 | goto out; | |
840 | } | |
841 | ||
842 | shift -= RADIX_TREE_MAP_SHIFT; | |
843 | slot = rcu_dereference_raw(slot->slots[i]); | |
844 | if (slot == NULL) | |
845 | goto out; | |
846 | } | |
847 | ||
848 | /* Bottom level: grab some items */ | |
849 | for (i = index & RADIX_TREE_MAP_MASK; i < RADIX_TREE_MAP_SIZE; i++) { | |
850 | index++; | |
851 | if (slot->slots[i]) { | |
852 | results[nr_found++] = &(slot->slots[i]); | |
853 | if (nr_found == max_items) | |
854 | goto out; | |
855 | } | |
856 | } | |
857 | out: | |
858 | *next_index = index; | |
859 | return nr_found; | |
860 | } | |
861 | ||
862 | /** | |
863 | * radix_tree_gang_lookup - perform multiple lookup on a radix tree | |
864 | * @root: radix tree root | |
865 | * @results: where the results of the lookup are placed | |
866 | * @first_index: start the lookup from this key | |
867 | * @max_items: place up to this many items at *results | |
868 | * | |
869 | * Performs an index-ascending scan of the tree for present items. Places | |
870 | * them at *@results and returns the number of items which were placed at | |
871 | * *@results. | |
872 | * | |
873 | * The implementation is naive. | |
874 | * | |
875 | * Like radix_tree_lookup, radix_tree_gang_lookup may be called under | |
876 | * rcu_read_lock. In this case, rather than the returned results being | |
877 | * an atomic snapshot of the tree at a single point in time, the semantics | |
878 | * of an RCU protected gang lookup are as though multiple radix_tree_lookups | |
879 | * have been issued in individual locks, and results stored in 'results'. | |
880 | */ | |
881 | unsigned int | |
882 | radix_tree_gang_lookup(struct radix_tree_root *root, void **results, | |
883 | unsigned long first_index, unsigned int max_items) | |
884 | { | |
885 | unsigned long max_index; | |
886 | struct radix_tree_node *node; | |
887 | unsigned long cur_index = first_index; | |
888 | unsigned int ret; | |
889 | ||
890 | node = rcu_dereference_raw(root->rnode); | |
891 | if (!node) | |
892 | return 0; | |
893 | ||
894 | if (!radix_tree_is_indirect_ptr(node)) { | |
895 | if (first_index > 0) | |
896 | return 0; | |
897 | results[0] = node; | |
898 | return 1; | |
899 | } | |
900 | node = radix_tree_indirect_to_ptr(node); | |
901 | ||
902 | max_index = radix_tree_maxindex(node->height); | |
903 | ||
904 | ret = 0; | |
905 | while (ret < max_items) { | |
906 | unsigned int nr_found, slots_found, i; | |
907 | unsigned long next_index; /* Index of next search */ | |
908 | ||
909 | if (cur_index > max_index) | |
910 | break; | |
911 | slots_found = __lookup(node, (void ***)results + ret, cur_index, | |
912 | max_items - ret, &next_index); | |
913 | nr_found = 0; | |
914 | for (i = 0; i < slots_found; i++) { | |
915 | struct radix_tree_node *slot; | |
916 | slot = *(((void ***)results)[ret + i]); | |
917 | if (!slot) | |
918 | continue; | |
919 | results[ret + nr_found] = rcu_dereference_raw(slot); | |
920 | nr_found++; | |
921 | } | |
922 | ret += nr_found; | |
923 | if (next_index == 0) | |
924 | break; | |
925 | cur_index = next_index; | |
926 | } | |
927 | ||
928 | return ret; | |
929 | } | |
930 | EXPORT_SYMBOL(radix_tree_gang_lookup); | |
931 | ||
932 | /** | |
933 | * radix_tree_gang_lookup_slot - perform multiple slot lookup on radix tree | |
934 | * @root: radix tree root | |
935 | * @results: where the results of the lookup are placed | |
936 | * @first_index: start the lookup from this key | |
937 | * @max_items: place up to this many items at *results | |
938 | * | |
939 | * Performs an index-ascending scan of the tree for present items. Places | |
940 | * their slots at *@results and returns the number of items which were | |
941 | * placed at *@results. | |
942 | * | |
943 | * The implementation is naive. | |
944 | * | |
945 | * Like radix_tree_gang_lookup as far as RCU and locking goes. Slots must | |
946 | * be dereferenced with radix_tree_deref_slot, and if using only RCU | |
947 | * protection, radix_tree_deref_slot may fail requiring a retry. | |
948 | */ | |
949 | unsigned int | |
950 | radix_tree_gang_lookup_slot(struct radix_tree_root *root, void ***results, | |
951 | unsigned long first_index, unsigned int max_items) | |
952 | { | |
953 | unsigned long max_index; | |
954 | struct radix_tree_node *node; | |
955 | unsigned long cur_index = first_index; | |
956 | unsigned int ret; | |
957 | ||
958 | node = rcu_dereference_raw(root->rnode); | |
959 | if (!node) | |
960 | return 0; | |
961 | ||
962 | if (!radix_tree_is_indirect_ptr(node)) { | |
963 | if (first_index > 0) | |
964 | return 0; | |
965 | results[0] = (void **)&root->rnode; | |
966 | return 1; | |
967 | } | |
968 | node = radix_tree_indirect_to_ptr(node); | |
969 | ||
970 | max_index = radix_tree_maxindex(node->height); | |
971 | ||
972 | ret = 0; | |
973 | while (ret < max_items) { | |
974 | unsigned int slots_found; | |
975 | unsigned long next_index; /* Index of next search */ | |
976 | ||
977 | if (cur_index > max_index) | |
978 | break; | |
979 | slots_found = __lookup(node, results + ret, cur_index, | |
980 | max_items - ret, &next_index); | |
981 | ret += slots_found; | |
982 | if (next_index == 0) | |
983 | break; | |
984 | cur_index = next_index; | |
985 | } | |
986 | ||
987 | return ret; | |
988 | } | |
989 | EXPORT_SYMBOL(radix_tree_gang_lookup_slot); | |
990 | ||
991 | /* | |
992 | * FIXME: the two tag_get()s here should use find_next_bit() instead of | |
993 | * open-coding the search. | |
994 | */ | |
995 | static unsigned int | |
996 | __lookup_tag(struct radix_tree_node *slot, void ***results, unsigned long index, | |
997 | unsigned int max_items, unsigned long *next_index, unsigned int tag) | |
998 | { | |
999 | unsigned int nr_found = 0; | |
1000 | unsigned int shift, height; | |
1001 | ||
1002 | height = slot->height; | |
1003 | if (height == 0) | |
1004 | goto out; | |
1005 | shift = (height-1) * RADIX_TREE_MAP_SHIFT; | |
1006 | ||
1007 | while (height > 0) { | |
1008 | unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK ; | |
1009 | ||
1010 | for (;;) { | |
1011 | if (tag_get(slot, tag, i)) | |
1012 | break; | |
1013 | index &= ~((1UL << shift) - 1); | |
1014 | index += 1UL << shift; | |
1015 | if (index == 0) | |
1016 | goto out; /* 32-bit wraparound */ | |
1017 | i++; | |
1018 | if (i == RADIX_TREE_MAP_SIZE) | |
1019 | goto out; | |
1020 | } | |
1021 | height--; | |
1022 | if (height == 0) { /* Bottom level: grab some items */ | |
1023 | unsigned long j = index & RADIX_TREE_MAP_MASK; | |
1024 | ||
1025 | for ( ; j < RADIX_TREE_MAP_SIZE; j++) { | |
1026 | index++; | |
1027 | if (!tag_get(slot, tag, j)) | |
1028 | continue; | |
1029 | /* | |
1030 | * Even though the tag was found set, we need to | |
1031 | * recheck that we have a non-NULL node, because | |
1032 | * if this lookup is lockless, it may have been | |
1033 | * subsequently deleted. | |
1034 | * | |
1035 | * Similar care must be taken in any place that | |
1036 | * lookup ->slots[x] without a lock (ie. can't | |
1037 | * rely on its value remaining the same). | |
1038 | */ | |
1039 | if (slot->slots[j]) { | |
1040 | results[nr_found++] = &(slot->slots[j]); | |
1041 | if (nr_found == max_items) | |
1042 | goto out; | |
1043 | } | |
1044 | } | |
1045 | } | |
1046 | shift -= RADIX_TREE_MAP_SHIFT; | |
1047 | slot = rcu_dereference_raw(slot->slots[i]); | |
1048 | if (slot == NULL) | |
1049 | break; | |
1050 | } | |
1051 | out: | |
1052 | *next_index = index; | |
1053 | return nr_found; | |
1054 | } | |
1055 | ||
1056 | /** | |
1057 | * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree | |
1058 | * based on a tag | |
1059 | * @root: radix tree root | |
1060 | * @results: where the results of the lookup are placed | |
1061 | * @first_index: start the lookup from this key | |
1062 | * @max_items: place up to this many items at *results | |
1063 | * @tag: the tag index (< RADIX_TREE_MAX_TAGS) | |
1064 | * | |
1065 | * Performs an index-ascending scan of the tree for present items which | |
1066 | * have the tag indexed by @tag set. Places the items at *@results and | |
1067 | * returns the number of items which were placed at *@results. | |
1068 | */ | |
1069 | unsigned int | |
1070 | radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results, | |
1071 | unsigned long first_index, unsigned int max_items, | |
1072 | unsigned int tag) | |
1073 | { | |
1074 | struct radix_tree_node *node; | |
1075 | unsigned long max_index; | |
1076 | unsigned long cur_index = first_index; | |
1077 | unsigned int ret; | |
1078 | ||
1079 | /* check the root's tag bit */ | |
1080 | if (!root_tag_get(root, tag)) | |
1081 | return 0; | |
1082 | ||
1083 | node = rcu_dereference_raw(root->rnode); | |
1084 | if (!node) | |
1085 | return 0; | |
1086 | ||
1087 | if (!radix_tree_is_indirect_ptr(node)) { | |
1088 | if (first_index > 0) | |
1089 | return 0; | |
1090 | results[0] = node; | |
1091 | return 1; | |
1092 | } | |
1093 | node = radix_tree_indirect_to_ptr(node); | |
1094 | ||
1095 | max_index = radix_tree_maxindex(node->height); | |
1096 | ||
1097 | ret = 0; | |
1098 | while (ret < max_items) { | |
1099 | unsigned int nr_found, slots_found, i; | |
1100 | unsigned long next_index; /* Index of next search */ | |
1101 | ||
1102 | if (cur_index > max_index) | |
1103 | break; | |
1104 | slots_found = __lookup_tag(node, (void ***)results + ret, | |
1105 | cur_index, max_items - ret, &next_index, tag); | |
1106 | nr_found = 0; | |
1107 | for (i = 0; i < slots_found; i++) { | |
1108 | struct radix_tree_node *slot; | |
1109 | slot = *(((void ***)results)[ret + i]); | |
1110 | if (!slot) | |
1111 | continue; | |
1112 | results[ret + nr_found] = rcu_dereference_raw(slot); | |
1113 | nr_found++; | |
1114 | } | |
1115 | ret += nr_found; | |
1116 | if (next_index == 0) | |
1117 | break; | |
1118 | cur_index = next_index; | |
1119 | } | |
1120 | ||
1121 | return ret; | |
1122 | } | |
1123 | EXPORT_SYMBOL(radix_tree_gang_lookup_tag); | |
1124 | ||
1125 | /** | |
1126 | * radix_tree_gang_lookup_tag_slot - perform multiple slot lookup on a | |
1127 | * radix tree based on a tag | |
1128 | * @root: radix tree root | |
1129 | * @results: where the results of the lookup are placed | |
1130 | * @first_index: start the lookup from this key | |
1131 | * @max_items: place up to this many items at *results | |
1132 | * @tag: the tag index (< RADIX_TREE_MAX_TAGS) | |
1133 | * | |
1134 | * Performs an index-ascending scan of the tree for present items which | |
1135 | * have the tag indexed by @tag set. Places the slots at *@results and | |
1136 | * returns the number of slots which were placed at *@results. | |
1137 | */ | |
1138 | unsigned int | |
1139 | radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results, | |
1140 | unsigned long first_index, unsigned int max_items, | |
1141 | unsigned int tag) | |
1142 | { | |
1143 | struct radix_tree_node *node; | |
1144 | unsigned long max_index; | |
1145 | unsigned long cur_index = first_index; | |
1146 | unsigned int ret; | |
1147 | ||
1148 | /* check the root's tag bit */ | |
1149 | if (!root_tag_get(root, tag)) | |
1150 | return 0; | |
1151 | ||
1152 | node = rcu_dereference_raw(root->rnode); | |
1153 | if (!node) | |
1154 | return 0; | |
1155 | ||
1156 | if (!radix_tree_is_indirect_ptr(node)) { | |
1157 | if (first_index > 0) | |
1158 | return 0; | |
1159 | results[0] = (void **)&root->rnode; | |
1160 | return 1; | |
1161 | } | |
1162 | node = radix_tree_indirect_to_ptr(node); | |
1163 | ||
1164 | max_index = radix_tree_maxindex(node->height); | |
1165 | ||
1166 | ret = 0; | |
1167 | while (ret < max_items) { | |
1168 | unsigned int slots_found; | |
1169 | unsigned long next_index; /* Index of next search */ | |
1170 | ||
1171 | if (cur_index > max_index) | |
1172 | break; | |
1173 | slots_found = __lookup_tag(node, results + ret, | |
1174 | cur_index, max_items - ret, &next_index, tag); | |
1175 | ret += slots_found; | |
1176 | if (next_index == 0) | |
1177 | break; | |
1178 | cur_index = next_index; | |
1179 | } | |
1180 | ||
1181 | return ret; | |
1182 | } | |
1183 | EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot); | |
1184 | ||
1185 | ||
1186 | /** | |
1187 | * radix_tree_shrink - shrink height of a radix tree to minimal | |
1188 | * @root radix tree root | |
1189 | */ | |
1190 | static inline void radix_tree_shrink(struct radix_tree_root *root) | |
1191 | { | |
1192 | /* try to shrink tree height */ | |
1193 | while (root->height > 0) { | |
1194 | struct radix_tree_node *to_free = root->rnode; | |
1195 | void *newptr; | |
1196 | ||
1197 | BUG_ON(!radix_tree_is_indirect_ptr(to_free)); | |
1198 | to_free = radix_tree_indirect_to_ptr(to_free); | |
1199 | ||
1200 | /* | |
1201 | * The candidate node has more than one child, or its child | |
1202 | * is not at the leftmost slot, we cannot shrink. | |
1203 | */ | |
1204 | if (to_free->count != 1) | |
1205 | break; | |
1206 | if (!to_free->slots[0]) | |
1207 | break; | |
1208 | ||
1209 | /* | |
1210 | * We don't need rcu_assign_pointer(), since we are simply | |
1211 | * moving the node from one part of the tree to another. If | |
1212 | * it was safe to dereference the old pointer to it | |
1213 | * (to_free->slots[0]), it will be safe to dereference the new | |
1214 | * one (root->rnode). | |
1215 | */ | |
1216 | newptr = to_free->slots[0]; | |
1217 | if (root->height > 1) | |
1218 | newptr = radix_tree_ptr_to_indirect(newptr); | |
1219 | root->rnode = newptr; | |
1220 | root->height--; | |
1221 | radix_tree_node_free(to_free); | |
1222 | } | |
1223 | } | |
1224 | ||
1225 | /** | |
1226 | * radix_tree_delete - delete an item from a radix tree | |
1227 | * @root: radix tree root | |
1228 | * @index: index key | |
1229 | * | |
1230 | * Remove the item at @index from the radix tree rooted at @root. | |
1231 | * | |
1232 | * Returns the address of the deleted item, or NULL if it was not present. | |
1233 | */ | |
1234 | void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) | |
1235 | { | |
1236 | /* | |
1237 | * The radix tree path needs to be one longer than the maximum path | |
1238 | * since the "list" is null terminated. | |
1239 | */ | |
1240 | struct radix_tree_path path[RADIX_TREE_MAX_PATH + 1], *pathp = path; | |
1241 | struct radix_tree_node *slot = NULL; | |
1242 | struct radix_tree_node *to_free; | |
1243 | unsigned int height, shift; | |
1244 | int tag; | |
1245 | int offset; | |
1246 | ||
1247 | height = root->height; | |
1248 | if (index > radix_tree_maxindex(height)) | |
1249 | goto out; | |
1250 | ||
1251 | slot = root->rnode; | |
1252 | if (height == 0) { | |
1253 | root_tag_clear_all(root); | |
1254 | root->rnode = NULL; | |
1255 | goto out; | |
1256 | } | |
1257 | slot = radix_tree_indirect_to_ptr(slot); | |
1258 | ||
1259 | shift = (height - 1) * RADIX_TREE_MAP_SHIFT; | |
1260 | pathp->node = NULL; | |
1261 | ||
1262 | do { | |
1263 | if (slot == NULL) | |
1264 | goto out; | |
1265 | ||
1266 | pathp++; | |
1267 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; | |
1268 | pathp->offset = offset; | |
1269 | pathp->node = slot; | |
1270 | slot = slot->slots[offset]; | |
1271 | shift -= RADIX_TREE_MAP_SHIFT; | |
1272 | height--; | |
1273 | } while (height > 0); | |
1274 | ||
1275 | if (slot == NULL) | |
1276 | goto out; | |
1277 | ||
1278 | /* | |
1279 | * Clear all tags associated with the just-deleted item | |
1280 | */ | |
1281 | for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) { | |
1282 | if (tag_get(pathp->node, tag, pathp->offset)) | |
1283 | radix_tree_tag_clear(root, index, tag); | |
1284 | } | |
1285 | ||
1286 | to_free = NULL; | |
1287 | /* Now free the nodes we do not need anymore */ | |
1288 | while (pathp->node) { | |
1289 | pathp->node->slots[pathp->offset] = NULL; | |
1290 | pathp->node->count--; | |
1291 | /* | |
1292 | * Queue the node for deferred freeing after the | |
1293 | * last reference to it disappears (set NULL, above). | |
1294 | */ | |
1295 | if (to_free) | |
1296 | radix_tree_node_free(to_free); | |
1297 | ||
1298 | if (pathp->node->count) { | |
1299 | if (pathp->node == | |
1300 | radix_tree_indirect_to_ptr(root->rnode)) | |
1301 | radix_tree_shrink(root); | |
1302 | goto out; | |
1303 | } | |
1304 | ||
1305 | /* Node with zero slots in use so free it */ | |
1306 | to_free = pathp->node; | |
1307 | pathp--; | |
1308 | ||
1309 | } | |
1310 | root_tag_clear_all(root); | |
1311 | root->height = 0; | |
1312 | root->rnode = NULL; | |
1313 | if (to_free) | |
1314 | radix_tree_node_free(to_free); | |
1315 | ||
1316 | out: | |
1317 | return slot; | |
1318 | } | |
1319 | EXPORT_SYMBOL(radix_tree_delete); | |
1320 | ||
1321 | /** | |
1322 | * radix_tree_tagged - test whether any items in the tree are tagged | |
1323 | * @root: radix tree root | |
1324 | * @tag: tag to test | |
1325 | */ | |
1326 | int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag) | |
1327 | { | |
1328 | return root_tag_get(root, tag); | |
1329 | } | |
1330 | EXPORT_SYMBOL(radix_tree_tagged); | |
1331 | ||
1332 | static void | |
1333 | radix_tree_node_ctor(void *node) | |
1334 | { | |
1335 | memset(node, 0, sizeof(struct radix_tree_node)); | |
1336 | } | |
1337 | ||
1338 | static __init unsigned long __maxindex(unsigned int height) | |
1339 | { | |
1340 | unsigned int width = height * RADIX_TREE_MAP_SHIFT; | |
1341 | int shift = RADIX_TREE_INDEX_BITS - width; | |
1342 | ||
1343 | if (shift < 0) | |
1344 | return ~0UL; | |
1345 | if (shift >= BITS_PER_LONG) | |
1346 | return 0UL; | |
1347 | return ~0UL >> shift; | |
1348 | } | |
1349 | ||
1350 | static __init void radix_tree_init_maxindex(void) | |
1351 | { | |
1352 | unsigned int i; | |
1353 | ||
1354 | for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++) | |
1355 | height_to_maxindex[i] = __maxindex(i); | |
1356 | } | |
1357 | ||
1358 | static int radix_tree_callback(struct notifier_block *nfb, | |
1359 | unsigned long action, | |
1360 | void *hcpu) | |
1361 | { | |
1362 | int cpu = (long)hcpu; | |
1363 | struct radix_tree_preload *rtp; | |
1364 | ||
1365 | /* Free per-cpu pool of perloaded nodes */ | |
1366 | if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) { | |
1367 | rtp = &per_cpu(radix_tree_preloads, cpu); | |
1368 | while (rtp->nr) { | |
1369 | kmem_cache_free(radix_tree_node_cachep, | |
1370 | rtp->nodes[rtp->nr-1]); | |
1371 | rtp->nodes[rtp->nr-1] = NULL; | |
1372 | rtp->nr--; | |
1373 | } | |
1374 | } | |
1375 | return NOTIFY_OK; | |
1376 | } | |
1377 | ||
1378 | void __init radix_tree_init(void) | |
1379 | { | |
1380 | radix_tree_node_cachep = kmem_cache_create("radix_tree_node", | |
1381 | sizeof(struct radix_tree_node), 0, | |
1382 | SLAB_PANIC | SLAB_RECLAIM_ACCOUNT, | |
1383 | radix_tree_node_ctor); | |
1384 | radix_tree_init_maxindex(); | |
1385 | hotcpu_notifier(radix_tree_callback, 0); | |
1386 | } |