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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 <clameter@sgi.com> | |
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/gfp.h> | |
32 | #include <linux/string.h> | |
33 | #include <linux/bitops.h> | |
34 | #include <linux/rcupdate.h> | |
35 | ||
36 | ||
37 | #ifdef __KERNEL__ | |
38 | #define RADIX_TREE_MAP_SHIFT (CONFIG_BASE_SMALL ? 4 : 6) | |
39 | #else | |
40 | #define RADIX_TREE_MAP_SHIFT 3 /* For more stressful testing */ | |
41 | #endif | |
42 | ||
43 | #define RADIX_TREE_MAP_SIZE (1UL << RADIX_TREE_MAP_SHIFT) | |
44 | #define RADIX_TREE_MAP_MASK (RADIX_TREE_MAP_SIZE-1) | |
45 | ||
46 | #define RADIX_TREE_TAG_LONGS \ | |
47 | ((RADIX_TREE_MAP_SIZE + BITS_PER_LONG - 1) / BITS_PER_LONG) | |
48 | ||
49 | struct radix_tree_node { | |
50 | unsigned int height; /* Height from the bottom */ | |
51 | unsigned int count; | |
52 | struct rcu_head rcu_head; | |
53 | void *slots[RADIX_TREE_MAP_SIZE]; | |
54 | unsigned long tags[RADIX_TREE_MAX_TAGS][RADIX_TREE_TAG_LONGS]; | |
55 | }; | |
56 | ||
57 | struct radix_tree_path { | |
58 | struct radix_tree_node *node; | |
59 | int offset; | |
60 | }; | |
61 | ||
62 | #define RADIX_TREE_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(unsigned long)) | |
63 | #define RADIX_TREE_MAX_PATH (DIV_ROUND_UP(RADIX_TREE_INDEX_BITS, \ | |
64 | RADIX_TREE_MAP_SHIFT)) | |
65 | ||
66 | /* | |
67 | * The height_to_maxindex array needs to be one deeper than the maximum | |
68 | * path as height 0 holds only 1 entry. | |
69 | */ | |
70 | static unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH + 1] __read_mostly; | |
71 | ||
72 | /* | |
73 | * Radix tree node cache. | |
74 | */ | |
75 | static struct kmem_cache *radix_tree_node_cachep; | |
76 | ||
77 | /* | |
78 | * Per-cpu pool of preloaded nodes | |
79 | */ | |
80 | struct radix_tree_preload { | |
81 | int nr; | |
82 | struct radix_tree_node *nodes[RADIX_TREE_MAX_PATH]; | |
83 | }; | |
84 | DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, }; | |
85 | ||
86 | static inline gfp_t root_gfp_mask(struct radix_tree_root *root) | |
87 | { | |
88 | return root->gfp_mask & __GFP_BITS_MASK; | |
89 | } | |
90 | ||
91 | /* | |
92 | * This assumes that the caller has performed appropriate preallocation, and | |
93 | * that the caller has pinned this thread of control to the current CPU. | |
94 | */ | |
95 | static struct radix_tree_node * | |
96 | radix_tree_node_alloc(struct radix_tree_root *root) | |
97 | { | |
98 | struct radix_tree_node *ret = NULL; | |
99 | gfp_t gfp_mask = root_gfp_mask(root); | |
100 | ||
101 | if (!(gfp_mask & __GFP_WAIT)) { | |
102 | struct radix_tree_preload *rtp; | |
103 | ||
104 | /* | |
105 | * Provided the caller has preloaded here, we will always | |
106 | * succeed in getting a node here (and never reach | |
107 | * kmem_cache_alloc) | |
108 | */ | |
109 | rtp = &__get_cpu_var(radix_tree_preloads); | |
110 | if (rtp->nr) { | |
111 | ret = rtp->nodes[rtp->nr - 1]; | |
112 | rtp->nodes[rtp->nr - 1] = NULL; | |
113 | rtp->nr--; | |
114 | } | |
115 | } | |
116 | if (ret == NULL) | |
117 | ret = kmem_cache_alloc(radix_tree_node_cachep, | |
118 | set_migrateflags(gfp_mask, __GFP_RECLAIMABLE)); | |
119 | ||
120 | BUG_ON(radix_tree_is_indirect_ptr(ret)); | |
121 | return ret; | |
122 | } | |
123 | ||
124 | static void radix_tree_node_rcu_free(struct rcu_head *head) | |
125 | { | |
126 | struct radix_tree_node *node = | |
127 | container_of(head, struct radix_tree_node, rcu_head); | |
128 | kmem_cache_free(radix_tree_node_cachep, node); | |
129 | } | |
130 | ||
131 | static inline void | |
132 | radix_tree_node_free(struct radix_tree_node *node) | |
133 | { | |
134 | call_rcu(&node->rcu_head, radix_tree_node_rcu_free); | |
135 | } | |
136 | ||
137 | /* | |
138 | * Load up this CPU's radix_tree_node buffer with sufficient objects to | |
139 | * ensure that the addition of a single element in the tree cannot fail. On | |
140 | * success, return zero, with preemption disabled. On error, return -ENOMEM | |
141 | * with preemption not disabled. | |
142 | */ | |
143 | int radix_tree_preload(gfp_t gfp_mask) | |
144 | { | |
145 | struct radix_tree_preload *rtp; | |
146 | struct radix_tree_node *node; | |
147 | int ret = -ENOMEM; | |
148 | ||
149 | preempt_disable(); | |
150 | rtp = &__get_cpu_var(radix_tree_preloads); | |
151 | while (rtp->nr < ARRAY_SIZE(rtp->nodes)) { | |
152 | preempt_enable(); | |
153 | node = kmem_cache_alloc(radix_tree_node_cachep, | |
154 | set_migrateflags(gfp_mask, __GFP_RECLAIMABLE)); | |
155 | if (node == NULL) | |
156 | goto out; | |
157 | preempt_disable(); | |
158 | rtp = &__get_cpu_var(radix_tree_preloads); | |
159 | if (rtp->nr < ARRAY_SIZE(rtp->nodes)) | |
160 | rtp->nodes[rtp->nr++] = node; | |
161 | else | |
162 | kmem_cache_free(radix_tree_node_cachep, node); | |
163 | } | |
164 | ret = 0; | |
165 | out: | |
166 | return ret; | |
167 | } | |
168 | EXPORT_SYMBOL(radix_tree_preload); | |
169 | ||
170 | static inline void tag_set(struct radix_tree_node *node, unsigned int tag, | |
171 | int offset) | |
172 | { | |
173 | __set_bit(offset, node->tags[tag]); | |
174 | } | |
175 | ||
176 | static inline void tag_clear(struct radix_tree_node *node, unsigned int tag, | |
177 | int offset) | |
178 | { | |
179 | __clear_bit(offset, node->tags[tag]); | |
180 | } | |
181 | ||
182 | static inline int tag_get(struct radix_tree_node *node, unsigned int tag, | |
183 | int offset) | |
184 | { | |
185 | return test_bit(offset, node->tags[tag]); | |
186 | } | |
187 | ||
188 | static inline void root_tag_set(struct radix_tree_root *root, unsigned int tag) | |
189 | { | |
190 | root->gfp_mask |= (__force gfp_t)(1 << (tag + __GFP_BITS_SHIFT)); | |
191 | } | |
192 | ||
193 | ||
194 | static inline void root_tag_clear(struct radix_tree_root *root, unsigned int tag) | |
195 | { | |
196 | root->gfp_mask &= (__force gfp_t)~(1 << (tag + __GFP_BITS_SHIFT)); | |
197 | } | |
198 | ||
199 | static inline void root_tag_clear_all(struct radix_tree_root *root) | |
200 | { | |
201 | root->gfp_mask &= __GFP_BITS_MASK; | |
202 | } | |
203 | ||
204 | static inline int root_tag_get(struct radix_tree_root *root, unsigned int tag) | |
205 | { | |
206 | return (__force unsigned)root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT)); | |
207 | } | |
208 | ||
209 | /* | |
210 | * Returns 1 if any slot in the node has this tag set. | |
211 | * Otherwise returns 0. | |
212 | */ | |
213 | static inline int any_tag_set(struct radix_tree_node *node, unsigned int tag) | |
214 | { | |
215 | int idx; | |
216 | for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) { | |
217 | if (node->tags[tag][idx]) | |
218 | return 1; | |
219 | } | |
220 | return 0; | |
221 | } | |
222 | ||
223 | /* | |
224 | * Return the maximum key which can be store into a | |
225 | * radix tree with height HEIGHT. | |
226 | */ | |
227 | static inline unsigned long radix_tree_maxindex(unsigned int height) | |
228 | { | |
229 | return height_to_maxindex[height]; | |
230 | } | |
231 | ||
232 | /* | |
233 | * Extend a radix tree so it can store key @index. | |
234 | */ | |
235 | static int radix_tree_extend(struct radix_tree_root *root, unsigned long index) | |
236 | { | |
237 | struct radix_tree_node *node; | |
238 | unsigned int height; | |
239 | int tag; | |
240 | ||
241 | /* Figure out what the height should be. */ | |
242 | height = root->height + 1; | |
243 | while (index > radix_tree_maxindex(height)) | |
244 | height++; | |
245 | ||
246 | if (root->rnode == NULL) { | |
247 | root->height = height; | |
248 | goto out; | |
249 | } | |
250 | ||
251 | do { | |
252 | unsigned int newheight; | |
253 | if (!(node = radix_tree_node_alloc(root))) | |
254 | return -ENOMEM; | |
255 | ||
256 | /* Increase the height. */ | |
257 | node->slots[0] = radix_tree_indirect_to_ptr(root->rnode); | |
258 | ||
259 | /* Propagate the aggregated tag info into the new root */ | |
260 | for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) { | |
261 | if (root_tag_get(root, tag)) | |
262 | tag_set(node, tag, 0); | |
263 | } | |
264 | ||
265 | newheight = root->height+1; | |
266 | node->height = newheight; | |
267 | node->count = 1; | |
268 | node = radix_tree_ptr_to_indirect(node); | |
269 | rcu_assign_pointer(root->rnode, node); | |
270 | root->height = newheight; | |
271 | } while (height > root->height); | |
272 | out: | |
273 | return 0; | |
274 | } | |
275 | ||
276 | /** | |
277 | * radix_tree_insert - insert into a radix tree | |
278 | * @root: radix tree root | |
279 | * @index: index key | |
280 | * @item: item to insert | |
281 | * | |
282 | * Insert an item into the radix tree at position @index. | |
283 | */ | |
284 | int radix_tree_insert(struct radix_tree_root *root, | |
285 | unsigned long index, void *item) | |
286 | { | |
287 | struct radix_tree_node *node = NULL, *slot; | |
288 | unsigned int height, shift; | |
289 | int offset; | |
290 | int error; | |
291 | ||
292 | BUG_ON(radix_tree_is_indirect_ptr(item)); | |
293 | ||
294 | /* Make sure the tree is high enough. */ | |
295 | if (index > radix_tree_maxindex(root->height)) { | |
296 | error = radix_tree_extend(root, index); | |
297 | if (error) | |
298 | return error; | |
299 | } | |
300 | ||
301 | slot = radix_tree_indirect_to_ptr(root->rnode); | |
302 | ||
303 | height = root->height; | |
304 | shift = (height-1) * RADIX_TREE_MAP_SHIFT; | |
305 | ||
306 | offset = 0; /* uninitialised var warning */ | |
307 | while (height > 0) { | |
308 | if (slot == NULL) { | |
309 | /* Have to add a child node. */ | |
310 | if (!(slot = radix_tree_node_alloc(root))) | |
311 | return -ENOMEM; | |
312 | slot->height = height; | |
313 | if (node) { | |
314 | rcu_assign_pointer(node->slots[offset], slot); | |
315 | node->count++; | |
316 | } else | |
317 | rcu_assign_pointer(root->rnode, | |
318 | radix_tree_ptr_to_indirect(slot)); | |
319 | } | |
320 | ||
321 | /* Go a level down */ | |
322 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; | |
323 | node = slot; | |
324 | slot = node->slots[offset]; | |
325 | shift -= RADIX_TREE_MAP_SHIFT; | |
326 | height--; | |
327 | } | |
328 | ||
329 | if (slot != NULL) | |
330 | return -EEXIST; | |
331 | ||
332 | if (node) { | |
333 | node->count++; | |
334 | rcu_assign_pointer(node->slots[offset], item); | |
335 | BUG_ON(tag_get(node, 0, offset)); | |
336 | BUG_ON(tag_get(node, 1, offset)); | |
337 | } else { | |
338 | rcu_assign_pointer(root->rnode, item); | |
339 | BUG_ON(root_tag_get(root, 0)); | |
340 | BUG_ON(root_tag_get(root, 1)); | |
341 | } | |
342 | ||
343 | return 0; | |
344 | } | |
345 | EXPORT_SYMBOL(radix_tree_insert); | |
346 | ||
347 | /** | |
348 | * radix_tree_lookup_slot - lookup a slot in a radix tree | |
349 | * @root: radix tree root | |
350 | * @index: index key | |
351 | * | |
352 | * Returns: the slot corresponding to the position @index in the | |
353 | * radix tree @root. This is useful for update-if-exists operations. | |
354 | * | |
355 | * This function cannot be called under rcu_read_lock, it must be | |
356 | * excluded from writers, as must the returned slot for subsequent | |
357 | * use by radix_tree_deref_slot() and radix_tree_replace slot. | |
358 | * Caller must hold tree write locked across slot lookup and | |
359 | * replace. | |
360 | */ | |
361 | void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index) | |
362 | { | |
363 | unsigned int height, shift; | |
364 | struct radix_tree_node *node, **slot; | |
365 | ||
366 | node = root->rnode; | |
367 | if (node == NULL) | |
368 | return NULL; | |
369 | ||
370 | if (!radix_tree_is_indirect_ptr(node)) { | |
371 | if (index > 0) | |
372 | return NULL; | |
373 | return (void **)&root->rnode; | |
374 | } | |
375 | node = radix_tree_indirect_to_ptr(node); | |
376 | ||
377 | height = node->height; | |
378 | if (index > radix_tree_maxindex(height)) | |
379 | return NULL; | |
380 | ||
381 | shift = (height-1) * RADIX_TREE_MAP_SHIFT; | |
382 | ||
383 | do { | |
384 | slot = (struct radix_tree_node **) | |
385 | (node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK)); | |
386 | node = *slot; | |
387 | if (node == NULL) | |
388 | return NULL; | |
389 | ||
390 | shift -= RADIX_TREE_MAP_SHIFT; | |
391 | height--; | |
392 | } while (height > 0); | |
393 | ||
394 | return (void **)slot; | |
395 | } | |
396 | EXPORT_SYMBOL(radix_tree_lookup_slot); | |
397 | ||
398 | /** | |
399 | * radix_tree_lookup - perform lookup operation on a radix tree | |
400 | * @root: radix tree root | |
401 | * @index: index key | |
402 | * | |
403 | * Lookup the item at the position @index in the radix tree @root. | |
404 | * | |
405 | * This function can be called under rcu_read_lock, however the caller | |
406 | * must manage lifetimes of leaf nodes (eg. RCU may also be used to free | |
407 | * them safely). No RCU barriers are required to access or modify the | |
408 | * returned item, however. | |
409 | */ | |
410 | void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index) | |
411 | { | |
412 | unsigned int height, shift; | |
413 | struct radix_tree_node *node, **slot; | |
414 | ||
415 | node = rcu_dereference(root->rnode); | |
416 | if (node == NULL) | |
417 | return NULL; | |
418 | ||
419 | if (!radix_tree_is_indirect_ptr(node)) { | |
420 | if (index > 0) | |
421 | return NULL; | |
422 | return node; | |
423 | } | |
424 | node = radix_tree_indirect_to_ptr(node); | |
425 | ||
426 | height = node->height; | |
427 | if (index > radix_tree_maxindex(height)) | |
428 | return NULL; | |
429 | ||
430 | shift = (height-1) * RADIX_TREE_MAP_SHIFT; | |
431 | ||
432 | do { | |
433 | slot = (struct radix_tree_node **) | |
434 | (node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK)); | |
435 | node = rcu_dereference(*slot); | |
436 | if (node == NULL) | |
437 | return NULL; | |
438 | ||
439 | shift -= RADIX_TREE_MAP_SHIFT; | |
440 | height--; | |
441 | } while (height > 0); | |
442 | ||
443 | return node; | |
444 | } | |
445 | EXPORT_SYMBOL(radix_tree_lookup); | |
446 | ||
447 | /** | |
448 | * radix_tree_tag_set - set a tag on a radix tree node | |
449 | * @root: radix tree root | |
450 | * @index: index key | |
451 | * @tag: tag index | |
452 | * | |
453 | * Set the search tag (which must be < RADIX_TREE_MAX_TAGS) | |
454 | * corresponding to @index in the radix tree. From | |
455 | * the root all the way down to the leaf node. | |
456 | * | |
457 | * Returns the address of the tagged item. Setting a tag on a not-present | |
458 | * item is a bug. | |
459 | */ | |
460 | void *radix_tree_tag_set(struct radix_tree_root *root, | |
461 | unsigned long index, unsigned int tag) | |
462 | { | |
463 | unsigned int height, shift; | |
464 | struct radix_tree_node *slot; | |
465 | ||
466 | height = root->height; | |
467 | BUG_ON(index > radix_tree_maxindex(height)); | |
468 | ||
469 | slot = radix_tree_indirect_to_ptr(root->rnode); | |
470 | shift = (height - 1) * RADIX_TREE_MAP_SHIFT; | |
471 | ||
472 | while (height > 0) { | |
473 | int offset; | |
474 | ||
475 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; | |
476 | if (!tag_get(slot, tag, offset)) | |
477 | tag_set(slot, tag, offset); | |
478 | slot = slot->slots[offset]; | |
479 | BUG_ON(slot == NULL); | |
480 | shift -= RADIX_TREE_MAP_SHIFT; | |
481 | height--; | |
482 | } | |
483 | ||
484 | /* set the root's tag bit */ | |
485 | if (slot && !root_tag_get(root, tag)) | |
486 | root_tag_set(root, tag); | |
487 | ||
488 | return slot; | |
489 | } | |
490 | EXPORT_SYMBOL(radix_tree_tag_set); | |
491 | ||
492 | /** | |
493 | * radix_tree_tag_clear - clear a tag on a radix tree node | |
494 | * @root: radix tree root | |
495 | * @index: index key | |
496 | * @tag: tag index | |
497 | * | |
498 | * Clear the search tag (which must be < RADIX_TREE_MAX_TAGS) | |
499 | * corresponding to @index in the radix tree. If | |
500 | * this causes the leaf node to have no tags set then clear the tag in the | |
501 | * next-to-leaf node, etc. | |
502 | * | |
503 | * Returns the address of the tagged item on success, else NULL. ie: | |
504 | * has the same return value and semantics as radix_tree_lookup(). | |
505 | */ | |
506 | void *radix_tree_tag_clear(struct radix_tree_root *root, | |
507 | unsigned long index, unsigned int tag) | |
508 | { | |
509 | /* | |
510 | * The radix tree path needs to be one longer than the maximum path | |
511 | * since the "list" is null terminated. | |
512 | */ | |
513 | struct radix_tree_path path[RADIX_TREE_MAX_PATH + 1], *pathp = path; | |
514 | struct radix_tree_node *slot = NULL; | |
515 | unsigned int height, shift; | |
516 | ||
517 | height = root->height; | |
518 | if (index > radix_tree_maxindex(height)) | |
519 | goto out; | |
520 | ||
521 | shift = (height - 1) * RADIX_TREE_MAP_SHIFT; | |
522 | pathp->node = NULL; | |
523 | slot = radix_tree_indirect_to_ptr(root->rnode); | |
524 | ||
525 | while (height > 0) { | |
526 | int offset; | |
527 | ||
528 | if (slot == NULL) | |
529 | goto out; | |
530 | ||
531 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; | |
532 | pathp[1].offset = offset; | |
533 | pathp[1].node = slot; | |
534 | slot = slot->slots[offset]; | |
535 | pathp++; | |
536 | shift -= RADIX_TREE_MAP_SHIFT; | |
537 | height--; | |
538 | } | |
539 | ||
540 | if (slot == NULL) | |
541 | goto out; | |
542 | ||
543 | while (pathp->node) { | |
544 | if (!tag_get(pathp->node, tag, pathp->offset)) | |
545 | goto out; | |
546 | tag_clear(pathp->node, tag, pathp->offset); | |
547 | if (any_tag_set(pathp->node, tag)) | |
548 | goto out; | |
549 | pathp--; | |
550 | } | |
551 | ||
552 | /* clear the root's tag bit */ | |
553 | if (root_tag_get(root, tag)) | |
554 | root_tag_clear(root, tag); | |
555 | ||
556 | out: | |
557 | return slot; | |
558 | } | |
559 | EXPORT_SYMBOL(radix_tree_tag_clear); | |
560 | ||
561 | #ifndef __KERNEL__ /* Only the test harness uses this at present */ | |
562 | /** | |
563 | * radix_tree_tag_get - get a tag on a radix tree node | |
564 | * @root: radix tree root | |
565 | * @index: index key | |
566 | * @tag: tag index (< RADIX_TREE_MAX_TAGS) | |
567 | * | |
568 | * Return values: | |
569 | * | |
570 | * 0: tag not present or not set | |
571 | * 1: tag set | |
572 | */ | |
573 | int radix_tree_tag_get(struct radix_tree_root *root, | |
574 | unsigned long index, unsigned int tag) | |
575 | { | |
576 | unsigned int height, shift; | |
577 | struct radix_tree_node *node; | |
578 | int saw_unset_tag = 0; | |
579 | ||
580 | /* check the root's tag bit */ | |
581 | if (!root_tag_get(root, tag)) | |
582 | return 0; | |
583 | ||
584 | node = rcu_dereference(root->rnode); | |
585 | if (node == NULL) | |
586 | return 0; | |
587 | ||
588 | if (!radix_tree_is_indirect_ptr(node)) | |
589 | return (index == 0); | |
590 | node = radix_tree_indirect_to_ptr(node); | |
591 | ||
592 | height = node->height; | |
593 | if (index > radix_tree_maxindex(height)) | |
594 | return 0; | |
595 | ||
596 | shift = (height - 1) * RADIX_TREE_MAP_SHIFT; | |
597 | ||
598 | for ( ; ; ) { | |
599 | int offset; | |
600 | ||
601 | if (node == NULL) | |
602 | return 0; | |
603 | ||
604 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; | |
605 | ||
606 | /* | |
607 | * This is just a debug check. Later, we can bale as soon as | |
608 | * we see an unset tag. | |
609 | */ | |
610 | if (!tag_get(node, tag, offset)) | |
611 | saw_unset_tag = 1; | |
612 | if (height == 1) { | |
613 | int ret = tag_get(node, tag, offset); | |
614 | ||
615 | BUG_ON(ret && saw_unset_tag); | |
616 | return !!ret; | |
617 | } | |
618 | node = rcu_dereference(node->slots[offset]); | |
619 | shift -= RADIX_TREE_MAP_SHIFT; | |
620 | height--; | |
621 | } | |
622 | } | |
623 | EXPORT_SYMBOL(radix_tree_tag_get); | |
624 | #endif | |
625 | ||
626 | /** | |
627 | * radix_tree_next_hole - find the next hole (not-present entry) | |
628 | * @root: tree root | |
629 | * @index: index key | |
630 | * @max_scan: maximum range to search | |
631 | * | |
632 | * Search the set [index, min(index+max_scan-1, MAX_INDEX)] for the lowest | |
633 | * indexed hole. | |
634 | * | |
635 | * Returns: the index of the hole if found, otherwise returns an index | |
636 | * outside of the set specified (in which case 'return - index >= max_scan' | |
637 | * will be true). | |
638 | * | |
639 | * radix_tree_next_hole may be called under rcu_read_lock. However, like | |
640 | * radix_tree_gang_lookup, this will not atomically search a snapshot of the | |
641 | * tree at a single point in time. For example, if a hole is created at index | |
642 | * 5, then subsequently a hole is created at index 10, radix_tree_next_hole | |
643 | * covering both indexes may return 10 if called under rcu_read_lock. | |
644 | */ | |
645 | unsigned long radix_tree_next_hole(struct radix_tree_root *root, | |
646 | unsigned long index, unsigned long max_scan) | |
647 | { | |
648 | unsigned long i; | |
649 | ||
650 | for (i = 0; i < max_scan; i++) { | |
651 | if (!radix_tree_lookup(root, index)) | |
652 | break; | |
653 | index++; | |
654 | if (index == 0) | |
655 | break; | |
656 | } | |
657 | ||
658 | return index; | |
659 | } | |
660 | EXPORT_SYMBOL(radix_tree_next_hole); | |
661 | ||
662 | static unsigned int | |
663 | __lookup(struct radix_tree_node *slot, void **results, unsigned long index, | |
664 | unsigned int max_items, unsigned long *next_index) | |
665 | { | |
666 | unsigned int nr_found = 0; | |
667 | unsigned int shift, height; | |
668 | unsigned long i; | |
669 | ||
670 | height = slot->height; | |
671 | if (height == 0) | |
672 | goto out; | |
673 | shift = (height-1) * RADIX_TREE_MAP_SHIFT; | |
674 | ||
675 | for ( ; height > 1; height--) { | |
676 | i = (index >> shift) & RADIX_TREE_MAP_MASK; | |
677 | for (;;) { | |
678 | if (slot->slots[i] != NULL) | |
679 | break; | |
680 | index &= ~((1UL << shift) - 1); | |
681 | index += 1UL << shift; | |
682 | if (index == 0) | |
683 | goto out; /* 32-bit wraparound */ | |
684 | i++; | |
685 | if (i == RADIX_TREE_MAP_SIZE) | |
686 | goto out; | |
687 | } | |
688 | ||
689 | shift -= RADIX_TREE_MAP_SHIFT; | |
690 | slot = rcu_dereference(slot->slots[i]); | |
691 | if (slot == NULL) | |
692 | goto out; | |
693 | } | |
694 | ||
695 | /* Bottom level: grab some items */ | |
696 | for (i = index & RADIX_TREE_MAP_MASK; i < RADIX_TREE_MAP_SIZE; i++) { | |
697 | struct radix_tree_node *node; | |
698 | index++; | |
699 | node = slot->slots[i]; | |
700 | if (node) { | |
701 | results[nr_found++] = rcu_dereference(node); | |
702 | if (nr_found == max_items) | |
703 | goto out; | |
704 | } | |
705 | } | |
706 | out: | |
707 | *next_index = index; | |
708 | return nr_found; | |
709 | } | |
710 | ||
711 | /** | |
712 | * radix_tree_gang_lookup - perform multiple lookup on a radix tree | |
713 | * @root: radix tree root | |
714 | * @results: where the results of the lookup are placed | |
715 | * @first_index: start the lookup from this key | |
716 | * @max_items: place up to this many items at *results | |
717 | * | |
718 | * Performs an index-ascending scan of the tree for present items. Places | |
719 | * them at *@results and returns the number of items which were placed at | |
720 | * *@results. | |
721 | * | |
722 | * The implementation is naive. | |
723 | * | |
724 | * Like radix_tree_lookup, radix_tree_gang_lookup may be called under | |
725 | * rcu_read_lock. In this case, rather than the returned results being | |
726 | * an atomic snapshot of the tree at a single point in time, the semantics | |
727 | * of an RCU protected gang lookup are as though multiple radix_tree_lookups | |
728 | * have been issued in individual locks, and results stored in 'results'. | |
729 | */ | |
730 | unsigned int | |
731 | radix_tree_gang_lookup(struct radix_tree_root *root, void **results, | |
732 | unsigned long first_index, unsigned int max_items) | |
733 | { | |
734 | unsigned long max_index; | |
735 | struct radix_tree_node *node; | |
736 | unsigned long cur_index = first_index; | |
737 | unsigned int ret; | |
738 | ||
739 | node = rcu_dereference(root->rnode); | |
740 | if (!node) | |
741 | return 0; | |
742 | ||
743 | if (!radix_tree_is_indirect_ptr(node)) { | |
744 | if (first_index > 0) | |
745 | return 0; | |
746 | results[0] = node; | |
747 | return 1; | |
748 | } | |
749 | node = radix_tree_indirect_to_ptr(node); | |
750 | ||
751 | max_index = radix_tree_maxindex(node->height); | |
752 | ||
753 | ret = 0; | |
754 | while (ret < max_items) { | |
755 | unsigned int nr_found; | |
756 | unsigned long next_index; /* Index of next search */ | |
757 | ||
758 | if (cur_index > max_index) | |
759 | break; | |
760 | nr_found = __lookup(node, results + ret, cur_index, | |
761 | max_items - ret, &next_index); | |
762 | ret += nr_found; | |
763 | if (next_index == 0) | |
764 | break; | |
765 | cur_index = next_index; | |
766 | } | |
767 | ||
768 | return ret; | |
769 | } | |
770 | EXPORT_SYMBOL(radix_tree_gang_lookup); | |
771 | ||
772 | /* | |
773 | * FIXME: the two tag_get()s here should use find_next_bit() instead of | |
774 | * open-coding the search. | |
775 | */ | |
776 | static unsigned int | |
777 | __lookup_tag(struct radix_tree_node *slot, void **results, unsigned long index, | |
778 | unsigned int max_items, unsigned long *next_index, unsigned int tag) | |
779 | { | |
780 | unsigned int nr_found = 0; | |
781 | unsigned int shift, height; | |
782 | ||
783 | height = slot->height; | |
784 | if (height == 0) | |
785 | goto out; | |
786 | shift = (height-1) * RADIX_TREE_MAP_SHIFT; | |
787 | ||
788 | while (height > 0) { | |
789 | unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK ; | |
790 | ||
791 | for (;;) { | |
792 | if (tag_get(slot, tag, i)) | |
793 | break; | |
794 | index &= ~((1UL << shift) - 1); | |
795 | index += 1UL << shift; | |
796 | if (index == 0) | |
797 | goto out; /* 32-bit wraparound */ | |
798 | i++; | |
799 | if (i == RADIX_TREE_MAP_SIZE) | |
800 | goto out; | |
801 | } | |
802 | height--; | |
803 | if (height == 0) { /* Bottom level: grab some items */ | |
804 | unsigned long j = index & RADIX_TREE_MAP_MASK; | |
805 | ||
806 | for ( ; j < RADIX_TREE_MAP_SIZE; j++) { | |
807 | struct radix_tree_node *node; | |
808 | index++; | |
809 | if (!tag_get(slot, tag, j)) | |
810 | continue; | |
811 | node = slot->slots[j]; | |
812 | /* | |
813 | * Even though the tag was found set, we need to | |
814 | * recheck that we have a non-NULL node, because | |
815 | * if this lookup is lockless, it may have been | |
816 | * subsequently deleted. | |
817 | * | |
818 | * Similar care must be taken in any place that | |
819 | * lookup ->slots[x] without a lock (ie. can't | |
820 | * rely on its value remaining the same). | |
821 | */ | |
822 | if (node) { | |
823 | node = rcu_dereference(node); | |
824 | results[nr_found++] = node; | |
825 | if (nr_found == max_items) | |
826 | goto out; | |
827 | } | |
828 | } | |
829 | } | |
830 | shift -= RADIX_TREE_MAP_SHIFT; | |
831 | slot = rcu_dereference(slot->slots[i]); | |
832 | if (slot == NULL) | |
833 | break; | |
834 | } | |
835 | out: | |
836 | *next_index = index; | |
837 | return nr_found; | |
838 | } | |
839 | ||
840 | /** | |
841 | * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree | |
842 | * based on a tag | |
843 | * @root: radix tree root | |
844 | * @results: where the results of the lookup are placed | |
845 | * @first_index: start the lookup from this key | |
846 | * @max_items: place up to this many items at *results | |
847 | * @tag: the tag index (< RADIX_TREE_MAX_TAGS) | |
848 | * | |
849 | * Performs an index-ascending scan of the tree for present items which | |
850 | * have the tag indexed by @tag set. Places the items at *@results and | |
851 | * returns the number of items which were placed at *@results. | |
852 | */ | |
853 | unsigned int | |
854 | radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results, | |
855 | unsigned long first_index, unsigned int max_items, | |
856 | unsigned int tag) | |
857 | { | |
858 | struct radix_tree_node *node; | |
859 | unsigned long max_index; | |
860 | unsigned long cur_index = first_index; | |
861 | unsigned int ret; | |
862 | ||
863 | /* check the root's tag bit */ | |
864 | if (!root_tag_get(root, tag)) | |
865 | return 0; | |
866 | ||
867 | node = rcu_dereference(root->rnode); | |
868 | if (!node) | |
869 | return 0; | |
870 | ||
871 | if (!radix_tree_is_indirect_ptr(node)) { | |
872 | if (first_index > 0) | |
873 | return 0; | |
874 | results[0] = node; | |
875 | return 1; | |
876 | } | |
877 | node = radix_tree_indirect_to_ptr(node); | |
878 | ||
879 | max_index = radix_tree_maxindex(node->height); | |
880 | ||
881 | ret = 0; | |
882 | while (ret < max_items) { | |
883 | unsigned int nr_found; | |
884 | unsigned long next_index; /* Index of next search */ | |
885 | ||
886 | if (cur_index > max_index) | |
887 | break; | |
888 | nr_found = __lookup_tag(node, results + ret, cur_index, | |
889 | max_items - ret, &next_index, tag); | |
890 | ret += nr_found; | |
891 | if (next_index == 0) | |
892 | break; | |
893 | cur_index = next_index; | |
894 | } | |
895 | ||
896 | return ret; | |
897 | } | |
898 | EXPORT_SYMBOL(radix_tree_gang_lookup_tag); | |
899 | ||
900 | /** | |
901 | * radix_tree_shrink - shrink height of a radix tree to minimal | |
902 | * @root radix tree root | |
903 | */ | |
904 | static inline void radix_tree_shrink(struct radix_tree_root *root) | |
905 | { | |
906 | /* try to shrink tree height */ | |
907 | while (root->height > 0) { | |
908 | struct radix_tree_node *to_free = root->rnode; | |
909 | void *newptr; | |
910 | ||
911 | BUG_ON(!radix_tree_is_indirect_ptr(to_free)); | |
912 | to_free = radix_tree_indirect_to_ptr(to_free); | |
913 | ||
914 | /* | |
915 | * The candidate node has more than one child, or its child | |
916 | * is not at the leftmost slot, we cannot shrink. | |
917 | */ | |
918 | if (to_free->count != 1) | |
919 | break; | |
920 | if (!to_free->slots[0]) | |
921 | break; | |
922 | ||
923 | /* | |
924 | * We don't need rcu_assign_pointer(), since we are simply | |
925 | * moving the node from one part of the tree to another. If | |
926 | * it was safe to dereference the old pointer to it | |
927 | * (to_free->slots[0]), it will be safe to dereference the new | |
928 | * one (root->rnode). | |
929 | */ | |
930 | newptr = to_free->slots[0]; | |
931 | if (root->height > 1) | |
932 | newptr = radix_tree_ptr_to_indirect(newptr); | |
933 | root->rnode = newptr; | |
934 | root->height--; | |
935 | /* must only free zeroed nodes into the slab */ | |
936 | tag_clear(to_free, 0, 0); | |
937 | tag_clear(to_free, 1, 0); | |
938 | to_free->slots[0] = NULL; | |
939 | to_free->count = 0; | |
940 | radix_tree_node_free(to_free); | |
941 | } | |
942 | } | |
943 | ||
944 | /** | |
945 | * radix_tree_delete - delete an item from a radix tree | |
946 | * @root: radix tree root | |
947 | * @index: index key | |
948 | * | |
949 | * Remove the item at @index from the radix tree rooted at @root. | |
950 | * | |
951 | * Returns the address of the deleted item, or NULL if it was not present. | |
952 | */ | |
953 | void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) | |
954 | { | |
955 | /* | |
956 | * The radix tree path needs to be one longer than the maximum path | |
957 | * since the "list" is null terminated. | |
958 | */ | |
959 | struct radix_tree_path path[RADIX_TREE_MAX_PATH + 1], *pathp = path; | |
960 | struct radix_tree_node *slot = NULL; | |
961 | struct radix_tree_node *to_free; | |
962 | unsigned int height, shift; | |
963 | int tag; | |
964 | int offset; | |
965 | ||
966 | height = root->height; | |
967 | if (index > radix_tree_maxindex(height)) | |
968 | goto out; | |
969 | ||
970 | slot = root->rnode; | |
971 | if (height == 0) { | |
972 | root_tag_clear_all(root); | |
973 | root->rnode = NULL; | |
974 | goto out; | |
975 | } | |
976 | slot = radix_tree_indirect_to_ptr(slot); | |
977 | ||
978 | shift = (height - 1) * RADIX_TREE_MAP_SHIFT; | |
979 | pathp->node = NULL; | |
980 | ||
981 | do { | |
982 | if (slot == NULL) | |
983 | goto out; | |
984 | ||
985 | pathp++; | |
986 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; | |
987 | pathp->offset = offset; | |
988 | pathp->node = slot; | |
989 | slot = slot->slots[offset]; | |
990 | shift -= RADIX_TREE_MAP_SHIFT; | |
991 | height--; | |
992 | } while (height > 0); | |
993 | ||
994 | if (slot == NULL) | |
995 | goto out; | |
996 | ||
997 | /* | |
998 | * Clear all tags associated with the just-deleted item | |
999 | */ | |
1000 | for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) { | |
1001 | if (tag_get(pathp->node, tag, pathp->offset)) | |
1002 | radix_tree_tag_clear(root, index, tag); | |
1003 | } | |
1004 | ||
1005 | to_free = NULL; | |
1006 | /* Now free the nodes we do not need anymore */ | |
1007 | while (pathp->node) { | |
1008 | pathp->node->slots[pathp->offset] = NULL; | |
1009 | pathp->node->count--; | |
1010 | /* | |
1011 | * Queue the node for deferred freeing after the | |
1012 | * last reference to it disappears (set NULL, above). | |
1013 | */ | |
1014 | if (to_free) | |
1015 | radix_tree_node_free(to_free); | |
1016 | ||
1017 | if (pathp->node->count) { | |
1018 | if (pathp->node == | |
1019 | radix_tree_indirect_to_ptr(root->rnode)) | |
1020 | radix_tree_shrink(root); | |
1021 | goto out; | |
1022 | } | |
1023 | ||
1024 | /* Node with zero slots in use so free it */ | |
1025 | to_free = pathp->node; | |
1026 | pathp--; | |
1027 | ||
1028 | } | |
1029 | root_tag_clear_all(root); | |
1030 | root->height = 0; | |
1031 | root->rnode = NULL; | |
1032 | if (to_free) | |
1033 | radix_tree_node_free(to_free); | |
1034 | ||
1035 | out: | |
1036 | return slot; | |
1037 | } | |
1038 | EXPORT_SYMBOL(radix_tree_delete); | |
1039 | ||
1040 | /** | |
1041 | * radix_tree_tagged - test whether any items in the tree are tagged | |
1042 | * @root: radix tree root | |
1043 | * @tag: tag to test | |
1044 | */ | |
1045 | int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag) | |
1046 | { | |
1047 | return root_tag_get(root, tag); | |
1048 | } | |
1049 | EXPORT_SYMBOL(radix_tree_tagged); | |
1050 | ||
1051 | static void | |
1052 | radix_tree_node_ctor(struct kmem_cache *cachep, void *node) | |
1053 | { | |
1054 | memset(node, 0, sizeof(struct radix_tree_node)); | |
1055 | } | |
1056 | ||
1057 | static __init unsigned long __maxindex(unsigned int height) | |
1058 | { | |
1059 | unsigned int width = height * RADIX_TREE_MAP_SHIFT; | |
1060 | int shift = RADIX_TREE_INDEX_BITS - width; | |
1061 | ||
1062 | if (shift < 0) | |
1063 | return ~0UL; | |
1064 | if (shift >= BITS_PER_LONG) | |
1065 | return 0UL; | |
1066 | return ~0UL >> shift; | |
1067 | } | |
1068 | ||
1069 | static __init void radix_tree_init_maxindex(void) | |
1070 | { | |
1071 | unsigned int i; | |
1072 | ||
1073 | for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++) | |
1074 | height_to_maxindex[i] = __maxindex(i); | |
1075 | } | |
1076 | ||
1077 | static int radix_tree_callback(struct notifier_block *nfb, | |
1078 | unsigned long action, | |
1079 | void *hcpu) | |
1080 | { | |
1081 | int cpu = (long)hcpu; | |
1082 | struct radix_tree_preload *rtp; | |
1083 | ||
1084 | /* Free per-cpu pool of perloaded nodes */ | |
1085 | if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) { | |
1086 | rtp = &per_cpu(radix_tree_preloads, cpu); | |
1087 | while (rtp->nr) { | |
1088 | kmem_cache_free(radix_tree_node_cachep, | |
1089 | rtp->nodes[rtp->nr-1]); | |
1090 | rtp->nodes[rtp->nr-1] = NULL; | |
1091 | rtp->nr--; | |
1092 | } | |
1093 | } | |
1094 | return NOTIFY_OK; | |
1095 | } | |
1096 | ||
1097 | void __init radix_tree_init(void) | |
1098 | { | |
1099 | radix_tree_node_cachep = kmem_cache_create("radix_tree_node", | |
1100 | sizeof(struct radix_tree_node), 0, | |
1101 | SLAB_PANIC, radix_tree_node_ctor); | |
1102 | radix_tree_init_maxindex(); | |
1103 | hotcpu_notifier(radix_tree_callback, 0); | |
1104 | } |