V4L/DVB (5912): Clean up duplicate includes in drivers/media/
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / lib / radix-tree.c
blob514efb200be6775dd57633a71987a7dcfe2b9ee9
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
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.
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.
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.
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>
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
43 #define RADIX_TREE_MAP_SIZE (1UL << RADIX_TREE_MAP_SHIFT)
44 #define RADIX_TREE_MAP_MASK (RADIX_TREE_MAP_SIZE-1)
46 #define RADIX_TREE_TAG_LONGS \
47 ((RADIX_TREE_MAP_SIZE + BITS_PER_LONG - 1) / BITS_PER_LONG)
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];
57 struct radix_tree_path {
58 struct radix_tree_node *node;
59 int offset;
62 #define RADIX_TREE_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(unsigned long))
63 #define RADIX_TREE_MAX_PATH (RADIX_TREE_INDEX_BITS/RADIX_TREE_MAP_SHIFT + 2)
65 static unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH] __read_mostly;
68 * Radix tree node cache.
70 static struct kmem_cache *radix_tree_node_cachep;
73 * Per-cpu pool of preloaded nodes
75 struct radix_tree_preload {
76 int nr;
77 struct radix_tree_node *nodes[RADIX_TREE_MAX_PATH];
79 DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, };
81 static inline gfp_t root_gfp_mask(struct radix_tree_root *root)
83 return root->gfp_mask & __GFP_BITS_MASK;
87 * This assumes that the caller has performed appropriate preallocation, and
88 * that the caller has pinned this thread of control to the current CPU.
90 static struct radix_tree_node *
91 radix_tree_node_alloc(struct radix_tree_root *root)
93 struct radix_tree_node *ret;
94 gfp_t gfp_mask = root_gfp_mask(root);
96 ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
97 if (ret == NULL && !(gfp_mask & __GFP_WAIT)) {
98 struct radix_tree_preload *rtp;
100 rtp = &__get_cpu_var(radix_tree_preloads);
101 if (rtp->nr) {
102 ret = rtp->nodes[rtp->nr - 1];
103 rtp->nodes[rtp->nr - 1] = NULL;
104 rtp->nr--;
107 BUG_ON(radix_tree_is_direct_ptr(ret));
108 return ret;
111 static void radix_tree_node_rcu_free(struct rcu_head *head)
113 struct radix_tree_node *node =
114 container_of(head, struct radix_tree_node, rcu_head);
115 kmem_cache_free(radix_tree_node_cachep, node);
118 static inline void
119 radix_tree_node_free(struct radix_tree_node *node)
121 call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
125 * Load up this CPU's radix_tree_node buffer with sufficient objects to
126 * ensure that the addition of a single element in the tree cannot fail. On
127 * success, return zero, with preemption disabled. On error, return -ENOMEM
128 * with preemption not disabled.
130 int radix_tree_preload(gfp_t gfp_mask)
132 struct radix_tree_preload *rtp;
133 struct radix_tree_node *node;
134 int ret = -ENOMEM;
136 preempt_disable();
137 rtp = &__get_cpu_var(radix_tree_preloads);
138 while (rtp->nr < ARRAY_SIZE(rtp->nodes)) {
139 preempt_enable();
140 node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
141 if (node == NULL)
142 goto out;
143 preempt_disable();
144 rtp = &__get_cpu_var(radix_tree_preloads);
145 if (rtp->nr < ARRAY_SIZE(rtp->nodes))
146 rtp->nodes[rtp->nr++] = node;
147 else
148 kmem_cache_free(radix_tree_node_cachep, node);
150 ret = 0;
151 out:
152 return ret;
154 EXPORT_SYMBOL(radix_tree_preload);
156 static inline void tag_set(struct radix_tree_node *node, unsigned int tag,
157 int offset)
159 __set_bit(offset, node->tags[tag]);
162 static inline void tag_clear(struct radix_tree_node *node, unsigned int tag,
163 int offset)
165 __clear_bit(offset, node->tags[tag]);
168 static inline int tag_get(struct radix_tree_node *node, unsigned int tag,
169 int offset)
171 return test_bit(offset, node->tags[tag]);
174 static inline void root_tag_set(struct radix_tree_root *root, unsigned int tag)
176 root->gfp_mask |= (__force gfp_t)(1 << (tag + __GFP_BITS_SHIFT));
180 static inline void root_tag_clear(struct radix_tree_root *root, unsigned int tag)
182 root->gfp_mask &= (__force gfp_t)~(1 << (tag + __GFP_BITS_SHIFT));
185 static inline void root_tag_clear_all(struct radix_tree_root *root)
187 root->gfp_mask &= __GFP_BITS_MASK;
190 static inline int root_tag_get(struct radix_tree_root *root, unsigned int tag)
192 return (__force unsigned)root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT));
196 * Returns 1 if any slot in the node has this tag set.
197 * Otherwise returns 0.
199 static inline int any_tag_set(struct radix_tree_node *node, unsigned int tag)
201 int idx;
202 for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
203 if (node->tags[tag][idx])
204 return 1;
206 return 0;
210 * Return the maximum key which can be store into a
211 * radix tree with height HEIGHT.
213 static inline unsigned long radix_tree_maxindex(unsigned int height)
215 return height_to_maxindex[height];
219 * Extend a radix tree so it can store key @index.
221 static int radix_tree_extend(struct radix_tree_root *root, unsigned long index)
223 struct radix_tree_node *node;
224 unsigned int height;
225 int tag;
227 /* Figure out what the height should be. */
228 height = root->height + 1;
229 while (index > radix_tree_maxindex(height))
230 height++;
232 if (root->rnode == NULL) {
233 root->height = height;
234 goto out;
237 do {
238 unsigned int newheight;
239 if (!(node = radix_tree_node_alloc(root)))
240 return -ENOMEM;
242 /* Increase the height. */
243 node->slots[0] = radix_tree_direct_to_ptr(root->rnode);
245 /* Propagate the aggregated tag info into the new root */
246 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
247 if (root_tag_get(root, tag))
248 tag_set(node, tag, 0);
251 newheight = root->height+1;
252 node->height = newheight;
253 node->count = 1;
254 rcu_assign_pointer(root->rnode, node);
255 root->height = newheight;
256 } while (height > root->height);
257 out:
258 return 0;
262 * radix_tree_insert - insert into a radix tree
263 * @root: radix tree root
264 * @index: index key
265 * @item: item to insert
267 * Insert an item into the radix tree at position @index.
269 int radix_tree_insert(struct radix_tree_root *root,
270 unsigned long index, void *item)
272 struct radix_tree_node *node = NULL, *slot;
273 unsigned int height, shift;
274 int offset;
275 int error;
277 BUG_ON(radix_tree_is_direct_ptr(item));
279 /* Make sure the tree is high enough. */
280 if (index > radix_tree_maxindex(root->height)) {
281 error = radix_tree_extend(root, index);
282 if (error)
283 return error;
286 slot = root->rnode;
287 height = root->height;
288 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
290 offset = 0; /* uninitialised var warning */
291 while (height > 0) {
292 if (slot == NULL) {
293 /* Have to add a child node. */
294 if (!(slot = radix_tree_node_alloc(root)))
295 return -ENOMEM;
296 slot->height = height;
297 if (node) {
298 rcu_assign_pointer(node->slots[offset], slot);
299 node->count++;
300 } else
301 rcu_assign_pointer(root->rnode, slot);
304 /* Go a level down */
305 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
306 node = slot;
307 slot = node->slots[offset];
308 shift -= RADIX_TREE_MAP_SHIFT;
309 height--;
312 if (slot != NULL)
313 return -EEXIST;
315 if (node) {
316 node->count++;
317 rcu_assign_pointer(node->slots[offset], item);
318 BUG_ON(tag_get(node, 0, offset));
319 BUG_ON(tag_get(node, 1, offset));
320 } else {
321 rcu_assign_pointer(root->rnode, radix_tree_ptr_to_direct(item));
322 BUG_ON(root_tag_get(root, 0));
323 BUG_ON(root_tag_get(root, 1));
326 return 0;
328 EXPORT_SYMBOL(radix_tree_insert);
331 * radix_tree_lookup_slot - lookup a slot in a radix tree
332 * @root: radix tree root
333 * @index: index key
335 * Returns: the slot corresponding to the position @index in the
336 * radix tree @root. This is useful for update-if-exists operations.
338 * This function cannot be called under rcu_read_lock, it must be
339 * excluded from writers, as must the returned slot for subsequent
340 * use by radix_tree_deref_slot() and radix_tree_replace slot.
341 * Caller must hold tree write locked across slot lookup and
342 * replace.
344 void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index)
346 unsigned int height, shift;
347 struct radix_tree_node *node, **slot;
349 node = root->rnode;
350 if (node == NULL)
351 return NULL;
353 if (radix_tree_is_direct_ptr(node)) {
354 if (index > 0)
355 return NULL;
356 return (void **)&root->rnode;
359 height = node->height;
360 if (index > radix_tree_maxindex(height))
361 return NULL;
363 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
365 do {
366 slot = (struct radix_tree_node **)
367 (node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK));
368 node = *slot;
369 if (node == NULL)
370 return NULL;
372 shift -= RADIX_TREE_MAP_SHIFT;
373 height--;
374 } while (height > 0);
376 return (void **)slot;
378 EXPORT_SYMBOL(radix_tree_lookup_slot);
381 * radix_tree_lookup - perform lookup operation on a radix tree
382 * @root: radix tree root
383 * @index: index key
385 * Lookup the item at the position @index in the radix tree @root.
387 * This function can be called under rcu_read_lock, however the caller
388 * must manage lifetimes of leaf nodes (eg. RCU may also be used to free
389 * them safely). No RCU barriers are required to access or modify the
390 * returned item, however.
392 void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
394 unsigned int height, shift;
395 struct radix_tree_node *node, **slot;
397 node = rcu_dereference(root->rnode);
398 if (node == NULL)
399 return NULL;
401 if (radix_tree_is_direct_ptr(node)) {
402 if (index > 0)
403 return NULL;
404 return radix_tree_direct_to_ptr(node);
407 height = node->height;
408 if (index > radix_tree_maxindex(height))
409 return NULL;
411 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
413 do {
414 slot = (struct radix_tree_node **)
415 (node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK));
416 node = rcu_dereference(*slot);
417 if (node == NULL)
418 return NULL;
420 shift -= RADIX_TREE_MAP_SHIFT;
421 height--;
422 } while (height > 0);
424 return node;
426 EXPORT_SYMBOL(radix_tree_lookup);
429 * radix_tree_tag_set - set a tag on a radix tree node
430 * @root: radix tree root
431 * @index: index key
432 * @tag: tag index
434 * Set the search tag (which must be < RADIX_TREE_MAX_TAGS)
435 * corresponding to @index in the radix tree. From
436 * the root all the way down to the leaf node.
438 * Returns the address of the tagged item. Setting a tag on a not-present
439 * item is a bug.
441 void *radix_tree_tag_set(struct radix_tree_root *root,
442 unsigned long index, unsigned int tag)
444 unsigned int height, shift;
445 struct radix_tree_node *slot;
447 height = root->height;
448 BUG_ON(index > radix_tree_maxindex(height));
450 slot = root->rnode;
451 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
453 while (height > 0) {
454 int offset;
456 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
457 if (!tag_get(slot, tag, offset))
458 tag_set(slot, tag, offset);
459 slot = slot->slots[offset];
460 BUG_ON(slot == NULL);
461 shift -= RADIX_TREE_MAP_SHIFT;
462 height--;
465 /* set the root's tag bit */
466 if (slot && !root_tag_get(root, tag))
467 root_tag_set(root, tag);
469 return slot;
471 EXPORT_SYMBOL(radix_tree_tag_set);
474 * radix_tree_tag_clear - clear a tag on a radix tree node
475 * @root: radix tree root
476 * @index: index key
477 * @tag: tag index
479 * Clear the search tag (which must be < RADIX_TREE_MAX_TAGS)
480 * corresponding to @index in the radix tree. If
481 * this causes the leaf node to have no tags set then clear the tag in the
482 * next-to-leaf node, etc.
484 * Returns the address of the tagged item on success, else NULL. ie:
485 * has the same return value and semantics as radix_tree_lookup().
487 void *radix_tree_tag_clear(struct radix_tree_root *root,
488 unsigned long index, unsigned int tag)
490 struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path;
491 struct radix_tree_node *slot = NULL;
492 unsigned int height, shift;
494 height = root->height;
495 if (index > radix_tree_maxindex(height))
496 goto out;
498 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
499 pathp->node = NULL;
500 slot = root->rnode;
502 while (height > 0) {
503 int offset;
505 if (slot == NULL)
506 goto out;
508 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
509 pathp[1].offset = offset;
510 pathp[1].node = slot;
511 slot = slot->slots[offset];
512 pathp++;
513 shift -= RADIX_TREE_MAP_SHIFT;
514 height--;
517 if (slot == NULL)
518 goto out;
520 while (pathp->node) {
521 if (!tag_get(pathp->node, tag, pathp->offset))
522 goto out;
523 tag_clear(pathp->node, tag, pathp->offset);
524 if (any_tag_set(pathp->node, tag))
525 goto out;
526 pathp--;
529 /* clear the root's tag bit */
530 if (root_tag_get(root, tag))
531 root_tag_clear(root, tag);
533 out:
534 return slot;
536 EXPORT_SYMBOL(radix_tree_tag_clear);
538 #ifndef __KERNEL__ /* Only the test harness uses this at present */
540 * radix_tree_tag_get - get a tag on a radix tree node
541 * @root: radix tree root
542 * @index: index key
543 * @tag: tag index (< RADIX_TREE_MAX_TAGS)
545 * Return values:
547 * 0: tag not present or not set
548 * 1: tag set
550 int radix_tree_tag_get(struct radix_tree_root *root,
551 unsigned long index, unsigned int tag)
553 unsigned int height, shift;
554 struct radix_tree_node *node;
555 int saw_unset_tag = 0;
557 /* check the root's tag bit */
558 if (!root_tag_get(root, tag))
559 return 0;
561 node = rcu_dereference(root->rnode);
562 if (node == NULL)
563 return 0;
565 if (radix_tree_is_direct_ptr(node))
566 return (index == 0);
568 height = node->height;
569 if (index > radix_tree_maxindex(height))
570 return 0;
572 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
574 for ( ; ; ) {
575 int offset;
577 if (node == NULL)
578 return 0;
580 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
583 * This is just a debug check. Later, we can bale as soon as
584 * we see an unset tag.
586 if (!tag_get(node, tag, offset))
587 saw_unset_tag = 1;
588 if (height == 1) {
589 int ret = tag_get(node, tag, offset);
591 BUG_ON(ret && saw_unset_tag);
592 return !!ret;
594 node = rcu_dereference(node->slots[offset]);
595 shift -= RADIX_TREE_MAP_SHIFT;
596 height--;
599 EXPORT_SYMBOL(radix_tree_tag_get);
600 #endif
602 static unsigned int
603 __lookup(struct radix_tree_node *slot, void **results, unsigned long index,
604 unsigned int max_items, unsigned long *next_index)
606 unsigned int nr_found = 0;
607 unsigned int shift, height;
608 unsigned long i;
610 height = slot->height;
611 if (height == 0)
612 goto out;
613 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
615 for ( ; height > 1; height--) {
616 i = (index >> shift) & RADIX_TREE_MAP_MASK;
617 for (;;) {
618 if (slot->slots[i] != NULL)
619 break;
620 index &= ~((1UL << shift) - 1);
621 index += 1UL << shift;
622 if (index == 0)
623 goto out; /* 32-bit wraparound */
624 i++;
625 if (i == RADIX_TREE_MAP_SIZE)
626 goto out;
629 shift -= RADIX_TREE_MAP_SHIFT;
630 slot = rcu_dereference(slot->slots[i]);
631 if (slot == NULL)
632 goto out;
635 /* Bottom level: grab some items */
636 for (i = index & RADIX_TREE_MAP_MASK; i < RADIX_TREE_MAP_SIZE; i++) {
637 struct radix_tree_node *node;
638 index++;
639 node = slot->slots[i];
640 if (node) {
641 results[nr_found++] = rcu_dereference(node);
642 if (nr_found == max_items)
643 goto out;
646 out:
647 *next_index = index;
648 return nr_found;
652 * radix_tree_gang_lookup - perform multiple lookup on a radix tree
653 * @root: radix tree root
654 * @results: where the results of the lookup are placed
655 * @first_index: start the lookup from this key
656 * @max_items: place up to this many items at *results
658 * Performs an index-ascending scan of the tree for present items. Places
659 * them at *@results and returns the number of items which were placed at
660 * *@results.
662 * The implementation is naive.
664 * Like radix_tree_lookup, radix_tree_gang_lookup may be called under
665 * rcu_read_lock. In this case, rather than the returned results being
666 * an atomic snapshot of the tree at a single point in time, the semantics
667 * of an RCU protected gang lookup are as though multiple radix_tree_lookups
668 * have been issued in individual locks, and results stored in 'results'.
670 unsigned int
671 radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
672 unsigned long first_index, unsigned int max_items)
674 unsigned long max_index;
675 struct radix_tree_node *node;
676 unsigned long cur_index = first_index;
677 unsigned int ret;
679 node = rcu_dereference(root->rnode);
680 if (!node)
681 return 0;
683 if (radix_tree_is_direct_ptr(node)) {
684 if (first_index > 0)
685 return 0;
686 node = radix_tree_direct_to_ptr(node);
687 results[0] = rcu_dereference(node);
688 return 1;
691 max_index = radix_tree_maxindex(node->height);
693 ret = 0;
694 while (ret < max_items) {
695 unsigned int nr_found;
696 unsigned long next_index; /* Index of next search */
698 if (cur_index > max_index)
699 break;
700 nr_found = __lookup(node, results + ret, cur_index,
701 max_items - ret, &next_index);
702 ret += nr_found;
703 if (next_index == 0)
704 break;
705 cur_index = next_index;
708 return ret;
710 EXPORT_SYMBOL(radix_tree_gang_lookup);
713 * FIXME: the two tag_get()s here should use find_next_bit() instead of
714 * open-coding the search.
716 static unsigned int
717 __lookup_tag(struct radix_tree_node *slot, void **results, unsigned long index,
718 unsigned int max_items, unsigned long *next_index, unsigned int tag)
720 unsigned int nr_found = 0;
721 unsigned int shift, height;
723 height = slot->height;
724 if (height == 0)
725 goto out;
726 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
728 while (height > 0) {
729 unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK ;
731 for (;;) {
732 if (tag_get(slot, tag, i))
733 break;
734 index &= ~((1UL << shift) - 1);
735 index += 1UL << shift;
736 if (index == 0)
737 goto out; /* 32-bit wraparound */
738 i++;
739 if (i == RADIX_TREE_MAP_SIZE)
740 goto out;
742 height--;
743 if (height == 0) { /* Bottom level: grab some items */
744 unsigned long j = index & RADIX_TREE_MAP_MASK;
746 for ( ; j < RADIX_TREE_MAP_SIZE; j++) {
747 struct radix_tree_node *node;
748 index++;
749 if (!tag_get(slot, tag, j))
750 continue;
751 node = slot->slots[j];
753 * Even though the tag was found set, we need to
754 * recheck that we have a non-NULL node, because
755 * if this lookup is lockless, it may have been
756 * subsequently deleted.
758 * Similar care must be taken in any place that
759 * lookup ->slots[x] without a lock (ie. can't
760 * rely on its value remaining the same).
762 if (node) {
763 node = rcu_dereference(node);
764 results[nr_found++] = node;
765 if (nr_found == max_items)
766 goto out;
770 shift -= RADIX_TREE_MAP_SHIFT;
771 slot = rcu_dereference(slot->slots[i]);
772 if (slot == NULL)
773 break;
775 out:
776 *next_index = index;
777 return nr_found;
781 * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree
782 * based on a tag
783 * @root: radix tree root
784 * @results: where the results of the lookup are placed
785 * @first_index: start the lookup from this key
786 * @max_items: place up to this many items at *results
787 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
789 * Performs an index-ascending scan of the tree for present items which
790 * have the tag indexed by @tag set. Places the items at *@results and
791 * returns the number of items which were placed at *@results.
793 unsigned int
794 radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
795 unsigned long first_index, unsigned int max_items,
796 unsigned int tag)
798 struct radix_tree_node *node;
799 unsigned long max_index;
800 unsigned long cur_index = first_index;
801 unsigned int ret;
803 /* check the root's tag bit */
804 if (!root_tag_get(root, tag))
805 return 0;
807 node = rcu_dereference(root->rnode);
808 if (!node)
809 return 0;
811 if (radix_tree_is_direct_ptr(node)) {
812 if (first_index > 0)
813 return 0;
814 node = radix_tree_direct_to_ptr(node);
815 results[0] = rcu_dereference(node);
816 return 1;
819 max_index = radix_tree_maxindex(node->height);
821 ret = 0;
822 while (ret < max_items) {
823 unsigned int nr_found;
824 unsigned long next_index; /* Index of next search */
826 if (cur_index > max_index)
827 break;
828 nr_found = __lookup_tag(node, results + ret, cur_index,
829 max_items - ret, &next_index, tag);
830 ret += nr_found;
831 if (next_index == 0)
832 break;
833 cur_index = next_index;
836 return ret;
838 EXPORT_SYMBOL(radix_tree_gang_lookup_tag);
841 * radix_tree_shrink - shrink height of a radix tree to minimal
842 * @root radix tree root
844 static inline void radix_tree_shrink(struct radix_tree_root *root)
846 /* try to shrink tree height */
847 while (root->height > 0 &&
848 root->rnode->count == 1 &&
849 root->rnode->slots[0]) {
850 struct radix_tree_node *to_free = root->rnode;
851 void *newptr;
854 * We don't need rcu_assign_pointer(), since we are simply
855 * moving the node from one part of the tree to another. If
856 * it was safe to dereference the old pointer to it
857 * (to_free->slots[0]), it will be safe to dereference the new
858 * one (root->rnode).
860 newptr = to_free->slots[0];
861 if (root->height == 1)
862 newptr = radix_tree_ptr_to_direct(newptr);
863 root->rnode = newptr;
864 root->height--;
865 /* must only free zeroed nodes into the slab */
866 tag_clear(to_free, 0, 0);
867 tag_clear(to_free, 1, 0);
868 to_free->slots[0] = NULL;
869 to_free->count = 0;
870 radix_tree_node_free(to_free);
875 * radix_tree_delete - delete an item from a radix tree
876 * @root: radix tree root
877 * @index: index key
879 * Remove the item at @index from the radix tree rooted at @root.
881 * Returns the address of the deleted item, or NULL if it was not present.
883 void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
885 struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path;
886 struct radix_tree_node *slot = NULL;
887 struct radix_tree_node *to_free;
888 unsigned int height, shift;
889 int tag;
890 int offset;
892 height = root->height;
893 if (index > radix_tree_maxindex(height))
894 goto out;
896 slot = root->rnode;
897 if (height == 0 && root->rnode) {
898 slot = radix_tree_direct_to_ptr(slot);
899 root_tag_clear_all(root);
900 root->rnode = NULL;
901 goto out;
904 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
905 pathp->node = NULL;
907 do {
908 if (slot == NULL)
909 goto out;
911 pathp++;
912 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
913 pathp->offset = offset;
914 pathp->node = slot;
915 slot = slot->slots[offset];
916 shift -= RADIX_TREE_MAP_SHIFT;
917 height--;
918 } while (height > 0);
920 if (slot == NULL)
921 goto out;
924 * Clear all tags associated with the just-deleted item
926 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
927 if (tag_get(pathp->node, tag, pathp->offset))
928 radix_tree_tag_clear(root, index, tag);
931 to_free = NULL;
932 /* Now free the nodes we do not need anymore */
933 while (pathp->node) {
934 pathp->node->slots[pathp->offset] = NULL;
935 pathp->node->count--;
937 * Queue the node for deferred freeing after the
938 * last reference to it disappears (set NULL, above).
940 if (to_free)
941 radix_tree_node_free(to_free);
943 if (pathp->node->count) {
944 if (pathp->node == root->rnode)
945 radix_tree_shrink(root);
946 goto out;
949 /* Node with zero slots in use so free it */
950 to_free = pathp->node;
951 pathp--;
954 root_tag_clear_all(root);
955 root->height = 0;
956 root->rnode = NULL;
957 if (to_free)
958 radix_tree_node_free(to_free);
960 out:
961 return slot;
963 EXPORT_SYMBOL(radix_tree_delete);
966 * radix_tree_tagged - test whether any items in the tree are tagged
967 * @root: radix tree root
968 * @tag: tag to test
970 int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag)
972 return root_tag_get(root, tag);
974 EXPORT_SYMBOL(radix_tree_tagged);
976 static void
977 radix_tree_node_ctor(void *node, struct kmem_cache *cachep, unsigned long flags)
979 memset(node, 0, sizeof(struct radix_tree_node));
982 static __init unsigned long __maxindex(unsigned int height)
984 unsigned int tmp = height * RADIX_TREE_MAP_SHIFT;
985 unsigned long index = (~0UL >> (RADIX_TREE_INDEX_BITS - tmp - 1)) >> 1;
987 if (tmp >= RADIX_TREE_INDEX_BITS)
988 index = ~0UL;
989 return index;
992 static __init void radix_tree_init_maxindex(void)
994 unsigned int i;
996 for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++)
997 height_to_maxindex[i] = __maxindex(i);
1000 static int radix_tree_callback(struct notifier_block *nfb,
1001 unsigned long action,
1002 void *hcpu)
1004 int cpu = (long)hcpu;
1005 struct radix_tree_preload *rtp;
1007 /* Free per-cpu pool of perloaded nodes */
1008 if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
1009 rtp = &per_cpu(radix_tree_preloads, cpu);
1010 while (rtp->nr) {
1011 kmem_cache_free(radix_tree_node_cachep,
1012 rtp->nodes[rtp->nr-1]);
1013 rtp->nodes[rtp->nr-1] = NULL;
1014 rtp->nr--;
1017 return NOTIFY_OK;
1020 void __init radix_tree_init(void)
1022 radix_tree_node_cachep = kmem_cache_create("radix_tree_node",
1023 sizeof(struct radix_tree_node), 0,
1024 SLAB_PANIC, radix_tree_node_ctor);
1025 radix_tree_init_maxindex();
1026 hotcpu_notifier(radix_tree_callback, 0);