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>
38 #define RADIX_TREE_MAP_SHIFT (CONFIG_BASE_SMALL ? 4 : 6)
40 #define RADIX_TREE_MAP_SHIFT 3 /* For more stressful testing */
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 */
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;
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))
67 * The height_to_maxindex array needs to be one deeper than the maximum
68 * path as height 0 holds only 1 entry.
70 static unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH + 1] __read_mostly;
73 * Radix tree node cache.
75 static struct kmem_cache *radix_tree_node_cachep;
78 * Per-cpu pool of preloaded nodes
80 struct radix_tree_preload {
82 struct radix_tree_node *nodes[RADIX_TREE_MAX_PATH];
84 DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, };
86 static inline gfp_t root_gfp_mask(struct radix_tree_root *root)
88 return root->gfp_mask & __GFP_BITS_MASK;
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.
95 static struct radix_tree_node *
96 radix_tree_node_alloc(struct radix_tree_root *root)
98 struct radix_tree_node *ret;
99 gfp_t gfp_mask = root_gfp_mask(root);
101 ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
102 if (ret == NULL && !(gfp_mask & __GFP_WAIT)) {
103 struct radix_tree_preload *rtp;
105 rtp = &__get_cpu_var(radix_tree_preloads);
107 ret = rtp->nodes[rtp->nr - 1];
108 rtp->nodes[rtp->nr - 1] = NULL;
112 BUG_ON(radix_tree_is_indirect_ptr(ret));
116 static void radix_tree_node_rcu_free(struct rcu_head *head)
118 struct radix_tree_node *node =
119 container_of(head, struct radix_tree_node, rcu_head);
120 kmem_cache_free(radix_tree_node_cachep, node);
124 radix_tree_node_free(struct radix_tree_node *node)
126 call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
130 * Load up this CPU's radix_tree_node buffer with sufficient objects to
131 * ensure that the addition of a single element in the tree cannot fail. On
132 * success, return zero, with preemption disabled. On error, return -ENOMEM
133 * with preemption not disabled.
135 int radix_tree_preload(gfp_t gfp_mask)
137 struct radix_tree_preload *rtp;
138 struct radix_tree_node *node;
142 rtp = &__get_cpu_var(radix_tree_preloads);
143 while (rtp->nr < ARRAY_SIZE(rtp->nodes)) {
145 node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
149 rtp = &__get_cpu_var(radix_tree_preloads);
150 if (rtp->nr < ARRAY_SIZE(rtp->nodes))
151 rtp->nodes[rtp->nr++] = node;
153 kmem_cache_free(radix_tree_node_cachep, node);
159 EXPORT_SYMBOL(radix_tree_preload);
161 static inline void tag_set(struct radix_tree_node *node, unsigned int tag,
164 __set_bit(offset, node->tags[tag]);
167 static inline void tag_clear(struct radix_tree_node *node, unsigned int tag,
170 __clear_bit(offset, node->tags[tag]);
173 static inline int tag_get(struct radix_tree_node *node, unsigned int tag,
176 return test_bit(offset, node->tags[tag]);
179 static inline void root_tag_set(struct radix_tree_root *root, unsigned int tag)
181 root->gfp_mask |= (__force gfp_t)(1 << (tag + __GFP_BITS_SHIFT));
185 static inline void root_tag_clear(struct radix_tree_root *root, unsigned int tag)
187 root->gfp_mask &= (__force gfp_t)~(1 << (tag + __GFP_BITS_SHIFT));
190 static inline void root_tag_clear_all(struct radix_tree_root *root)
192 root->gfp_mask &= __GFP_BITS_MASK;
195 static inline int root_tag_get(struct radix_tree_root *root, unsigned int tag)
197 return (__force unsigned)root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT));
201 * Returns 1 if any slot in the node has this tag set.
202 * Otherwise returns 0.
204 static inline int any_tag_set(struct radix_tree_node *node, unsigned int tag)
207 for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
208 if (node->tags[tag][idx])
215 * Return the maximum key which can be store into a
216 * radix tree with height HEIGHT.
218 static inline unsigned long radix_tree_maxindex(unsigned int height)
220 return height_to_maxindex[height];
224 * Extend a radix tree so it can store key @index.
226 static int radix_tree_extend(struct radix_tree_root *root, unsigned long index)
228 struct radix_tree_node *node;
232 /* Figure out what the height should be. */
233 height = root->height + 1;
234 while (index > radix_tree_maxindex(height))
237 if (root->rnode == NULL) {
238 root->height = height;
243 unsigned int newheight;
244 if (!(node = radix_tree_node_alloc(root)))
247 /* Increase the height. */
248 node->slots[0] = radix_tree_indirect_to_ptr(root->rnode);
250 /* Propagate the aggregated tag info into the new root */
251 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
252 if (root_tag_get(root, tag))
253 tag_set(node, tag, 0);
256 newheight = root->height+1;
257 node->height = newheight;
259 node = radix_tree_ptr_to_indirect(node);
260 rcu_assign_pointer(root->rnode, node);
261 root->height = newheight;
262 } while (height > root->height);
268 * radix_tree_insert - insert into a radix tree
269 * @root: radix tree root
271 * @item: item to insert
273 * Insert an item into the radix tree at position @index.
275 int radix_tree_insert(struct radix_tree_root *root,
276 unsigned long index, void *item)
278 struct radix_tree_node *node = NULL, *slot;
279 unsigned int height, shift;
283 BUG_ON(radix_tree_is_indirect_ptr(item));
285 /* Make sure the tree is high enough. */
286 if (index > radix_tree_maxindex(root->height)) {
287 error = radix_tree_extend(root, index);
292 slot = radix_tree_indirect_to_ptr(root->rnode);
294 height = root->height;
295 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
297 offset = 0; /* uninitialised var warning */
300 /* Have to add a child node. */
301 if (!(slot = radix_tree_node_alloc(root)))
303 slot->height = height;
305 rcu_assign_pointer(node->slots[offset], slot);
308 rcu_assign_pointer(root->rnode,
309 radix_tree_ptr_to_indirect(slot));
312 /* Go a level down */
313 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
315 slot = node->slots[offset];
316 shift -= RADIX_TREE_MAP_SHIFT;
325 rcu_assign_pointer(node->slots[offset], item);
326 BUG_ON(tag_get(node, 0, offset));
327 BUG_ON(tag_get(node, 1, offset));
329 rcu_assign_pointer(root->rnode, item);
330 BUG_ON(root_tag_get(root, 0));
331 BUG_ON(root_tag_get(root, 1));
336 EXPORT_SYMBOL(radix_tree_insert);
339 * radix_tree_lookup_slot - lookup a slot in a radix tree
340 * @root: radix tree root
343 * Returns: the slot corresponding to the position @index in the
344 * radix tree @root. This is useful for update-if-exists operations.
346 * This function cannot be called under rcu_read_lock, it must be
347 * excluded from writers, as must the returned slot for subsequent
348 * use by radix_tree_deref_slot() and radix_tree_replace slot.
349 * Caller must hold tree write locked across slot lookup and
352 void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index)
354 unsigned int height, shift;
355 struct radix_tree_node *node, **slot;
361 if (!radix_tree_is_indirect_ptr(node)) {
364 return (void **)&root->rnode;
366 node = radix_tree_indirect_to_ptr(node);
368 height = node->height;
369 if (index > radix_tree_maxindex(height))
372 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
375 slot = (struct radix_tree_node **)
376 (node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK));
381 shift -= RADIX_TREE_MAP_SHIFT;
383 } while (height > 0);
385 return (void **)slot;
387 EXPORT_SYMBOL(radix_tree_lookup_slot);
390 * radix_tree_lookup - perform lookup operation on a radix tree
391 * @root: radix tree root
394 * Lookup the item at the position @index in the radix tree @root.
396 * This function can be called under rcu_read_lock, however the caller
397 * must manage lifetimes of leaf nodes (eg. RCU may also be used to free
398 * them safely). No RCU barriers are required to access or modify the
399 * returned item, however.
401 void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
403 unsigned int height, shift;
404 struct radix_tree_node *node, **slot;
406 node = rcu_dereference(root->rnode);
410 if (!radix_tree_is_indirect_ptr(node)) {
415 node = radix_tree_indirect_to_ptr(node);
417 height = node->height;
418 if (index > radix_tree_maxindex(height))
421 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
424 slot = (struct radix_tree_node **)
425 (node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK));
426 node = rcu_dereference(*slot);
430 shift -= RADIX_TREE_MAP_SHIFT;
432 } while (height > 0);
436 EXPORT_SYMBOL(radix_tree_lookup);
439 * radix_tree_tag_set - set a tag on a radix tree node
440 * @root: radix tree root
444 * Set the search tag (which must be < RADIX_TREE_MAX_TAGS)
445 * corresponding to @index in the radix tree. From
446 * the root all the way down to the leaf node.
448 * Returns the address of the tagged item. Setting a tag on a not-present
451 void *radix_tree_tag_set(struct radix_tree_root *root,
452 unsigned long index, unsigned int tag)
454 unsigned int height, shift;
455 struct radix_tree_node *slot;
457 height = root->height;
458 BUG_ON(index > radix_tree_maxindex(height));
460 slot = radix_tree_indirect_to_ptr(root->rnode);
461 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
466 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
467 if (!tag_get(slot, tag, offset))
468 tag_set(slot, tag, offset);
469 slot = slot->slots[offset];
470 BUG_ON(slot == NULL);
471 shift -= RADIX_TREE_MAP_SHIFT;
475 /* set the root's tag bit */
476 if (slot && !root_tag_get(root, tag))
477 root_tag_set(root, tag);
481 EXPORT_SYMBOL(radix_tree_tag_set);
484 * radix_tree_tag_clear - clear a tag on a radix tree node
485 * @root: radix tree root
489 * Clear the search tag (which must be < RADIX_TREE_MAX_TAGS)
490 * corresponding to @index in the radix tree. If
491 * this causes the leaf node to have no tags set then clear the tag in the
492 * next-to-leaf node, etc.
494 * Returns the address of the tagged item on success, else NULL. ie:
495 * has the same return value and semantics as radix_tree_lookup().
497 void *radix_tree_tag_clear(struct radix_tree_root *root,
498 unsigned long index, unsigned int tag)
501 * The radix tree path needs to be one longer than the maximum path
502 * since the "list" is null terminated.
504 struct radix_tree_path path[RADIX_TREE_MAX_PATH + 1], *pathp = path;
505 struct radix_tree_node *slot = NULL;
506 unsigned int height, shift;
508 height = root->height;
509 if (index > radix_tree_maxindex(height))
512 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
514 slot = radix_tree_indirect_to_ptr(root->rnode);
522 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
523 pathp[1].offset = offset;
524 pathp[1].node = slot;
525 slot = slot->slots[offset];
527 shift -= RADIX_TREE_MAP_SHIFT;
534 while (pathp->node) {
535 if (!tag_get(pathp->node, tag, pathp->offset))
537 tag_clear(pathp->node, tag, pathp->offset);
538 if (any_tag_set(pathp->node, tag))
543 /* clear the root's tag bit */
544 if (root_tag_get(root, tag))
545 root_tag_clear(root, tag);
550 EXPORT_SYMBOL(radix_tree_tag_clear);
552 #ifndef __KERNEL__ /* Only the test harness uses this at present */
554 * radix_tree_tag_get - get a tag on a radix tree node
555 * @root: radix tree root
557 * @tag: tag index (< RADIX_TREE_MAX_TAGS)
561 * 0: tag not present or not set
564 int radix_tree_tag_get(struct radix_tree_root *root,
565 unsigned long index, unsigned int tag)
567 unsigned int height, shift;
568 struct radix_tree_node *node;
569 int saw_unset_tag = 0;
571 /* check the root's tag bit */
572 if (!root_tag_get(root, tag))
575 node = rcu_dereference(root->rnode);
579 if (!radix_tree_is_indirect_ptr(node))
581 node = radix_tree_indirect_to_ptr(node);
583 height = node->height;
584 if (index > radix_tree_maxindex(height))
587 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
595 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
598 * This is just a debug check. Later, we can bale as soon as
599 * we see an unset tag.
601 if (!tag_get(node, tag, offset))
604 int ret = tag_get(node, tag, offset);
606 BUG_ON(ret && saw_unset_tag);
609 node = rcu_dereference(node->slots[offset]);
610 shift -= RADIX_TREE_MAP_SHIFT;
614 EXPORT_SYMBOL(radix_tree_tag_get);
618 * radix_tree_next_hole - find the next hole (not-present entry)
621 * @max_scan: maximum range to search
623 * Search the set [index, min(index+max_scan-1, MAX_INDEX)] for the lowest
626 * Returns: the index of the hole if found, otherwise returns an index
627 * outside of the set specified (in which case 'return - index >= max_scan'
630 * radix_tree_next_hole may be called under rcu_read_lock. However, like
631 * radix_tree_gang_lookup, this will not atomically search a snapshot of the
632 * tree at a single point in time. For example, if a hole is created at index
633 * 5, then subsequently a hole is created at index 10, radix_tree_next_hole
634 * covering both indexes may return 10 if called under rcu_read_lock.
636 unsigned long radix_tree_next_hole(struct radix_tree_root *root,
637 unsigned long index, unsigned long max_scan)
641 for (i = 0; i < max_scan; i++) {
642 if (!radix_tree_lookup(root, index))
651 EXPORT_SYMBOL(radix_tree_next_hole);
654 __lookup(struct radix_tree_node *slot, void **results, unsigned long index,
655 unsigned int max_items, unsigned long *next_index)
657 unsigned int nr_found = 0;
658 unsigned int shift, height;
661 height = slot->height;
664 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
666 for ( ; height > 1; height--) {
667 i = (index >> shift) & RADIX_TREE_MAP_MASK;
669 if (slot->slots[i] != NULL)
671 index &= ~((1UL << shift) - 1);
672 index += 1UL << shift;
674 goto out; /* 32-bit wraparound */
676 if (i == RADIX_TREE_MAP_SIZE)
680 shift -= RADIX_TREE_MAP_SHIFT;
681 slot = rcu_dereference(slot->slots[i]);
686 /* Bottom level: grab some items */
687 for (i = index & RADIX_TREE_MAP_MASK; i < RADIX_TREE_MAP_SIZE; i++) {
688 struct radix_tree_node *node;
690 node = slot->slots[i];
692 results[nr_found++] = rcu_dereference(node);
693 if (nr_found == max_items)
703 * radix_tree_gang_lookup - perform multiple lookup on a radix tree
704 * @root: radix tree root
705 * @results: where the results of the lookup are placed
706 * @first_index: start the lookup from this key
707 * @max_items: place up to this many items at *results
709 * Performs an index-ascending scan of the tree for present items. Places
710 * them at *@results and returns the number of items which were placed at
713 * The implementation is naive.
715 * Like radix_tree_lookup, radix_tree_gang_lookup may be called under
716 * rcu_read_lock. In this case, rather than the returned results being
717 * an atomic snapshot of the tree at a single point in time, the semantics
718 * of an RCU protected gang lookup are as though multiple radix_tree_lookups
719 * have been issued in individual locks, and results stored in 'results'.
722 radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
723 unsigned long first_index, unsigned int max_items)
725 unsigned long max_index;
726 struct radix_tree_node *node;
727 unsigned long cur_index = first_index;
730 node = rcu_dereference(root->rnode);
734 if (!radix_tree_is_indirect_ptr(node)) {
740 node = radix_tree_indirect_to_ptr(node);
742 max_index = radix_tree_maxindex(node->height);
745 while (ret < max_items) {
746 unsigned int nr_found;
747 unsigned long next_index; /* Index of next search */
749 if (cur_index > max_index)
751 nr_found = __lookup(node, results + ret, cur_index,
752 max_items - ret, &next_index);
756 cur_index = next_index;
761 EXPORT_SYMBOL(radix_tree_gang_lookup);
764 * FIXME: the two tag_get()s here should use find_next_bit() instead of
765 * open-coding the search.
768 __lookup_tag(struct radix_tree_node *slot, void **results, unsigned long index,
769 unsigned int max_items, unsigned long *next_index, unsigned int tag)
771 unsigned int nr_found = 0;
772 unsigned int shift, height;
774 height = slot->height;
777 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
780 unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK ;
783 if (tag_get(slot, tag, i))
785 index &= ~((1UL << shift) - 1);
786 index += 1UL << shift;
788 goto out; /* 32-bit wraparound */
790 if (i == RADIX_TREE_MAP_SIZE)
794 if (height == 0) { /* Bottom level: grab some items */
795 unsigned long j = index & RADIX_TREE_MAP_MASK;
797 for ( ; j < RADIX_TREE_MAP_SIZE; j++) {
798 struct radix_tree_node *node;
800 if (!tag_get(slot, tag, j))
802 node = slot->slots[j];
804 * Even though the tag was found set, we need to
805 * recheck that we have a non-NULL node, because
806 * if this lookup is lockless, it may have been
807 * subsequently deleted.
809 * Similar care must be taken in any place that
810 * lookup ->slots[x] without a lock (ie. can't
811 * rely on its value remaining the same).
814 node = rcu_dereference(node);
815 results[nr_found++] = node;
816 if (nr_found == max_items)
821 shift -= RADIX_TREE_MAP_SHIFT;
822 slot = rcu_dereference(slot->slots[i]);
832 * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree
834 * @root: radix tree root
835 * @results: where the results of the lookup are placed
836 * @first_index: start the lookup from this key
837 * @max_items: place up to this many items at *results
838 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
840 * Performs an index-ascending scan of the tree for present items which
841 * have the tag indexed by @tag set. Places the items at *@results and
842 * returns the number of items which were placed at *@results.
845 radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
846 unsigned long first_index, unsigned int max_items,
849 struct radix_tree_node *node;
850 unsigned long max_index;
851 unsigned long cur_index = first_index;
854 /* check the root's tag bit */
855 if (!root_tag_get(root, tag))
858 node = rcu_dereference(root->rnode);
862 if (!radix_tree_is_indirect_ptr(node)) {
868 node = radix_tree_indirect_to_ptr(node);
870 max_index = radix_tree_maxindex(node->height);
873 while (ret < max_items) {
874 unsigned int nr_found;
875 unsigned long next_index; /* Index of next search */
877 if (cur_index > max_index)
879 nr_found = __lookup_tag(node, results + ret, cur_index,
880 max_items - ret, &next_index, tag);
884 cur_index = next_index;
889 EXPORT_SYMBOL(radix_tree_gang_lookup_tag);
892 * radix_tree_shrink - shrink height of a radix tree to minimal
893 * @root radix tree root
895 static inline void radix_tree_shrink(struct radix_tree_root *root)
897 /* try to shrink tree height */
898 while (root->height > 0) {
899 struct radix_tree_node *to_free = root->rnode;
902 BUG_ON(!radix_tree_is_indirect_ptr(to_free));
903 to_free = radix_tree_indirect_to_ptr(to_free);
906 * The candidate node has more than one child, or its child
907 * is not at the leftmost slot, we cannot shrink.
909 if (to_free->count != 1)
911 if (!to_free->slots[0])
915 * We don't need rcu_assign_pointer(), since we are simply
916 * moving the node from one part of the tree to another. If
917 * it was safe to dereference the old pointer to it
918 * (to_free->slots[0]), it will be safe to dereference the new
921 newptr = to_free->slots[0];
922 if (root->height > 1)
923 newptr = radix_tree_ptr_to_indirect(newptr);
924 root->rnode = newptr;
926 /* must only free zeroed nodes into the slab */
927 tag_clear(to_free, 0, 0);
928 tag_clear(to_free, 1, 0);
929 to_free->slots[0] = NULL;
931 radix_tree_node_free(to_free);
936 * radix_tree_delete - delete an item from a radix tree
937 * @root: radix tree root
940 * Remove the item at @index from the radix tree rooted at @root.
942 * Returns the address of the deleted item, or NULL if it was not present.
944 void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
947 * The radix tree path needs to be one longer than the maximum path
948 * since the "list" is null terminated.
950 struct radix_tree_path path[RADIX_TREE_MAX_PATH + 1], *pathp = path;
951 struct radix_tree_node *slot = NULL;
952 struct radix_tree_node *to_free;
953 unsigned int height, shift;
957 height = root->height;
958 if (index > radix_tree_maxindex(height))
963 root_tag_clear_all(root);
967 slot = radix_tree_indirect_to_ptr(slot);
969 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
977 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
978 pathp->offset = offset;
980 slot = slot->slots[offset];
981 shift -= RADIX_TREE_MAP_SHIFT;
983 } while (height > 0);
989 * Clear all tags associated with the just-deleted item
991 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
992 if (tag_get(pathp->node, tag, pathp->offset))
993 radix_tree_tag_clear(root, index, tag);
997 /* Now free the nodes we do not need anymore */
998 while (pathp->node) {
999 pathp->node->slots[pathp->offset] = NULL;
1000 pathp->node->count--;
1002 * Queue the node for deferred freeing after the
1003 * last reference to it disappears (set NULL, above).
1006 radix_tree_node_free(to_free);
1008 if (pathp->node->count) {
1010 radix_tree_indirect_to_ptr(root->rnode))
1011 radix_tree_shrink(root);
1015 /* Node with zero slots in use so free it */
1016 to_free = pathp->node;
1020 root_tag_clear_all(root);
1024 radix_tree_node_free(to_free);
1029 EXPORT_SYMBOL(radix_tree_delete);
1032 * radix_tree_tagged - test whether any items in the tree are tagged
1033 * @root: radix tree root
1036 int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag)
1038 return root_tag_get(root, tag);
1040 EXPORT_SYMBOL(radix_tree_tagged);
1043 radix_tree_node_ctor(void *node, struct kmem_cache *cachep, unsigned long flags)
1045 memset(node, 0, sizeof(struct radix_tree_node));
1048 static __init unsigned long __maxindex(unsigned int height)
1050 unsigned int tmp = height * RADIX_TREE_MAP_SHIFT;
1051 unsigned long index = (~0UL >> (RADIX_TREE_INDEX_BITS - tmp - 1)) >> 1;
1053 if (tmp >= RADIX_TREE_INDEX_BITS)
1058 static __init void radix_tree_init_maxindex(void)
1062 for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++)
1063 height_to_maxindex[i] = __maxindex(i);
1066 static int radix_tree_callback(struct notifier_block *nfb,
1067 unsigned long action,
1070 int cpu = (long)hcpu;
1071 struct radix_tree_preload *rtp;
1073 /* Free per-cpu pool of perloaded nodes */
1074 if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
1075 rtp = &per_cpu(radix_tree_preloads, cpu);
1077 kmem_cache_free(radix_tree_node_cachep,
1078 rtp->nodes[rtp->nr-1]);
1079 rtp->nodes[rtp->nr-1] = NULL;
1086 void __init radix_tree_init(void)
1088 radix_tree_node_cachep = kmem_cache_create("radix_tree_node",
1089 sizeof(struct radix_tree_node), 0,
1090 SLAB_PANIC, radix_tree_node_ctor);
1091 radix_tree_init_maxindex();
1092 hotcpu_notifier(radix_tree_callback, 0);