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 = NULL;
99 gfp_t gfp_mask = root_gfp_mask(root);
101 if (!(gfp_mask & __GFP_WAIT)) {
102 struct radix_tree_preload *rtp;
105 * Provided the caller has preloaded here, we will always
106 * succeed in getting a node here (and never reach
109 rtp = &__get_cpu_var(radix_tree_preloads);
111 ret = rtp->nodes[rtp->nr - 1];
112 rtp->nodes[rtp->nr - 1] = NULL;
117 ret = kmem_cache_alloc(radix_tree_node_cachep,
118 set_migrateflags(gfp_mask, __GFP_RECLAIMABLE));
120 BUG_ON(radix_tree_is_indirect_ptr(ret));
124 static void radix_tree_node_rcu_free(struct rcu_head *head)
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);
132 radix_tree_node_free(struct radix_tree_node *node)
134 call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
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.
143 int radix_tree_preload(gfp_t gfp_mask)
145 struct radix_tree_preload *rtp;
146 struct radix_tree_node *node;
150 rtp = &__get_cpu_var(radix_tree_preloads);
151 while (rtp->nr < ARRAY_SIZE(rtp->nodes)) {
153 node = kmem_cache_alloc(radix_tree_node_cachep,
154 set_migrateflags(gfp_mask, __GFP_RECLAIMABLE));
158 rtp = &__get_cpu_var(radix_tree_preloads);
159 if (rtp->nr < ARRAY_SIZE(rtp->nodes))
160 rtp->nodes[rtp->nr++] = node;
162 kmem_cache_free(radix_tree_node_cachep, node);
168 EXPORT_SYMBOL(radix_tree_preload);
170 static inline void tag_set(struct radix_tree_node *node, unsigned int tag,
173 __set_bit(offset, node->tags[tag]);
176 static inline void tag_clear(struct radix_tree_node *node, unsigned int tag,
179 __clear_bit(offset, node->tags[tag]);
182 static inline int tag_get(struct radix_tree_node *node, unsigned int tag,
185 return test_bit(offset, node->tags[tag]);
188 static inline void root_tag_set(struct radix_tree_root *root, unsigned int tag)
190 root->gfp_mask |= (__force gfp_t)(1 << (tag + __GFP_BITS_SHIFT));
194 static inline void root_tag_clear(struct radix_tree_root *root, unsigned int tag)
196 root->gfp_mask &= (__force gfp_t)~(1 << (tag + __GFP_BITS_SHIFT));
199 static inline void root_tag_clear_all(struct radix_tree_root *root)
201 root->gfp_mask &= __GFP_BITS_MASK;
204 static inline int root_tag_get(struct radix_tree_root *root, unsigned int tag)
206 return (__force unsigned)root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT));
210 * Returns 1 if any slot in the node has this tag set.
211 * Otherwise returns 0.
213 static inline int any_tag_set(struct radix_tree_node *node, unsigned int tag)
216 for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
217 if (node->tags[tag][idx])
224 * Return the maximum key which can be store into a
225 * radix tree with height HEIGHT.
227 static inline unsigned long radix_tree_maxindex(unsigned int height)
229 return height_to_maxindex[height];
233 * Extend a radix tree so it can store key @index.
235 static int radix_tree_extend(struct radix_tree_root *root, unsigned long index)
237 struct radix_tree_node *node;
241 /* Figure out what the height should be. */
242 height = root->height + 1;
243 while (index > radix_tree_maxindex(height))
246 if (root->rnode == NULL) {
247 root->height = height;
252 unsigned int newheight;
253 if (!(node = radix_tree_node_alloc(root)))
256 /* Increase the height. */
257 node->slots[0] = radix_tree_indirect_to_ptr(root->rnode);
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);
265 newheight = root->height+1;
266 node->height = newheight;
268 node = radix_tree_ptr_to_indirect(node);
269 rcu_assign_pointer(root->rnode, node);
270 root->height = newheight;
271 } while (height > root->height);
277 * radix_tree_insert - insert into a radix tree
278 * @root: radix tree root
280 * @item: item to insert
282 * Insert an item into the radix tree at position @index.
284 int radix_tree_insert(struct radix_tree_root *root,
285 unsigned long index, void *item)
287 struct radix_tree_node *node = NULL, *slot;
288 unsigned int height, shift;
292 BUG_ON(radix_tree_is_indirect_ptr(item));
294 /* Make sure the tree is high enough. */
295 if (index > radix_tree_maxindex(root->height)) {
296 error = radix_tree_extend(root, index);
301 slot = radix_tree_indirect_to_ptr(root->rnode);
303 height = root->height;
304 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
306 offset = 0; /* uninitialised var warning */
309 /* Have to add a child node. */
310 if (!(slot = radix_tree_node_alloc(root)))
312 slot->height = height;
314 rcu_assign_pointer(node->slots[offset], slot);
317 rcu_assign_pointer(root->rnode,
318 radix_tree_ptr_to_indirect(slot));
321 /* Go a level down */
322 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
324 slot = node->slots[offset];
325 shift -= RADIX_TREE_MAP_SHIFT;
334 rcu_assign_pointer(node->slots[offset], item);
335 BUG_ON(tag_get(node, 0, offset));
336 BUG_ON(tag_get(node, 1, offset));
338 rcu_assign_pointer(root->rnode, item);
339 BUG_ON(root_tag_get(root, 0));
340 BUG_ON(root_tag_get(root, 1));
345 EXPORT_SYMBOL(radix_tree_insert);
348 * radix_tree_lookup_slot - lookup a slot in a radix tree
349 * @root: radix tree root
352 * Returns: the slot corresponding to the position @index in the
353 * radix tree @root. This is useful for update-if-exists operations.
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
361 void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index)
363 unsigned int height, shift;
364 struct radix_tree_node *node, **slot;
370 if (!radix_tree_is_indirect_ptr(node)) {
373 return (void **)&root->rnode;
375 node = radix_tree_indirect_to_ptr(node);
377 height = node->height;
378 if (index > radix_tree_maxindex(height))
381 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
384 slot = (struct radix_tree_node **)
385 (node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK));
390 shift -= RADIX_TREE_MAP_SHIFT;
392 } while (height > 0);
394 return (void **)slot;
396 EXPORT_SYMBOL(radix_tree_lookup_slot);
399 * radix_tree_lookup - perform lookup operation on a radix tree
400 * @root: radix tree root
403 * Lookup the item at the position @index in the radix tree @root.
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.
410 void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
412 unsigned int height, shift;
413 struct radix_tree_node *node, **slot;
415 node = rcu_dereference(root->rnode);
419 if (!radix_tree_is_indirect_ptr(node)) {
424 node = radix_tree_indirect_to_ptr(node);
426 height = node->height;
427 if (index > radix_tree_maxindex(height))
430 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
433 slot = (struct radix_tree_node **)
434 (node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK));
435 node = rcu_dereference(*slot);
439 shift -= RADIX_TREE_MAP_SHIFT;
441 } while (height > 0);
445 EXPORT_SYMBOL(radix_tree_lookup);
448 * radix_tree_tag_set - set a tag on a radix tree node
449 * @root: radix tree root
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.
457 * Returns the address of the tagged item. Setting a tag on a not-present
460 void *radix_tree_tag_set(struct radix_tree_root *root,
461 unsigned long index, unsigned int tag)
463 unsigned int height, shift;
464 struct radix_tree_node *slot;
466 height = root->height;
467 BUG_ON(index > radix_tree_maxindex(height));
469 slot = radix_tree_indirect_to_ptr(root->rnode);
470 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
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;
484 /* set the root's tag bit */
485 if (slot && !root_tag_get(root, tag))
486 root_tag_set(root, tag);
490 EXPORT_SYMBOL(radix_tree_tag_set);
493 * radix_tree_tag_clear - clear a tag on a radix tree node
494 * @root: radix tree root
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.
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().
506 void *radix_tree_tag_clear(struct radix_tree_root *root,
507 unsigned long index, unsigned int tag)
510 * The radix tree path needs to be one longer than the maximum path
511 * since the "list" is null terminated.
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;
517 height = root->height;
518 if (index > radix_tree_maxindex(height))
521 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
523 slot = radix_tree_indirect_to_ptr(root->rnode);
531 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
532 pathp[1].offset = offset;
533 pathp[1].node = slot;
534 slot = slot->slots[offset];
536 shift -= RADIX_TREE_MAP_SHIFT;
543 while (pathp->node) {
544 if (!tag_get(pathp->node, tag, pathp->offset))
546 tag_clear(pathp->node, tag, pathp->offset);
547 if (any_tag_set(pathp->node, tag))
552 /* clear the root's tag bit */
553 if (root_tag_get(root, tag))
554 root_tag_clear(root, tag);
559 EXPORT_SYMBOL(radix_tree_tag_clear);
561 #ifndef __KERNEL__ /* Only the test harness uses this at present */
563 * radix_tree_tag_get - get a tag on a radix tree node
564 * @root: radix tree root
566 * @tag: tag index (< RADIX_TREE_MAX_TAGS)
570 * 0: tag not present or not set
573 int radix_tree_tag_get(struct radix_tree_root *root,
574 unsigned long index, unsigned int tag)
576 unsigned int height, shift;
577 struct radix_tree_node *node;
578 int saw_unset_tag = 0;
580 /* check the root's tag bit */
581 if (!root_tag_get(root, tag))
584 node = rcu_dereference(root->rnode);
588 if (!radix_tree_is_indirect_ptr(node))
590 node = radix_tree_indirect_to_ptr(node);
592 height = node->height;
593 if (index > radix_tree_maxindex(height))
596 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
604 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
607 * This is just a debug check. Later, we can bale as soon as
608 * we see an unset tag.
610 if (!tag_get(node, tag, offset))
613 int ret = tag_get(node, tag, offset);
615 BUG_ON(ret && saw_unset_tag);
618 node = rcu_dereference(node->slots[offset]);
619 shift -= RADIX_TREE_MAP_SHIFT;
623 EXPORT_SYMBOL(radix_tree_tag_get);
627 * radix_tree_next_hole - find the next hole (not-present entry)
630 * @max_scan: maximum range to search
632 * Search the set [index, min(index+max_scan-1, MAX_INDEX)] for the lowest
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'
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.
645 unsigned long radix_tree_next_hole(struct radix_tree_root *root,
646 unsigned long index, unsigned long max_scan)
650 for (i = 0; i < max_scan; i++) {
651 if (!radix_tree_lookup(root, index))
660 EXPORT_SYMBOL(radix_tree_next_hole);
663 __lookup(struct radix_tree_node *slot, void **results, unsigned long index,
664 unsigned int max_items, unsigned long *next_index)
666 unsigned int nr_found = 0;
667 unsigned int shift, height;
670 height = slot->height;
673 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
675 for ( ; height > 1; height--) {
676 i = (index >> shift) & RADIX_TREE_MAP_MASK;
678 if (slot->slots[i] != NULL)
680 index &= ~((1UL << shift) - 1);
681 index += 1UL << shift;
683 goto out; /* 32-bit wraparound */
685 if (i == RADIX_TREE_MAP_SIZE)
689 shift -= RADIX_TREE_MAP_SHIFT;
690 slot = rcu_dereference(slot->slots[i]);
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;
699 node = slot->slots[i];
701 results[nr_found++] = rcu_dereference(node);
702 if (nr_found == max_items)
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
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
722 * The implementation is naive.
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'.
731 radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
732 unsigned long first_index, unsigned int max_items)
734 unsigned long max_index;
735 struct radix_tree_node *node;
736 unsigned long cur_index = first_index;
739 node = rcu_dereference(root->rnode);
743 if (!radix_tree_is_indirect_ptr(node)) {
749 node = radix_tree_indirect_to_ptr(node);
751 max_index = radix_tree_maxindex(node->height);
754 while (ret < max_items) {
755 unsigned int nr_found;
756 unsigned long next_index; /* Index of next search */
758 if (cur_index > max_index)
760 nr_found = __lookup(node, results + ret, cur_index,
761 max_items - ret, &next_index);
765 cur_index = next_index;
770 EXPORT_SYMBOL(radix_tree_gang_lookup);
773 * FIXME: the two tag_get()s here should use find_next_bit() instead of
774 * open-coding the search.
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)
780 unsigned int nr_found = 0;
781 unsigned int shift, height;
783 height = slot->height;
786 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
789 unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK ;
792 if (tag_get(slot, tag, i))
794 index &= ~((1UL << shift) - 1);
795 index += 1UL << shift;
797 goto out; /* 32-bit wraparound */
799 if (i == RADIX_TREE_MAP_SIZE)
803 if (height == 0) { /* Bottom level: grab some items */
804 unsigned long j = index & RADIX_TREE_MAP_MASK;
806 for ( ; j < RADIX_TREE_MAP_SIZE; j++) {
807 struct radix_tree_node *node;
809 if (!tag_get(slot, tag, j))
811 node = slot->slots[j];
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.
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).
823 node = rcu_dereference(node);
824 results[nr_found++] = node;
825 if (nr_found == max_items)
830 shift -= RADIX_TREE_MAP_SHIFT;
831 slot = rcu_dereference(slot->slots[i]);
841 * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree
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)
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.
854 radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
855 unsigned long first_index, unsigned int max_items,
858 struct radix_tree_node *node;
859 unsigned long max_index;
860 unsigned long cur_index = first_index;
863 /* check the root's tag bit */
864 if (!root_tag_get(root, tag))
867 node = rcu_dereference(root->rnode);
871 if (!radix_tree_is_indirect_ptr(node)) {
877 node = radix_tree_indirect_to_ptr(node);
879 max_index = radix_tree_maxindex(node->height);
882 while (ret < max_items) {
883 unsigned int nr_found;
884 unsigned long next_index; /* Index of next search */
886 if (cur_index > max_index)
888 nr_found = __lookup_tag(node, results + ret, cur_index,
889 max_items - ret, &next_index, tag);
893 cur_index = next_index;
898 EXPORT_SYMBOL(radix_tree_gang_lookup_tag);
901 * radix_tree_shrink - shrink height of a radix tree to minimal
902 * @root radix tree root
904 static inline void radix_tree_shrink(struct radix_tree_root *root)
906 /* try to shrink tree height */
907 while (root->height > 0) {
908 struct radix_tree_node *to_free = root->rnode;
911 BUG_ON(!radix_tree_is_indirect_ptr(to_free));
912 to_free = radix_tree_indirect_to_ptr(to_free);
915 * The candidate node has more than one child, or its child
916 * is not at the leftmost slot, we cannot shrink.
918 if (to_free->count != 1)
920 if (!to_free->slots[0])
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
930 newptr = to_free->slots[0];
931 if (root->height > 1)
932 newptr = radix_tree_ptr_to_indirect(newptr);
933 root->rnode = newptr;
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;
940 radix_tree_node_free(to_free);
945 * radix_tree_delete - delete an item from a radix tree
946 * @root: radix tree root
949 * Remove the item at @index from the radix tree rooted at @root.
951 * Returns the address of the deleted item, or NULL if it was not present.
953 void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
956 * The radix tree path needs to be one longer than the maximum path
957 * since the "list" is null terminated.
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;
966 height = root->height;
967 if (index > radix_tree_maxindex(height))
972 root_tag_clear_all(root);
976 slot = radix_tree_indirect_to_ptr(slot);
978 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
986 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
987 pathp->offset = offset;
989 slot = slot->slots[offset];
990 shift -= RADIX_TREE_MAP_SHIFT;
992 } while (height > 0);
998 * Clear all tags associated with the just-deleted item
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);
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--;
1011 * Queue the node for deferred freeing after the
1012 * last reference to it disappears (set NULL, above).
1015 radix_tree_node_free(to_free);
1017 if (pathp->node->count) {
1019 radix_tree_indirect_to_ptr(root->rnode))
1020 radix_tree_shrink(root);
1024 /* Node with zero slots in use so free it */
1025 to_free = pathp->node;
1029 root_tag_clear_all(root);
1033 radix_tree_node_free(to_free);
1038 EXPORT_SYMBOL(radix_tree_delete);
1041 * radix_tree_tagged - test whether any items in the tree are tagged
1042 * @root: radix tree root
1045 int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag)
1047 return root_tag_get(root, tag);
1049 EXPORT_SYMBOL(radix_tree_tagged);
1052 radix_tree_node_ctor(struct kmem_cache *cachep, void *node)
1054 memset(node, 0, sizeof(struct radix_tree_node));
1057 static __init unsigned long __maxindex(unsigned int height)
1059 unsigned int width = height * RADIX_TREE_MAP_SHIFT;
1060 int shift = RADIX_TREE_INDEX_BITS - width;
1064 if (shift >= BITS_PER_LONG)
1066 return ~0UL >> shift;
1069 static __init void radix_tree_init_maxindex(void)
1073 for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++)
1074 height_to_maxindex[i] = __maxindex(i);
1077 static int radix_tree_callback(struct notifier_block *nfb,
1078 unsigned long action,
1081 int cpu = (long)hcpu;
1082 struct radix_tree_preload *rtp;
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);
1088 kmem_cache_free(radix_tree_node_cachep,
1089 rtp->nodes[rtp->nr-1]);
1090 rtp->nodes[rtp->nr-1] = NULL;
1097 void __init radix_tree_init(void)
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);