2 * Copyright (C) 2001 Momchil Velikov
3 * Portions Copyright (C) 2001 Christoph Hellwig
4 * Copyright (C) 2005 SGI, Christoph Lameter
5 * Copyright (C) 2006 Nick Piggin
6 * Copyright (C) 2012 Konstantin Khlebnikov
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License as
10 * published by the Free Software Foundation; either version 2, or (at
11 * your option) any later version.
13 * This program is distributed in the hope that it will be useful, but
14 * WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23 #include <linux/errno.h>
24 #include <linux/init.h>
25 #include <linux/kernel.h>
26 #include <linux/export.h>
27 #include <linux/radix-tree.h>
28 #include <linux/percpu.h>
29 #include <linux/slab.h>
30 #include <linux/kmemleak.h>
31 #include <linux/notifier.h>
32 #include <linux/cpu.h>
33 #include <linux/string.h>
34 #include <linux/bitops.h>
35 #include <linux/rcupdate.h>
36 #include <linux/preempt.h> /* in_interrupt() */
40 * The height_to_maxindex array needs to be one deeper than the maximum
41 * path as height 0 holds only 1 entry.
43 static unsigned long height_to_maxindex
[RADIX_TREE_MAX_PATH
+ 1] __read_mostly
;
46 * Radix tree node cache.
48 static struct kmem_cache
*radix_tree_node_cachep
;
51 * The radix tree is variable-height, so an insert operation not only has
52 * to build the branch to its corresponding item, it also has to build the
53 * branch to existing items if the size has to be increased (by
56 * The worst case is a zero height tree with just a single item at index 0,
57 * and then inserting an item at index ULONG_MAX. This requires 2 new branches
58 * of RADIX_TREE_MAX_PATH size to be created, with only the root node shared.
61 #define RADIX_TREE_PRELOAD_SIZE (RADIX_TREE_MAX_PATH * 2 - 1)
64 * Per-cpu pool of preloaded nodes
66 struct radix_tree_preload
{
68 /* nodes->private_data points to next preallocated node */
69 struct radix_tree_node
*nodes
;
71 static DEFINE_PER_CPU(struct radix_tree_preload
, radix_tree_preloads
) = { 0, };
73 static inline void *ptr_to_indirect(void *ptr
)
75 return (void *)((unsigned long)ptr
| RADIX_TREE_INDIRECT_PTR
);
78 #define RADIX_TREE_RETRY ptr_to_indirect(NULL)
80 #ifdef CONFIG_RADIX_TREE_MULTIORDER
81 /* Sibling slots point directly to another slot in the same node */
82 static inline bool is_sibling_entry(struct radix_tree_node
*parent
, void *node
)
85 return (parent
->slots
<= ptr
) &&
86 (ptr
< parent
->slots
+ RADIX_TREE_MAP_SIZE
);
89 static inline bool is_sibling_entry(struct radix_tree_node
*parent
, void *node
)
95 static inline unsigned long get_slot_offset(struct radix_tree_node
*parent
,
98 return slot
- parent
->slots
;
101 static unsigned radix_tree_descend(struct radix_tree_node
*parent
,
102 struct radix_tree_node
**nodep
, unsigned offset
)
104 void **entry
= rcu_dereference_raw(parent
->slots
[offset
]);
106 #ifdef CONFIG_RADIX_TREE_MULTIORDER
107 if (radix_tree_is_indirect_ptr(entry
)) {
108 unsigned long siboff
= get_slot_offset(parent
, entry
);
109 if (siboff
< RADIX_TREE_MAP_SIZE
) {
111 entry
= rcu_dereference_raw(parent
->slots
[offset
]);
116 *nodep
= (void *)entry
;
120 static inline gfp_t
root_gfp_mask(struct radix_tree_root
*root
)
122 return root
->gfp_mask
& __GFP_BITS_MASK
;
125 static inline void tag_set(struct radix_tree_node
*node
, unsigned int tag
,
128 __set_bit(offset
, node
->tags
[tag
]);
131 static inline void tag_clear(struct radix_tree_node
*node
, unsigned int tag
,
134 __clear_bit(offset
, node
->tags
[tag
]);
137 static inline int tag_get(struct radix_tree_node
*node
, unsigned int tag
,
140 return test_bit(offset
, node
->tags
[tag
]);
143 static inline void root_tag_set(struct radix_tree_root
*root
, unsigned int tag
)
145 root
->gfp_mask
|= (__force gfp_t
)(1 << (tag
+ __GFP_BITS_SHIFT
));
148 static inline void root_tag_clear(struct radix_tree_root
*root
, unsigned int tag
)
150 root
->gfp_mask
&= (__force gfp_t
)~(1 << (tag
+ __GFP_BITS_SHIFT
));
153 static inline void root_tag_clear_all(struct radix_tree_root
*root
)
155 root
->gfp_mask
&= __GFP_BITS_MASK
;
158 static inline int root_tag_get(struct radix_tree_root
*root
, unsigned int tag
)
160 return (__force
unsigned)root
->gfp_mask
& (1 << (tag
+ __GFP_BITS_SHIFT
));
163 static inline unsigned root_tags_get(struct radix_tree_root
*root
)
165 return (__force
unsigned)root
->gfp_mask
>> __GFP_BITS_SHIFT
;
169 * Returns 1 if any slot in the node has this tag set.
170 * Otherwise returns 0.
172 static inline int any_tag_set(struct radix_tree_node
*node
, unsigned int tag
)
175 for (idx
= 0; idx
< RADIX_TREE_TAG_LONGS
; idx
++) {
176 if (node
->tags
[tag
][idx
])
183 * radix_tree_find_next_bit - find the next set bit in a memory region
185 * @addr: The address to base the search on
186 * @size: The bitmap size in bits
187 * @offset: The bitnumber to start searching at
189 * Unrollable variant of find_next_bit() for constant size arrays.
190 * Tail bits starting from size to roundup(size, BITS_PER_LONG) must be zero.
191 * Returns next bit offset, or size if nothing found.
193 static __always_inline
unsigned long
194 radix_tree_find_next_bit(const unsigned long *addr
,
195 unsigned long size
, unsigned long offset
)
197 if (!__builtin_constant_p(size
))
198 return find_next_bit(addr
, size
, offset
);
203 addr
+= offset
/ BITS_PER_LONG
;
204 tmp
= *addr
>> (offset
% BITS_PER_LONG
);
206 return __ffs(tmp
) + offset
;
207 offset
= (offset
+ BITS_PER_LONG
) & ~(BITS_PER_LONG
- 1);
208 while (offset
< size
) {
211 return __ffs(tmp
) + offset
;
212 offset
+= BITS_PER_LONG
;
219 static void dump_node(struct radix_tree_node
*node
, unsigned offset
,
220 unsigned shift
, unsigned long index
)
224 pr_debug("radix node: %p offset %d tags %lx %lx %lx path %x count %d parent %p\n",
226 node
->tags
[0][0], node
->tags
[1][0], node
->tags
[2][0],
227 node
->path
, node
->count
, node
->parent
);
229 for (i
= 0; i
< RADIX_TREE_MAP_SIZE
; i
++) {
230 unsigned long first
= index
| (i
<< shift
);
231 unsigned long last
= first
| ((1UL << shift
) - 1);
232 void *entry
= node
->slots
[i
];
235 if (is_sibling_entry(node
, entry
)) {
236 pr_debug("radix sblng %p offset %ld val %p indices %ld-%ld\n",
238 *(void **)indirect_to_ptr(entry
),
240 } else if (!radix_tree_is_indirect_ptr(entry
)) {
241 pr_debug("radix entry %p offset %ld indices %ld-%ld\n",
242 entry
, i
, first
, last
);
244 dump_node(indirect_to_ptr(entry
), i
,
245 shift
- RADIX_TREE_MAP_SHIFT
, first
);
251 static void radix_tree_dump(struct radix_tree_root
*root
)
253 pr_debug("radix root: %p height %d rnode %p tags %x\n",
254 root
, root
->height
, root
->rnode
,
255 root
->gfp_mask
>> __GFP_BITS_SHIFT
);
256 if (!radix_tree_is_indirect_ptr(root
->rnode
))
258 dump_node(indirect_to_ptr(root
->rnode
), 0,
259 (root
->height
- 1) * RADIX_TREE_MAP_SHIFT
, 0);
264 * This assumes that the caller has performed appropriate preallocation, and
265 * that the caller has pinned this thread of control to the current CPU.
267 static struct radix_tree_node
*
268 radix_tree_node_alloc(struct radix_tree_root
*root
)
270 struct radix_tree_node
*ret
= NULL
;
271 gfp_t gfp_mask
= root_gfp_mask(root
);
274 * Preload code isn't irq safe and it doesn't make sence to use
275 * preloading in the interrupt anyway as all the allocations have to
276 * be atomic. So just do normal allocation when in interrupt.
278 if (!gfpflags_allow_blocking(gfp_mask
) && !in_interrupt()) {
279 struct radix_tree_preload
*rtp
;
282 * Even if the caller has preloaded, try to allocate from the
283 * cache first for the new node to get accounted.
285 ret
= kmem_cache_alloc(radix_tree_node_cachep
,
286 gfp_mask
| __GFP_ACCOUNT
| __GFP_NOWARN
);
291 * Provided the caller has preloaded here, we will always
292 * succeed in getting a node here (and never reach
295 rtp
= this_cpu_ptr(&radix_tree_preloads
);
298 rtp
->nodes
= ret
->private_data
;
299 ret
->private_data
= NULL
;
303 * Update the allocation stack trace as this is more useful
306 kmemleak_update_trace(ret
);
309 ret
= kmem_cache_alloc(radix_tree_node_cachep
,
310 gfp_mask
| __GFP_ACCOUNT
);
312 BUG_ON(radix_tree_is_indirect_ptr(ret
));
316 static void radix_tree_node_rcu_free(struct rcu_head
*head
)
318 struct radix_tree_node
*node
=
319 container_of(head
, struct radix_tree_node
, rcu_head
);
323 * must only free zeroed nodes into the slab. radix_tree_shrink
324 * can leave us with a non-NULL entry in the first slot, so clear
325 * that here to make sure.
327 for (i
= 0; i
< RADIX_TREE_MAX_TAGS
; i
++)
328 tag_clear(node
, i
, 0);
330 node
->slots
[0] = NULL
;
333 kmem_cache_free(radix_tree_node_cachep
, node
);
337 radix_tree_node_free(struct radix_tree_node
*node
)
339 call_rcu(&node
->rcu_head
, radix_tree_node_rcu_free
);
343 * Load up this CPU's radix_tree_node buffer with sufficient objects to
344 * ensure that the addition of a single element in the tree cannot fail. On
345 * success, return zero, with preemption disabled. On error, return -ENOMEM
346 * with preemption not disabled.
348 * To make use of this facility, the radix tree must be initialised without
349 * __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE().
351 static int __radix_tree_preload(gfp_t gfp_mask
)
353 struct radix_tree_preload
*rtp
;
354 struct radix_tree_node
*node
;
358 rtp
= this_cpu_ptr(&radix_tree_preloads
);
359 while (rtp
->nr
< RADIX_TREE_PRELOAD_SIZE
) {
361 node
= kmem_cache_alloc(radix_tree_node_cachep
, gfp_mask
);
365 rtp
= this_cpu_ptr(&radix_tree_preloads
);
366 if (rtp
->nr
< RADIX_TREE_PRELOAD_SIZE
) {
367 node
->private_data
= rtp
->nodes
;
371 kmem_cache_free(radix_tree_node_cachep
, node
);
380 * Load up this CPU's radix_tree_node buffer with sufficient objects to
381 * ensure that the addition of a single element in the tree cannot fail. On
382 * success, return zero, with preemption disabled. On error, return -ENOMEM
383 * with preemption not disabled.
385 * To make use of this facility, the radix tree must be initialised without
386 * __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE().
388 int radix_tree_preload(gfp_t gfp_mask
)
390 /* Warn on non-sensical use... */
391 WARN_ON_ONCE(!gfpflags_allow_blocking(gfp_mask
));
392 return __radix_tree_preload(gfp_mask
);
394 EXPORT_SYMBOL(radix_tree_preload
);
397 * The same as above function, except we don't guarantee preloading happens.
398 * We do it, if we decide it helps. On success, return zero with preemption
399 * disabled. On error, return -ENOMEM with preemption not disabled.
401 int radix_tree_maybe_preload(gfp_t gfp_mask
)
403 if (gfpflags_allow_blocking(gfp_mask
))
404 return __radix_tree_preload(gfp_mask
);
405 /* Preloading doesn't help anything with this gfp mask, skip it */
409 EXPORT_SYMBOL(radix_tree_maybe_preload
);
412 * Return the maximum key which can be store into a
413 * radix tree with height HEIGHT.
415 static inline unsigned long radix_tree_maxindex(unsigned int height
)
417 return height_to_maxindex
[height
];
420 static inline unsigned long node_maxindex(struct radix_tree_node
*node
)
422 return radix_tree_maxindex(node
->path
& RADIX_TREE_HEIGHT_MASK
);
425 static unsigned radix_tree_load_root(struct radix_tree_root
*root
,
426 struct radix_tree_node
**nodep
, unsigned long *maxindex
)
428 struct radix_tree_node
*node
= rcu_dereference_raw(root
->rnode
);
432 if (likely(radix_tree_is_indirect_ptr(node
))) {
433 node
= indirect_to_ptr(node
);
434 *maxindex
= node_maxindex(node
);
435 return (node
->path
& RADIX_TREE_HEIGHT_MASK
) *
436 RADIX_TREE_MAP_SHIFT
;
444 * Extend a radix tree so it can store key @index.
446 static int radix_tree_extend(struct radix_tree_root
*root
,
449 struct radix_tree_node
*node
;
450 struct radix_tree_node
*slot
;
454 /* Figure out what the height should be. */
455 height
= root
->height
+ 1;
456 while (index
> radix_tree_maxindex(height
))
459 if (root
->rnode
== NULL
) {
460 root
->height
= height
;
465 unsigned int newheight
;
466 if (!(node
= radix_tree_node_alloc(root
)))
469 /* Propagate the aggregated tag info into the new root */
470 for (tag
= 0; tag
< RADIX_TREE_MAX_TAGS
; tag
++) {
471 if (root_tag_get(root
, tag
))
472 tag_set(node
, tag
, 0);
475 /* Increase the height. */
476 newheight
= root
->height
+1;
477 BUG_ON(newheight
& ~RADIX_TREE_HEIGHT_MASK
);
478 node
->path
= newheight
;
482 if (radix_tree_is_indirect_ptr(slot
)) {
483 slot
= indirect_to_ptr(slot
);
485 slot
= ptr_to_indirect(slot
);
487 node
->slots
[0] = slot
;
488 node
= ptr_to_indirect(node
);
489 rcu_assign_pointer(root
->rnode
, node
);
490 root
->height
= newheight
;
491 } while (height
> root
->height
);
493 return height
* RADIX_TREE_MAP_SHIFT
;
497 * __radix_tree_create - create a slot in a radix tree
498 * @root: radix tree root
500 * @order: index occupies 2^order aligned slots
501 * @nodep: returns node
502 * @slotp: returns slot
504 * Create, if necessary, and return the node and slot for an item
505 * at position @index in the radix tree @root.
507 * Until there is more than one item in the tree, no nodes are
508 * allocated and @root->rnode is used as a direct slot instead of
509 * pointing to a node, in which case *@nodep will be NULL.
511 * Returns -ENOMEM, or 0 for success.
513 int __radix_tree_create(struct radix_tree_root
*root
, unsigned long index
,
514 unsigned order
, struct radix_tree_node
**nodep
,
517 struct radix_tree_node
*node
= NULL
, *slot
;
518 unsigned long maxindex
;
519 unsigned int height
, shift
, offset
;
520 unsigned long max
= index
| ((1UL << order
) - 1);
522 shift
= radix_tree_load_root(root
, &slot
, &maxindex
);
524 /* Make sure the tree is high enough. */
525 if (max
> maxindex
) {
526 int error
= radix_tree_extend(root
, max
);
531 if (order
== shift
) {
532 shift
+= RADIX_TREE_MAP_SHIFT
;
537 height
= root
->height
;
539 offset
= 0; /* uninitialised var warning */
540 while (shift
> order
) {
542 /* Have to add a child node. */
543 if (!(slot
= radix_tree_node_alloc(root
)))
548 rcu_assign_pointer(node
->slots
[offset
],
549 ptr_to_indirect(slot
));
551 slot
->path
|= offset
<< RADIX_TREE_HEIGHT_SHIFT
;
553 rcu_assign_pointer(root
->rnode
,
554 ptr_to_indirect(slot
));
555 } else if (!radix_tree_is_indirect_ptr(slot
))
558 /* Go a level down */
560 shift
-= RADIX_TREE_MAP_SHIFT
;
561 node
= indirect_to_ptr(slot
);
562 offset
= (index
>> shift
) & RADIX_TREE_MAP_MASK
;
563 offset
= radix_tree_descend(node
, &slot
, offset
);
566 #ifdef CONFIG_RADIX_TREE_MULTIORDER
567 /* Insert pointers to the canonical entry */
569 int i
, n
= 1 << (order
- shift
);
570 offset
= offset
& ~(n
- 1);
571 slot
= ptr_to_indirect(&node
->slots
[offset
]);
572 for (i
= 0; i
< n
; i
++) {
573 if (node
->slots
[offset
+ i
])
577 for (i
= 1; i
< n
; i
++) {
578 rcu_assign_pointer(node
->slots
[offset
+ i
], slot
);
587 *slotp
= node
? node
->slots
+ offset
: (void **)&root
->rnode
;
592 * __radix_tree_insert - insert into a radix tree
593 * @root: radix tree root
595 * @order: key covers the 2^order indices around index
596 * @item: item to insert
598 * Insert an item into the radix tree at position @index.
600 int __radix_tree_insert(struct radix_tree_root
*root
, unsigned long index
,
601 unsigned order
, void *item
)
603 struct radix_tree_node
*node
;
607 BUG_ON(radix_tree_is_indirect_ptr(item
));
609 error
= __radix_tree_create(root
, index
, order
, &node
, &slot
);
614 rcu_assign_pointer(*slot
, item
);
617 unsigned offset
= get_slot_offset(node
, slot
);
619 BUG_ON(tag_get(node
, 0, offset
));
620 BUG_ON(tag_get(node
, 1, offset
));
621 BUG_ON(tag_get(node
, 2, offset
));
623 BUG_ON(root_tags_get(root
));
628 EXPORT_SYMBOL(__radix_tree_insert
);
631 * __radix_tree_lookup - lookup an item in a radix tree
632 * @root: radix tree root
634 * @nodep: returns node
635 * @slotp: returns slot
637 * Lookup and return the item at position @index in the radix
640 * Until there is more than one item in the tree, no nodes are
641 * allocated and @root->rnode is used as a direct slot instead of
642 * pointing to a node, in which case *@nodep will be NULL.
644 void *__radix_tree_lookup(struct radix_tree_root
*root
, unsigned long index
,
645 struct radix_tree_node
**nodep
, void ***slotp
)
647 struct radix_tree_node
*node
, *parent
;
648 unsigned long maxindex
;
654 slot
= (void **)&root
->rnode
;
655 shift
= radix_tree_load_root(root
, &node
, &maxindex
);
656 if (index
> maxindex
)
659 while (radix_tree_is_indirect_ptr(node
)) {
662 if (node
== RADIX_TREE_RETRY
)
664 parent
= indirect_to_ptr(node
);
665 shift
-= RADIX_TREE_MAP_SHIFT
;
666 offset
= (index
>> shift
) & RADIX_TREE_MAP_MASK
;
667 offset
= radix_tree_descend(parent
, &node
, offset
);
668 slot
= parent
->slots
+ offset
;
679 * radix_tree_lookup_slot - lookup a slot in a radix tree
680 * @root: radix tree root
683 * Returns: the slot corresponding to the position @index in the
684 * radix tree @root. This is useful for update-if-exists operations.
686 * This function can be called under rcu_read_lock iff the slot is not
687 * modified by radix_tree_replace_slot, otherwise it must be called
688 * exclusive from other writers. Any dereference of the slot must be done
689 * using radix_tree_deref_slot.
691 void **radix_tree_lookup_slot(struct radix_tree_root
*root
, unsigned long index
)
695 if (!__radix_tree_lookup(root
, index
, NULL
, &slot
))
699 EXPORT_SYMBOL(radix_tree_lookup_slot
);
702 * radix_tree_lookup - perform lookup operation on a radix tree
703 * @root: radix tree root
706 * Lookup the item at the position @index in the radix tree @root.
708 * This function can be called under rcu_read_lock, however the caller
709 * must manage lifetimes of leaf nodes (eg. RCU may also be used to free
710 * them safely). No RCU barriers are required to access or modify the
711 * returned item, however.
713 void *radix_tree_lookup(struct radix_tree_root
*root
, unsigned long index
)
715 return __radix_tree_lookup(root
, index
, NULL
, NULL
);
717 EXPORT_SYMBOL(radix_tree_lookup
);
720 * radix_tree_tag_set - set a tag on a radix tree node
721 * @root: radix tree root
725 * Set the search tag (which must be < RADIX_TREE_MAX_TAGS)
726 * corresponding to @index in the radix tree. From
727 * the root all the way down to the leaf node.
729 * Returns the address of the tagged item. Setting a tag on a not-present
732 void *radix_tree_tag_set(struct radix_tree_root
*root
,
733 unsigned long index
, unsigned int tag
)
735 struct radix_tree_node
*node
, *parent
;
736 unsigned long maxindex
;
739 shift
= radix_tree_load_root(root
, &node
, &maxindex
);
740 BUG_ON(index
> maxindex
);
742 while (radix_tree_is_indirect_ptr(node
)) {
745 shift
-= RADIX_TREE_MAP_SHIFT
;
746 offset
= (index
>> shift
) & RADIX_TREE_MAP_MASK
;
748 parent
= indirect_to_ptr(node
);
749 offset
= radix_tree_descend(parent
, &node
, offset
);
752 if (!tag_get(parent
, tag
, offset
))
753 tag_set(parent
, tag
, offset
);
756 /* set the root's tag bit */
757 if (!root_tag_get(root
, tag
))
758 root_tag_set(root
, tag
);
762 EXPORT_SYMBOL(radix_tree_tag_set
);
765 * radix_tree_tag_clear - clear a tag on a radix tree node
766 * @root: radix tree root
770 * Clear the search tag (which must be < RADIX_TREE_MAX_TAGS)
771 * corresponding to @index in the radix tree. If
772 * this causes the leaf node to have no tags set then clear the tag in the
773 * next-to-leaf node, etc.
775 * Returns the address of the tagged item on success, else NULL. ie:
776 * has the same return value and semantics as radix_tree_lookup().
778 void *radix_tree_tag_clear(struct radix_tree_root
*root
,
779 unsigned long index
, unsigned int tag
)
781 struct radix_tree_node
*node
, *parent
;
782 unsigned long maxindex
;
784 int uninitialized_var(offset
);
786 shift
= radix_tree_load_root(root
, &node
, &maxindex
);
787 if (index
> maxindex
)
792 while (radix_tree_is_indirect_ptr(node
)) {
793 shift
-= RADIX_TREE_MAP_SHIFT
;
794 offset
= (index
>> shift
) & RADIX_TREE_MAP_MASK
;
796 parent
= indirect_to_ptr(node
);
797 offset
= radix_tree_descend(parent
, &node
, offset
);
806 if (!tag_get(parent
, tag
, offset
))
808 tag_clear(parent
, tag
, offset
);
809 if (any_tag_set(parent
, tag
))
812 index
>>= RADIX_TREE_MAP_SHIFT
;
813 offset
= index
& RADIX_TREE_MAP_MASK
;
814 parent
= parent
->parent
;
817 /* clear the root's tag bit */
818 if (root_tag_get(root
, tag
))
819 root_tag_clear(root
, tag
);
824 EXPORT_SYMBOL(radix_tree_tag_clear
);
827 * radix_tree_tag_get - get a tag on a radix tree node
828 * @root: radix tree root
830 * @tag: tag index (< RADIX_TREE_MAX_TAGS)
834 * 0: tag not present or not set
837 * Note that the return value of this function may not be relied on, even if
838 * the RCU lock is held, unless tag modification and node deletion are excluded
841 int radix_tree_tag_get(struct radix_tree_root
*root
,
842 unsigned long index
, unsigned int tag
)
844 struct radix_tree_node
*node
, *parent
;
845 unsigned long maxindex
;
848 if (!root_tag_get(root
, tag
))
851 shift
= radix_tree_load_root(root
, &node
, &maxindex
);
852 if (index
> maxindex
)
857 while (radix_tree_is_indirect_ptr(node
)) {
860 shift
-= RADIX_TREE_MAP_SHIFT
;
861 offset
= (index
>> shift
) & RADIX_TREE_MAP_MASK
;
863 parent
= indirect_to_ptr(node
);
864 offset
= radix_tree_descend(parent
, &node
, offset
);
868 if (!tag_get(parent
, tag
, offset
))
870 if (node
== RADIX_TREE_RETRY
)
876 EXPORT_SYMBOL(radix_tree_tag_get
);
878 static inline void __set_iter_shift(struct radix_tree_iter
*iter
,
881 #ifdef CONFIG_RADIX_TREE_MULTIORDER
887 * radix_tree_next_chunk - find next chunk of slots for iteration
889 * @root: radix tree root
890 * @iter: iterator state
891 * @flags: RADIX_TREE_ITER_* flags and tag index
892 * Returns: pointer to chunk first slot, or NULL if iteration is over
894 void **radix_tree_next_chunk(struct radix_tree_root
*root
,
895 struct radix_tree_iter
*iter
, unsigned flags
)
897 unsigned shift
, tag
= flags
& RADIX_TREE_ITER_TAG_MASK
;
898 struct radix_tree_node
*rnode
, *node
;
899 unsigned long index
, offset
, maxindex
;
901 if ((flags
& RADIX_TREE_ITER_TAGGED
) && !root_tag_get(root
, tag
))
905 * Catch next_index overflow after ~0UL. iter->index never overflows
906 * during iterating; it can be zero only at the beginning.
907 * And we cannot overflow iter->next_index in a single step,
908 * because RADIX_TREE_MAP_SHIFT < BITS_PER_LONG.
910 * This condition also used by radix_tree_next_slot() to stop
911 * contiguous iterating, and forbid swithing to the next chunk.
913 index
= iter
->next_index
;
914 if (!index
&& iter
->index
)
918 shift
= radix_tree_load_root(root
, &rnode
, &maxindex
);
919 if (index
> maxindex
)
922 if (radix_tree_is_indirect_ptr(rnode
)) {
923 rnode
= indirect_to_ptr(rnode
);
925 /* Single-slot tree */
927 iter
->next_index
= maxindex
+ 1;
929 __set_iter_shift(iter
, shift
);
930 return (void **)&root
->rnode
;
934 shift
-= RADIX_TREE_MAP_SHIFT
;
935 offset
= index
>> shift
;
939 struct radix_tree_node
*slot
;
940 unsigned new_off
= radix_tree_descend(node
, &slot
, offset
);
942 if (new_off
< offset
) {
944 index
&= ~((RADIX_TREE_MAP_SIZE
<< shift
) - 1);
945 index
|= offset
<< shift
;
948 if ((flags
& RADIX_TREE_ITER_TAGGED
) ?
949 !tag_get(node
, tag
, offset
) : !slot
) {
951 if (flags
& RADIX_TREE_ITER_CONTIG
)
954 if (flags
& RADIX_TREE_ITER_TAGGED
)
955 offset
= radix_tree_find_next_bit(
960 while (++offset
< RADIX_TREE_MAP_SIZE
) {
961 void *slot
= node
->slots
[offset
];
962 if (is_sibling_entry(node
, slot
))
967 index
&= ~((RADIX_TREE_MAP_SIZE
<< shift
) - 1);
968 index
+= offset
<< shift
;
969 /* Overflow after ~0UL */
972 if (offset
== RADIX_TREE_MAP_SIZE
)
974 slot
= rcu_dereference_raw(node
->slots
[offset
]);
977 if ((slot
== NULL
) || (slot
== RADIX_TREE_RETRY
))
979 if (!radix_tree_is_indirect_ptr(slot
))
982 node
= indirect_to_ptr(slot
);
983 shift
-= RADIX_TREE_MAP_SHIFT
;
984 offset
= (index
>> shift
) & RADIX_TREE_MAP_MASK
;
987 /* Update the iterator state */
988 iter
->index
= index
& ~((1 << shift
) - 1);
989 iter
->next_index
= (index
| ((RADIX_TREE_MAP_SIZE
<< shift
) - 1)) + 1;
990 __set_iter_shift(iter
, shift
);
992 /* Construct iter->tags bit-mask from node->tags[tag] array */
993 if (flags
& RADIX_TREE_ITER_TAGGED
) {
994 unsigned tag_long
, tag_bit
;
996 tag_long
= offset
/ BITS_PER_LONG
;
997 tag_bit
= offset
% BITS_PER_LONG
;
998 iter
->tags
= node
->tags
[tag
][tag_long
] >> tag_bit
;
999 /* This never happens if RADIX_TREE_TAG_LONGS == 1 */
1000 if (tag_long
< RADIX_TREE_TAG_LONGS
- 1) {
1001 /* Pick tags from next element */
1003 iter
->tags
|= node
->tags
[tag
][tag_long
+ 1] <<
1004 (BITS_PER_LONG
- tag_bit
);
1005 /* Clip chunk size, here only BITS_PER_LONG tags */
1006 iter
->next_index
= index
+ BITS_PER_LONG
;
1010 return node
->slots
+ offset
;
1012 EXPORT_SYMBOL(radix_tree_next_chunk
);
1015 * radix_tree_range_tag_if_tagged - for each item in given range set given
1016 * tag if item has another tag set
1017 * @root: radix tree root
1018 * @first_indexp: pointer to a starting index of a range to scan
1019 * @last_index: last index of a range to scan
1020 * @nr_to_tag: maximum number items to tag
1021 * @iftag: tag index to test
1022 * @settag: tag index to set if tested tag is set
1024 * This function scans range of radix tree from first_index to last_index
1025 * (inclusive). For each item in the range if iftag is set, the function sets
1026 * also settag. The function stops either after tagging nr_to_tag items or
1027 * after reaching last_index.
1029 * The tags must be set from the leaf level only and propagated back up the
1030 * path to the root. We must do this so that we resolve the full path before
1031 * setting any tags on intermediate nodes. If we set tags as we descend, then
1032 * we can get to the leaf node and find that the index that has the iftag
1033 * set is outside the range we are scanning. This reults in dangling tags and
1034 * can lead to problems with later tag operations (e.g. livelocks on lookups).
1036 * The function returns number of leaves where the tag was set and sets
1037 * *first_indexp to the first unscanned index.
1038 * WARNING! *first_indexp can wrap if last_index is ULONG_MAX. Caller must
1039 * be prepared to handle that.
1041 unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root
*root
,
1042 unsigned long *first_indexp
, unsigned long last_index
,
1043 unsigned long nr_to_tag
,
1044 unsigned int iftag
, unsigned int settag
)
1046 struct radix_tree_node
*slot
, *node
= NULL
;
1047 unsigned long maxindex
;
1048 unsigned int shift
= radix_tree_load_root(root
, &slot
, &maxindex
);
1049 unsigned long tagged
= 0;
1050 unsigned long index
= *first_indexp
;
1052 last_index
= min(last_index
, maxindex
);
1053 if (index
> last_index
)
1057 if (!root_tag_get(root
, iftag
)) {
1058 *first_indexp
= last_index
+ 1;
1061 if (!radix_tree_is_indirect_ptr(slot
)) {
1062 *first_indexp
= last_index
+ 1;
1063 root_tag_set(root
, settag
);
1067 node
= indirect_to_ptr(slot
);
1068 shift
-= RADIX_TREE_MAP_SHIFT
;
1071 unsigned long upindex
;
1074 offset
= (index
>> shift
) & RADIX_TREE_MAP_MASK
;
1075 offset
= radix_tree_descend(node
, &slot
, offset
);
1078 if (!tag_get(node
, iftag
, offset
))
1080 /* Sibling slots never have tags set on them */
1081 if (radix_tree_is_indirect_ptr(slot
)) {
1082 node
= indirect_to_ptr(slot
);
1083 shift
-= RADIX_TREE_MAP_SHIFT
;
1089 tag_set(node
, settag
, offset
);
1091 slot
= node
->parent
;
1092 /* walk back up the path tagging interior nodes */
1093 upindex
= index
>> shift
;
1095 upindex
>>= RADIX_TREE_MAP_SHIFT
;
1096 offset
= upindex
& RADIX_TREE_MAP_MASK
;
1098 /* stop if we find a node with the tag already set */
1099 if (tag_get(slot
, settag
, offset
))
1101 tag_set(slot
, settag
, offset
);
1102 slot
= slot
->parent
;
1106 /* Go to next item at level determined by 'shift' */
1107 index
= ((index
>> shift
) + 1) << shift
;
1108 /* Overflow can happen when last_index is ~0UL... */
1109 if (index
> last_index
|| !index
)
1111 offset
= (index
>> shift
) & RADIX_TREE_MAP_MASK
;
1112 while (offset
== 0) {
1114 * We've fully scanned this node. Go up. Because
1115 * last_index is guaranteed to be in the tree, what
1116 * we do below cannot wander astray.
1118 node
= node
->parent
;
1119 shift
+= RADIX_TREE_MAP_SHIFT
;
1120 offset
= (index
>> shift
) & RADIX_TREE_MAP_MASK
;
1122 if (is_sibling_entry(node
, node
->slots
[offset
]))
1124 if (tagged
>= nr_to_tag
)
1128 * We need not to tag the root tag if there is no tag which is set with
1129 * settag within the range from *first_indexp to last_index.
1132 root_tag_set(root
, settag
);
1133 *first_indexp
= index
;
1137 EXPORT_SYMBOL(radix_tree_range_tag_if_tagged
);
1140 * radix_tree_gang_lookup - perform multiple lookup on a radix tree
1141 * @root: radix tree root
1142 * @results: where the results of the lookup are placed
1143 * @first_index: start the lookup from this key
1144 * @max_items: place up to this many items at *results
1146 * Performs an index-ascending scan of the tree for present items. Places
1147 * them at *@results and returns the number of items which were placed at
1150 * The implementation is naive.
1152 * Like radix_tree_lookup, radix_tree_gang_lookup may be called under
1153 * rcu_read_lock. In this case, rather than the returned results being
1154 * an atomic snapshot of the tree at a single point in time, the semantics
1155 * of an RCU protected gang lookup are as though multiple radix_tree_lookups
1156 * have been issued in individual locks, and results stored in 'results'.
1159 radix_tree_gang_lookup(struct radix_tree_root
*root
, void **results
,
1160 unsigned long first_index
, unsigned int max_items
)
1162 struct radix_tree_iter iter
;
1164 unsigned int ret
= 0;
1166 if (unlikely(!max_items
))
1169 radix_tree_for_each_slot(slot
, root
, &iter
, first_index
) {
1170 results
[ret
] = rcu_dereference_raw(*slot
);
1173 if (radix_tree_is_indirect_ptr(results
[ret
])) {
1174 slot
= radix_tree_iter_retry(&iter
);
1177 if (++ret
== max_items
)
1183 EXPORT_SYMBOL(radix_tree_gang_lookup
);
1186 * radix_tree_gang_lookup_slot - perform multiple slot lookup on radix tree
1187 * @root: radix tree root
1188 * @results: where the results of the lookup are placed
1189 * @indices: where their indices should be placed (but usually NULL)
1190 * @first_index: start the lookup from this key
1191 * @max_items: place up to this many items at *results
1193 * Performs an index-ascending scan of the tree for present items. Places
1194 * their slots at *@results and returns the number of items which were
1195 * placed at *@results.
1197 * The implementation is naive.
1199 * Like radix_tree_gang_lookup as far as RCU and locking goes. Slots must
1200 * be dereferenced with radix_tree_deref_slot, and if using only RCU
1201 * protection, radix_tree_deref_slot may fail requiring a retry.
1204 radix_tree_gang_lookup_slot(struct radix_tree_root
*root
,
1205 void ***results
, unsigned long *indices
,
1206 unsigned long first_index
, unsigned int max_items
)
1208 struct radix_tree_iter iter
;
1210 unsigned int ret
= 0;
1212 if (unlikely(!max_items
))
1215 radix_tree_for_each_slot(slot
, root
, &iter
, first_index
) {
1216 results
[ret
] = slot
;
1218 indices
[ret
] = iter
.index
;
1219 if (++ret
== max_items
)
1225 EXPORT_SYMBOL(radix_tree_gang_lookup_slot
);
1228 * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree
1230 * @root: radix tree root
1231 * @results: where the results of the lookup are placed
1232 * @first_index: start the lookup from this key
1233 * @max_items: place up to this many items at *results
1234 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
1236 * Performs an index-ascending scan of the tree for present items which
1237 * have the tag indexed by @tag set. Places the items at *@results and
1238 * returns the number of items which were placed at *@results.
1241 radix_tree_gang_lookup_tag(struct radix_tree_root
*root
, void **results
,
1242 unsigned long first_index
, unsigned int max_items
,
1245 struct radix_tree_iter iter
;
1247 unsigned int ret
= 0;
1249 if (unlikely(!max_items
))
1252 radix_tree_for_each_tagged(slot
, root
, &iter
, first_index
, tag
) {
1253 results
[ret
] = rcu_dereference_raw(*slot
);
1256 if (radix_tree_is_indirect_ptr(results
[ret
])) {
1257 slot
= radix_tree_iter_retry(&iter
);
1260 if (++ret
== max_items
)
1266 EXPORT_SYMBOL(radix_tree_gang_lookup_tag
);
1269 * radix_tree_gang_lookup_tag_slot - perform multiple slot lookup on a
1270 * radix tree based on a tag
1271 * @root: radix tree root
1272 * @results: where the results of the lookup are placed
1273 * @first_index: start the lookup from this key
1274 * @max_items: place up to this many items at *results
1275 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
1277 * Performs an index-ascending scan of the tree for present items which
1278 * have the tag indexed by @tag set. Places the slots at *@results and
1279 * returns the number of slots which were placed at *@results.
1282 radix_tree_gang_lookup_tag_slot(struct radix_tree_root
*root
, void ***results
,
1283 unsigned long first_index
, unsigned int max_items
,
1286 struct radix_tree_iter iter
;
1288 unsigned int ret
= 0;
1290 if (unlikely(!max_items
))
1293 radix_tree_for_each_tagged(slot
, root
, &iter
, first_index
, tag
) {
1294 results
[ret
] = slot
;
1295 if (++ret
== max_items
)
1301 EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot
);
1303 #if defined(CONFIG_SHMEM) && defined(CONFIG_SWAP)
1304 #include <linux/sched.h> /* for cond_resched() */
1306 struct locate_info
{
1307 unsigned long found_index
;
1312 * This linear search is at present only useful to shmem_unuse_inode().
1314 static unsigned long __locate(struct radix_tree_node
*slot
, void *item
,
1315 unsigned long index
, struct locate_info
*info
)
1317 unsigned int shift
, height
;
1320 height
= slot
->path
& RADIX_TREE_HEIGHT_MASK
;
1321 shift
= height
* RADIX_TREE_MAP_SHIFT
;
1324 shift
-= RADIX_TREE_MAP_SHIFT
;
1326 for (i
= (index
>> shift
) & RADIX_TREE_MAP_MASK
;
1327 i
< RADIX_TREE_MAP_SIZE
;
1328 i
++, index
+= (1UL << shift
)) {
1329 struct radix_tree_node
*node
=
1330 rcu_dereference_raw(slot
->slots
[i
]);
1331 if (node
== RADIX_TREE_RETRY
)
1333 if (!radix_tree_is_indirect_ptr(node
)) {
1335 info
->found_index
= index
;
1341 node
= indirect_to_ptr(node
);
1342 if (is_sibling_entry(slot
, node
))
1347 if (i
== RADIX_TREE_MAP_SIZE
)
1352 if ((index
== 0) && (i
== RADIX_TREE_MAP_SIZE
))
1358 * radix_tree_locate_item - search through radix tree for item
1359 * @root: radix tree root
1360 * @item: item to be found
1362 * Returns index where item was found, or -1 if not found.
1363 * Caller must hold no lock (since this time-consuming function needs
1364 * to be preemptible), and must check afterwards if item is still there.
1366 unsigned long radix_tree_locate_item(struct radix_tree_root
*root
, void *item
)
1368 struct radix_tree_node
*node
;
1369 unsigned long max_index
;
1370 unsigned long cur_index
= 0;
1371 struct locate_info info
= {
1378 node
= rcu_dereference_raw(root
->rnode
);
1379 if (!radix_tree_is_indirect_ptr(node
)) {
1382 info
.found_index
= 0;
1386 node
= indirect_to_ptr(node
);
1388 max_index
= node_maxindex(node
);
1389 if (cur_index
> max_index
) {
1394 cur_index
= __locate(node
, item
, cur_index
, &info
);
1397 } while (!info
.stop
&& cur_index
<= max_index
);
1399 return info
.found_index
;
1402 unsigned long radix_tree_locate_item(struct radix_tree_root
*root
, void *item
)
1406 #endif /* CONFIG_SHMEM && CONFIG_SWAP */
1409 * radix_tree_shrink - shrink height of a radix tree to minimal
1410 * @root radix tree root
1412 static inline void radix_tree_shrink(struct radix_tree_root
*root
)
1414 /* try to shrink tree height */
1415 while (root
->height
> 0) {
1416 struct radix_tree_node
*to_free
= root
->rnode
;
1417 struct radix_tree_node
*slot
;
1419 BUG_ON(!radix_tree_is_indirect_ptr(to_free
));
1420 to_free
= indirect_to_ptr(to_free
);
1423 * The candidate node has more than one child, or its child
1424 * is not at the leftmost slot, or it is a multiorder entry,
1427 if (to_free
->count
!= 1)
1429 slot
= to_free
->slots
[0];
1432 if (!radix_tree_is_indirect_ptr(slot
) && (root
->height
> 1))
1435 if (radix_tree_is_indirect_ptr(slot
)) {
1436 slot
= indirect_to_ptr(slot
);
1437 slot
->parent
= NULL
;
1438 slot
= ptr_to_indirect(slot
);
1442 * We don't need rcu_assign_pointer(), since we are simply
1443 * moving the node from one part of the tree to another: if it
1444 * was safe to dereference the old pointer to it
1445 * (to_free->slots[0]), it will be safe to dereference the new
1446 * one (root->rnode) as far as dependent read barriers go.
1452 * We have a dilemma here. The node's slot[0] must not be
1453 * NULLed in case there are concurrent lookups expecting to
1454 * find the item. However if this was a bottom-level node,
1455 * then it may be subject to the slot pointer being visible
1456 * to callers dereferencing it. If item corresponding to
1457 * slot[0] is subsequently deleted, these callers would expect
1458 * their slot to become empty sooner or later.
1460 * For example, lockless pagecache will look up a slot, deref
1461 * the page pointer, and if the page is 0 refcount it means it
1462 * was concurrently deleted from pagecache so try the deref
1463 * again. Fortunately there is already a requirement for logic
1464 * to retry the entire slot lookup -- the indirect pointer
1465 * problem (replacing direct root node with an indirect pointer
1466 * also results in a stale slot). So tag the slot as indirect
1467 * to force callers to retry.
1469 if (!radix_tree_is_indirect_ptr(slot
))
1470 to_free
->slots
[0] = RADIX_TREE_RETRY
;
1472 radix_tree_node_free(to_free
);
1477 * __radix_tree_delete_node - try to free node after clearing a slot
1478 * @root: radix tree root
1479 * @node: node containing @index
1481 * After clearing the slot at @index in @node from radix tree
1482 * rooted at @root, call this function to attempt freeing the
1483 * node and shrinking the tree.
1485 * Returns %true if @node was freed, %false otherwise.
1487 bool __radix_tree_delete_node(struct radix_tree_root
*root
,
1488 struct radix_tree_node
*node
)
1490 bool deleted
= false;
1493 struct radix_tree_node
*parent
;
1496 if (node
== indirect_to_ptr(root
->rnode
)) {
1497 radix_tree_shrink(root
);
1498 if (root
->height
== 0)
1504 parent
= node
->parent
;
1506 unsigned int offset
;
1508 offset
= node
->path
>> RADIX_TREE_HEIGHT_SHIFT
;
1509 parent
->slots
[offset
] = NULL
;
1512 root_tag_clear_all(root
);
1517 radix_tree_node_free(node
);
1526 static inline void delete_sibling_entries(struct radix_tree_node
*node
,
1527 void *ptr
, unsigned offset
)
1529 #ifdef CONFIG_RADIX_TREE_MULTIORDER
1531 for (i
= 1; offset
+ i
< RADIX_TREE_MAP_SIZE
; i
++) {
1532 if (node
->slots
[offset
+ i
] != ptr
)
1534 node
->slots
[offset
+ i
] = NULL
;
1541 * radix_tree_delete_item - delete an item from a radix tree
1542 * @root: radix tree root
1544 * @item: expected item
1546 * Remove @item at @index from the radix tree rooted at @root.
1548 * Returns the address of the deleted item, or NULL if it was not present
1549 * or the entry at the given @index was not @item.
1551 void *radix_tree_delete_item(struct radix_tree_root
*root
,
1552 unsigned long index
, void *item
)
1554 struct radix_tree_node
*node
;
1555 unsigned int offset
;
1560 entry
= __radix_tree_lookup(root
, index
, &node
, &slot
);
1564 if (item
&& entry
!= item
)
1568 root_tag_clear_all(root
);
1573 offset
= get_slot_offset(node
, slot
);
1576 * Clear all tags associated with the item to be deleted.
1577 * This way of doing it would be inefficient, but seldom is any set.
1579 for (tag
= 0; tag
< RADIX_TREE_MAX_TAGS
; tag
++) {
1580 if (tag_get(node
, tag
, offset
))
1581 radix_tree_tag_clear(root
, index
, tag
);
1584 delete_sibling_entries(node
, ptr_to_indirect(slot
), offset
);
1585 node
->slots
[offset
] = NULL
;
1588 __radix_tree_delete_node(root
, node
);
1592 EXPORT_SYMBOL(radix_tree_delete_item
);
1595 * radix_tree_delete - delete an item from a radix tree
1596 * @root: radix tree root
1599 * Remove the item at @index from the radix tree rooted at @root.
1601 * Returns the address of the deleted item, or NULL if it was not present.
1603 void *radix_tree_delete(struct radix_tree_root
*root
, unsigned long index
)
1605 return radix_tree_delete_item(root
, index
, NULL
);
1607 EXPORT_SYMBOL(radix_tree_delete
);
1610 * radix_tree_tagged - test whether any items in the tree are tagged
1611 * @root: radix tree root
1614 int radix_tree_tagged(struct radix_tree_root
*root
, unsigned int tag
)
1616 return root_tag_get(root
, tag
);
1618 EXPORT_SYMBOL(radix_tree_tagged
);
1621 radix_tree_node_ctor(void *arg
)
1623 struct radix_tree_node
*node
= arg
;
1625 memset(node
, 0, sizeof(*node
));
1626 INIT_LIST_HEAD(&node
->private_list
);
1629 static __init
unsigned long __maxindex(unsigned int height
)
1631 unsigned int width
= height
* RADIX_TREE_MAP_SHIFT
;
1632 int shift
= RADIX_TREE_INDEX_BITS
- width
;
1636 if (shift
>= BITS_PER_LONG
)
1638 return ~0UL >> shift
;
1641 static __init
void radix_tree_init_maxindex(void)
1645 for (i
= 0; i
< ARRAY_SIZE(height_to_maxindex
); i
++)
1646 height_to_maxindex
[i
] = __maxindex(i
);
1649 static int radix_tree_callback(struct notifier_block
*nfb
,
1650 unsigned long action
,
1653 int cpu
= (long)hcpu
;
1654 struct radix_tree_preload
*rtp
;
1655 struct radix_tree_node
*node
;
1657 /* Free per-cpu pool of perloaded nodes */
1658 if (action
== CPU_DEAD
|| action
== CPU_DEAD_FROZEN
) {
1659 rtp
= &per_cpu(radix_tree_preloads
, cpu
);
1662 rtp
->nodes
= node
->private_data
;
1663 kmem_cache_free(radix_tree_node_cachep
, node
);
1670 void __init
radix_tree_init(void)
1672 radix_tree_node_cachep
= kmem_cache_create("radix_tree_node",
1673 sizeof(struct radix_tree_node
), 0,
1674 SLAB_PANIC
| SLAB_RECLAIM_ACCOUNT
,
1675 radix_tree_node_ctor
);
1676 radix_tree_init_maxindex();
1677 hotcpu_notifier(radix_tree_callback
, 0);