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
7 * Copyright (C) 2016 Intel, Matthew Wilcox
8 * Copyright (C) 2016 Intel, Ross Zwisler
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License as
12 * published by the Free Software Foundation; either version 2, or (at
13 * your option) any later version.
15 * This program is distributed in the hope that it will be useful, but
16 * WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 * General Public License for more details.
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
25 #include <linux/errno.h>
26 #include <linux/init.h>
27 #include <linux/kernel.h>
28 #include <linux/export.h>
29 #include <linux/radix-tree.h>
30 #include <linux/percpu.h>
31 #include <linux/slab.h>
32 #include <linux/kmemleak.h>
33 #include <linux/notifier.h>
34 #include <linux/cpu.h>
35 #include <linux/string.h>
36 #include <linux/bitops.h>
37 #include <linux/rcupdate.h>
38 #include <linux/preempt.h> /* in_interrupt() */
42 * The height_to_maxindex array needs to be one deeper than the maximum
43 * path as height 0 holds only 1 entry.
45 static unsigned long height_to_maxindex
[RADIX_TREE_MAX_PATH
+ 1] __read_mostly
;
48 * Radix tree node cache.
50 static struct kmem_cache
*radix_tree_node_cachep
;
53 * The radix tree is variable-height, so an insert operation not only has
54 * to build the branch to its corresponding item, it also has to build the
55 * branch to existing items if the size has to be increased (by
58 * The worst case is a zero height tree with just a single item at index 0,
59 * and then inserting an item at index ULONG_MAX. This requires 2 new branches
60 * of RADIX_TREE_MAX_PATH size to be created, with only the root node shared.
63 #define RADIX_TREE_PRELOAD_SIZE (RADIX_TREE_MAX_PATH * 2 - 1)
66 * Per-cpu pool of preloaded nodes
68 struct radix_tree_preload
{
70 /* nodes->private_data points to next preallocated node */
71 struct radix_tree_node
*nodes
;
73 static DEFINE_PER_CPU(struct radix_tree_preload
, radix_tree_preloads
) = { 0, };
75 static inline void *ptr_to_indirect(void *ptr
)
77 return (void *)((unsigned long)ptr
| RADIX_TREE_INDIRECT_PTR
);
80 #define RADIX_TREE_RETRY ptr_to_indirect(NULL)
82 #ifdef CONFIG_RADIX_TREE_MULTIORDER
83 /* Sibling slots point directly to another slot in the same node */
84 static inline bool is_sibling_entry(struct radix_tree_node
*parent
, void *node
)
87 return (parent
->slots
<= ptr
) &&
88 (ptr
< parent
->slots
+ RADIX_TREE_MAP_SIZE
);
91 static inline bool is_sibling_entry(struct radix_tree_node
*parent
, void *node
)
97 static inline unsigned long get_slot_offset(struct radix_tree_node
*parent
,
100 return slot
- parent
->slots
;
103 static unsigned radix_tree_descend(struct radix_tree_node
*parent
,
104 struct radix_tree_node
**nodep
, unsigned offset
)
106 void **entry
= rcu_dereference_raw(parent
->slots
[offset
]);
108 #ifdef CONFIG_RADIX_TREE_MULTIORDER
109 if (radix_tree_is_indirect_ptr(entry
)) {
110 unsigned long siboff
= get_slot_offset(parent
, entry
);
111 if (siboff
< RADIX_TREE_MAP_SIZE
) {
113 entry
= rcu_dereference_raw(parent
->slots
[offset
]);
118 *nodep
= (void *)entry
;
122 static inline gfp_t
root_gfp_mask(struct radix_tree_root
*root
)
124 return root
->gfp_mask
& __GFP_BITS_MASK
;
127 static inline void tag_set(struct radix_tree_node
*node
, unsigned int tag
,
130 __set_bit(offset
, node
->tags
[tag
]);
133 static inline void tag_clear(struct radix_tree_node
*node
, unsigned int tag
,
136 __clear_bit(offset
, node
->tags
[tag
]);
139 static inline int tag_get(struct radix_tree_node
*node
, unsigned int tag
,
142 return test_bit(offset
, node
->tags
[tag
]);
145 static inline void root_tag_set(struct radix_tree_root
*root
, unsigned int tag
)
147 root
->gfp_mask
|= (__force gfp_t
)(1 << (tag
+ __GFP_BITS_SHIFT
));
150 static inline void root_tag_clear(struct radix_tree_root
*root
, unsigned tag
)
152 root
->gfp_mask
&= (__force gfp_t
)~(1 << (tag
+ __GFP_BITS_SHIFT
));
155 static inline void root_tag_clear_all(struct radix_tree_root
*root
)
157 root
->gfp_mask
&= __GFP_BITS_MASK
;
160 static inline int root_tag_get(struct radix_tree_root
*root
, unsigned int tag
)
162 return (__force
int)root
->gfp_mask
& (1 << (tag
+ __GFP_BITS_SHIFT
));
165 static inline unsigned root_tags_get(struct radix_tree_root
*root
)
167 return (__force
unsigned)root
->gfp_mask
>> __GFP_BITS_SHIFT
;
171 * Returns 1 if any slot in the node has this tag set.
172 * Otherwise returns 0.
174 static inline int any_tag_set(struct radix_tree_node
*node
, unsigned int tag
)
177 for (idx
= 0; idx
< RADIX_TREE_TAG_LONGS
; idx
++) {
178 if (node
->tags
[tag
][idx
])
185 * radix_tree_find_next_bit - find the next set bit in a memory region
187 * @addr: The address to base the search on
188 * @size: The bitmap size in bits
189 * @offset: The bitnumber to start searching at
191 * Unrollable variant of find_next_bit() for constant size arrays.
192 * Tail bits starting from size to roundup(size, BITS_PER_LONG) must be zero.
193 * Returns next bit offset, or size if nothing found.
195 static __always_inline
unsigned long
196 radix_tree_find_next_bit(const unsigned long *addr
,
197 unsigned long size
, unsigned long offset
)
199 if (!__builtin_constant_p(size
))
200 return find_next_bit(addr
, size
, offset
);
205 addr
+= offset
/ BITS_PER_LONG
;
206 tmp
= *addr
>> (offset
% BITS_PER_LONG
);
208 return __ffs(tmp
) + offset
;
209 offset
= (offset
+ BITS_PER_LONG
) & ~(BITS_PER_LONG
- 1);
210 while (offset
< size
) {
213 return __ffs(tmp
) + offset
;
214 offset
+= BITS_PER_LONG
;
221 static void dump_node(struct radix_tree_node
*node
, unsigned offset
,
222 unsigned shift
, unsigned long index
)
226 pr_debug("radix node: %p offset %d tags %lx %lx %lx path %x count %d parent %p\n",
228 node
->tags
[0][0], node
->tags
[1][0], node
->tags
[2][0],
229 node
->path
, node
->count
, node
->parent
);
231 for (i
= 0; i
< RADIX_TREE_MAP_SIZE
; i
++) {
232 unsigned long first
= index
| (i
<< shift
);
233 unsigned long last
= first
| ((1UL << shift
) - 1);
234 void *entry
= node
->slots
[i
];
237 if (is_sibling_entry(node
, entry
)) {
238 pr_debug("radix sblng %p offset %ld val %p indices %ld-%ld\n",
240 *(void **)indirect_to_ptr(entry
),
242 } else if (!radix_tree_is_indirect_ptr(entry
)) {
243 pr_debug("radix entry %p offset %ld indices %ld-%ld\n",
244 entry
, i
, first
, last
);
246 dump_node(indirect_to_ptr(entry
), i
,
247 shift
- RADIX_TREE_MAP_SHIFT
, first
);
253 static void radix_tree_dump(struct radix_tree_root
*root
)
255 pr_debug("radix root: %p height %d rnode %p tags %x\n",
256 root
, root
->height
, root
->rnode
,
257 root
->gfp_mask
>> __GFP_BITS_SHIFT
);
258 if (!radix_tree_is_indirect_ptr(root
->rnode
))
260 dump_node(indirect_to_ptr(root
->rnode
), 0,
261 (root
->height
- 1) * RADIX_TREE_MAP_SHIFT
, 0);
266 * This assumes that the caller has performed appropriate preallocation, and
267 * that the caller has pinned this thread of control to the current CPU.
269 static struct radix_tree_node
*
270 radix_tree_node_alloc(struct radix_tree_root
*root
)
272 struct radix_tree_node
*ret
= NULL
;
273 gfp_t gfp_mask
= root_gfp_mask(root
);
276 * Preload code isn't irq safe and it doesn't make sense to use
277 * preloading during an interrupt anyway as all the allocations have
278 * to be atomic. So just do normal allocation when in interrupt.
280 if (!gfpflags_allow_blocking(gfp_mask
) && !in_interrupt()) {
281 struct radix_tree_preload
*rtp
;
284 * Even if the caller has preloaded, try to allocate from the
285 * cache first for the new node to get accounted.
287 ret
= kmem_cache_alloc(radix_tree_node_cachep
,
288 gfp_mask
| __GFP_ACCOUNT
| __GFP_NOWARN
);
293 * Provided the caller has preloaded here, we will always
294 * succeed in getting a node here (and never reach
297 rtp
= this_cpu_ptr(&radix_tree_preloads
);
300 rtp
->nodes
= ret
->private_data
;
301 ret
->private_data
= NULL
;
305 * Update the allocation stack trace as this is more useful
308 kmemleak_update_trace(ret
);
311 ret
= kmem_cache_alloc(radix_tree_node_cachep
,
312 gfp_mask
| __GFP_ACCOUNT
);
314 BUG_ON(radix_tree_is_indirect_ptr(ret
));
318 static void radix_tree_node_rcu_free(struct rcu_head
*head
)
320 struct radix_tree_node
*node
=
321 container_of(head
, struct radix_tree_node
, rcu_head
);
325 * must only free zeroed nodes into the slab. radix_tree_shrink
326 * can leave us with a non-NULL entry in the first slot, so clear
327 * that here to make sure.
329 for (i
= 0; i
< RADIX_TREE_MAX_TAGS
; i
++)
330 tag_clear(node
, i
, 0);
332 node
->slots
[0] = NULL
;
335 kmem_cache_free(radix_tree_node_cachep
, node
);
339 radix_tree_node_free(struct radix_tree_node
*node
)
341 call_rcu(&node
->rcu_head
, radix_tree_node_rcu_free
);
345 * Load up this CPU's radix_tree_node buffer with sufficient objects to
346 * ensure that the addition of a single element in the tree cannot fail. On
347 * success, return zero, with preemption disabled. On error, return -ENOMEM
348 * with preemption not disabled.
350 * To make use of this facility, the radix tree must be initialised without
351 * __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE().
353 static int __radix_tree_preload(gfp_t gfp_mask
)
355 struct radix_tree_preload
*rtp
;
356 struct radix_tree_node
*node
;
360 rtp
= this_cpu_ptr(&radix_tree_preloads
);
361 while (rtp
->nr
< RADIX_TREE_PRELOAD_SIZE
) {
363 node
= kmem_cache_alloc(radix_tree_node_cachep
, gfp_mask
);
367 rtp
= this_cpu_ptr(&radix_tree_preloads
);
368 if (rtp
->nr
< RADIX_TREE_PRELOAD_SIZE
) {
369 node
->private_data
= rtp
->nodes
;
373 kmem_cache_free(radix_tree_node_cachep
, node
);
382 * Load up this CPU's radix_tree_node buffer with sufficient objects to
383 * ensure that the addition of a single element in the tree cannot fail. On
384 * success, return zero, with preemption disabled. On error, return -ENOMEM
385 * with preemption not disabled.
387 * To make use of this facility, the radix tree must be initialised without
388 * __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE().
390 int radix_tree_preload(gfp_t gfp_mask
)
392 /* Warn on non-sensical use... */
393 WARN_ON_ONCE(!gfpflags_allow_blocking(gfp_mask
));
394 return __radix_tree_preload(gfp_mask
);
396 EXPORT_SYMBOL(radix_tree_preload
);
399 * The same as above function, except we don't guarantee preloading happens.
400 * We do it, if we decide it helps. On success, return zero with preemption
401 * disabled. On error, return -ENOMEM with preemption not disabled.
403 int radix_tree_maybe_preload(gfp_t gfp_mask
)
405 if (gfpflags_allow_blocking(gfp_mask
))
406 return __radix_tree_preload(gfp_mask
);
407 /* Preloading doesn't help anything with this gfp mask, skip it */
411 EXPORT_SYMBOL(radix_tree_maybe_preload
);
414 * Return the maximum key which can be store into a
415 * radix tree with height HEIGHT.
417 static inline unsigned long radix_tree_maxindex(unsigned int height
)
419 return height_to_maxindex
[height
];
422 static inline unsigned long node_maxindex(struct radix_tree_node
*node
)
424 return radix_tree_maxindex(node
->path
& RADIX_TREE_HEIGHT_MASK
);
427 static unsigned radix_tree_load_root(struct radix_tree_root
*root
,
428 struct radix_tree_node
**nodep
, unsigned long *maxindex
)
430 struct radix_tree_node
*node
= rcu_dereference_raw(root
->rnode
);
434 if (likely(radix_tree_is_indirect_ptr(node
))) {
435 node
= indirect_to_ptr(node
);
436 *maxindex
= node_maxindex(node
);
437 return (node
->path
& RADIX_TREE_HEIGHT_MASK
) *
438 RADIX_TREE_MAP_SHIFT
;
446 * Extend a radix tree so it can store key @index.
448 static int radix_tree_extend(struct radix_tree_root
*root
,
451 struct radix_tree_node
*slot
;
455 /* Figure out what the height should be. */
456 height
= root
->height
+ 1;
457 while (index
> radix_tree_maxindex(height
))
460 if (root
->rnode
== NULL
) {
461 root
->height
= height
;
466 unsigned int newheight
;
467 struct radix_tree_node
*node
= radix_tree_node_alloc(root
);
472 /* Propagate the aggregated tag info into the new root */
473 for (tag
= 0; tag
< RADIX_TREE_MAX_TAGS
; tag
++) {
474 if (root_tag_get(root
, tag
))
475 tag_set(node
, tag
, 0);
478 /* Increase the height. */
479 newheight
= root
->height
+1;
480 BUG_ON(newheight
& ~RADIX_TREE_HEIGHT_MASK
);
481 node
->path
= newheight
;
485 if (radix_tree_is_indirect_ptr(slot
)) {
486 slot
= indirect_to_ptr(slot
);
488 slot
= ptr_to_indirect(slot
);
490 node
->slots
[0] = slot
;
491 node
= ptr_to_indirect(node
);
492 rcu_assign_pointer(root
->rnode
, node
);
493 root
->height
= newheight
;
494 } while (height
> root
->height
);
496 return height
* RADIX_TREE_MAP_SHIFT
;
500 * __radix_tree_create - create a slot in a radix tree
501 * @root: radix tree root
503 * @order: index occupies 2^order aligned slots
504 * @nodep: returns node
505 * @slotp: returns slot
507 * Create, if necessary, and return the node and slot for an item
508 * at position @index in the radix tree @root.
510 * Until there is more than one item in the tree, no nodes are
511 * allocated and @root->rnode is used as a direct slot instead of
512 * pointing to a node, in which case *@nodep will be NULL.
514 * Returns -ENOMEM, or 0 for success.
516 int __radix_tree_create(struct radix_tree_root
*root
, unsigned long index
,
517 unsigned order
, struct radix_tree_node
**nodep
,
520 struct radix_tree_node
*node
= NULL
, *slot
;
521 unsigned long maxindex
;
522 unsigned int height
, shift
, offset
;
523 unsigned long max
= index
| ((1UL << order
) - 1);
525 shift
= radix_tree_load_root(root
, &slot
, &maxindex
);
527 /* Make sure the tree is high enough. */
528 if (max
> maxindex
) {
529 int error
= radix_tree_extend(root
, max
);
534 if (order
== shift
) {
535 shift
+= RADIX_TREE_MAP_SHIFT
;
540 height
= root
->height
;
542 offset
= 0; /* uninitialised var warning */
543 while (shift
> order
) {
545 /* Have to add a child node. */
546 slot
= radix_tree_node_alloc(root
);
552 rcu_assign_pointer(node
->slots
[offset
],
553 ptr_to_indirect(slot
));
555 slot
->path
|= offset
<< RADIX_TREE_HEIGHT_SHIFT
;
557 rcu_assign_pointer(root
->rnode
,
558 ptr_to_indirect(slot
));
559 } else if (!radix_tree_is_indirect_ptr(slot
))
562 /* Go a level down */
564 shift
-= RADIX_TREE_MAP_SHIFT
;
565 node
= indirect_to_ptr(slot
);
566 offset
= (index
>> shift
) & RADIX_TREE_MAP_MASK
;
567 offset
= radix_tree_descend(node
, &slot
, offset
);
570 #ifdef CONFIG_RADIX_TREE_MULTIORDER
571 /* Insert pointers to the canonical entry */
573 int i
, n
= 1 << (order
- shift
);
574 offset
= offset
& ~(n
- 1);
575 slot
= ptr_to_indirect(&node
->slots
[offset
]);
576 for (i
= 0; i
< n
; i
++) {
577 if (node
->slots
[offset
+ i
])
581 for (i
= 1; i
< n
; i
++) {
582 rcu_assign_pointer(node
->slots
[offset
+ i
], slot
);
591 *slotp
= node
? node
->slots
+ offset
: (void **)&root
->rnode
;
596 * __radix_tree_insert - insert into a radix tree
597 * @root: radix tree root
599 * @order: key covers the 2^order indices around index
600 * @item: item to insert
602 * Insert an item into the radix tree at position @index.
604 int __radix_tree_insert(struct radix_tree_root
*root
, unsigned long index
,
605 unsigned order
, void *item
)
607 struct radix_tree_node
*node
;
611 BUG_ON(radix_tree_is_indirect_ptr(item
));
613 error
= __radix_tree_create(root
, index
, order
, &node
, &slot
);
618 rcu_assign_pointer(*slot
, item
);
621 unsigned offset
= get_slot_offset(node
, slot
);
623 BUG_ON(tag_get(node
, 0, offset
));
624 BUG_ON(tag_get(node
, 1, offset
));
625 BUG_ON(tag_get(node
, 2, offset
));
627 BUG_ON(root_tags_get(root
));
632 EXPORT_SYMBOL(__radix_tree_insert
);
635 * __radix_tree_lookup - lookup an item in a radix tree
636 * @root: radix tree root
638 * @nodep: returns node
639 * @slotp: returns slot
641 * Lookup and return the item at position @index in the radix
644 * Until there is more than one item in the tree, no nodes are
645 * allocated and @root->rnode is used as a direct slot instead of
646 * pointing to a node, in which case *@nodep will be NULL.
648 void *__radix_tree_lookup(struct radix_tree_root
*root
, unsigned long index
,
649 struct radix_tree_node
**nodep
, void ***slotp
)
651 struct radix_tree_node
*node
, *parent
;
652 unsigned long maxindex
;
658 slot
= (void **)&root
->rnode
;
659 shift
= radix_tree_load_root(root
, &node
, &maxindex
);
660 if (index
> maxindex
)
663 while (radix_tree_is_indirect_ptr(node
)) {
666 if (node
== RADIX_TREE_RETRY
)
668 parent
= indirect_to_ptr(node
);
669 shift
-= RADIX_TREE_MAP_SHIFT
;
670 offset
= (index
>> shift
) & RADIX_TREE_MAP_MASK
;
671 offset
= radix_tree_descend(parent
, &node
, offset
);
672 slot
= parent
->slots
+ offset
;
683 * radix_tree_lookup_slot - lookup a slot in a radix tree
684 * @root: radix tree root
687 * Returns: the slot corresponding to the position @index in the
688 * radix tree @root. This is useful for update-if-exists operations.
690 * This function can be called under rcu_read_lock iff the slot is not
691 * modified by radix_tree_replace_slot, otherwise it must be called
692 * exclusive from other writers. Any dereference of the slot must be done
693 * using radix_tree_deref_slot.
695 void **radix_tree_lookup_slot(struct radix_tree_root
*root
, unsigned long index
)
699 if (!__radix_tree_lookup(root
, index
, NULL
, &slot
))
703 EXPORT_SYMBOL(radix_tree_lookup_slot
);
706 * radix_tree_lookup - perform lookup operation on a radix tree
707 * @root: radix tree root
710 * Lookup the item at the position @index in the radix tree @root.
712 * This function can be called under rcu_read_lock, however the caller
713 * must manage lifetimes of leaf nodes (eg. RCU may also be used to free
714 * them safely). No RCU barriers are required to access or modify the
715 * returned item, however.
717 void *radix_tree_lookup(struct radix_tree_root
*root
, unsigned long index
)
719 return __radix_tree_lookup(root
, index
, NULL
, NULL
);
721 EXPORT_SYMBOL(radix_tree_lookup
);
724 * radix_tree_tag_set - set a tag on a radix tree node
725 * @root: radix tree root
729 * Set the search tag (which must be < RADIX_TREE_MAX_TAGS)
730 * corresponding to @index in the radix tree. From
731 * the root all the way down to the leaf node.
733 * Returns the address of the tagged item. Setting a tag on a not-present
736 void *radix_tree_tag_set(struct radix_tree_root
*root
,
737 unsigned long index
, unsigned int tag
)
739 struct radix_tree_node
*node
, *parent
;
740 unsigned long maxindex
;
743 shift
= radix_tree_load_root(root
, &node
, &maxindex
);
744 BUG_ON(index
> maxindex
);
746 while (radix_tree_is_indirect_ptr(node
)) {
749 shift
-= RADIX_TREE_MAP_SHIFT
;
750 offset
= (index
>> shift
) & RADIX_TREE_MAP_MASK
;
752 parent
= indirect_to_ptr(node
);
753 offset
= radix_tree_descend(parent
, &node
, offset
);
756 if (!tag_get(parent
, tag
, offset
))
757 tag_set(parent
, tag
, offset
);
760 /* set the root's tag bit */
761 if (!root_tag_get(root
, tag
))
762 root_tag_set(root
, tag
);
766 EXPORT_SYMBOL(radix_tree_tag_set
);
769 * radix_tree_tag_clear - clear a tag on a radix tree node
770 * @root: radix tree root
774 * Clear the search tag (which must be < RADIX_TREE_MAX_TAGS)
775 * corresponding to @index in the radix tree. If this causes
776 * the leaf node to have no tags set then clear the tag in the
777 * next-to-leaf node, etc.
779 * Returns the address of the tagged item on success, else NULL. ie:
780 * has the same return value and semantics as radix_tree_lookup().
782 void *radix_tree_tag_clear(struct radix_tree_root
*root
,
783 unsigned long index
, unsigned int tag
)
785 struct radix_tree_node
*node
, *parent
;
786 unsigned long maxindex
;
788 int uninitialized_var(offset
);
790 shift
= radix_tree_load_root(root
, &node
, &maxindex
);
791 if (index
> maxindex
)
796 while (radix_tree_is_indirect_ptr(node
)) {
797 shift
-= RADIX_TREE_MAP_SHIFT
;
798 offset
= (index
>> shift
) & RADIX_TREE_MAP_MASK
;
800 parent
= indirect_to_ptr(node
);
801 offset
= radix_tree_descend(parent
, &node
, offset
);
810 if (!tag_get(parent
, tag
, offset
))
812 tag_clear(parent
, tag
, offset
);
813 if (any_tag_set(parent
, tag
))
816 index
>>= RADIX_TREE_MAP_SHIFT
;
817 offset
= index
& RADIX_TREE_MAP_MASK
;
818 parent
= parent
->parent
;
821 /* clear the root's tag bit */
822 if (root_tag_get(root
, tag
))
823 root_tag_clear(root
, tag
);
828 EXPORT_SYMBOL(radix_tree_tag_clear
);
831 * radix_tree_tag_get - get a tag on a radix tree node
832 * @root: radix tree root
834 * @tag: tag index (< RADIX_TREE_MAX_TAGS)
838 * 0: tag not present or not set
841 * Note that the return value of this function may not be relied on, even if
842 * the RCU lock is held, unless tag modification and node deletion are excluded
845 int radix_tree_tag_get(struct radix_tree_root
*root
,
846 unsigned long index
, unsigned int tag
)
848 struct radix_tree_node
*node
, *parent
;
849 unsigned long maxindex
;
852 if (!root_tag_get(root
, tag
))
855 shift
= radix_tree_load_root(root
, &node
, &maxindex
);
856 if (index
> maxindex
)
861 while (radix_tree_is_indirect_ptr(node
)) {
864 shift
-= RADIX_TREE_MAP_SHIFT
;
865 offset
= (index
>> shift
) & RADIX_TREE_MAP_MASK
;
867 parent
= indirect_to_ptr(node
);
868 offset
= radix_tree_descend(parent
, &node
, offset
);
872 if (!tag_get(parent
, tag
, offset
))
874 if (node
== RADIX_TREE_RETRY
)
880 EXPORT_SYMBOL(radix_tree_tag_get
);
882 static inline void __set_iter_shift(struct radix_tree_iter
*iter
,
885 #ifdef CONFIG_RADIX_TREE_MULTIORDER
891 * radix_tree_next_chunk - find next chunk of slots for iteration
893 * @root: radix tree root
894 * @iter: iterator state
895 * @flags: RADIX_TREE_ITER_* flags and tag index
896 * Returns: pointer to chunk first slot, or NULL if iteration is over
898 void **radix_tree_next_chunk(struct radix_tree_root
*root
,
899 struct radix_tree_iter
*iter
, unsigned flags
)
901 unsigned shift
, tag
= flags
& RADIX_TREE_ITER_TAG_MASK
;
902 struct radix_tree_node
*rnode
, *node
;
903 unsigned long index
, offset
, maxindex
;
905 if ((flags
& RADIX_TREE_ITER_TAGGED
) && !root_tag_get(root
, tag
))
909 * Catch next_index overflow after ~0UL. iter->index never overflows
910 * during iterating; it can be zero only at the beginning.
911 * And we cannot overflow iter->next_index in a single step,
912 * because RADIX_TREE_MAP_SHIFT < BITS_PER_LONG.
914 * This condition also used by radix_tree_next_slot() to stop
915 * contiguous iterating, and forbid swithing to the next chunk.
917 index
= iter
->next_index
;
918 if (!index
&& iter
->index
)
922 shift
= radix_tree_load_root(root
, &rnode
, &maxindex
);
923 if (index
> maxindex
)
926 if (radix_tree_is_indirect_ptr(rnode
)) {
927 rnode
= indirect_to_ptr(rnode
);
929 /* Single-slot tree */
931 iter
->next_index
= maxindex
+ 1;
933 __set_iter_shift(iter
, shift
);
934 return (void **)&root
->rnode
;
938 shift
-= RADIX_TREE_MAP_SHIFT
;
939 offset
= index
>> shift
;
943 struct radix_tree_node
*slot
;
944 unsigned new_off
= radix_tree_descend(node
, &slot
, offset
);
946 if (new_off
< offset
) {
948 index
&= ~((RADIX_TREE_MAP_SIZE
<< shift
) - 1);
949 index
|= offset
<< shift
;
952 if ((flags
& RADIX_TREE_ITER_TAGGED
) ?
953 !tag_get(node
, tag
, offset
) : !slot
) {
955 if (flags
& RADIX_TREE_ITER_CONTIG
)
958 if (flags
& RADIX_TREE_ITER_TAGGED
)
959 offset
= radix_tree_find_next_bit(
964 while (++offset
< RADIX_TREE_MAP_SIZE
) {
965 void *slot
= node
->slots
[offset
];
966 if (is_sibling_entry(node
, slot
))
971 index
&= ~((RADIX_TREE_MAP_SIZE
<< shift
) - 1);
972 index
+= offset
<< shift
;
973 /* Overflow after ~0UL */
976 if (offset
== RADIX_TREE_MAP_SIZE
)
978 slot
= rcu_dereference_raw(node
->slots
[offset
]);
981 if ((slot
== NULL
) || (slot
== RADIX_TREE_RETRY
))
983 if (!radix_tree_is_indirect_ptr(slot
))
986 node
= indirect_to_ptr(slot
);
987 shift
-= RADIX_TREE_MAP_SHIFT
;
988 offset
= (index
>> shift
) & RADIX_TREE_MAP_MASK
;
991 /* Update the iterator state */
992 iter
->index
= index
& ~((1 << shift
) - 1);
993 iter
->next_index
= (index
| ((RADIX_TREE_MAP_SIZE
<< shift
) - 1)) + 1;
994 __set_iter_shift(iter
, shift
);
996 /* Construct iter->tags bit-mask from node->tags[tag] array */
997 if (flags
& RADIX_TREE_ITER_TAGGED
) {
998 unsigned tag_long
, tag_bit
;
1000 tag_long
= offset
/ BITS_PER_LONG
;
1001 tag_bit
= offset
% BITS_PER_LONG
;
1002 iter
->tags
= node
->tags
[tag
][tag_long
] >> tag_bit
;
1003 /* This never happens if RADIX_TREE_TAG_LONGS == 1 */
1004 if (tag_long
< RADIX_TREE_TAG_LONGS
- 1) {
1005 /* Pick tags from next element */
1007 iter
->tags
|= node
->tags
[tag
][tag_long
+ 1] <<
1008 (BITS_PER_LONG
- tag_bit
);
1009 /* Clip chunk size, here only BITS_PER_LONG tags */
1010 iter
->next_index
= index
+ BITS_PER_LONG
;
1014 return node
->slots
+ offset
;
1016 EXPORT_SYMBOL(radix_tree_next_chunk
);
1019 * radix_tree_range_tag_if_tagged - for each item in given range set given
1020 * tag if item has another tag set
1021 * @root: radix tree root
1022 * @first_indexp: pointer to a starting index of a range to scan
1023 * @last_index: last index of a range to scan
1024 * @nr_to_tag: maximum number items to tag
1025 * @iftag: tag index to test
1026 * @settag: tag index to set if tested tag is set
1028 * This function scans range of radix tree from first_index to last_index
1029 * (inclusive). For each item in the range if iftag is set, the function sets
1030 * also settag. The function stops either after tagging nr_to_tag items or
1031 * after reaching last_index.
1033 * The tags must be set from the leaf level only and propagated back up the
1034 * path to the root. We must do this so that we resolve the full path before
1035 * setting any tags on intermediate nodes. If we set tags as we descend, then
1036 * we can get to the leaf node and find that the index that has the iftag
1037 * set is outside the range we are scanning. This reults in dangling tags and
1038 * can lead to problems with later tag operations (e.g. livelocks on lookups).
1040 * The function returns the number of leaves where the tag was set and sets
1041 * *first_indexp to the first unscanned index.
1042 * WARNING! *first_indexp can wrap if last_index is ULONG_MAX. Caller must
1043 * be prepared to handle that.
1045 unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root
*root
,
1046 unsigned long *first_indexp
, unsigned long last_index
,
1047 unsigned long nr_to_tag
,
1048 unsigned int iftag
, unsigned int settag
)
1050 struct radix_tree_node
*slot
, *node
= NULL
;
1051 unsigned long maxindex
;
1052 unsigned int shift
= radix_tree_load_root(root
, &slot
, &maxindex
);
1053 unsigned long tagged
= 0;
1054 unsigned long index
= *first_indexp
;
1056 last_index
= min(last_index
, maxindex
);
1057 if (index
> last_index
)
1061 if (!root_tag_get(root
, iftag
)) {
1062 *first_indexp
= last_index
+ 1;
1065 if (!radix_tree_is_indirect_ptr(slot
)) {
1066 *first_indexp
= last_index
+ 1;
1067 root_tag_set(root
, settag
);
1071 node
= indirect_to_ptr(slot
);
1072 shift
-= RADIX_TREE_MAP_SHIFT
;
1075 unsigned long upindex
;
1078 offset
= (index
>> shift
) & RADIX_TREE_MAP_MASK
;
1079 offset
= radix_tree_descend(node
, &slot
, offset
);
1082 if (!tag_get(node
, iftag
, offset
))
1084 /* Sibling slots never have tags set on them */
1085 if (radix_tree_is_indirect_ptr(slot
)) {
1086 node
= indirect_to_ptr(slot
);
1087 shift
-= RADIX_TREE_MAP_SHIFT
;
1093 tag_set(node
, settag
, offset
);
1095 slot
= node
->parent
;
1096 /* walk back up the path tagging interior nodes */
1097 upindex
= index
>> shift
;
1099 upindex
>>= RADIX_TREE_MAP_SHIFT
;
1100 offset
= upindex
& RADIX_TREE_MAP_MASK
;
1102 /* stop if we find a node with the tag already set */
1103 if (tag_get(slot
, settag
, offset
))
1105 tag_set(slot
, settag
, offset
);
1106 slot
= slot
->parent
;
1110 /* Go to next item at level determined by 'shift' */
1111 index
= ((index
>> shift
) + 1) << shift
;
1112 /* Overflow can happen when last_index is ~0UL... */
1113 if (index
> last_index
|| !index
)
1115 offset
= (index
>> shift
) & RADIX_TREE_MAP_MASK
;
1116 while (offset
== 0) {
1118 * We've fully scanned this node. Go up. Because
1119 * last_index is guaranteed to be in the tree, what
1120 * we do below cannot wander astray.
1122 node
= node
->parent
;
1123 shift
+= RADIX_TREE_MAP_SHIFT
;
1124 offset
= (index
>> shift
) & RADIX_TREE_MAP_MASK
;
1126 if (is_sibling_entry(node
, node
->slots
[offset
]))
1128 if (tagged
>= nr_to_tag
)
1132 * We need not to tag the root tag if there is no tag which is set with
1133 * settag within the range from *first_indexp to last_index.
1136 root_tag_set(root
, settag
);
1137 *first_indexp
= index
;
1141 EXPORT_SYMBOL(radix_tree_range_tag_if_tagged
);
1144 * radix_tree_gang_lookup - perform multiple lookup on a radix tree
1145 * @root: radix tree root
1146 * @results: where the results of the lookup are placed
1147 * @first_index: start the lookup from this key
1148 * @max_items: place up to this many items at *results
1150 * Performs an index-ascending scan of the tree for present items. Places
1151 * them at *@results and returns the number of items which were placed at
1154 * The implementation is naive.
1156 * Like radix_tree_lookup, radix_tree_gang_lookup may be called under
1157 * rcu_read_lock. In this case, rather than the returned results being
1158 * an atomic snapshot of the tree at a single point in time, the
1159 * semantics of an RCU protected gang lookup are as though multiple
1160 * radix_tree_lookups have been issued in individual locks, and results
1161 * stored in 'results'.
1164 radix_tree_gang_lookup(struct radix_tree_root
*root
, void **results
,
1165 unsigned long first_index
, unsigned int max_items
)
1167 struct radix_tree_iter iter
;
1169 unsigned int ret
= 0;
1171 if (unlikely(!max_items
))
1174 radix_tree_for_each_slot(slot
, root
, &iter
, first_index
) {
1175 results
[ret
] = rcu_dereference_raw(*slot
);
1178 if (radix_tree_is_indirect_ptr(results
[ret
])) {
1179 slot
= radix_tree_iter_retry(&iter
);
1182 if (++ret
== max_items
)
1188 EXPORT_SYMBOL(radix_tree_gang_lookup
);
1191 * radix_tree_gang_lookup_slot - perform multiple slot lookup on radix tree
1192 * @root: radix tree root
1193 * @results: where the results of the lookup are placed
1194 * @indices: where their indices should be placed (but usually NULL)
1195 * @first_index: start the lookup from this key
1196 * @max_items: place up to this many items at *results
1198 * Performs an index-ascending scan of the tree for present items. Places
1199 * their slots at *@results and returns the number of items which were
1200 * placed at *@results.
1202 * The implementation is naive.
1204 * Like radix_tree_gang_lookup as far as RCU and locking goes. Slots must
1205 * be dereferenced with radix_tree_deref_slot, and if using only RCU
1206 * protection, radix_tree_deref_slot may fail requiring a retry.
1209 radix_tree_gang_lookup_slot(struct radix_tree_root
*root
,
1210 void ***results
, unsigned long *indices
,
1211 unsigned long first_index
, unsigned int max_items
)
1213 struct radix_tree_iter iter
;
1215 unsigned int ret
= 0;
1217 if (unlikely(!max_items
))
1220 radix_tree_for_each_slot(slot
, root
, &iter
, first_index
) {
1221 results
[ret
] = slot
;
1223 indices
[ret
] = iter
.index
;
1224 if (++ret
== max_items
)
1230 EXPORT_SYMBOL(radix_tree_gang_lookup_slot
);
1233 * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree
1235 * @root: radix tree root
1236 * @results: where the results of the lookup are placed
1237 * @first_index: start the lookup from this key
1238 * @max_items: place up to this many items at *results
1239 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
1241 * Performs an index-ascending scan of the tree for present items which
1242 * have the tag indexed by @tag set. Places the items at *@results and
1243 * returns the number of items which were placed at *@results.
1246 radix_tree_gang_lookup_tag(struct radix_tree_root
*root
, void **results
,
1247 unsigned long first_index
, unsigned int max_items
,
1250 struct radix_tree_iter iter
;
1252 unsigned int ret
= 0;
1254 if (unlikely(!max_items
))
1257 radix_tree_for_each_tagged(slot
, root
, &iter
, first_index
, tag
) {
1258 results
[ret
] = rcu_dereference_raw(*slot
);
1261 if (radix_tree_is_indirect_ptr(results
[ret
])) {
1262 slot
= radix_tree_iter_retry(&iter
);
1265 if (++ret
== max_items
)
1271 EXPORT_SYMBOL(radix_tree_gang_lookup_tag
);
1274 * radix_tree_gang_lookup_tag_slot - perform multiple slot lookup on a
1275 * radix tree based on a tag
1276 * @root: radix tree root
1277 * @results: where the results of the lookup are placed
1278 * @first_index: start the lookup from this key
1279 * @max_items: place up to this many items at *results
1280 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
1282 * Performs an index-ascending scan of the tree for present items which
1283 * have the tag indexed by @tag set. Places the slots at *@results and
1284 * returns the number of slots which were placed at *@results.
1287 radix_tree_gang_lookup_tag_slot(struct radix_tree_root
*root
, void ***results
,
1288 unsigned long first_index
, unsigned int max_items
,
1291 struct radix_tree_iter iter
;
1293 unsigned int ret
= 0;
1295 if (unlikely(!max_items
))
1298 radix_tree_for_each_tagged(slot
, root
, &iter
, first_index
, tag
) {
1299 results
[ret
] = slot
;
1300 if (++ret
== max_items
)
1306 EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot
);
1308 #if defined(CONFIG_SHMEM) && defined(CONFIG_SWAP)
1309 #include <linux/sched.h> /* for cond_resched() */
1311 struct locate_info
{
1312 unsigned long found_index
;
1317 * This linear search is at present only useful to shmem_unuse_inode().
1319 static unsigned long __locate(struct radix_tree_node
*slot
, void *item
,
1320 unsigned long index
, struct locate_info
*info
)
1322 unsigned int shift
, height
;
1325 height
= slot
->path
& RADIX_TREE_HEIGHT_MASK
;
1326 shift
= height
* RADIX_TREE_MAP_SHIFT
;
1329 shift
-= RADIX_TREE_MAP_SHIFT
;
1331 for (i
= (index
>> shift
) & RADIX_TREE_MAP_MASK
;
1332 i
< RADIX_TREE_MAP_SIZE
;
1333 i
++, index
+= (1UL << shift
)) {
1334 struct radix_tree_node
*node
=
1335 rcu_dereference_raw(slot
->slots
[i
]);
1336 if (node
== RADIX_TREE_RETRY
)
1338 if (!radix_tree_is_indirect_ptr(node
)) {
1340 info
->found_index
= index
;
1346 node
= indirect_to_ptr(node
);
1347 if (is_sibling_entry(slot
, node
))
1352 if (i
== RADIX_TREE_MAP_SIZE
)
1357 if ((index
== 0) && (i
== RADIX_TREE_MAP_SIZE
))
1363 * radix_tree_locate_item - search through radix tree for item
1364 * @root: radix tree root
1365 * @item: item to be found
1367 * Returns index where item was found, or -1 if not found.
1368 * Caller must hold no lock (since this time-consuming function needs
1369 * to be preemptible), and must check afterwards if item is still there.
1371 unsigned long radix_tree_locate_item(struct radix_tree_root
*root
, void *item
)
1373 struct radix_tree_node
*node
;
1374 unsigned long max_index
;
1375 unsigned long cur_index
= 0;
1376 struct locate_info info
= {
1383 node
= rcu_dereference_raw(root
->rnode
);
1384 if (!radix_tree_is_indirect_ptr(node
)) {
1387 info
.found_index
= 0;
1391 node
= indirect_to_ptr(node
);
1393 max_index
= node_maxindex(node
);
1394 if (cur_index
> max_index
) {
1399 cur_index
= __locate(node
, item
, cur_index
, &info
);
1402 } while (!info
.stop
&& cur_index
<= max_index
);
1404 return info
.found_index
;
1407 unsigned long radix_tree_locate_item(struct radix_tree_root
*root
, void *item
)
1411 #endif /* CONFIG_SHMEM && CONFIG_SWAP */
1414 * radix_tree_shrink - shrink height of a radix tree to minimal
1415 * @root radix tree root
1417 static inline void radix_tree_shrink(struct radix_tree_root
*root
)
1419 /* try to shrink tree height */
1420 while (root
->height
> 0) {
1421 struct radix_tree_node
*to_free
= root
->rnode
;
1422 struct radix_tree_node
*slot
;
1424 BUG_ON(!radix_tree_is_indirect_ptr(to_free
));
1425 to_free
= indirect_to_ptr(to_free
);
1428 * The candidate node has more than one child, or its child
1429 * is not at the leftmost slot, or it is a multiorder entry,
1432 if (to_free
->count
!= 1)
1434 slot
= to_free
->slots
[0];
1437 if (!radix_tree_is_indirect_ptr(slot
) && (root
->height
> 1))
1440 if (radix_tree_is_indirect_ptr(slot
)) {
1441 slot
= indirect_to_ptr(slot
);
1442 slot
->parent
= NULL
;
1443 slot
= ptr_to_indirect(slot
);
1447 * We don't need rcu_assign_pointer(), since we are simply
1448 * moving the node from one part of the tree to another: if it
1449 * was safe to dereference the old pointer to it
1450 * (to_free->slots[0]), it will be safe to dereference the new
1451 * one (root->rnode) as far as dependent read barriers go.
1457 * We have a dilemma here. The node's slot[0] must not be
1458 * NULLed in case there are concurrent lookups expecting to
1459 * find the item. However if this was a bottom-level node,
1460 * then it may be subject to the slot pointer being visible
1461 * to callers dereferencing it. If item corresponding to
1462 * slot[0] is subsequently deleted, these callers would expect
1463 * their slot to become empty sooner or later.
1465 * For example, lockless pagecache will look up a slot, deref
1466 * the page pointer, and if the page has 0 refcount it means it
1467 * was concurrently deleted from pagecache so try the deref
1468 * again. Fortunately there is already a requirement for logic
1469 * to retry the entire slot lookup -- the indirect pointer
1470 * problem (replacing direct root node with an indirect pointer
1471 * also results in a stale slot). So tag the slot as indirect
1472 * to force callers to retry.
1474 if (!radix_tree_is_indirect_ptr(slot
))
1475 to_free
->slots
[0] = RADIX_TREE_RETRY
;
1477 radix_tree_node_free(to_free
);
1482 * __radix_tree_delete_node - try to free node after clearing a slot
1483 * @root: radix tree root
1484 * @node: node containing @index
1486 * After clearing the slot at @index in @node from radix tree
1487 * rooted at @root, call this function to attempt freeing the
1488 * node and shrinking the tree.
1490 * Returns %true if @node was freed, %false otherwise.
1492 bool __radix_tree_delete_node(struct radix_tree_root
*root
,
1493 struct radix_tree_node
*node
)
1495 bool deleted
= false;
1498 struct radix_tree_node
*parent
;
1501 if (node
== indirect_to_ptr(root
->rnode
)) {
1502 radix_tree_shrink(root
);
1503 if (root
->height
== 0)
1509 parent
= node
->parent
;
1511 unsigned int offset
;
1513 offset
= node
->path
>> RADIX_TREE_HEIGHT_SHIFT
;
1514 parent
->slots
[offset
] = NULL
;
1517 root_tag_clear_all(root
);
1522 radix_tree_node_free(node
);
1531 static inline void delete_sibling_entries(struct radix_tree_node
*node
,
1532 void *ptr
, unsigned offset
)
1534 #ifdef CONFIG_RADIX_TREE_MULTIORDER
1536 for (i
= 1; offset
+ i
< RADIX_TREE_MAP_SIZE
; i
++) {
1537 if (node
->slots
[offset
+ i
] != ptr
)
1539 node
->slots
[offset
+ i
] = NULL
;
1546 * radix_tree_delete_item - delete an item from a radix tree
1547 * @root: radix tree root
1549 * @item: expected item
1551 * Remove @item at @index from the radix tree rooted at @root.
1553 * Returns the address of the deleted item, or NULL if it was not present
1554 * or the entry at the given @index was not @item.
1556 void *radix_tree_delete_item(struct radix_tree_root
*root
,
1557 unsigned long index
, void *item
)
1559 struct radix_tree_node
*node
;
1560 unsigned int offset
;
1565 entry
= __radix_tree_lookup(root
, index
, &node
, &slot
);
1569 if (item
&& entry
!= item
)
1573 root_tag_clear_all(root
);
1578 offset
= get_slot_offset(node
, slot
);
1581 * Clear all tags associated with the item to be deleted.
1582 * This way of doing it would be inefficient, but seldom is any set.
1584 for (tag
= 0; tag
< RADIX_TREE_MAX_TAGS
; tag
++) {
1585 if (tag_get(node
, tag
, offset
))
1586 radix_tree_tag_clear(root
, index
, tag
);
1589 delete_sibling_entries(node
, ptr_to_indirect(slot
), offset
);
1590 node
->slots
[offset
] = NULL
;
1593 __radix_tree_delete_node(root
, node
);
1597 EXPORT_SYMBOL(radix_tree_delete_item
);
1600 * radix_tree_delete - delete an item from a radix tree
1601 * @root: radix tree root
1604 * Remove the item at @index from the radix tree rooted at @root.
1606 * Returns the address of the deleted item, or NULL if it was not present.
1608 void *radix_tree_delete(struct radix_tree_root
*root
, unsigned long index
)
1610 return radix_tree_delete_item(root
, index
, NULL
);
1612 EXPORT_SYMBOL(radix_tree_delete
);
1615 * radix_tree_tagged - test whether any items in the tree are tagged
1616 * @root: radix tree root
1619 int radix_tree_tagged(struct radix_tree_root
*root
, unsigned int tag
)
1621 return root_tag_get(root
, tag
);
1623 EXPORT_SYMBOL(radix_tree_tagged
);
1626 radix_tree_node_ctor(void *arg
)
1628 struct radix_tree_node
*node
= arg
;
1630 memset(node
, 0, sizeof(*node
));
1631 INIT_LIST_HEAD(&node
->private_list
);
1634 static __init
unsigned long __maxindex(unsigned int height
)
1636 unsigned int width
= height
* RADIX_TREE_MAP_SHIFT
;
1637 int shift
= RADIX_TREE_INDEX_BITS
- width
;
1641 if (shift
>= BITS_PER_LONG
)
1643 return ~0UL >> shift
;
1646 static __init
void radix_tree_init_maxindex(void)
1650 for (i
= 0; i
< ARRAY_SIZE(height_to_maxindex
); i
++)
1651 height_to_maxindex
[i
] = __maxindex(i
);
1654 static int radix_tree_callback(struct notifier_block
*nfb
,
1655 unsigned long action
, void *hcpu
)
1657 int cpu
= (long)hcpu
;
1658 struct radix_tree_preload
*rtp
;
1659 struct radix_tree_node
*node
;
1661 /* Free per-cpu pool of preloaded nodes */
1662 if (action
== CPU_DEAD
|| action
== CPU_DEAD_FROZEN
) {
1663 rtp
= &per_cpu(radix_tree_preloads
, cpu
);
1666 rtp
->nodes
= node
->private_data
;
1667 kmem_cache_free(radix_tree_node_cachep
, node
);
1674 void __init
radix_tree_init(void)
1676 radix_tree_node_cachep
= kmem_cache_create("radix_tree_node",
1677 sizeof(struct radix_tree_node
), 0,
1678 SLAB_PANIC
| SLAB_RECLAIM_ACCOUNT
,
1679 radix_tree_node_ctor
);
1680 radix_tree_init_maxindex();
1681 hotcpu_notifier(radix_tree_callback
, 0);