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/cpu.h>
26 #include <linux/errno.h>
27 #include <linux/init.h>
28 #include <linux/kernel.h>
29 #include <linux/export.h>
30 #include <linux/radix-tree.h>
31 #include <linux/percpu.h>
32 #include <linux/slab.h>
33 #include <linux/kmemleak.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() */
41 /* Number of nodes in fully populated tree of given height */
42 static unsigned long height_to_maxnodes
[RADIX_TREE_MAX_PATH
+ 1] __read_mostly
;
45 * Radix tree node cache.
47 static struct kmem_cache
*radix_tree_node_cachep
;
50 * The radix tree is variable-height, so an insert operation not only has
51 * to build the branch to its corresponding item, it also has to build the
52 * branch to existing items if the size has to be increased (by
55 * The worst case is a zero height tree with just a single item at index 0,
56 * and then inserting an item at index ULONG_MAX. This requires 2 new branches
57 * of RADIX_TREE_MAX_PATH size to be created, with only the root node shared.
60 #define RADIX_TREE_PRELOAD_SIZE (RADIX_TREE_MAX_PATH * 2 - 1)
63 * Per-cpu pool of preloaded nodes
65 struct radix_tree_preload
{
67 /* nodes->private_data points to next preallocated node */
68 struct radix_tree_node
*nodes
;
70 static DEFINE_PER_CPU(struct radix_tree_preload
, radix_tree_preloads
) = { 0, };
72 static inline struct radix_tree_node
*entry_to_node(void *ptr
)
74 return (void *)((unsigned long)ptr
& ~RADIX_TREE_INTERNAL_NODE
);
77 static inline void *node_to_entry(void *ptr
)
79 return (void *)((unsigned long)ptr
| RADIX_TREE_INTERNAL_NODE
);
82 #define RADIX_TREE_RETRY node_to_entry(NULL)
84 #ifdef CONFIG_RADIX_TREE_MULTIORDER
85 /* Sibling slots point directly to another slot in the same node */
86 static inline bool is_sibling_entry(struct radix_tree_node
*parent
, void *node
)
89 return (parent
->slots
<= ptr
) &&
90 (ptr
< parent
->slots
+ RADIX_TREE_MAP_SIZE
);
93 static inline bool is_sibling_entry(struct radix_tree_node
*parent
, void *node
)
99 static inline unsigned long get_slot_offset(struct radix_tree_node
*parent
,
102 return slot
- parent
->slots
;
105 static unsigned int radix_tree_descend(struct radix_tree_node
*parent
,
106 struct radix_tree_node
**nodep
, unsigned long index
)
108 unsigned int offset
= (index
>> parent
->shift
) & RADIX_TREE_MAP_MASK
;
109 void **entry
= rcu_dereference_raw(parent
->slots
[offset
]);
111 #ifdef CONFIG_RADIX_TREE_MULTIORDER
112 if (radix_tree_is_internal_node(entry
)) {
113 if (is_sibling_entry(parent
, entry
)) {
114 void **sibentry
= (void **) entry_to_node(entry
);
115 offset
= get_slot_offset(parent
, sibentry
);
116 entry
= rcu_dereference_raw(*sibentry
);
121 *nodep
= (void *)entry
;
125 static inline gfp_t
root_gfp_mask(struct radix_tree_root
*root
)
127 return root
->gfp_mask
& __GFP_BITS_MASK
;
130 static inline void tag_set(struct radix_tree_node
*node
, unsigned int tag
,
133 __set_bit(offset
, node
->tags
[tag
]);
136 static inline void tag_clear(struct radix_tree_node
*node
, unsigned int tag
,
139 __clear_bit(offset
, node
->tags
[tag
]);
142 static inline int tag_get(struct radix_tree_node
*node
, unsigned int tag
,
145 return test_bit(offset
, node
->tags
[tag
]);
148 static inline void root_tag_set(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(struct radix_tree_root
*root
, unsigned tag
)
155 root
->gfp_mask
&= (__force gfp_t
)~(1 << (tag
+ __GFP_BITS_SHIFT
));
158 static inline void root_tag_clear_all(struct radix_tree_root
*root
)
160 root
->gfp_mask
&= __GFP_BITS_MASK
;
163 static inline int root_tag_get(struct radix_tree_root
*root
, unsigned int tag
)
165 return (__force
int)root
->gfp_mask
& (1 << (tag
+ __GFP_BITS_SHIFT
));
168 static inline unsigned root_tags_get(struct radix_tree_root
*root
)
170 return (__force
unsigned)root
->gfp_mask
>> __GFP_BITS_SHIFT
;
174 * Returns 1 if any slot in the node has this tag set.
175 * Otherwise returns 0.
177 static inline int any_tag_set(struct radix_tree_node
*node
, unsigned int tag
)
180 for (idx
= 0; idx
< RADIX_TREE_TAG_LONGS
; idx
++) {
181 if (node
->tags
[tag
][idx
])
188 * radix_tree_find_next_bit - find the next set bit in a memory region
190 * @addr: The address to base the search on
191 * @size: The bitmap size in bits
192 * @offset: The bitnumber to start searching at
194 * Unrollable variant of find_next_bit() for constant size arrays.
195 * Tail bits starting from size to roundup(size, BITS_PER_LONG) must be zero.
196 * Returns next bit offset, or size if nothing found.
198 static __always_inline
unsigned long
199 radix_tree_find_next_bit(struct radix_tree_node
*node
, unsigned int tag
,
200 unsigned long offset
)
202 const unsigned long *addr
= node
->tags
[tag
];
204 if (offset
< RADIX_TREE_MAP_SIZE
) {
207 addr
+= offset
/ BITS_PER_LONG
;
208 tmp
= *addr
>> (offset
% BITS_PER_LONG
);
210 return __ffs(tmp
) + offset
;
211 offset
= (offset
+ BITS_PER_LONG
) & ~(BITS_PER_LONG
- 1);
212 while (offset
< RADIX_TREE_MAP_SIZE
) {
215 return __ffs(tmp
) + offset
;
216 offset
+= BITS_PER_LONG
;
219 return RADIX_TREE_MAP_SIZE
;
222 static unsigned int iter_offset(const struct radix_tree_iter
*iter
)
224 return (iter
->index
>> iter_shift(iter
)) & RADIX_TREE_MAP_MASK
;
228 * The maximum index which can be stored in a radix tree
230 static inline unsigned long shift_maxindex(unsigned int shift
)
232 return (RADIX_TREE_MAP_SIZE
<< shift
) - 1;
235 static inline unsigned long node_maxindex(struct radix_tree_node
*node
)
237 return shift_maxindex(node
->shift
);
241 static void dump_node(struct radix_tree_node
*node
, unsigned long index
)
245 pr_debug("radix node: %p offset %d indices %lu-%lu parent %p tags %lx %lx %lx shift %d count %d exceptional %d\n",
246 node
, node
->offset
, index
, index
| node_maxindex(node
),
248 node
->tags
[0][0], node
->tags
[1][0], node
->tags
[2][0],
249 node
->shift
, node
->count
, node
->exceptional
);
251 for (i
= 0; i
< RADIX_TREE_MAP_SIZE
; i
++) {
252 unsigned long first
= index
| (i
<< node
->shift
);
253 unsigned long last
= first
| ((1UL << node
->shift
) - 1);
254 void *entry
= node
->slots
[i
];
257 if (entry
== RADIX_TREE_RETRY
) {
258 pr_debug("radix retry offset %ld indices %lu-%lu parent %p\n",
259 i
, first
, last
, node
);
260 } else if (!radix_tree_is_internal_node(entry
)) {
261 pr_debug("radix entry %p offset %ld indices %lu-%lu parent %p\n",
262 entry
, i
, first
, last
, node
);
263 } else if (is_sibling_entry(node
, entry
)) {
264 pr_debug("radix sblng %p offset %ld indices %lu-%lu parent %p val %p\n",
265 entry
, i
, first
, last
, node
,
266 *(void **)entry_to_node(entry
));
268 dump_node(entry_to_node(entry
), first
);
274 static void radix_tree_dump(struct radix_tree_root
*root
)
276 pr_debug("radix root: %p rnode %p tags %x\n",
278 root
->gfp_mask
>> __GFP_BITS_SHIFT
);
279 if (!radix_tree_is_internal_node(root
->rnode
))
281 dump_node(entry_to_node(root
->rnode
), 0);
286 * This assumes that the caller has performed appropriate preallocation, and
287 * that the caller has pinned this thread of control to the current CPU.
289 static struct radix_tree_node
*
290 radix_tree_node_alloc(struct radix_tree_root
*root
,
291 struct radix_tree_node
*parent
,
292 unsigned int shift
, unsigned int offset
,
293 unsigned int count
, unsigned int exceptional
)
295 struct radix_tree_node
*ret
= NULL
;
296 gfp_t gfp_mask
= root_gfp_mask(root
);
299 * Preload code isn't irq safe and it doesn't make sense to use
300 * preloading during an interrupt anyway as all the allocations have
301 * to be atomic. So just do normal allocation when in interrupt.
303 if (!gfpflags_allow_blocking(gfp_mask
) && !in_interrupt()) {
304 struct radix_tree_preload
*rtp
;
307 * Even if the caller has preloaded, try to allocate from the
308 * cache first for the new node to get accounted to the memory
311 ret
= kmem_cache_alloc(radix_tree_node_cachep
,
312 gfp_mask
| __GFP_NOWARN
);
317 * Provided the caller has preloaded here, we will always
318 * succeed in getting a node here (and never reach
321 rtp
= this_cpu_ptr(&radix_tree_preloads
);
324 rtp
->nodes
= ret
->private_data
;
325 ret
->private_data
= NULL
;
329 * Update the allocation stack trace as this is more useful
332 kmemleak_update_trace(ret
);
335 ret
= kmem_cache_alloc(radix_tree_node_cachep
, gfp_mask
);
337 BUG_ON(radix_tree_is_internal_node(ret
));
339 ret
->parent
= parent
;
341 ret
->offset
= offset
;
343 ret
->exceptional
= exceptional
;
348 static void radix_tree_node_rcu_free(struct rcu_head
*head
)
350 struct radix_tree_node
*node
=
351 container_of(head
, struct radix_tree_node
, rcu_head
);
354 * Must only free zeroed nodes into the slab. We can be left with
355 * non-NULL entries by radix_tree_free_nodes, so clear the entries
358 memset(node
->slots
, 0, sizeof(node
->slots
));
359 memset(node
->tags
, 0, sizeof(node
->tags
));
360 INIT_LIST_HEAD(&node
->private_list
);
362 kmem_cache_free(radix_tree_node_cachep
, node
);
366 radix_tree_node_free(struct radix_tree_node
*node
)
368 call_rcu(&node
->rcu_head
, radix_tree_node_rcu_free
);
372 * Load up this CPU's radix_tree_node buffer with sufficient objects to
373 * ensure that the addition of a single element in the tree cannot fail. On
374 * success, return zero, with preemption disabled. On error, return -ENOMEM
375 * with preemption not disabled.
377 * To make use of this facility, the radix tree must be initialised without
378 * __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE().
380 static int __radix_tree_preload(gfp_t gfp_mask
, unsigned nr
)
382 struct radix_tree_preload
*rtp
;
383 struct radix_tree_node
*node
;
387 * Nodes preloaded by one cgroup can be be used by another cgroup, so
388 * they should never be accounted to any particular memory cgroup.
390 gfp_mask
&= ~__GFP_ACCOUNT
;
393 rtp
= this_cpu_ptr(&radix_tree_preloads
);
394 while (rtp
->nr
< nr
) {
396 node
= kmem_cache_alloc(radix_tree_node_cachep
, gfp_mask
);
400 rtp
= this_cpu_ptr(&radix_tree_preloads
);
402 node
->private_data
= rtp
->nodes
;
406 kmem_cache_free(radix_tree_node_cachep
, node
);
415 * Load up this CPU's radix_tree_node buffer with sufficient objects to
416 * ensure that the addition of a single element in the tree cannot fail. On
417 * success, return zero, with preemption disabled. On error, return -ENOMEM
418 * with preemption not disabled.
420 * To make use of this facility, the radix tree must be initialised without
421 * __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE().
423 int radix_tree_preload(gfp_t gfp_mask
)
425 /* Warn on non-sensical use... */
426 WARN_ON_ONCE(!gfpflags_allow_blocking(gfp_mask
));
427 return __radix_tree_preload(gfp_mask
, RADIX_TREE_PRELOAD_SIZE
);
429 EXPORT_SYMBOL(radix_tree_preload
);
432 * The same as above function, except we don't guarantee preloading happens.
433 * We do it, if we decide it helps. On success, return zero with preemption
434 * disabled. On error, return -ENOMEM with preemption not disabled.
436 int radix_tree_maybe_preload(gfp_t gfp_mask
)
438 if (gfpflags_allow_blocking(gfp_mask
))
439 return __radix_tree_preload(gfp_mask
, RADIX_TREE_PRELOAD_SIZE
);
440 /* Preloading doesn't help anything with this gfp mask, skip it */
444 EXPORT_SYMBOL(radix_tree_maybe_preload
);
446 #ifdef CONFIG_RADIX_TREE_MULTIORDER
448 * Preload with enough objects to ensure that we can split a single entry
449 * of order @old_order into many entries of size @new_order
451 int radix_tree_split_preload(unsigned int old_order
, unsigned int new_order
,
454 unsigned top
= 1 << (old_order
% RADIX_TREE_MAP_SHIFT
);
455 unsigned layers
= (old_order
/ RADIX_TREE_MAP_SHIFT
) -
456 (new_order
/ RADIX_TREE_MAP_SHIFT
);
459 WARN_ON_ONCE(!gfpflags_allow_blocking(gfp_mask
));
460 BUG_ON(new_order
>= old_order
);
463 nr
= nr
* RADIX_TREE_MAP_SIZE
+ 1;
464 return __radix_tree_preload(gfp_mask
, top
* nr
);
469 * The same as function above, but preload number of nodes required to insert
470 * (1 << order) continuous naturally-aligned elements.
472 int radix_tree_maybe_preload_order(gfp_t gfp_mask
, int order
)
474 unsigned long nr_subtrees
;
475 int nr_nodes
, subtree_height
;
477 /* Preloading doesn't help anything with this gfp mask, skip it */
478 if (!gfpflags_allow_blocking(gfp_mask
)) {
484 * Calculate number and height of fully populated subtrees it takes to
485 * store (1 << order) elements.
487 nr_subtrees
= 1 << order
;
488 for (subtree_height
= 0; nr_subtrees
> RADIX_TREE_MAP_SIZE
;
490 nr_subtrees
>>= RADIX_TREE_MAP_SHIFT
;
493 * The worst case is zero height tree with a single item at index 0 and
494 * then inserting items starting at ULONG_MAX - (1 << order).
496 * This requires RADIX_TREE_MAX_PATH nodes to build branch from root to
499 nr_nodes
= RADIX_TREE_MAX_PATH
;
501 /* Plus branch to fully populated subtrees. */
502 nr_nodes
+= RADIX_TREE_MAX_PATH
- subtree_height
;
504 /* Root node is shared. */
507 /* Plus nodes required to build subtrees. */
508 nr_nodes
+= nr_subtrees
* height_to_maxnodes
[subtree_height
];
510 return __radix_tree_preload(gfp_mask
, nr_nodes
);
513 static unsigned radix_tree_load_root(struct radix_tree_root
*root
,
514 struct radix_tree_node
**nodep
, unsigned long *maxindex
)
516 struct radix_tree_node
*node
= rcu_dereference_raw(root
->rnode
);
520 if (likely(radix_tree_is_internal_node(node
))) {
521 node
= entry_to_node(node
);
522 *maxindex
= node_maxindex(node
);
523 return node
->shift
+ RADIX_TREE_MAP_SHIFT
;
531 * Extend a radix tree so it can store key @index.
533 static int radix_tree_extend(struct radix_tree_root
*root
,
534 unsigned long index
, unsigned int shift
)
536 struct radix_tree_node
*slot
;
537 unsigned int maxshift
;
540 /* Figure out what the shift should be. */
542 while (index
> shift_maxindex(maxshift
))
543 maxshift
+= RADIX_TREE_MAP_SHIFT
;
550 struct radix_tree_node
*node
= radix_tree_node_alloc(root
,
551 NULL
, shift
, 0, 1, 0);
555 /* Propagate the aggregated tag info into the new root */
556 for (tag
= 0; tag
< RADIX_TREE_MAX_TAGS
; tag
++) {
557 if (root_tag_get(root
, tag
))
558 tag_set(node
, tag
, 0);
561 BUG_ON(shift
> BITS_PER_LONG
);
562 if (radix_tree_is_internal_node(slot
)) {
563 entry_to_node(slot
)->parent
= node
;
564 } else if (radix_tree_exceptional_entry(slot
)) {
565 /* Moving an exceptional root->rnode to a node */
566 node
->exceptional
= 1;
568 node
->slots
[0] = slot
;
569 slot
= node_to_entry(node
);
570 rcu_assign_pointer(root
->rnode
, slot
);
571 shift
+= RADIX_TREE_MAP_SHIFT
;
572 } while (shift
<= maxshift
);
574 return maxshift
+ RADIX_TREE_MAP_SHIFT
;
578 * radix_tree_shrink - shrink radix tree to minimum height
579 * @root radix tree root
581 static inline void radix_tree_shrink(struct radix_tree_root
*root
,
582 radix_tree_update_node_t update_node
,
586 struct radix_tree_node
*node
= root
->rnode
;
587 struct radix_tree_node
*child
;
589 if (!radix_tree_is_internal_node(node
))
591 node
= entry_to_node(node
);
594 * The candidate node has more than one child, or its child
595 * is not at the leftmost slot, or the child is a multiorder
596 * entry, we cannot shrink.
598 if (node
->count
!= 1)
600 child
= node
->slots
[0];
603 if (!radix_tree_is_internal_node(child
) && node
->shift
)
606 if (radix_tree_is_internal_node(child
))
607 entry_to_node(child
)->parent
= NULL
;
610 * We don't need rcu_assign_pointer(), since we are simply
611 * moving the node from one part of the tree to another: if it
612 * was safe to dereference the old pointer to it
613 * (node->slots[0]), it will be safe to dereference the new
614 * one (root->rnode) as far as dependent read barriers go.
619 * We have a dilemma here. The node's slot[0] must not be
620 * NULLed in case there are concurrent lookups expecting to
621 * find the item. However if this was a bottom-level node,
622 * then it may be subject to the slot pointer being visible
623 * to callers dereferencing it. If item corresponding to
624 * slot[0] is subsequently deleted, these callers would expect
625 * their slot to become empty sooner or later.
627 * For example, lockless pagecache will look up a slot, deref
628 * the page pointer, and if the page has 0 refcount it means it
629 * was concurrently deleted from pagecache so try the deref
630 * again. Fortunately there is already a requirement for logic
631 * to retry the entire slot lookup -- the indirect pointer
632 * problem (replacing direct root node with an indirect pointer
633 * also results in a stale slot). So tag the slot as indirect
634 * to force callers to retry.
637 if (!radix_tree_is_internal_node(child
)) {
638 node
->slots
[0] = RADIX_TREE_RETRY
;
640 update_node(node
, private);
643 radix_tree_node_free(node
);
647 static void delete_node(struct radix_tree_root
*root
,
648 struct radix_tree_node
*node
,
649 radix_tree_update_node_t update_node
, void *private)
652 struct radix_tree_node
*parent
;
655 if (node
== entry_to_node(root
->rnode
))
656 radix_tree_shrink(root
, update_node
, private);
660 parent
= node
->parent
;
662 parent
->slots
[node
->offset
] = NULL
;
665 root_tag_clear_all(root
);
669 radix_tree_node_free(node
);
676 * __radix_tree_create - create a slot in a radix tree
677 * @root: radix tree root
679 * @order: index occupies 2^order aligned slots
680 * @nodep: returns node
681 * @slotp: returns slot
683 * Create, if necessary, and return the node and slot for an item
684 * at position @index in the radix tree @root.
686 * Until there is more than one item in the tree, no nodes are
687 * allocated and @root->rnode is used as a direct slot instead of
688 * pointing to a node, in which case *@nodep will be NULL.
690 * Returns -ENOMEM, or 0 for success.
692 int __radix_tree_create(struct radix_tree_root
*root
, unsigned long index
,
693 unsigned order
, struct radix_tree_node
**nodep
,
696 struct radix_tree_node
*node
= NULL
, *child
;
697 void **slot
= (void **)&root
->rnode
;
698 unsigned long maxindex
;
699 unsigned int shift
, offset
= 0;
700 unsigned long max
= index
| ((1UL << order
) - 1);
702 shift
= radix_tree_load_root(root
, &child
, &maxindex
);
704 /* Make sure the tree is high enough. */
705 if (order
> 0 && max
== ((1UL << order
) - 1))
707 if (max
> maxindex
) {
708 int error
= radix_tree_extend(root
, max
, shift
);
715 while (shift
> order
) {
716 shift
-= RADIX_TREE_MAP_SHIFT
;
718 /* Have to add a child node. */
719 child
= radix_tree_node_alloc(root
, node
, shift
,
723 rcu_assign_pointer(*slot
, node_to_entry(child
));
726 } else if (!radix_tree_is_internal_node(child
))
729 /* Go a level down */
730 node
= entry_to_node(child
);
731 offset
= radix_tree_descend(node
, &child
, index
);
732 slot
= &node
->slots
[offset
];
742 #ifdef CONFIG_RADIX_TREE_MULTIORDER
744 * Free any nodes below this node. The tree is presumed to not need
745 * shrinking, and any user data in the tree is presumed to not need a
746 * destructor called on it. If we need to add a destructor, we can
747 * add that functionality later. Note that we may not clear tags or
748 * slots from the tree as an RCU walker may still have a pointer into
749 * this subtree. We could replace the entries with RADIX_TREE_RETRY,
750 * but we'll still have to clear those in rcu_free.
752 static void radix_tree_free_nodes(struct radix_tree_node
*node
)
755 struct radix_tree_node
*child
= entry_to_node(node
);
758 void *entry
= child
->slots
[offset
];
759 if (radix_tree_is_internal_node(entry
) &&
760 !is_sibling_entry(child
, entry
)) {
761 child
= entry_to_node(entry
);
766 while (offset
== RADIX_TREE_MAP_SIZE
) {
767 struct radix_tree_node
*old
= child
;
768 offset
= child
->offset
+ 1;
769 child
= child
->parent
;
770 radix_tree_node_free(old
);
771 if (old
== entry_to_node(node
))
777 static inline int insert_entries(struct radix_tree_node
*node
, void **slot
,
778 void *item
, unsigned order
, bool replace
)
780 struct radix_tree_node
*child
;
781 unsigned i
, n
, tag
, offset
, tags
= 0;
784 if (order
> node
->shift
)
785 n
= 1 << (order
- node
->shift
);
788 offset
= get_slot_offset(node
, slot
);
795 offset
= offset
& ~(n
- 1);
796 slot
= &node
->slots
[offset
];
798 child
= node_to_entry(slot
);
800 for (i
= 0; i
< n
; i
++) {
804 for (tag
= 0; tag
< RADIX_TREE_MAX_TAGS
; tag
++)
805 if (tag_get(node
, tag
, offset
+ i
))
812 for (i
= 0; i
< n
; i
++) {
813 struct radix_tree_node
*old
= slot
[i
];
815 rcu_assign_pointer(slot
[i
], child
);
816 for (tag
= 0; tag
< RADIX_TREE_MAX_TAGS
; tag
++)
817 if (tags
& (1 << tag
))
818 tag_clear(node
, tag
, offset
+ i
);
820 rcu_assign_pointer(slot
[i
], item
);
821 for (tag
= 0; tag
< RADIX_TREE_MAX_TAGS
; tag
++)
822 if (tags
& (1 << tag
))
823 tag_set(node
, tag
, offset
);
825 if (radix_tree_is_internal_node(old
) &&
826 !is_sibling_entry(node
, old
) &&
827 (old
!= RADIX_TREE_RETRY
))
828 radix_tree_free_nodes(old
);
829 if (radix_tree_exceptional_entry(old
))
834 if (radix_tree_exceptional_entry(item
))
835 node
->exceptional
+= n
;
840 static inline int insert_entries(struct radix_tree_node
*node
, void **slot
,
841 void *item
, unsigned order
, bool replace
)
845 rcu_assign_pointer(*slot
, item
);
848 if (radix_tree_exceptional_entry(item
))
856 * __radix_tree_insert - insert into a radix tree
857 * @root: radix tree root
859 * @order: key covers the 2^order indices around index
860 * @item: item to insert
862 * Insert an item into the radix tree at position @index.
864 int __radix_tree_insert(struct radix_tree_root
*root
, unsigned long index
,
865 unsigned order
, void *item
)
867 struct radix_tree_node
*node
;
871 BUG_ON(radix_tree_is_internal_node(item
));
873 error
= __radix_tree_create(root
, index
, order
, &node
, &slot
);
877 error
= insert_entries(node
, slot
, item
, order
, false);
882 unsigned offset
= get_slot_offset(node
, slot
);
883 BUG_ON(tag_get(node
, 0, offset
));
884 BUG_ON(tag_get(node
, 1, offset
));
885 BUG_ON(tag_get(node
, 2, offset
));
887 BUG_ON(root_tags_get(root
));
892 EXPORT_SYMBOL(__radix_tree_insert
);
895 * __radix_tree_lookup - lookup an item in a radix tree
896 * @root: radix tree root
898 * @nodep: returns node
899 * @slotp: returns slot
901 * Lookup and return the item at position @index in the radix
904 * Until there is more than one item in the tree, no nodes are
905 * allocated and @root->rnode is used as a direct slot instead of
906 * pointing to a node, in which case *@nodep will be NULL.
908 void *__radix_tree_lookup(struct radix_tree_root
*root
, unsigned long index
,
909 struct radix_tree_node
**nodep
, void ***slotp
)
911 struct radix_tree_node
*node
, *parent
;
912 unsigned long maxindex
;
917 slot
= (void **)&root
->rnode
;
918 radix_tree_load_root(root
, &node
, &maxindex
);
919 if (index
> maxindex
)
922 while (radix_tree_is_internal_node(node
)) {
925 if (node
== RADIX_TREE_RETRY
)
927 parent
= entry_to_node(node
);
928 offset
= radix_tree_descend(parent
, &node
, index
);
929 slot
= parent
->slots
+ offset
;
940 * radix_tree_lookup_slot - lookup a slot in a radix tree
941 * @root: radix tree root
944 * Returns: the slot corresponding to the position @index in the
945 * radix tree @root. This is useful for update-if-exists operations.
947 * This function can be called under rcu_read_lock iff the slot is not
948 * modified by radix_tree_replace_slot, otherwise it must be called
949 * exclusive from other writers. Any dereference of the slot must be done
950 * using radix_tree_deref_slot.
952 void **radix_tree_lookup_slot(struct radix_tree_root
*root
, unsigned long index
)
956 if (!__radix_tree_lookup(root
, index
, NULL
, &slot
))
960 EXPORT_SYMBOL(radix_tree_lookup_slot
);
963 * radix_tree_lookup - perform lookup operation on a radix tree
964 * @root: radix tree root
967 * Lookup the item at the position @index in the radix tree @root.
969 * This function can be called under rcu_read_lock, however the caller
970 * must manage lifetimes of leaf nodes (eg. RCU may also be used to free
971 * them safely). No RCU barriers are required to access or modify the
972 * returned item, however.
974 void *radix_tree_lookup(struct radix_tree_root
*root
, unsigned long index
)
976 return __radix_tree_lookup(root
, index
, NULL
, NULL
);
978 EXPORT_SYMBOL(radix_tree_lookup
);
980 static inline int slot_count(struct radix_tree_node
*node
,
984 #ifdef CONFIG_RADIX_TREE_MULTIORDER
985 void *ptr
= node_to_entry(slot
);
986 unsigned offset
= get_slot_offset(node
, slot
);
989 for (i
= 1; offset
+ i
< RADIX_TREE_MAP_SIZE
; i
++) {
990 if (node
->slots
[offset
+ i
] != ptr
)
998 static void replace_slot(struct radix_tree_root
*root
,
999 struct radix_tree_node
*node
,
1000 void **slot
, void *item
,
1001 bool warn_typeswitch
)
1003 void *old
= rcu_dereference_raw(*slot
);
1004 int count
, exceptional
;
1006 WARN_ON_ONCE(radix_tree_is_internal_node(item
));
1008 count
= !!item
- !!old
;
1009 exceptional
= !!radix_tree_exceptional_entry(item
) -
1010 !!radix_tree_exceptional_entry(old
);
1012 WARN_ON_ONCE(warn_typeswitch
&& (count
|| exceptional
));
1015 node
->count
+= count
;
1017 exceptional
*= slot_count(node
, slot
);
1018 node
->exceptional
+= exceptional
;
1022 rcu_assign_pointer(*slot
, item
);
1025 static inline void delete_sibling_entries(struct radix_tree_node
*node
,
1028 #ifdef CONFIG_RADIX_TREE_MULTIORDER
1029 bool exceptional
= radix_tree_exceptional_entry(*slot
);
1030 void *ptr
= node_to_entry(slot
);
1031 unsigned offset
= get_slot_offset(node
, slot
);
1034 for (i
= 1; offset
+ i
< RADIX_TREE_MAP_SIZE
; i
++) {
1035 if (node
->slots
[offset
+ i
] != ptr
)
1037 node
->slots
[offset
+ i
] = NULL
;
1040 node
->exceptional
--;
1046 * __radix_tree_replace - replace item in a slot
1047 * @root: radix tree root
1048 * @node: pointer to tree node
1049 * @slot: pointer to slot in @node
1050 * @item: new item to store in the slot.
1051 * @update_node: callback for changing leaf nodes
1052 * @private: private data to pass to @update_node
1054 * For use with __radix_tree_lookup(). Caller must hold tree write locked
1055 * across slot lookup and replacement.
1057 void __radix_tree_replace(struct radix_tree_root
*root
,
1058 struct radix_tree_node
*node
,
1059 void **slot
, void *item
,
1060 radix_tree_update_node_t update_node
, void *private)
1063 delete_sibling_entries(node
, slot
);
1065 * This function supports replacing exceptional entries and
1066 * deleting entries, but that needs accounting against the
1067 * node unless the slot is root->rnode.
1069 replace_slot(root
, node
, slot
, item
,
1070 !node
&& slot
!= (void **)&root
->rnode
);
1076 update_node(node
, private);
1078 delete_node(root
, node
, update_node
, private);
1082 * radix_tree_replace_slot - replace item in a slot
1083 * @root: radix tree root
1084 * @slot: pointer to slot
1085 * @item: new item to store in the slot.
1087 * For use with radix_tree_lookup_slot(), radix_tree_gang_lookup_slot(),
1088 * radix_tree_gang_lookup_tag_slot(). Caller must hold tree write locked
1089 * across slot lookup and replacement.
1091 * NOTE: This cannot be used to switch between non-entries (empty slots),
1092 * regular entries, and exceptional entries, as that requires accounting
1093 * inside the radix tree node. When switching from one type of entry or
1094 * deleting, use __radix_tree_lookup() and __radix_tree_replace() or
1095 * radix_tree_iter_replace().
1097 void radix_tree_replace_slot(struct radix_tree_root
*root
,
1098 void **slot
, void *item
)
1100 replace_slot(root
, NULL
, slot
, item
, true);
1104 * radix_tree_iter_replace - replace item in a slot
1105 * @root: radix tree root
1106 * @slot: pointer to slot
1107 * @item: new item to store in the slot.
1109 * For use with radix_tree_split() and radix_tree_for_each_slot().
1110 * Caller must hold tree write locked across split and replacement.
1112 void radix_tree_iter_replace(struct radix_tree_root
*root
,
1113 const struct radix_tree_iter
*iter
, void **slot
, void *item
)
1115 __radix_tree_replace(root
, iter
->node
, slot
, item
, NULL
, NULL
);
1118 #ifdef CONFIG_RADIX_TREE_MULTIORDER
1120 * radix_tree_join - replace multiple entries with one multiorder entry
1121 * @root: radix tree root
1122 * @index: an index inside the new entry
1123 * @order: order of the new entry
1126 * Call this function to replace several entries with one larger entry.
1127 * The existing entries are presumed to not need freeing as a result of
1130 * The replacement entry will have all the tags set on it that were set
1131 * on any of the entries it is replacing.
1133 int radix_tree_join(struct radix_tree_root
*root
, unsigned long index
,
1134 unsigned order
, void *item
)
1136 struct radix_tree_node
*node
;
1140 BUG_ON(radix_tree_is_internal_node(item
));
1142 error
= __radix_tree_create(root
, index
, order
, &node
, &slot
);
1144 error
= insert_entries(node
, slot
, item
, order
, true);
1152 * radix_tree_split - Split an entry into smaller entries
1153 * @root: radix tree root
1154 * @index: An index within the large entry
1155 * @order: Order of new entries
1157 * Call this function as the first step in replacing a multiorder entry
1158 * with several entries of lower order. After this function returns,
1159 * loop over the relevant portion of the tree using radix_tree_for_each_slot()
1160 * and call radix_tree_iter_replace() to set up each new entry.
1162 * The tags from this entry are replicated to all the new entries.
1164 * The radix tree should be locked against modification during the entire
1165 * replacement operation. Lock-free lookups will see RADIX_TREE_RETRY which
1166 * should prompt RCU walkers to restart the lookup from the root.
1168 int radix_tree_split(struct radix_tree_root
*root
, unsigned long index
,
1171 struct radix_tree_node
*parent
, *node
, *child
;
1173 unsigned int offset
, end
;
1174 unsigned n
, tag
, tags
= 0;
1176 if (!__radix_tree_lookup(root
, index
, &parent
, &slot
))
1181 offset
= get_slot_offset(parent
, slot
);
1183 for (tag
= 0; tag
< RADIX_TREE_MAX_TAGS
; tag
++)
1184 if (tag_get(parent
, tag
, offset
))
1187 for (end
= offset
+ 1; end
< RADIX_TREE_MAP_SIZE
; end
++) {
1188 if (!is_sibling_entry(parent
, parent
->slots
[end
]))
1190 for (tag
= 0; tag
< RADIX_TREE_MAX_TAGS
; tag
++)
1191 if (tags
& (1 << tag
))
1192 tag_set(parent
, tag
, end
);
1193 /* rcu_assign_pointer ensures tags are set before RETRY */
1194 rcu_assign_pointer(parent
->slots
[end
], RADIX_TREE_RETRY
);
1196 rcu_assign_pointer(parent
->slots
[offset
], RADIX_TREE_RETRY
);
1197 parent
->exceptional
-= (end
- offset
);
1199 if (order
== parent
->shift
)
1201 if (order
> parent
->shift
) {
1202 while (offset
< end
)
1203 offset
+= insert_entries(parent
, &parent
->slots
[offset
],
1204 RADIX_TREE_RETRY
, order
, true);
1211 if (node
->shift
> order
) {
1212 child
= radix_tree_node_alloc(root
, node
,
1213 node
->shift
- RADIX_TREE_MAP_SHIFT
,
1217 if (node
!= parent
) {
1219 node
->slots
[offset
] = node_to_entry(child
);
1220 for (tag
= 0; tag
< RADIX_TREE_MAX_TAGS
; tag
++)
1221 if (tags
& (1 << tag
))
1222 tag_set(node
, tag
, offset
);
1230 n
= insert_entries(node
, &node
->slots
[offset
],
1231 RADIX_TREE_RETRY
, order
, false);
1232 BUG_ON(n
> RADIX_TREE_MAP_SIZE
);
1234 for (tag
= 0; tag
< RADIX_TREE_MAX_TAGS
; tag
++)
1235 if (tags
& (1 << tag
))
1236 tag_set(node
, tag
, offset
);
1239 while (offset
== RADIX_TREE_MAP_SIZE
) {
1242 offset
= node
->offset
;
1244 node
= node
->parent
;
1245 rcu_assign_pointer(node
->slots
[offset
],
1246 node_to_entry(child
));
1249 if ((node
== parent
) && (offset
== end
))
1254 /* Shouldn't happen; did user forget to preload? */
1255 /* TODO: free all the allocated nodes */
1262 * radix_tree_tag_set - set a tag on a radix tree node
1263 * @root: radix tree root
1267 * Set the search tag (which must be < RADIX_TREE_MAX_TAGS)
1268 * corresponding to @index in the radix tree. From
1269 * the root all the way down to the leaf node.
1271 * Returns the address of the tagged item. Setting a tag on a not-present
1274 void *radix_tree_tag_set(struct radix_tree_root
*root
,
1275 unsigned long index
, unsigned int tag
)
1277 struct radix_tree_node
*node
, *parent
;
1278 unsigned long maxindex
;
1280 radix_tree_load_root(root
, &node
, &maxindex
);
1281 BUG_ON(index
> maxindex
);
1283 while (radix_tree_is_internal_node(node
)) {
1286 parent
= entry_to_node(node
);
1287 offset
= radix_tree_descend(parent
, &node
, index
);
1290 if (!tag_get(parent
, tag
, offset
))
1291 tag_set(parent
, tag
, offset
);
1294 /* set the root's tag bit */
1295 if (!root_tag_get(root
, tag
))
1296 root_tag_set(root
, tag
);
1300 EXPORT_SYMBOL(radix_tree_tag_set
);
1302 static void node_tag_clear(struct radix_tree_root
*root
,
1303 struct radix_tree_node
*node
,
1304 unsigned int tag
, unsigned int offset
)
1307 if (!tag_get(node
, tag
, offset
))
1309 tag_clear(node
, tag
, offset
);
1310 if (any_tag_set(node
, tag
))
1313 offset
= node
->offset
;
1314 node
= node
->parent
;
1317 /* clear the root's tag bit */
1318 if (root_tag_get(root
, tag
))
1319 root_tag_clear(root
, tag
);
1322 static void node_tag_set(struct radix_tree_root
*root
,
1323 struct radix_tree_node
*node
,
1324 unsigned int tag
, unsigned int offset
)
1327 if (tag_get(node
, tag
, offset
))
1329 tag_set(node
, tag
, offset
);
1330 offset
= node
->offset
;
1331 node
= node
->parent
;
1334 if (!root_tag_get(root
, tag
))
1335 root_tag_set(root
, tag
);
1339 * radix_tree_iter_tag_set - set a tag on the current iterator entry
1340 * @root: radix tree root
1341 * @iter: iterator state
1344 void radix_tree_iter_tag_set(struct radix_tree_root
*root
,
1345 const struct radix_tree_iter
*iter
, unsigned int tag
)
1347 node_tag_set(root
, iter
->node
, tag
, iter_offset(iter
));
1351 * radix_tree_tag_clear - clear a tag on a radix tree node
1352 * @root: radix tree root
1356 * Clear the search tag (which must be < RADIX_TREE_MAX_TAGS)
1357 * corresponding to @index in the radix tree. If this causes
1358 * the leaf node to have no tags set then clear the tag in the
1359 * next-to-leaf node, etc.
1361 * Returns the address of the tagged item on success, else NULL. ie:
1362 * has the same return value and semantics as radix_tree_lookup().
1364 void *radix_tree_tag_clear(struct radix_tree_root
*root
,
1365 unsigned long index
, unsigned int tag
)
1367 struct radix_tree_node
*node
, *parent
;
1368 unsigned long maxindex
;
1369 int uninitialized_var(offset
);
1371 radix_tree_load_root(root
, &node
, &maxindex
);
1372 if (index
> maxindex
)
1377 while (radix_tree_is_internal_node(node
)) {
1378 parent
= entry_to_node(node
);
1379 offset
= radix_tree_descend(parent
, &node
, index
);
1383 node_tag_clear(root
, parent
, tag
, offset
);
1387 EXPORT_SYMBOL(radix_tree_tag_clear
);
1390 * radix_tree_tag_get - get a tag on a radix tree node
1391 * @root: radix tree root
1393 * @tag: tag index (< RADIX_TREE_MAX_TAGS)
1397 * 0: tag not present or not set
1400 * Note that the return value of this function may not be relied on, even if
1401 * the RCU lock is held, unless tag modification and node deletion are excluded
1404 int radix_tree_tag_get(struct radix_tree_root
*root
,
1405 unsigned long index
, unsigned int tag
)
1407 struct radix_tree_node
*node
, *parent
;
1408 unsigned long maxindex
;
1410 if (!root_tag_get(root
, tag
))
1413 radix_tree_load_root(root
, &node
, &maxindex
);
1414 if (index
> maxindex
)
1419 while (radix_tree_is_internal_node(node
)) {
1422 parent
= entry_to_node(node
);
1423 offset
= radix_tree_descend(parent
, &node
, index
);
1427 if (!tag_get(parent
, tag
, offset
))
1429 if (node
== RADIX_TREE_RETRY
)
1435 EXPORT_SYMBOL(radix_tree_tag_get
);
1437 static inline void __set_iter_shift(struct radix_tree_iter
*iter
,
1440 #ifdef CONFIG_RADIX_TREE_MULTIORDER
1441 iter
->shift
= shift
;
1445 /* Construct iter->tags bit-mask from node->tags[tag] array */
1446 static void set_iter_tags(struct radix_tree_iter
*iter
,
1447 struct radix_tree_node
*node
, unsigned offset
,
1450 unsigned tag_long
= offset
/ BITS_PER_LONG
;
1451 unsigned tag_bit
= offset
% BITS_PER_LONG
;
1453 iter
->tags
= node
->tags
[tag
][tag_long
] >> tag_bit
;
1455 /* This never happens if RADIX_TREE_TAG_LONGS == 1 */
1456 if (tag_long
< RADIX_TREE_TAG_LONGS
- 1) {
1457 /* Pick tags from next element */
1459 iter
->tags
|= node
->tags
[tag
][tag_long
+ 1] <<
1460 (BITS_PER_LONG
- tag_bit
);
1461 /* Clip chunk size, here only BITS_PER_LONG tags */
1462 iter
->next_index
= __radix_tree_iter_add(iter
, BITS_PER_LONG
);
1466 #ifdef CONFIG_RADIX_TREE_MULTIORDER
1467 static void **skip_siblings(struct radix_tree_node
**nodep
,
1468 void **slot
, struct radix_tree_iter
*iter
)
1470 void *sib
= node_to_entry(slot
- 1);
1472 while (iter
->index
< iter
->next_index
) {
1473 *nodep
= rcu_dereference_raw(*slot
);
1474 if (*nodep
&& *nodep
!= sib
)
1477 iter
->index
= __radix_tree_iter_add(iter
, 1);
1485 void ** __radix_tree_next_slot(void **slot
, struct radix_tree_iter
*iter
,
1488 unsigned tag
= flags
& RADIX_TREE_ITER_TAG_MASK
;
1489 struct radix_tree_node
*node
= rcu_dereference_raw(*slot
);
1491 slot
= skip_siblings(&node
, slot
, iter
);
1493 while (radix_tree_is_internal_node(node
)) {
1495 unsigned long next_index
;
1497 if (node
== RADIX_TREE_RETRY
)
1499 node
= entry_to_node(node
);
1501 iter
->shift
= node
->shift
;
1503 if (flags
& RADIX_TREE_ITER_TAGGED
) {
1504 offset
= radix_tree_find_next_bit(node
, tag
, 0);
1505 if (offset
== RADIX_TREE_MAP_SIZE
)
1507 slot
= &node
->slots
[offset
];
1508 iter
->index
= __radix_tree_iter_add(iter
, offset
);
1509 set_iter_tags(iter
, node
, offset
, tag
);
1510 node
= rcu_dereference_raw(*slot
);
1513 slot
= &node
->slots
[0];
1515 node
= rcu_dereference_raw(*slot
);
1520 if (offset
== RADIX_TREE_MAP_SIZE
)
1523 iter
->index
= __radix_tree_iter_add(iter
, offset
);
1525 if ((flags
& RADIX_TREE_ITER_CONTIG
) && (offset
> 0))
1527 next_index
= (iter
->index
| shift_maxindex(iter
->shift
)) + 1;
1528 if (next_index
< iter
->next_index
)
1529 iter
->next_index
= next_index
;
1534 iter
->next_index
= 0;
1537 EXPORT_SYMBOL(__radix_tree_next_slot
);
1539 static void **skip_siblings(struct radix_tree_node
**nodep
,
1540 void **slot
, struct radix_tree_iter
*iter
)
1546 void **radix_tree_iter_resume(void **slot
, struct radix_tree_iter
*iter
)
1548 struct radix_tree_node
*node
;
1551 iter
->index
= __radix_tree_iter_add(iter
, 1);
1552 node
= rcu_dereference_raw(*slot
);
1553 skip_siblings(&node
, slot
, iter
);
1554 iter
->next_index
= iter
->index
;
1558 EXPORT_SYMBOL(radix_tree_iter_resume
);
1561 * radix_tree_next_chunk - find next chunk of slots for iteration
1563 * @root: radix tree root
1564 * @iter: iterator state
1565 * @flags: RADIX_TREE_ITER_* flags and tag index
1566 * Returns: pointer to chunk first slot, or NULL if iteration is over
1568 void **radix_tree_next_chunk(struct radix_tree_root
*root
,
1569 struct radix_tree_iter
*iter
, unsigned flags
)
1571 unsigned tag
= flags
& RADIX_TREE_ITER_TAG_MASK
;
1572 struct radix_tree_node
*node
, *child
;
1573 unsigned long index
, offset
, maxindex
;
1575 if ((flags
& RADIX_TREE_ITER_TAGGED
) && !root_tag_get(root
, tag
))
1579 * Catch next_index overflow after ~0UL. iter->index never overflows
1580 * during iterating; it can be zero only at the beginning.
1581 * And we cannot overflow iter->next_index in a single step,
1582 * because RADIX_TREE_MAP_SHIFT < BITS_PER_LONG.
1584 * This condition also used by radix_tree_next_slot() to stop
1585 * contiguous iterating, and forbid switching to the next chunk.
1587 index
= iter
->next_index
;
1588 if (!index
&& iter
->index
)
1592 radix_tree_load_root(root
, &child
, &maxindex
);
1593 if (index
> maxindex
)
1598 if (!radix_tree_is_internal_node(child
)) {
1599 /* Single-slot tree */
1600 iter
->index
= index
;
1601 iter
->next_index
= maxindex
+ 1;
1604 __set_iter_shift(iter
, 0);
1605 return (void **)&root
->rnode
;
1609 node
= entry_to_node(child
);
1610 offset
= radix_tree_descend(node
, &child
, index
);
1612 if ((flags
& RADIX_TREE_ITER_TAGGED
) ?
1613 !tag_get(node
, tag
, offset
) : !child
) {
1615 if (flags
& RADIX_TREE_ITER_CONTIG
)
1618 if (flags
& RADIX_TREE_ITER_TAGGED
)
1619 offset
= radix_tree_find_next_bit(node
, tag
,
1622 while (++offset
< RADIX_TREE_MAP_SIZE
) {
1623 void *slot
= node
->slots
[offset
];
1624 if (is_sibling_entry(node
, slot
))
1629 index
&= ~node_maxindex(node
);
1630 index
+= offset
<< node
->shift
;
1631 /* Overflow after ~0UL */
1634 if (offset
== RADIX_TREE_MAP_SIZE
)
1636 child
= rcu_dereference_raw(node
->slots
[offset
]);
1641 if (child
== RADIX_TREE_RETRY
)
1643 } while (radix_tree_is_internal_node(child
));
1645 /* Update the iterator state */
1646 iter
->index
= (index
&~ node_maxindex(node
)) | (offset
<< node
->shift
);
1647 iter
->next_index
= (index
| node_maxindex(node
)) + 1;
1649 __set_iter_shift(iter
, node
->shift
);
1651 if (flags
& RADIX_TREE_ITER_TAGGED
)
1652 set_iter_tags(iter
, node
, offset
, tag
);
1654 return node
->slots
+ offset
;
1656 EXPORT_SYMBOL(radix_tree_next_chunk
);
1659 * radix_tree_gang_lookup - perform multiple lookup on a radix tree
1660 * @root: radix tree root
1661 * @results: where the results of the lookup are placed
1662 * @first_index: start the lookup from this key
1663 * @max_items: place up to this many items at *results
1665 * Performs an index-ascending scan of the tree for present items. Places
1666 * them at *@results and returns the number of items which were placed at
1669 * The implementation is naive.
1671 * Like radix_tree_lookup, radix_tree_gang_lookup may be called under
1672 * rcu_read_lock. In this case, rather than the returned results being
1673 * an atomic snapshot of the tree at a single point in time, the
1674 * semantics of an RCU protected gang lookup are as though multiple
1675 * radix_tree_lookups have been issued in individual locks, and results
1676 * stored in 'results'.
1679 radix_tree_gang_lookup(struct radix_tree_root
*root
, void **results
,
1680 unsigned long first_index
, unsigned int max_items
)
1682 struct radix_tree_iter iter
;
1684 unsigned int ret
= 0;
1686 if (unlikely(!max_items
))
1689 radix_tree_for_each_slot(slot
, root
, &iter
, first_index
) {
1690 results
[ret
] = rcu_dereference_raw(*slot
);
1693 if (radix_tree_is_internal_node(results
[ret
])) {
1694 slot
= radix_tree_iter_retry(&iter
);
1697 if (++ret
== max_items
)
1703 EXPORT_SYMBOL(radix_tree_gang_lookup
);
1706 * radix_tree_gang_lookup_slot - perform multiple slot lookup on radix tree
1707 * @root: radix tree root
1708 * @results: where the results of the lookup are placed
1709 * @indices: where their indices should be placed (but usually NULL)
1710 * @first_index: start the lookup from this key
1711 * @max_items: place up to this many items at *results
1713 * Performs an index-ascending scan of the tree for present items. Places
1714 * their slots at *@results and returns the number of items which were
1715 * placed at *@results.
1717 * The implementation is naive.
1719 * Like radix_tree_gang_lookup as far as RCU and locking goes. Slots must
1720 * be dereferenced with radix_tree_deref_slot, and if using only RCU
1721 * protection, radix_tree_deref_slot may fail requiring a retry.
1724 radix_tree_gang_lookup_slot(struct radix_tree_root
*root
,
1725 void ***results
, unsigned long *indices
,
1726 unsigned long first_index
, unsigned int max_items
)
1728 struct radix_tree_iter iter
;
1730 unsigned int ret
= 0;
1732 if (unlikely(!max_items
))
1735 radix_tree_for_each_slot(slot
, root
, &iter
, first_index
) {
1736 results
[ret
] = slot
;
1738 indices
[ret
] = iter
.index
;
1739 if (++ret
== max_items
)
1745 EXPORT_SYMBOL(radix_tree_gang_lookup_slot
);
1748 * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree
1750 * @root: radix tree root
1751 * @results: where the results of the lookup are placed
1752 * @first_index: start the lookup from this key
1753 * @max_items: place up to this many items at *results
1754 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
1756 * Performs an index-ascending scan of the tree for present items which
1757 * have the tag indexed by @tag set. Places the items at *@results and
1758 * returns the number of items which were placed at *@results.
1761 radix_tree_gang_lookup_tag(struct radix_tree_root
*root
, void **results
,
1762 unsigned long first_index
, unsigned int max_items
,
1765 struct radix_tree_iter iter
;
1767 unsigned int ret
= 0;
1769 if (unlikely(!max_items
))
1772 radix_tree_for_each_tagged(slot
, root
, &iter
, first_index
, tag
) {
1773 results
[ret
] = rcu_dereference_raw(*slot
);
1776 if (radix_tree_is_internal_node(results
[ret
])) {
1777 slot
= radix_tree_iter_retry(&iter
);
1780 if (++ret
== max_items
)
1786 EXPORT_SYMBOL(radix_tree_gang_lookup_tag
);
1789 * radix_tree_gang_lookup_tag_slot - perform multiple slot lookup on a
1790 * radix tree based on a tag
1791 * @root: radix tree root
1792 * @results: where the results of the lookup are placed
1793 * @first_index: start the lookup from this key
1794 * @max_items: place up to this many items at *results
1795 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
1797 * Performs an index-ascending scan of the tree for present items which
1798 * have the tag indexed by @tag set. Places the slots at *@results and
1799 * returns the number of slots which were placed at *@results.
1802 radix_tree_gang_lookup_tag_slot(struct radix_tree_root
*root
, void ***results
,
1803 unsigned long first_index
, unsigned int max_items
,
1806 struct radix_tree_iter iter
;
1808 unsigned int ret
= 0;
1810 if (unlikely(!max_items
))
1813 radix_tree_for_each_tagged(slot
, root
, &iter
, first_index
, tag
) {
1814 results
[ret
] = slot
;
1815 if (++ret
== max_items
)
1821 EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot
);
1824 * __radix_tree_delete_node - try to free node after clearing a slot
1825 * @root: radix tree root
1826 * @node: node containing @index
1828 * After clearing the slot at @index in @node from radix tree
1829 * rooted at @root, call this function to attempt freeing the
1830 * node and shrinking the tree.
1832 void __radix_tree_delete_node(struct radix_tree_root
*root
,
1833 struct radix_tree_node
*node
)
1835 delete_node(root
, node
, NULL
, NULL
);
1839 * radix_tree_delete_item - delete an item from a radix tree
1840 * @root: radix tree root
1842 * @item: expected item
1844 * Remove @item at @index from the radix tree rooted at @root.
1846 * Returns the address of the deleted item, or NULL if it was not present
1847 * or the entry at the given @index was not @item.
1849 void *radix_tree_delete_item(struct radix_tree_root
*root
,
1850 unsigned long index
, void *item
)
1852 struct radix_tree_node
*node
;
1853 unsigned int offset
;
1858 entry
= __radix_tree_lookup(root
, index
, &node
, &slot
);
1862 if (item
&& entry
!= item
)
1866 root_tag_clear_all(root
);
1871 offset
= get_slot_offset(node
, slot
);
1873 /* Clear all tags associated with the item to be deleted. */
1874 for (tag
= 0; tag
< RADIX_TREE_MAX_TAGS
; tag
++)
1875 node_tag_clear(root
, node
, tag
, offset
);
1877 __radix_tree_replace(root
, node
, slot
, NULL
, NULL
, NULL
);
1881 EXPORT_SYMBOL(radix_tree_delete_item
);
1884 * radix_tree_delete - delete an item from a radix tree
1885 * @root: radix tree root
1888 * Remove the item at @index from the radix tree rooted at @root.
1890 * Returns the address of the deleted item, or NULL if it was not present.
1892 void *radix_tree_delete(struct radix_tree_root
*root
, unsigned long index
)
1894 return radix_tree_delete_item(root
, index
, NULL
);
1896 EXPORT_SYMBOL(radix_tree_delete
);
1898 void radix_tree_clear_tags(struct radix_tree_root
*root
,
1899 struct radix_tree_node
*node
,
1903 unsigned int tag
, offset
= get_slot_offset(node
, slot
);
1904 for (tag
= 0; tag
< RADIX_TREE_MAX_TAGS
; tag
++)
1905 node_tag_clear(root
, node
, tag
, offset
);
1907 /* Clear root node tags */
1908 root
->gfp_mask
&= __GFP_BITS_MASK
;
1913 * radix_tree_tagged - test whether any items in the tree are tagged
1914 * @root: radix tree root
1917 int radix_tree_tagged(struct radix_tree_root
*root
, unsigned int tag
)
1919 return root_tag_get(root
, tag
);
1921 EXPORT_SYMBOL(radix_tree_tagged
);
1924 radix_tree_node_ctor(void *arg
)
1926 struct radix_tree_node
*node
= arg
;
1928 memset(node
, 0, sizeof(*node
));
1929 INIT_LIST_HEAD(&node
->private_list
);
1932 static __init
unsigned long __maxindex(unsigned int height
)
1934 unsigned int width
= height
* RADIX_TREE_MAP_SHIFT
;
1935 int shift
= RADIX_TREE_INDEX_BITS
- width
;
1939 if (shift
>= BITS_PER_LONG
)
1941 return ~0UL >> shift
;
1944 static __init
void radix_tree_init_maxnodes(void)
1946 unsigned long height_to_maxindex
[RADIX_TREE_MAX_PATH
+ 1];
1949 for (i
= 0; i
< ARRAY_SIZE(height_to_maxindex
); i
++)
1950 height_to_maxindex
[i
] = __maxindex(i
);
1951 for (i
= 0; i
< ARRAY_SIZE(height_to_maxnodes
); i
++) {
1952 for (j
= i
; j
> 0; j
--)
1953 height_to_maxnodes
[i
] += height_to_maxindex
[j
- 1] + 1;
1957 static int radix_tree_cpu_dead(unsigned int cpu
)
1959 struct radix_tree_preload
*rtp
;
1960 struct radix_tree_node
*node
;
1962 /* Free per-cpu pool of preloaded nodes */
1963 rtp
= &per_cpu(radix_tree_preloads
, cpu
);
1966 rtp
->nodes
= node
->private_data
;
1967 kmem_cache_free(radix_tree_node_cachep
, node
);
1973 void __init
radix_tree_init(void)
1976 radix_tree_node_cachep
= kmem_cache_create("radix_tree_node",
1977 sizeof(struct radix_tree_node
), 0,
1978 SLAB_PANIC
| SLAB_RECLAIM_ACCOUNT
,
1979 radix_tree_node_ctor
);
1980 radix_tree_init_maxnodes();
1981 ret
= cpuhp_setup_state_nocalls(CPUHP_RADIX_DEAD
, "lib/radix:dead",
1982 NULL
, radix_tree_cpu_dead
);