2 * Copyright (C) 2001 Momchil Velikov
3 * Portions Copyright (C) 2001 Christoph Hellwig
4 * Copyright (C) 2005 SGI, Christoph Lameter
5 * Copyright (C) 2006 Nick Piggin
6 * Copyright (C) 2012 Konstantin Khlebnikov
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License as
10 * published by the Free Software Foundation; either version 2, or (at
11 * your option) any later version.
13 * This program is distributed in the hope that it will be useful, but
14 * WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23 #include <linux/errno.h>
24 #include <linux/init.h>
25 #include <linux/kernel.h>
26 #include <linux/export.h>
27 #include <linux/radix-tree.h>
28 #include <linux/percpu.h>
29 #include <linux/slab.h>
30 #include <linux/kmemleak.h>
31 #include <linux/notifier.h>
32 #include <linux/cpu.h>
33 #include <linux/string.h>
34 #include <linux/bitops.h>
35 #include <linux/rcupdate.h>
36 #include <linux/preempt.h> /* in_interrupt() */
40 * The height_to_maxindex array needs to be one deeper than the maximum
41 * path as height 0 holds only 1 entry.
43 static unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH + 1] __read_mostly;
46 * Radix tree node cache.
48 static struct kmem_cache *radix_tree_node_cachep;
51 * The radix tree is variable-height, so an insert operation not only has
52 * to build the branch to its corresponding item, it also has to build the
53 * branch to existing items if the size has to be increased (by
56 * The worst case is a zero height tree with just a single item at index 0,
57 * and then inserting an item at index ULONG_MAX. This requires 2 new branches
58 * of RADIX_TREE_MAX_PATH size to be created, with only the root node shared.
61 #define RADIX_TREE_PRELOAD_SIZE (RADIX_TREE_MAX_PATH * 2 - 1)
64 * Per-cpu pool of preloaded nodes
66 struct radix_tree_preload {
68 /* nodes->private_data points to next preallocated node */
69 struct radix_tree_node *nodes;
71 static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, };
73 static inline void *ptr_to_indirect(void *ptr)
75 return (void *)((unsigned long)ptr | RADIX_TREE_INDIRECT_PTR);
78 static inline void *indirect_to_ptr(void *ptr)
80 return (void *)((unsigned long)ptr & ~RADIX_TREE_INDIRECT_PTR);
83 #ifdef CONFIG_RADIX_TREE_MULTIORDER
84 /* Sibling slots point directly to another slot in the same node */
85 static inline bool is_sibling_entry(struct radix_tree_node *parent, void *node)
88 return (parent->slots <= ptr) &&
89 (ptr < parent->slots + RADIX_TREE_MAP_SIZE);
92 static inline bool is_sibling_entry(struct radix_tree_node *parent, void *node)
98 static inline unsigned long get_slot_offset(struct radix_tree_node *parent,
101 return slot - parent->slots;
104 static unsigned radix_tree_descend(struct radix_tree_node *parent,
105 struct radix_tree_node **nodep, unsigned offset)
107 void **entry = rcu_dereference_raw(parent->slots[offset]);
109 #ifdef CONFIG_RADIX_TREE_MULTIORDER
110 if (radix_tree_is_indirect_ptr(entry)) {
111 unsigned long siboff = get_slot_offset(parent, entry);
112 if (siboff < RADIX_TREE_MAP_SIZE) {
114 entry = rcu_dereference_raw(parent->slots[offset]);
119 *nodep = (void *)entry;
123 static inline gfp_t root_gfp_mask(struct radix_tree_root *root)
125 return root->gfp_mask & __GFP_BITS_MASK;
128 static inline void tag_set(struct radix_tree_node *node, unsigned int tag,
131 __set_bit(offset, node->tags[tag]);
134 static inline void tag_clear(struct radix_tree_node *node, unsigned int tag,
137 __clear_bit(offset, node->tags[tag]);
140 static inline int tag_get(struct radix_tree_node *node, unsigned int tag,
143 return test_bit(offset, node->tags[tag]);
146 static inline void root_tag_set(struct radix_tree_root *root, unsigned int tag)
148 root->gfp_mask |= (__force gfp_t)(1 << (tag + __GFP_BITS_SHIFT));
151 static inline void root_tag_clear(struct radix_tree_root *root, unsigned int tag)
153 root->gfp_mask &= (__force gfp_t)~(1 << (tag + __GFP_BITS_SHIFT));
156 static inline void root_tag_clear_all(struct radix_tree_root *root)
158 root->gfp_mask &= __GFP_BITS_MASK;
161 static inline int root_tag_get(struct radix_tree_root *root, unsigned int tag)
163 return (__force unsigned)root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT));
167 * Returns 1 if any slot in the node has this tag set.
168 * Otherwise returns 0.
170 static inline int any_tag_set(struct radix_tree_node *node, unsigned int tag)
173 for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
174 if (node->tags[tag][idx])
181 * radix_tree_find_next_bit - find the next set bit in a memory region
183 * @addr: The address to base the search on
184 * @size: The bitmap size in bits
185 * @offset: The bitnumber to start searching at
187 * Unrollable variant of find_next_bit() for constant size arrays.
188 * Tail bits starting from size to roundup(size, BITS_PER_LONG) must be zero.
189 * Returns next bit offset, or size if nothing found.
191 static __always_inline unsigned long
192 radix_tree_find_next_bit(const unsigned long *addr,
193 unsigned long size, unsigned long offset)
195 if (!__builtin_constant_p(size))
196 return find_next_bit(addr, size, offset);
201 addr += offset / BITS_PER_LONG;
202 tmp = *addr >> (offset % BITS_PER_LONG);
204 return __ffs(tmp) + offset;
205 offset = (offset + BITS_PER_LONG) & ~(BITS_PER_LONG - 1);
206 while (offset < size) {
209 return __ffs(tmp) + offset;
210 offset += BITS_PER_LONG;
217 static void dump_node(void *slot, int height, int offset)
219 struct radix_tree_node *node;
226 pr_debug("radix entry %p offset %d\n", slot, offset);
230 node = indirect_to_ptr(slot);
231 pr_debug("radix node: %p offset %d tags %lx %lx %lx path %x count %d parent %p\n",
232 slot, offset, node->tags[0][0], node->tags[1][0],
233 node->tags[2][0], node->path, node->count, node->parent);
235 for (i = 0; i < RADIX_TREE_MAP_SIZE; i++)
236 dump_node(node->slots[i], height - 1, i);
240 static void radix_tree_dump(struct radix_tree_root *root)
242 pr_debug("radix root: %p height %d rnode %p tags %x\n",
243 root, root->height, root->rnode,
244 root->gfp_mask >> __GFP_BITS_SHIFT);
245 if (!radix_tree_is_indirect_ptr(root->rnode))
247 dump_node(root->rnode, root->height, 0);
252 * This assumes that the caller has performed appropriate preallocation, and
253 * that the caller has pinned this thread of control to the current CPU.
255 static struct radix_tree_node *
256 radix_tree_node_alloc(struct radix_tree_root *root)
258 struct radix_tree_node *ret = NULL;
259 gfp_t gfp_mask = root_gfp_mask(root);
262 * Preload code isn't irq safe and it doesn't make sence to use
263 * preloading in the interrupt anyway as all the allocations have to
264 * be atomic. So just do normal allocation when in interrupt.
266 if (!gfpflags_allow_blocking(gfp_mask) && !in_interrupt()) {
267 struct radix_tree_preload *rtp;
270 * Even if the caller has preloaded, try to allocate from the
271 * cache first for the new node to get accounted.
273 ret = kmem_cache_alloc(radix_tree_node_cachep,
274 gfp_mask | __GFP_ACCOUNT | __GFP_NOWARN);
279 * Provided the caller has preloaded here, we will always
280 * succeed in getting a node here (and never reach
283 rtp = this_cpu_ptr(&radix_tree_preloads);
286 rtp->nodes = ret->private_data;
287 ret->private_data = NULL;
291 * Update the allocation stack trace as this is more useful
294 kmemleak_update_trace(ret);
297 ret = kmem_cache_alloc(radix_tree_node_cachep,
298 gfp_mask | __GFP_ACCOUNT);
300 BUG_ON(radix_tree_is_indirect_ptr(ret));
304 static void radix_tree_node_rcu_free(struct rcu_head *head)
306 struct radix_tree_node *node =
307 container_of(head, struct radix_tree_node, rcu_head);
311 * must only free zeroed nodes into the slab. radix_tree_shrink
312 * can leave us with a non-NULL entry in the first slot, so clear
313 * that here to make sure.
315 for (i = 0; i < RADIX_TREE_MAX_TAGS; i++)
316 tag_clear(node, i, 0);
318 node->slots[0] = NULL;
321 kmem_cache_free(radix_tree_node_cachep, node);
325 radix_tree_node_free(struct radix_tree_node *node)
327 call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
331 * Load up this CPU's radix_tree_node buffer with sufficient objects to
332 * ensure that the addition of a single element in the tree cannot fail. On
333 * success, return zero, with preemption disabled. On error, return -ENOMEM
334 * with preemption not disabled.
336 * To make use of this facility, the radix tree must be initialised without
337 * __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE().
339 static int __radix_tree_preload(gfp_t gfp_mask)
341 struct radix_tree_preload *rtp;
342 struct radix_tree_node *node;
346 rtp = this_cpu_ptr(&radix_tree_preloads);
347 while (rtp->nr < RADIX_TREE_PRELOAD_SIZE) {
349 node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
353 rtp = this_cpu_ptr(&radix_tree_preloads);
354 if (rtp->nr < RADIX_TREE_PRELOAD_SIZE) {
355 node->private_data = rtp->nodes;
359 kmem_cache_free(radix_tree_node_cachep, node);
368 * Load up this CPU's radix_tree_node buffer with sufficient objects to
369 * ensure that the addition of a single element in the tree cannot fail. On
370 * success, return zero, with preemption disabled. On error, return -ENOMEM
371 * with preemption not disabled.
373 * To make use of this facility, the radix tree must be initialised without
374 * __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE().
376 int radix_tree_preload(gfp_t gfp_mask)
378 /* Warn on non-sensical use... */
379 WARN_ON_ONCE(!gfpflags_allow_blocking(gfp_mask));
380 return __radix_tree_preload(gfp_mask);
382 EXPORT_SYMBOL(radix_tree_preload);
385 * The same as above function, except we don't guarantee preloading happens.
386 * We do it, if we decide it helps. On success, return zero with preemption
387 * disabled. On error, return -ENOMEM with preemption not disabled.
389 int radix_tree_maybe_preload(gfp_t gfp_mask)
391 if (gfpflags_allow_blocking(gfp_mask))
392 return __radix_tree_preload(gfp_mask);
393 /* Preloading doesn't help anything with this gfp mask, skip it */
397 EXPORT_SYMBOL(radix_tree_maybe_preload);
400 * Return the maximum key which can be store into a
401 * radix tree with height HEIGHT.
403 static inline unsigned long radix_tree_maxindex(unsigned int height)
405 return height_to_maxindex[height];
409 * Extend a radix tree so it can store key @index.
411 static int radix_tree_extend(struct radix_tree_root *root,
412 unsigned long index, unsigned order)
414 struct radix_tree_node *node;
415 struct radix_tree_node *slot;
419 /* Figure out what the height should be. */
420 height = root->height + 1;
421 while (index > radix_tree_maxindex(height))
424 if ((root->rnode == NULL) && (order == 0)) {
425 root->height = height;
430 unsigned int newheight;
431 if (!(node = radix_tree_node_alloc(root)))
434 /* Propagate the aggregated tag info into the new root */
435 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
436 if (root_tag_get(root, tag))
437 tag_set(node, tag, 0);
440 /* Increase the height. */
441 newheight = root->height+1;
442 BUG_ON(newheight & ~RADIX_TREE_HEIGHT_MASK);
443 node->path = newheight;
447 if (radix_tree_is_indirect_ptr(slot) && newheight > 1) {
448 slot = indirect_to_ptr(slot);
450 slot = ptr_to_indirect(slot);
452 node->slots[0] = slot;
453 node = ptr_to_indirect(node);
454 rcu_assign_pointer(root->rnode, node);
455 root->height = newheight;
456 } while (height > root->height);
462 * __radix_tree_create - create a slot in a radix tree
463 * @root: radix tree root
465 * @order: index occupies 2^order aligned slots
466 * @nodep: returns node
467 * @slotp: returns slot
469 * Create, if necessary, and return the node and slot for an item
470 * at position @index in the radix tree @root.
472 * Until there is more than one item in the tree, no nodes are
473 * allocated and @root->rnode is used as a direct slot instead of
474 * pointing to a node, in which case *@nodep will be NULL.
476 * Returns -ENOMEM, or 0 for success.
478 int __radix_tree_create(struct radix_tree_root *root, unsigned long index,
479 unsigned order, struct radix_tree_node **nodep,
482 struct radix_tree_node *node = NULL, *slot;
483 unsigned int height, shift, offset;
486 BUG_ON((0 < order) && (order < RADIX_TREE_MAP_SHIFT));
488 /* Make sure the tree is high enough. */
489 if (index > radix_tree_maxindex(root->height)) {
490 error = radix_tree_extend(root, index, order);
497 height = root->height;
498 shift = height * RADIX_TREE_MAP_SHIFT;
500 offset = 0; /* uninitialised var warning */
501 while (shift > order) {
503 /* Have to add a child node. */
504 if (!(slot = radix_tree_node_alloc(root)))
509 rcu_assign_pointer(node->slots[offset],
510 ptr_to_indirect(slot));
512 slot->path |= offset << RADIX_TREE_HEIGHT_SHIFT;
514 rcu_assign_pointer(root->rnode,
515 ptr_to_indirect(slot));
516 } else if (!radix_tree_is_indirect_ptr(slot))
519 /* Go a level down */
521 shift -= RADIX_TREE_MAP_SHIFT;
522 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
523 node = indirect_to_ptr(slot);
524 slot = node->slots[offset];
527 #ifdef CONFIG_RADIX_TREE_MULTIORDER
528 /* Insert pointers to the canonical entry */
530 int i, n = 1 << (order - shift);
531 offset = offset & ~(n - 1);
532 slot = ptr_to_indirect(&node->slots[offset]);
533 for (i = 0; i < n; i++) {
534 if (node->slots[offset + i])
538 for (i = 1; i < n; i++) {
539 rcu_assign_pointer(node->slots[offset + i], slot);
548 *slotp = node ? node->slots + offset : (void **)&root->rnode;
553 * __radix_tree_insert - insert into a radix tree
554 * @root: radix tree root
556 * @order: key covers the 2^order indices around index
557 * @item: item to insert
559 * Insert an item into the radix tree at position @index.
561 int __radix_tree_insert(struct radix_tree_root *root, unsigned long index,
562 unsigned order, void *item)
564 struct radix_tree_node *node;
568 BUG_ON(radix_tree_is_indirect_ptr(item));
570 error = __radix_tree_create(root, index, order, &node, &slot);
575 rcu_assign_pointer(*slot, item);
579 BUG_ON(tag_get(node, 0, index & RADIX_TREE_MAP_MASK));
580 BUG_ON(tag_get(node, 1, index & RADIX_TREE_MAP_MASK));
582 BUG_ON(root_tag_get(root, 0));
583 BUG_ON(root_tag_get(root, 1));
588 EXPORT_SYMBOL(__radix_tree_insert);
591 * __radix_tree_lookup - lookup an item in a radix tree
592 * @root: radix tree root
594 * @nodep: returns node
595 * @slotp: returns slot
597 * Lookup and return the item at position @index in the radix
600 * Until there is more than one item in the tree, no nodes are
601 * allocated and @root->rnode is used as a direct slot instead of
602 * pointing to a node, in which case *@nodep will be NULL.
604 void *__radix_tree_lookup(struct radix_tree_root *root, unsigned long index,
605 struct radix_tree_node **nodep, void ***slotp)
607 struct radix_tree_node *node, *parent;
608 unsigned int height, shift;
611 node = rcu_dereference_raw(root->rnode);
615 if (!radix_tree_is_indirect_ptr(node)) {
622 *slotp = (void **)&root->rnode;
625 node = indirect_to_ptr(node);
627 height = node->path & RADIX_TREE_HEIGHT_MASK;
628 if (index > radix_tree_maxindex(height))
631 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
635 slot = node->slots + ((index >> shift) & RADIX_TREE_MAP_MASK);
636 node = rcu_dereference_raw(*slot);
639 if (!radix_tree_is_indirect_ptr(node))
641 node = indirect_to_ptr(node);
643 shift -= RADIX_TREE_MAP_SHIFT;
645 } while (height > 0);
655 * radix_tree_lookup_slot - lookup a slot in a radix tree
656 * @root: radix tree root
659 * Returns: the slot corresponding to the position @index in the
660 * radix tree @root. This is useful for update-if-exists operations.
662 * This function can be called under rcu_read_lock iff the slot is not
663 * modified by radix_tree_replace_slot, otherwise it must be called
664 * exclusive from other writers. Any dereference of the slot must be done
665 * using radix_tree_deref_slot.
667 void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index)
671 if (!__radix_tree_lookup(root, index, NULL, &slot))
675 EXPORT_SYMBOL(radix_tree_lookup_slot);
678 * radix_tree_lookup - perform lookup operation on a radix tree
679 * @root: radix tree root
682 * Lookup the item at the position @index in the radix tree @root.
684 * This function can be called under rcu_read_lock, however the caller
685 * must manage lifetimes of leaf nodes (eg. RCU may also be used to free
686 * them safely). No RCU barriers are required to access or modify the
687 * returned item, however.
689 void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
691 return __radix_tree_lookup(root, index, NULL, NULL);
693 EXPORT_SYMBOL(radix_tree_lookup);
696 * radix_tree_tag_set - set a tag on a radix tree node
697 * @root: radix tree root
701 * Set the search tag (which must be < RADIX_TREE_MAX_TAGS)
702 * corresponding to @index in the radix tree. From
703 * the root all the way down to the leaf node.
705 * Returns the address of the tagged item. Setting a tag on a not-present
708 void *radix_tree_tag_set(struct radix_tree_root *root,
709 unsigned long index, unsigned int tag)
711 unsigned int height, shift;
712 struct radix_tree_node *slot;
714 height = root->height;
715 BUG_ON(index > radix_tree_maxindex(height));
717 slot = indirect_to_ptr(root->rnode);
718 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
723 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
724 if (!tag_get(slot, tag, offset))
725 tag_set(slot, tag, offset);
726 slot = slot->slots[offset];
727 BUG_ON(slot == NULL);
728 if (!radix_tree_is_indirect_ptr(slot))
730 slot = indirect_to_ptr(slot);
731 shift -= RADIX_TREE_MAP_SHIFT;
735 /* set the root's tag bit */
736 if (slot && !root_tag_get(root, tag))
737 root_tag_set(root, tag);
741 EXPORT_SYMBOL(radix_tree_tag_set);
744 * radix_tree_tag_clear - clear a tag on a radix tree node
745 * @root: radix tree root
749 * Clear the search tag (which must be < RADIX_TREE_MAX_TAGS)
750 * corresponding to @index in the radix tree. If
751 * this causes the leaf node to have no tags set then clear the tag in the
752 * next-to-leaf node, etc.
754 * Returns the address of the tagged item on success, else NULL. ie:
755 * has the same return value and semantics as radix_tree_lookup().
757 void *radix_tree_tag_clear(struct radix_tree_root *root,
758 unsigned long index, unsigned int tag)
760 struct radix_tree_node *node = NULL;
761 struct radix_tree_node *slot = NULL;
762 unsigned int height, shift;
763 int uninitialized_var(offset);
765 height = root->height;
766 if (index > radix_tree_maxindex(height))
769 shift = height * RADIX_TREE_MAP_SHIFT;
775 if (!radix_tree_is_indirect_ptr(slot))
777 slot = indirect_to_ptr(slot);
779 shift -= RADIX_TREE_MAP_SHIFT;
780 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
782 slot = slot->slots[offset];
789 if (!tag_get(node, tag, offset))
791 tag_clear(node, tag, offset);
792 if (any_tag_set(node, tag))
795 index >>= RADIX_TREE_MAP_SHIFT;
796 offset = index & RADIX_TREE_MAP_MASK;
800 /* clear the root's tag bit */
801 if (root_tag_get(root, tag))
802 root_tag_clear(root, tag);
807 EXPORT_SYMBOL(radix_tree_tag_clear);
810 * radix_tree_tag_get - get a tag on a radix tree node
811 * @root: radix tree root
813 * @tag: tag index (< RADIX_TREE_MAX_TAGS)
817 * 0: tag not present or not set
820 * Note that the return value of this function may not be relied on, even if
821 * the RCU lock is held, unless tag modification and node deletion are excluded
824 int radix_tree_tag_get(struct radix_tree_root *root,
825 unsigned long index, unsigned int tag)
827 unsigned int height, shift;
828 struct radix_tree_node *node;
830 /* check the root's tag bit */
831 if (!root_tag_get(root, tag))
834 node = rcu_dereference_raw(root->rnode);
838 if (!radix_tree_is_indirect_ptr(node))
840 node = indirect_to_ptr(node);
842 height = node->path & RADIX_TREE_HEIGHT_MASK;
843 if (index > radix_tree_maxindex(height))
846 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
853 node = indirect_to_ptr(node);
855 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
856 if (!tag_get(node, tag, offset))
860 node = rcu_dereference_raw(node->slots[offset]);
861 if (!radix_tree_is_indirect_ptr(node))
863 shift -= RADIX_TREE_MAP_SHIFT;
867 EXPORT_SYMBOL(radix_tree_tag_get);
870 * radix_tree_next_chunk - find next chunk of slots for iteration
872 * @root: radix tree root
873 * @iter: iterator state
874 * @flags: RADIX_TREE_ITER_* flags and tag index
875 * Returns: pointer to chunk first slot, or NULL if iteration is over
877 void **radix_tree_next_chunk(struct radix_tree_root *root,
878 struct radix_tree_iter *iter, unsigned flags)
880 unsigned shift, tag = flags & RADIX_TREE_ITER_TAG_MASK;
881 struct radix_tree_node *rnode, *node;
882 unsigned long index, offset, height;
884 if ((flags & RADIX_TREE_ITER_TAGGED) && !root_tag_get(root, tag))
888 * Catch next_index overflow after ~0UL. iter->index never overflows
889 * during iterating; it can be zero only at the beginning.
890 * And we cannot overflow iter->next_index in a single step,
891 * because RADIX_TREE_MAP_SHIFT < BITS_PER_LONG.
893 * This condition also used by radix_tree_next_slot() to stop
894 * contiguous iterating, and forbid swithing to the next chunk.
896 index = iter->next_index;
897 if (!index && iter->index)
900 rnode = rcu_dereference_raw(root->rnode);
901 if (radix_tree_is_indirect_ptr(rnode)) {
902 rnode = indirect_to_ptr(rnode);
903 } else if (rnode && !index) {
904 /* Single-slot tree */
906 iter->next_index = 1;
908 return (void **)&root->rnode;
913 height = rnode->path & RADIX_TREE_HEIGHT_MASK;
914 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
915 offset = index >> shift;
917 /* Index outside of the tree */
918 if (offset >= RADIX_TREE_MAP_SIZE)
923 struct radix_tree_node *slot;
924 if ((flags & RADIX_TREE_ITER_TAGGED) ?
925 !test_bit(offset, node->tags[tag]) :
926 !node->slots[offset]) {
928 if (flags & RADIX_TREE_ITER_CONTIG)
931 if (flags & RADIX_TREE_ITER_TAGGED)
932 offset = radix_tree_find_next_bit(
937 while (++offset < RADIX_TREE_MAP_SIZE) {
938 if (node->slots[offset])
941 index &= ~((RADIX_TREE_MAP_SIZE << shift) - 1);
942 index += offset << shift;
943 /* Overflow after ~0UL */
946 if (offset == RADIX_TREE_MAP_SIZE)
950 /* This is leaf-node */
954 slot = rcu_dereference_raw(node->slots[offset]);
957 if (!radix_tree_is_indirect_ptr(slot))
959 node = indirect_to_ptr(slot);
960 shift -= RADIX_TREE_MAP_SHIFT;
961 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
964 /* Update the iterator state */
966 iter->next_index = (index | RADIX_TREE_MAP_MASK) + 1;
968 /* Construct iter->tags bit-mask from node->tags[tag] array */
969 if (flags & RADIX_TREE_ITER_TAGGED) {
970 unsigned tag_long, tag_bit;
972 tag_long = offset / BITS_PER_LONG;
973 tag_bit = offset % BITS_PER_LONG;
974 iter->tags = node->tags[tag][tag_long] >> tag_bit;
975 /* This never happens if RADIX_TREE_TAG_LONGS == 1 */
976 if (tag_long < RADIX_TREE_TAG_LONGS - 1) {
977 /* Pick tags from next element */
979 iter->tags |= node->tags[tag][tag_long + 1] <<
980 (BITS_PER_LONG - tag_bit);
981 /* Clip chunk size, here only BITS_PER_LONG tags */
982 iter->next_index = index + BITS_PER_LONG;
986 return node->slots + offset;
988 EXPORT_SYMBOL(radix_tree_next_chunk);
991 * radix_tree_range_tag_if_tagged - for each item in given range set given
992 * tag if item has another tag set
993 * @root: radix tree root
994 * @first_indexp: pointer to a starting index of a range to scan
995 * @last_index: last index of a range to scan
996 * @nr_to_tag: maximum number items to tag
997 * @iftag: tag index to test
998 * @settag: tag index to set if tested tag is set
1000 * This function scans range of radix tree from first_index to last_index
1001 * (inclusive). For each item in the range if iftag is set, the function sets
1002 * also settag. The function stops either after tagging nr_to_tag items or
1003 * after reaching last_index.
1005 * The tags must be set from the leaf level only and propagated back up the
1006 * path to the root. We must do this so that we resolve the full path before
1007 * setting any tags on intermediate nodes. If we set tags as we descend, then
1008 * we can get to the leaf node and find that the index that has the iftag
1009 * set is outside the range we are scanning. This reults in dangling tags and
1010 * can lead to problems with later tag operations (e.g. livelocks on lookups).
1012 * The function returns number of leaves where the tag was set and sets
1013 * *first_indexp to the first unscanned index.
1014 * WARNING! *first_indexp can wrap if last_index is ULONG_MAX. Caller must
1015 * be prepared to handle that.
1017 unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root,
1018 unsigned long *first_indexp, unsigned long last_index,
1019 unsigned long nr_to_tag,
1020 unsigned int iftag, unsigned int settag)
1022 unsigned int height = root->height;
1023 struct radix_tree_node *node = NULL;
1024 struct radix_tree_node *slot;
1026 unsigned long tagged = 0;
1027 unsigned long index = *first_indexp;
1029 last_index = min(last_index, radix_tree_maxindex(height));
1030 if (index > last_index)
1034 if (!root_tag_get(root, iftag)) {
1035 *first_indexp = last_index + 1;
1039 *first_indexp = last_index + 1;
1040 root_tag_set(root, settag);
1044 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
1045 slot = indirect_to_ptr(root->rnode);
1048 unsigned long upindex;
1051 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
1052 if (!slot->slots[offset])
1054 if (!tag_get(slot, iftag, offset))
1058 slot = slot->slots[offset];
1059 if (radix_tree_is_indirect_ptr(slot)) {
1060 slot = indirect_to_ptr(slot);
1061 shift -= RADIX_TREE_MAP_SHIFT;
1065 node = node->parent;
1070 tagged += 1 << shift;
1071 tag_set(slot, settag, offset);
1073 /* walk back up the path tagging interior nodes */
1076 upindex >>= RADIX_TREE_MAP_SHIFT;
1077 offset = upindex & RADIX_TREE_MAP_MASK;
1079 /* stop if we find a node with the tag already set */
1080 if (tag_get(node, settag, offset))
1082 tag_set(node, settag, offset);
1083 node = node->parent;
1087 * Small optimization: now clear that node pointer.
1088 * Since all of this slot's ancestors now have the tag set
1089 * from setting it above, we have no further need to walk
1090 * back up the tree setting tags, until we update slot to
1091 * point to another radix_tree_node.
1096 /* Go to next item at level determined by 'shift' */
1097 index = ((index >> shift) + 1) << shift;
1098 /* Overflow can happen when last_index is ~0UL... */
1099 if (index > last_index || !index)
1101 if (tagged >= nr_to_tag)
1103 while (((index >> shift) & RADIX_TREE_MAP_MASK) == 0) {
1105 * We've fully scanned this node. Go up. Because
1106 * last_index is guaranteed to be in the tree, what
1107 * we do below cannot wander astray.
1109 slot = slot->parent;
1110 shift += RADIX_TREE_MAP_SHIFT;
1114 * We need not to tag the root tag if there is no tag which is set with
1115 * settag within the range from *first_indexp to last_index.
1118 root_tag_set(root, settag);
1119 *first_indexp = index;
1123 EXPORT_SYMBOL(radix_tree_range_tag_if_tagged);
1126 * radix_tree_gang_lookup - perform multiple lookup on a radix tree
1127 * @root: radix tree root
1128 * @results: where the results of the lookup are placed
1129 * @first_index: start the lookup from this key
1130 * @max_items: place up to this many items at *results
1132 * Performs an index-ascending scan of the tree for present items. Places
1133 * them at *@results and returns the number of items which were placed at
1136 * The implementation is naive.
1138 * Like radix_tree_lookup, radix_tree_gang_lookup may be called under
1139 * rcu_read_lock. In this case, rather than the returned results being
1140 * an atomic snapshot of the tree at a single point in time, the semantics
1141 * of an RCU protected gang lookup are as though multiple radix_tree_lookups
1142 * have been issued in individual locks, and results stored in 'results'.
1145 radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
1146 unsigned long first_index, unsigned int max_items)
1148 struct radix_tree_iter iter;
1150 unsigned int ret = 0;
1152 if (unlikely(!max_items))
1155 radix_tree_for_each_slot(slot, root, &iter, first_index) {
1156 results[ret] = rcu_dereference_raw(*slot);
1159 if (radix_tree_is_indirect_ptr(results[ret])) {
1160 slot = radix_tree_iter_retry(&iter);
1163 if (++ret == max_items)
1169 EXPORT_SYMBOL(radix_tree_gang_lookup);
1172 * radix_tree_gang_lookup_slot - perform multiple slot lookup on radix tree
1173 * @root: radix tree root
1174 * @results: where the results of the lookup are placed
1175 * @indices: where their indices should be placed (but usually NULL)
1176 * @first_index: start the lookup from this key
1177 * @max_items: place up to this many items at *results
1179 * Performs an index-ascending scan of the tree for present items. Places
1180 * their slots at *@results and returns the number of items which were
1181 * placed at *@results.
1183 * The implementation is naive.
1185 * Like radix_tree_gang_lookup as far as RCU and locking goes. Slots must
1186 * be dereferenced with radix_tree_deref_slot, and if using only RCU
1187 * protection, radix_tree_deref_slot may fail requiring a retry.
1190 radix_tree_gang_lookup_slot(struct radix_tree_root *root,
1191 void ***results, unsigned long *indices,
1192 unsigned long first_index, unsigned int max_items)
1194 struct radix_tree_iter iter;
1196 unsigned int ret = 0;
1198 if (unlikely(!max_items))
1201 radix_tree_for_each_slot(slot, root, &iter, first_index) {
1202 results[ret] = slot;
1204 indices[ret] = iter.index;
1205 if (++ret == max_items)
1211 EXPORT_SYMBOL(radix_tree_gang_lookup_slot);
1214 * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree
1216 * @root: radix tree root
1217 * @results: where the results of the lookup are placed
1218 * @first_index: start the lookup from this key
1219 * @max_items: place up to this many items at *results
1220 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
1222 * Performs an index-ascending scan of the tree for present items which
1223 * have the tag indexed by @tag set. Places the items at *@results and
1224 * returns the number of items which were placed at *@results.
1227 radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
1228 unsigned long first_index, unsigned int max_items,
1231 struct radix_tree_iter iter;
1233 unsigned int ret = 0;
1235 if (unlikely(!max_items))
1238 radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) {
1239 results[ret] = rcu_dereference_raw(*slot);
1242 if (radix_tree_is_indirect_ptr(results[ret])) {
1243 slot = radix_tree_iter_retry(&iter);
1246 if (++ret == max_items)
1252 EXPORT_SYMBOL(radix_tree_gang_lookup_tag);
1255 * radix_tree_gang_lookup_tag_slot - perform multiple slot lookup on a
1256 * radix tree based on a tag
1257 * @root: radix tree root
1258 * @results: where the results of the lookup are placed
1259 * @first_index: start the lookup from this key
1260 * @max_items: place up to this many items at *results
1261 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
1263 * Performs an index-ascending scan of the tree for present items which
1264 * have the tag indexed by @tag set. Places the slots at *@results and
1265 * returns the number of slots which were placed at *@results.
1268 radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results,
1269 unsigned long first_index, unsigned int max_items,
1272 struct radix_tree_iter iter;
1274 unsigned int ret = 0;
1276 if (unlikely(!max_items))
1279 radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) {
1280 results[ret] = slot;
1281 if (++ret == max_items)
1287 EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot);
1289 #if defined(CONFIG_SHMEM) && defined(CONFIG_SWAP)
1290 #include <linux/sched.h> /* for cond_resched() */
1293 * This linear search is at present only useful to shmem_unuse_inode().
1295 static unsigned long __locate(struct radix_tree_node *slot, void *item,
1296 unsigned long index, unsigned long *found_index)
1298 unsigned int shift, height;
1301 height = slot->path & RADIX_TREE_HEIGHT_MASK;
1302 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
1304 for ( ; height > 1; height--) {
1305 i = (index >> shift) & RADIX_TREE_MAP_MASK;
1307 if (slot->slots[i] != NULL)
1309 index &= ~((1UL << shift) - 1);
1310 index += 1UL << shift;
1312 goto out; /* 32-bit wraparound */
1314 if (i == RADIX_TREE_MAP_SIZE)
1318 slot = rcu_dereference_raw(slot->slots[i]);
1321 if (!radix_tree_is_indirect_ptr(slot)) {
1323 *found_index = index + i;
1330 slot = indirect_to_ptr(slot);
1331 shift -= RADIX_TREE_MAP_SHIFT;
1334 /* Bottom level: check items */
1335 for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) {
1336 if (slot->slots[i] == item) {
1337 *found_index = index + i;
1342 index += RADIX_TREE_MAP_SIZE;
1348 * radix_tree_locate_item - search through radix tree for item
1349 * @root: radix tree root
1350 * @item: item to be found
1352 * Returns index where item was found, or -1 if not found.
1353 * Caller must hold no lock (since this time-consuming function needs
1354 * to be preemptible), and must check afterwards if item is still there.
1356 unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item)
1358 struct radix_tree_node *node;
1359 unsigned long max_index;
1360 unsigned long cur_index = 0;
1361 unsigned long found_index = -1;
1365 node = rcu_dereference_raw(root->rnode);
1366 if (!radix_tree_is_indirect_ptr(node)) {
1373 node = indirect_to_ptr(node);
1374 max_index = radix_tree_maxindex(node->path &
1375 RADIX_TREE_HEIGHT_MASK);
1376 if (cur_index > max_index) {
1381 cur_index = __locate(node, item, cur_index, &found_index);
1384 } while (cur_index != 0 && cur_index <= max_index);
1389 unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item)
1393 #endif /* CONFIG_SHMEM && CONFIG_SWAP */
1396 * radix_tree_shrink - shrink height of a radix tree to minimal
1397 * @root radix tree root
1399 static inline void radix_tree_shrink(struct radix_tree_root *root)
1401 /* try to shrink tree height */
1402 while (root->height > 0) {
1403 struct radix_tree_node *to_free = root->rnode;
1404 struct radix_tree_node *slot;
1406 BUG_ON(!radix_tree_is_indirect_ptr(to_free));
1407 to_free = indirect_to_ptr(to_free);
1410 * The candidate node has more than one child, or its child
1411 * is not at the leftmost slot, or it is a multiorder entry,
1414 if (to_free->count != 1)
1416 slot = to_free->slots[0];
1421 * We don't need rcu_assign_pointer(), since we are simply
1422 * moving the node from one part of the tree to another: if it
1423 * was safe to dereference the old pointer to it
1424 * (to_free->slots[0]), it will be safe to dereference the new
1425 * one (root->rnode) as far as dependent read barriers go.
1427 if (root->height > 1) {
1428 if (!radix_tree_is_indirect_ptr(slot))
1431 slot = indirect_to_ptr(slot);
1432 slot->parent = NULL;
1433 slot = ptr_to_indirect(slot);
1439 * We have a dilemma here. The node's slot[0] must not be
1440 * NULLed in case there are concurrent lookups expecting to
1441 * find the item. However if this was a bottom-level node,
1442 * then it may be subject to the slot pointer being visible
1443 * to callers dereferencing it. If item corresponding to
1444 * slot[0] is subsequently deleted, these callers would expect
1445 * their slot to become empty sooner or later.
1447 * For example, lockless pagecache will look up a slot, deref
1448 * the page pointer, and if the page is 0 refcount it means it
1449 * was concurrently deleted from pagecache so try the deref
1450 * again. Fortunately there is already a requirement for logic
1451 * to retry the entire slot lookup -- the indirect pointer
1452 * problem (replacing direct root node with an indirect pointer
1453 * also results in a stale slot). So tag the slot as indirect
1454 * to force callers to retry.
1456 if (root->height == 0)
1457 *((unsigned long *)&to_free->slots[0]) |=
1458 RADIX_TREE_INDIRECT_PTR;
1460 radix_tree_node_free(to_free);
1465 * __radix_tree_delete_node - try to free node after clearing a slot
1466 * @root: radix tree root
1467 * @node: node containing @index
1469 * After clearing the slot at @index in @node from radix tree
1470 * rooted at @root, call this function to attempt freeing the
1471 * node and shrinking the tree.
1473 * Returns %true if @node was freed, %false otherwise.
1475 bool __radix_tree_delete_node(struct radix_tree_root *root,
1476 struct radix_tree_node *node)
1478 bool deleted = false;
1481 struct radix_tree_node *parent;
1484 if (node == indirect_to_ptr(root->rnode)) {
1485 radix_tree_shrink(root);
1486 if (root->height == 0)
1492 parent = node->parent;
1494 unsigned int offset;
1496 offset = node->path >> RADIX_TREE_HEIGHT_SHIFT;
1497 parent->slots[offset] = NULL;
1500 root_tag_clear_all(root);
1505 radix_tree_node_free(node);
1514 static inline void delete_sibling_entries(struct radix_tree_node *node,
1515 void *ptr, unsigned offset)
1517 #ifdef CONFIG_RADIX_TREE_MULTIORDER
1519 for (i = 1; offset + i < RADIX_TREE_MAP_SIZE; i++) {
1520 if (node->slots[offset + i] != ptr)
1522 node->slots[offset + i] = NULL;
1529 * radix_tree_delete_item - delete an item from a radix tree
1530 * @root: radix tree root
1532 * @item: expected item
1534 * Remove @item at @index from the radix tree rooted at @root.
1536 * Returns the address of the deleted item, or NULL if it was not present
1537 * or the entry at the given @index was not @item.
1539 void *radix_tree_delete_item(struct radix_tree_root *root,
1540 unsigned long index, void *item)
1542 struct radix_tree_node *node;
1543 unsigned int offset;
1548 entry = __radix_tree_lookup(root, index, &node, &slot);
1552 if (item && entry != item)
1556 root_tag_clear_all(root);
1561 offset = get_slot_offset(node, slot);
1564 * Clear all tags associated with the item to be deleted.
1565 * This way of doing it would be inefficient, but seldom is any set.
1567 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
1568 if (tag_get(node, tag, offset))
1569 radix_tree_tag_clear(root, index, tag);
1572 delete_sibling_entries(node, ptr_to_indirect(slot), offset);
1573 node->slots[offset] = NULL;
1576 __radix_tree_delete_node(root, node);
1580 EXPORT_SYMBOL(radix_tree_delete_item);
1583 * radix_tree_delete - delete an item from a radix tree
1584 * @root: radix tree root
1587 * Remove the item at @index from the radix tree rooted at @root.
1589 * Returns the address of the deleted item, or NULL if it was not present.
1591 void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
1593 return radix_tree_delete_item(root, index, NULL);
1595 EXPORT_SYMBOL(radix_tree_delete);
1598 * radix_tree_tagged - test whether any items in the tree are tagged
1599 * @root: radix tree root
1602 int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag)
1604 return root_tag_get(root, tag);
1606 EXPORT_SYMBOL(radix_tree_tagged);
1609 radix_tree_node_ctor(void *arg)
1611 struct radix_tree_node *node = arg;
1613 memset(node, 0, sizeof(*node));
1614 INIT_LIST_HEAD(&node->private_list);
1617 static __init unsigned long __maxindex(unsigned int height)
1619 unsigned int width = height * RADIX_TREE_MAP_SHIFT;
1620 int shift = RADIX_TREE_INDEX_BITS - width;
1624 if (shift >= BITS_PER_LONG)
1626 return ~0UL >> shift;
1629 static __init void radix_tree_init_maxindex(void)
1633 for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++)
1634 height_to_maxindex[i] = __maxindex(i);
1637 static int radix_tree_callback(struct notifier_block *nfb,
1638 unsigned long action,
1641 int cpu = (long)hcpu;
1642 struct radix_tree_preload *rtp;
1643 struct radix_tree_node *node;
1645 /* Free per-cpu pool of perloaded nodes */
1646 if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
1647 rtp = &per_cpu(radix_tree_preloads, cpu);
1650 rtp->nodes = node->private_data;
1651 kmem_cache_free(radix_tree_node_cachep, node);
1658 void __init radix_tree_init(void)
1660 radix_tree_node_cachep = kmem_cache_create("radix_tree_node",
1661 sizeof(struct radix_tree_node), 0,
1662 SLAB_PANIC | SLAB_RECLAIM_ACCOUNT,
1663 radix_tree_node_ctor);
1664 radix_tree_init_maxindex();
1665 hotcpu_notifier(radix_tree_callback, 0);