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/bitmap.h>
26 #include <linux/bitops.h>
27 #include <linux/cpu.h>
28 #include <linux/errno.h>
29 #include <linux/export.h>
30 #include <linux/idr.h>
31 #include <linux/init.h>
32 #include <linux/kernel.h>
33 #include <linux/kmemleak.h>
34 #include <linux/percpu.h>
35 #include <linux/preempt.h> /* in_interrupt() */
36 #include <linux/radix-tree.h>
37 #include <linux/rcupdate.h>
38 #include <linux/slab.h>
39 #include <linux/string.h>
42 /* Number of nodes in fully populated tree of given height */
43 static unsigned long height_to_maxnodes[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 * The IDR does not have to be as high as the radix tree since it uses
65 * signed integers, not unsigned longs.
67 #define IDR_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(int) - 1)
68 #define IDR_MAX_PATH (DIV_ROUND_UP(IDR_INDEX_BITS, \
69 RADIX_TREE_MAP_SHIFT))
70 #define IDR_PRELOAD_SIZE (IDR_MAX_PATH * 2 - 1)
73 * The IDA is even shorter since it uses a bitmap at the last level.
75 #define IDA_INDEX_BITS (8 * sizeof(int) - 1 - ilog2(IDA_BITMAP_BITS))
76 #define IDA_MAX_PATH (DIV_ROUND_UP(IDA_INDEX_BITS, \
77 RADIX_TREE_MAP_SHIFT))
78 #define IDA_PRELOAD_SIZE (IDA_MAX_PATH * 2 - 1)
81 * Per-cpu pool of preloaded nodes
83 struct radix_tree_preload {
85 /* nodes->parent points to next preallocated node */
86 struct radix_tree_node *nodes;
88 static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, };
90 static inline struct radix_tree_node *entry_to_node(void *ptr)
92 return (void *)((unsigned long)ptr & ~RADIX_TREE_INTERNAL_NODE);
95 static inline void *node_to_entry(void *ptr)
97 return (void *)((unsigned long)ptr | RADIX_TREE_INTERNAL_NODE);
100 #define RADIX_TREE_RETRY node_to_entry(NULL)
102 #ifdef CONFIG_RADIX_TREE_MULTIORDER
103 /* Sibling slots point directly to another slot in the same node */
105 bool is_sibling_entry(const struct radix_tree_node *parent, void *node)
108 return (parent->slots <= ptr) &&
109 (ptr < parent->slots + RADIX_TREE_MAP_SIZE);
113 bool is_sibling_entry(const struct radix_tree_node *parent, void *node)
120 unsigned long get_slot_offset(const struct radix_tree_node *parent, void **slot)
122 return slot - parent->slots;
125 static unsigned int radix_tree_descend(const struct radix_tree_node *parent,
126 struct radix_tree_node **nodep, unsigned long index)
128 unsigned int offset = (index >> parent->shift) & RADIX_TREE_MAP_MASK;
129 void **entry = rcu_dereference_raw(parent->slots[offset]);
131 #ifdef CONFIG_RADIX_TREE_MULTIORDER
132 if (radix_tree_is_internal_node(entry)) {
133 if (is_sibling_entry(parent, entry)) {
134 void **sibentry = (void **) entry_to_node(entry);
135 offset = get_slot_offset(parent, sibentry);
136 entry = rcu_dereference_raw(*sibentry);
141 *nodep = (void *)entry;
145 static inline gfp_t root_gfp_mask(const struct radix_tree_root *root)
147 return root->gfp_mask & __GFP_BITS_MASK;
150 static inline void tag_set(struct radix_tree_node *node, unsigned int tag,
153 __set_bit(offset, node->tags[tag]);
156 static inline void tag_clear(struct radix_tree_node *node, unsigned int tag,
159 __clear_bit(offset, node->tags[tag]);
162 static inline int tag_get(const struct radix_tree_node *node, unsigned int tag,
165 return test_bit(offset, node->tags[tag]);
168 static inline void root_tag_set(struct radix_tree_root *root, unsigned tag)
170 root->gfp_mask |= (__force gfp_t)(1 << (tag + ROOT_TAG_SHIFT));
173 static inline void root_tag_clear(struct radix_tree_root *root, unsigned tag)
175 root->gfp_mask &= (__force gfp_t)~(1 << (tag + ROOT_TAG_SHIFT));
178 static inline void root_tag_clear_all(struct radix_tree_root *root)
180 root->gfp_mask &= (1 << ROOT_TAG_SHIFT) - 1;
183 static inline int root_tag_get(const struct radix_tree_root *root, unsigned tag)
185 return (__force int)root->gfp_mask & (1 << (tag + ROOT_TAG_SHIFT));
188 static inline unsigned root_tags_get(const struct radix_tree_root *root)
190 return (__force unsigned)root->gfp_mask >> ROOT_TAG_SHIFT;
193 static inline bool is_idr(const struct radix_tree_root *root)
195 return !!(root->gfp_mask & ROOT_IS_IDR);
199 * Returns 1 if any slot in the node has this tag set.
200 * Otherwise returns 0.
202 static inline int any_tag_set(const struct radix_tree_node *node,
206 for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
207 if (node->tags[tag][idx])
213 static inline void all_tag_set(struct radix_tree_node *node, unsigned int tag)
215 bitmap_fill(node->tags[tag], RADIX_TREE_MAP_SIZE);
219 * radix_tree_find_next_bit - find the next set bit in a memory region
221 * @addr: The address to base the search on
222 * @size: The bitmap size in bits
223 * @offset: The bitnumber to start searching at
225 * Unrollable variant of find_next_bit() for constant size arrays.
226 * Tail bits starting from size to roundup(size, BITS_PER_LONG) must be zero.
227 * Returns next bit offset, or size if nothing found.
229 static __always_inline unsigned long
230 radix_tree_find_next_bit(struct radix_tree_node *node, unsigned int tag,
231 unsigned long offset)
233 const unsigned long *addr = node->tags[tag];
235 if (offset < RADIX_TREE_MAP_SIZE) {
238 addr += offset / BITS_PER_LONG;
239 tmp = *addr >> (offset % BITS_PER_LONG);
241 return __ffs(tmp) + offset;
242 offset = (offset + BITS_PER_LONG) & ~(BITS_PER_LONG - 1);
243 while (offset < RADIX_TREE_MAP_SIZE) {
246 return __ffs(tmp) + offset;
247 offset += BITS_PER_LONG;
250 return RADIX_TREE_MAP_SIZE;
253 static unsigned int iter_offset(const struct radix_tree_iter *iter)
255 return (iter->index >> iter_shift(iter)) & RADIX_TREE_MAP_MASK;
259 * The maximum index which can be stored in a radix tree
261 static inline unsigned long shift_maxindex(unsigned int shift)
263 return (RADIX_TREE_MAP_SIZE << shift) - 1;
266 static inline unsigned long node_maxindex(const struct radix_tree_node *node)
268 return shift_maxindex(node->shift);
271 static unsigned long next_index(unsigned long index,
272 const struct radix_tree_node *node,
273 unsigned long offset)
275 return (index & ~node_maxindex(node)) + (offset << node->shift);
279 static void dump_node(struct radix_tree_node *node, unsigned long index)
283 pr_debug("radix node: %p offset %d indices %lu-%lu parent %p tags %lx %lx %lx shift %d count %d exceptional %d\n",
284 node, node->offset, index, index | node_maxindex(node),
286 node->tags[0][0], node->tags[1][0], node->tags[2][0],
287 node->shift, node->count, node->exceptional);
289 for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) {
290 unsigned long first = index | (i << node->shift);
291 unsigned long last = first | ((1UL << node->shift) - 1);
292 void *entry = node->slots[i];
295 if (entry == RADIX_TREE_RETRY) {
296 pr_debug("radix retry offset %ld indices %lu-%lu parent %p\n",
297 i, first, last, node);
298 } else if (!radix_tree_is_internal_node(entry)) {
299 pr_debug("radix entry %p offset %ld indices %lu-%lu parent %p\n",
300 entry, i, first, last, node);
301 } else if (is_sibling_entry(node, entry)) {
302 pr_debug("radix sblng %p offset %ld indices %lu-%lu parent %p val %p\n",
303 entry, i, first, last, node,
304 *(void **)entry_to_node(entry));
306 dump_node(entry_to_node(entry), first);
312 static void radix_tree_dump(struct radix_tree_root *root)
314 pr_debug("radix root: %p rnode %p tags %x\n",
316 root->gfp_mask >> ROOT_TAG_SHIFT);
317 if (!radix_tree_is_internal_node(root->rnode))
319 dump_node(entry_to_node(root->rnode), 0);
322 static void dump_ida_node(void *entry, unsigned long index)
329 if (radix_tree_is_internal_node(entry)) {
330 struct radix_tree_node *node = entry_to_node(entry);
332 pr_debug("ida node: %p offset %d indices %lu-%lu parent %p free %lx shift %d count %d\n",
333 node, node->offset, index * IDA_BITMAP_BITS,
334 ((index | node_maxindex(node)) + 1) *
336 node->parent, node->tags[0][0], node->shift,
338 for (i = 0; i < RADIX_TREE_MAP_SIZE; i++)
339 dump_ida_node(node->slots[i],
340 index | (i << node->shift));
341 } else if (radix_tree_exceptional_entry(entry)) {
342 pr_debug("ida excp: %p offset %d indices %lu-%lu data %lx\n",
343 entry, (int)(index & RADIX_TREE_MAP_MASK),
344 index * IDA_BITMAP_BITS,
345 index * IDA_BITMAP_BITS + BITS_PER_LONG -
346 RADIX_TREE_EXCEPTIONAL_SHIFT,
347 (unsigned long)entry >>
348 RADIX_TREE_EXCEPTIONAL_SHIFT);
350 struct ida_bitmap *bitmap = entry;
352 pr_debug("ida btmp: %p offset %d indices %lu-%lu data", bitmap,
353 (int)(index & RADIX_TREE_MAP_MASK),
354 index * IDA_BITMAP_BITS,
355 (index + 1) * IDA_BITMAP_BITS - 1);
356 for (i = 0; i < IDA_BITMAP_LONGS; i++)
357 pr_cont(" %lx", bitmap->bitmap[i]);
362 static void ida_dump(struct ida *ida)
364 struct radix_tree_root *root = &ida->ida_rt;
365 pr_debug("ida: %p node %p free %d\n", ida, root->rnode,
366 root->gfp_mask >> ROOT_TAG_SHIFT);
367 dump_ida_node(root->rnode, 0);
372 * This assumes that the caller has performed appropriate preallocation, and
373 * that the caller has pinned this thread of control to the current CPU.
375 static struct radix_tree_node *
376 radix_tree_node_alloc(gfp_t gfp_mask, struct radix_tree_node *parent,
377 struct radix_tree_root *root,
378 unsigned int shift, unsigned int offset,
379 unsigned int count, unsigned int exceptional)
381 struct radix_tree_node *ret = NULL;
384 * Preload code isn't irq safe and it doesn't make sense to use
385 * preloading during an interrupt anyway as all the allocations have
386 * to be atomic. So just do normal allocation when in interrupt.
388 if (!gfpflags_allow_blocking(gfp_mask) && !in_interrupt()) {
389 struct radix_tree_preload *rtp;
392 * Even if the caller has preloaded, try to allocate from the
393 * cache first for the new node to get accounted to the memory
396 ret = kmem_cache_alloc(radix_tree_node_cachep,
397 gfp_mask | __GFP_NOWARN);
402 * Provided the caller has preloaded here, we will always
403 * succeed in getting a node here (and never reach
406 rtp = this_cpu_ptr(&radix_tree_preloads);
409 rtp->nodes = ret->parent;
413 * Update the allocation stack trace as this is more useful
416 kmemleak_update_trace(ret);
419 ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
421 BUG_ON(radix_tree_is_internal_node(ret));
424 ret->offset = offset;
426 ret->exceptional = exceptional;
427 ret->parent = parent;
433 static void radix_tree_node_rcu_free(struct rcu_head *head)
435 struct radix_tree_node *node =
436 container_of(head, struct radix_tree_node, rcu_head);
439 * Must only free zeroed nodes into the slab. We can be left with
440 * non-NULL entries by radix_tree_free_nodes, so clear the entries
443 memset(node->slots, 0, sizeof(node->slots));
444 memset(node->tags, 0, sizeof(node->tags));
445 INIT_LIST_HEAD(&node->private_list);
447 kmem_cache_free(radix_tree_node_cachep, node);
451 radix_tree_node_free(struct radix_tree_node *node)
453 call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
457 * Load up this CPU's radix_tree_node buffer with sufficient objects to
458 * ensure that the addition of a single element in the tree cannot fail. On
459 * success, return zero, with preemption disabled. On error, return -ENOMEM
460 * with preemption not disabled.
462 * To make use of this facility, the radix tree must be initialised without
463 * __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE().
465 static int __radix_tree_preload(gfp_t gfp_mask, unsigned nr)
467 struct radix_tree_preload *rtp;
468 struct radix_tree_node *node;
472 * Nodes preloaded by one cgroup can be be used by another cgroup, so
473 * they should never be accounted to any particular memory cgroup.
475 gfp_mask &= ~__GFP_ACCOUNT;
478 rtp = this_cpu_ptr(&radix_tree_preloads);
479 while (rtp->nr < nr) {
481 node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
485 rtp = this_cpu_ptr(&radix_tree_preloads);
487 node->parent = rtp->nodes;
491 kmem_cache_free(radix_tree_node_cachep, node);
500 * Load up this CPU's radix_tree_node buffer with sufficient objects to
501 * ensure that the addition of a single element in the tree cannot fail. On
502 * success, return zero, with preemption disabled. On error, return -ENOMEM
503 * with preemption not disabled.
505 * To make use of this facility, the radix tree must be initialised without
506 * __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE().
508 int radix_tree_preload(gfp_t gfp_mask)
510 /* Warn on non-sensical use... */
511 WARN_ON_ONCE(!gfpflags_allow_blocking(gfp_mask));
512 return __radix_tree_preload(gfp_mask, RADIX_TREE_PRELOAD_SIZE);
514 EXPORT_SYMBOL(radix_tree_preload);
517 * The same as above function, except we don't guarantee preloading happens.
518 * We do it, if we decide it helps. On success, return zero with preemption
519 * disabled. On error, return -ENOMEM with preemption not disabled.
521 int radix_tree_maybe_preload(gfp_t gfp_mask)
523 if (gfpflags_allow_blocking(gfp_mask))
524 return __radix_tree_preload(gfp_mask, RADIX_TREE_PRELOAD_SIZE);
525 /* Preloading doesn't help anything with this gfp mask, skip it */
529 EXPORT_SYMBOL(radix_tree_maybe_preload);
531 #ifdef CONFIG_RADIX_TREE_MULTIORDER
533 * Preload with enough objects to ensure that we can split a single entry
534 * of order @old_order into many entries of size @new_order
536 int radix_tree_split_preload(unsigned int old_order, unsigned int new_order,
539 unsigned top = 1 << (old_order % RADIX_TREE_MAP_SHIFT);
540 unsigned layers = (old_order / RADIX_TREE_MAP_SHIFT) -
541 (new_order / RADIX_TREE_MAP_SHIFT);
544 WARN_ON_ONCE(!gfpflags_allow_blocking(gfp_mask));
545 BUG_ON(new_order >= old_order);
548 nr = nr * RADIX_TREE_MAP_SIZE + 1;
549 return __radix_tree_preload(gfp_mask, top * nr);
554 * The same as function above, but preload number of nodes required to insert
555 * (1 << order) continuous naturally-aligned elements.
557 int radix_tree_maybe_preload_order(gfp_t gfp_mask, int order)
559 unsigned long nr_subtrees;
560 int nr_nodes, subtree_height;
562 /* Preloading doesn't help anything with this gfp mask, skip it */
563 if (!gfpflags_allow_blocking(gfp_mask)) {
569 * Calculate number and height of fully populated subtrees it takes to
570 * store (1 << order) elements.
572 nr_subtrees = 1 << order;
573 for (subtree_height = 0; nr_subtrees > RADIX_TREE_MAP_SIZE;
575 nr_subtrees >>= RADIX_TREE_MAP_SHIFT;
578 * The worst case is zero height tree with a single item at index 0 and
579 * then inserting items starting at ULONG_MAX - (1 << order).
581 * This requires RADIX_TREE_MAX_PATH nodes to build branch from root to
584 nr_nodes = RADIX_TREE_MAX_PATH;
586 /* Plus branch to fully populated subtrees. */
587 nr_nodes += RADIX_TREE_MAX_PATH - subtree_height;
589 /* Root node is shared. */
592 /* Plus nodes required to build subtrees. */
593 nr_nodes += nr_subtrees * height_to_maxnodes[subtree_height];
595 return __radix_tree_preload(gfp_mask, nr_nodes);
598 static unsigned radix_tree_load_root(const struct radix_tree_root *root,
599 struct radix_tree_node **nodep, unsigned long *maxindex)
601 struct radix_tree_node *node = rcu_dereference_raw(root->rnode);
605 if (likely(radix_tree_is_internal_node(node))) {
606 node = entry_to_node(node);
607 *maxindex = node_maxindex(node);
608 return node->shift + RADIX_TREE_MAP_SHIFT;
616 * Extend a radix tree so it can store key @index.
618 static int radix_tree_extend(struct radix_tree_root *root, gfp_t gfp,
619 unsigned long index, unsigned int shift)
621 struct radix_tree_node *slot;
622 unsigned int maxshift;
625 /* Figure out what the shift should be. */
627 while (index > shift_maxindex(maxshift))
628 maxshift += RADIX_TREE_MAP_SHIFT;
631 if (!slot && (!is_idr(root) || root_tag_get(root, IDR_FREE)))
635 struct radix_tree_node *node = radix_tree_node_alloc(gfp, NULL,
636 root, shift, 0, 1, 0);
641 all_tag_set(node, IDR_FREE);
642 if (!root_tag_get(root, IDR_FREE)) {
643 tag_clear(node, IDR_FREE, 0);
644 root_tag_set(root, IDR_FREE);
647 /* Propagate the aggregated tag info to the new child */
648 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
649 if (root_tag_get(root, tag))
650 tag_set(node, tag, 0);
654 BUG_ON(shift > BITS_PER_LONG);
655 if (radix_tree_is_internal_node(slot)) {
656 entry_to_node(slot)->parent = node;
657 } else if (radix_tree_exceptional_entry(slot)) {
658 /* Moving an exceptional root->rnode to a node */
659 node->exceptional = 1;
661 node->slots[0] = slot;
662 slot = node_to_entry(node);
663 rcu_assign_pointer(root->rnode, slot);
664 shift += RADIX_TREE_MAP_SHIFT;
665 } while (shift <= maxshift);
667 return maxshift + RADIX_TREE_MAP_SHIFT;
671 * radix_tree_shrink - shrink radix tree to minimum height
672 * @root radix tree root
674 static inline bool radix_tree_shrink(struct radix_tree_root *root,
675 radix_tree_update_node_t update_node,
681 struct radix_tree_node *node = root->rnode;
682 struct radix_tree_node *child;
684 if (!radix_tree_is_internal_node(node))
686 node = entry_to_node(node);
689 * The candidate node has more than one child, or its child
690 * is not at the leftmost slot, or the child is a multiorder
691 * entry, we cannot shrink.
693 if (node->count != 1)
695 child = node->slots[0];
698 if (!radix_tree_is_internal_node(child) && node->shift)
701 if (radix_tree_is_internal_node(child))
702 entry_to_node(child)->parent = NULL;
705 * We don't need rcu_assign_pointer(), since we are simply
706 * moving the node from one part of the tree to another: if it
707 * was safe to dereference the old pointer to it
708 * (node->slots[0]), it will be safe to dereference the new
709 * one (root->rnode) as far as dependent read barriers go.
712 if (is_idr(root) && !tag_get(node, IDR_FREE, 0))
713 root_tag_clear(root, IDR_FREE);
716 * We have a dilemma here. The node's slot[0] must not be
717 * NULLed in case there are concurrent lookups expecting to
718 * find the item. However if this was a bottom-level node,
719 * then it may be subject to the slot pointer being visible
720 * to callers dereferencing it. If item corresponding to
721 * slot[0] is subsequently deleted, these callers would expect
722 * their slot to become empty sooner or later.
724 * For example, lockless pagecache will look up a slot, deref
725 * the page pointer, and if the page has 0 refcount it means it
726 * was concurrently deleted from pagecache so try the deref
727 * again. Fortunately there is already a requirement for logic
728 * to retry the entire slot lookup -- the indirect pointer
729 * problem (replacing direct root node with an indirect pointer
730 * also results in a stale slot). So tag the slot as indirect
731 * to force callers to retry.
734 if (!radix_tree_is_internal_node(child)) {
735 node->slots[0] = RADIX_TREE_RETRY;
737 update_node(node, private);
740 WARN_ON_ONCE(!list_empty(&node->private_list));
741 radix_tree_node_free(node);
748 static bool delete_node(struct radix_tree_root *root,
749 struct radix_tree_node *node,
750 radix_tree_update_node_t update_node, void *private)
752 bool deleted = false;
755 struct radix_tree_node *parent;
758 if (node == entry_to_node(root->rnode))
759 deleted |= radix_tree_shrink(root, update_node,
764 parent = node->parent;
766 parent->slots[node->offset] = NULL;
770 * Shouldn't the tags already have all been cleared
774 root_tag_clear_all(root);
778 WARN_ON_ONCE(!list_empty(&node->private_list));
779 radix_tree_node_free(node);
789 * __radix_tree_create - create a slot in a radix tree
790 * @root: radix tree root
792 * @order: index occupies 2^order aligned slots
793 * @nodep: returns node
794 * @slotp: returns slot
796 * Create, if necessary, and return the node and slot for an item
797 * at position @index in the radix tree @root.
799 * Until there is more than one item in the tree, no nodes are
800 * allocated and @root->rnode is used as a direct slot instead of
801 * pointing to a node, in which case *@nodep will be NULL.
803 * Returns -ENOMEM, or 0 for success.
805 int __radix_tree_create(struct radix_tree_root *root, unsigned long index,
806 unsigned order, struct radix_tree_node **nodep,
809 struct radix_tree_node *node = NULL, *child;
810 void **slot = (void **)&root->rnode;
811 unsigned long maxindex;
812 unsigned int shift, offset = 0;
813 unsigned long max = index | ((1UL << order) - 1);
814 gfp_t gfp = root_gfp_mask(root);
816 shift = radix_tree_load_root(root, &child, &maxindex);
818 /* Make sure the tree is high enough. */
819 if (order > 0 && max == ((1UL << order) - 1))
821 if (max > maxindex) {
822 int error = radix_tree_extend(root, gfp, max, shift);
829 while (shift > order) {
830 shift -= RADIX_TREE_MAP_SHIFT;
832 /* Have to add a child node. */
833 child = radix_tree_node_alloc(gfp, node, root, shift,
837 rcu_assign_pointer(*slot, node_to_entry(child));
840 } else if (!radix_tree_is_internal_node(child))
843 /* Go a level down */
844 node = entry_to_node(child);
845 offset = radix_tree_descend(node, &child, index);
846 slot = &node->slots[offset];
857 * Free any nodes below this node. The tree is presumed to not need
858 * shrinking, and any user data in the tree is presumed to not need a
859 * destructor called on it. If we need to add a destructor, we can
860 * add that functionality later. Note that we may not clear tags or
861 * slots from the tree as an RCU walker may still have a pointer into
862 * this subtree. We could replace the entries with RADIX_TREE_RETRY,
863 * but we'll still have to clear those in rcu_free.
865 static void radix_tree_free_nodes(struct radix_tree_node *node)
868 struct radix_tree_node *child = entry_to_node(node);
871 void *entry = child->slots[offset];
872 if (radix_tree_is_internal_node(entry) &&
873 !is_sibling_entry(child, entry)) {
874 child = entry_to_node(entry);
879 while (offset == RADIX_TREE_MAP_SIZE) {
880 struct radix_tree_node *old = child;
881 offset = child->offset + 1;
882 child = child->parent;
883 WARN_ON_ONCE(!list_empty(&old->private_list));
884 radix_tree_node_free(old);
885 if (old == entry_to_node(node))
891 #ifdef CONFIG_RADIX_TREE_MULTIORDER
892 static inline int insert_entries(struct radix_tree_node *node, void **slot,
893 void *item, unsigned order, bool replace)
895 struct radix_tree_node *child;
896 unsigned i, n, tag, offset, tags = 0;
899 if (order > node->shift)
900 n = 1 << (order - node->shift);
903 offset = get_slot_offset(node, slot);
910 offset = offset & ~(n - 1);
911 slot = &node->slots[offset];
913 child = node_to_entry(slot);
915 for (i = 0; i < n; i++) {
919 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
920 if (tag_get(node, tag, offset + i))
927 for (i = 0; i < n; i++) {
928 struct radix_tree_node *old = slot[i];
930 rcu_assign_pointer(slot[i], child);
931 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
932 if (tags & (1 << tag))
933 tag_clear(node, tag, offset + i);
935 rcu_assign_pointer(slot[i], item);
936 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
937 if (tags & (1 << tag))
938 tag_set(node, tag, offset);
940 if (radix_tree_is_internal_node(old) &&
941 !is_sibling_entry(node, old) &&
942 (old != RADIX_TREE_RETRY))
943 radix_tree_free_nodes(old);
944 if (radix_tree_exceptional_entry(old))
949 if (radix_tree_exceptional_entry(item))
950 node->exceptional += n;
955 static inline int insert_entries(struct radix_tree_node *node, void **slot,
956 void *item, unsigned order, bool replace)
960 rcu_assign_pointer(*slot, item);
963 if (radix_tree_exceptional_entry(item))
971 * __radix_tree_insert - insert into a radix tree
972 * @root: radix tree root
974 * @order: key covers the 2^order indices around index
975 * @item: item to insert
977 * Insert an item into the radix tree at position @index.
979 int __radix_tree_insert(struct radix_tree_root *root, unsigned long index,
980 unsigned order, void *item)
982 struct radix_tree_node *node;
986 BUG_ON(radix_tree_is_internal_node(item));
988 error = __radix_tree_create(root, index, order, &node, &slot);
992 error = insert_entries(node, slot, item, order, false);
997 unsigned offset = get_slot_offset(node, slot);
998 BUG_ON(tag_get(node, 0, offset));
999 BUG_ON(tag_get(node, 1, offset));
1000 BUG_ON(tag_get(node, 2, offset));
1002 BUG_ON(root_tags_get(root));
1007 EXPORT_SYMBOL(__radix_tree_insert);
1010 * __radix_tree_lookup - lookup an item in a radix tree
1011 * @root: radix tree root
1013 * @nodep: returns node
1014 * @slotp: returns slot
1016 * Lookup and return the item at position @index in the radix
1019 * Until there is more than one item in the tree, no nodes are
1020 * allocated and @root->rnode is used as a direct slot instead of
1021 * pointing to a node, in which case *@nodep will be NULL.
1023 void *__radix_tree_lookup(const struct radix_tree_root *root,
1024 unsigned long index, struct radix_tree_node **nodep,
1027 struct radix_tree_node *node, *parent;
1028 unsigned long maxindex;
1033 slot = (void **)&root->rnode;
1034 radix_tree_load_root(root, &node, &maxindex);
1035 if (index > maxindex)
1038 while (radix_tree_is_internal_node(node)) {
1041 if (node == RADIX_TREE_RETRY)
1043 parent = entry_to_node(node);
1044 offset = radix_tree_descend(parent, &node, index);
1045 slot = parent->slots + offset;
1056 * radix_tree_lookup_slot - lookup a slot in a radix tree
1057 * @root: radix tree root
1060 * Returns: the slot corresponding to the position @index in the
1061 * radix tree @root. This is useful for update-if-exists operations.
1063 * This function can be called under rcu_read_lock iff the slot is not
1064 * modified by radix_tree_replace_slot, otherwise it must be called
1065 * exclusive from other writers. Any dereference of the slot must be done
1066 * using radix_tree_deref_slot.
1068 void **radix_tree_lookup_slot(const struct radix_tree_root *root,
1069 unsigned long index)
1073 if (!__radix_tree_lookup(root, index, NULL, &slot))
1077 EXPORT_SYMBOL(radix_tree_lookup_slot);
1080 * radix_tree_lookup - perform lookup operation on a radix tree
1081 * @root: radix tree root
1084 * Lookup the item at the position @index in the radix tree @root.
1086 * This function can be called under rcu_read_lock, however the caller
1087 * must manage lifetimes of leaf nodes (eg. RCU may also be used to free
1088 * them safely). No RCU barriers are required to access or modify the
1089 * returned item, however.
1091 void *radix_tree_lookup(const struct radix_tree_root *root, unsigned long index)
1093 return __radix_tree_lookup(root, index, NULL, NULL);
1095 EXPORT_SYMBOL(radix_tree_lookup);
1097 static inline void replace_sibling_entries(struct radix_tree_node *node,
1098 void **slot, int count, int exceptional)
1100 #ifdef CONFIG_RADIX_TREE_MULTIORDER
1101 void *ptr = node_to_entry(slot);
1102 unsigned offset = get_slot_offset(node, slot) + 1;
1104 while (offset < RADIX_TREE_MAP_SIZE) {
1105 if (node->slots[offset] != ptr)
1108 node->slots[offset] = NULL;
1111 node->exceptional += exceptional;
1117 static void replace_slot(void **slot, void *item, struct radix_tree_node *node,
1118 int count, int exceptional)
1120 if (WARN_ON_ONCE(radix_tree_is_internal_node(item)))
1123 if (node && (count || exceptional)) {
1124 node->count += count;
1125 node->exceptional += exceptional;
1126 replace_sibling_entries(node, slot, count, exceptional);
1129 rcu_assign_pointer(*slot, item);
1132 static bool node_tag_get(const struct radix_tree_root *root,
1133 const struct radix_tree_node *node,
1134 unsigned int tag, unsigned int offset)
1137 return tag_get(node, tag, offset);
1138 return root_tag_get(root, tag);
1142 * IDR users want to be able to store NULL in the tree, so if the slot isn't
1143 * free, don't adjust the count, even if it's transitioning between NULL and
1144 * non-NULL. For the IDA, we mark slots as being IDR_FREE while they still
1145 * have empty bits, but it only stores NULL in slots when they're being
1148 static int calculate_count(struct radix_tree_root *root,
1149 struct radix_tree_node *node, void **slot,
1150 void *item, void *old)
1153 unsigned offset = get_slot_offset(node, slot);
1154 bool free = node_tag_get(root, node, IDR_FREE, offset);
1160 return !!item - !!old;
1164 * __radix_tree_replace - replace item in a slot
1165 * @root: radix tree root
1166 * @node: pointer to tree node
1167 * @slot: pointer to slot in @node
1168 * @item: new item to store in the slot.
1169 * @update_node: callback for changing leaf nodes
1170 * @private: private data to pass to @update_node
1172 * For use with __radix_tree_lookup(). Caller must hold tree write locked
1173 * across slot lookup and replacement.
1175 void __radix_tree_replace(struct radix_tree_root *root,
1176 struct radix_tree_node *node,
1177 void **slot, void *item,
1178 radix_tree_update_node_t update_node, void *private)
1180 void *old = rcu_dereference_raw(*slot);
1181 int exceptional = !!radix_tree_exceptional_entry(item) -
1182 !!radix_tree_exceptional_entry(old);
1183 int count = calculate_count(root, node, slot, item, old);
1186 * This function supports replacing exceptional entries and
1187 * deleting entries, but that needs accounting against the
1188 * node unless the slot is root->rnode.
1190 WARN_ON_ONCE(!node && (slot != (void **)&root->rnode) &&
1191 (count || exceptional));
1192 replace_slot(slot, item, node, count, exceptional);
1198 update_node(node, private);
1200 delete_node(root, node, update_node, private);
1204 * radix_tree_replace_slot - replace item in a slot
1205 * @root: radix tree root
1206 * @slot: pointer to slot
1207 * @item: new item to store in the slot.
1209 * For use with radix_tree_lookup_slot(), radix_tree_gang_lookup_slot(),
1210 * radix_tree_gang_lookup_tag_slot(). Caller must hold tree write locked
1211 * across slot lookup and replacement.
1213 * NOTE: This cannot be used to switch between non-entries (empty slots),
1214 * regular entries, and exceptional entries, as that requires accounting
1215 * inside the radix tree node. When switching from one type of entry or
1216 * deleting, use __radix_tree_lookup() and __radix_tree_replace() or
1217 * radix_tree_iter_replace().
1219 void radix_tree_replace_slot(struct radix_tree_root *root,
1220 void **slot, void *item)
1222 __radix_tree_replace(root, NULL, slot, item, NULL, NULL);
1226 * radix_tree_iter_replace - replace item in a slot
1227 * @root: radix tree root
1228 * @slot: pointer to slot
1229 * @item: new item to store in the slot.
1231 * For use with radix_tree_split() and radix_tree_for_each_slot().
1232 * Caller must hold tree write locked across split and replacement.
1234 void radix_tree_iter_replace(struct radix_tree_root *root,
1235 const struct radix_tree_iter *iter, void **slot, void *item)
1237 __radix_tree_replace(root, iter->node, slot, item, NULL, NULL);
1240 #ifdef CONFIG_RADIX_TREE_MULTIORDER
1242 * radix_tree_join - replace multiple entries with one multiorder entry
1243 * @root: radix tree root
1244 * @index: an index inside the new entry
1245 * @order: order of the new entry
1248 * Call this function to replace several entries with one larger entry.
1249 * The existing entries are presumed to not need freeing as a result of
1252 * The replacement entry will have all the tags set on it that were set
1253 * on any of the entries it is replacing.
1255 int radix_tree_join(struct radix_tree_root *root, unsigned long index,
1256 unsigned order, void *item)
1258 struct radix_tree_node *node;
1262 BUG_ON(radix_tree_is_internal_node(item));
1264 error = __radix_tree_create(root, index, order, &node, &slot);
1266 error = insert_entries(node, slot, item, order, true);
1274 * radix_tree_split - Split an entry into smaller entries
1275 * @root: radix tree root
1276 * @index: An index within the large entry
1277 * @order: Order of new entries
1279 * Call this function as the first step in replacing a multiorder entry
1280 * with several entries of lower order. After this function returns,
1281 * loop over the relevant portion of the tree using radix_tree_for_each_slot()
1282 * and call radix_tree_iter_replace() to set up each new entry.
1284 * The tags from this entry are replicated to all the new entries.
1286 * The radix tree should be locked against modification during the entire
1287 * replacement operation. Lock-free lookups will see RADIX_TREE_RETRY which
1288 * should prompt RCU walkers to restart the lookup from the root.
1290 int radix_tree_split(struct radix_tree_root *root, unsigned long index,
1293 struct radix_tree_node *parent, *node, *child;
1295 unsigned int offset, end;
1296 unsigned n, tag, tags = 0;
1297 gfp_t gfp = root_gfp_mask(root);
1299 if (!__radix_tree_lookup(root, index, &parent, &slot))
1304 offset = get_slot_offset(parent, slot);
1306 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
1307 if (tag_get(parent, tag, offset))
1310 for (end = offset + 1; end < RADIX_TREE_MAP_SIZE; end++) {
1311 if (!is_sibling_entry(parent, parent->slots[end]))
1313 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
1314 if (tags & (1 << tag))
1315 tag_set(parent, tag, end);
1316 /* rcu_assign_pointer ensures tags are set before RETRY */
1317 rcu_assign_pointer(parent->slots[end], RADIX_TREE_RETRY);
1319 rcu_assign_pointer(parent->slots[offset], RADIX_TREE_RETRY);
1320 parent->exceptional -= (end - offset);
1322 if (order == parent->shift)
1324 if (order > parent->shift) {
1325 while (offset < end)
1326 offset += insert_entries(parent, &parent->slots[offset],
1327 RADIX_TREE_RETRY, order, true);
1334 if (node->shift > order) {
1335 child = radix_tree_node_alloc(gfp, node, root,
1336 node->shift - RADIX_TREE_MAP_SHIFT,
1340 if (node != parent) {
1342 node->slots[offset] = node_to_entry(child);
1343 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
1344 if (tags & (1 << tag))
1345 tag_set(node, tag, offset);
1353 n = insert_entries(node, &node->slots[offset],
1354 RADIX_TREE_RETRY, order, false);
1355 BUG_ON(n > RADIX_TREE_MAP_SIZE);
1357 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
1358 if (tags & (1 << tag))
1359 tag_set(node, tag, offset);
1362 while (offset == RADIX_TREE_MAP_SIZE) {
1365 offset = node->offset;
1367 node = node->parent;
1368 rcu_assign_pointer(node->slots[offset],
1369 node_to_entry(child));
1372 if ((node == parent) && (offset == end))
1377 /* Shouldn't happen; did user forget to preload? */
1378 /* TODO: free all the allocated nodes */
1384 static void node_tag_set(struct radix_tree_root *root,
1385 struct radix_tree_node *node,
1386 unsigned int tag, unsigned int offset)
1389 if (tag_get(node, tag, offset))
1391 tag_set(node, tag, offset);
1392 offset = node->offset;
1393 node = node->parent;
1396 if (!root_tag_get(root, tag))
1397 root_tag_set(root, tag);
1401 * radix_tree_tag_set - set a tag on a radix tree node
1402 * @root: radix tree root
1406 * Set the search tag (which must be < RADIX_TREE_MAX_TAGS)
1407 * corresponding to @index in the radix tree. From
1408 * the root all the way down to the leaf node.
1410 * Returns the address of the tagged item. Setting a tag on a not-present
1413 void *radix_tree_tag_set(struct radix_tree_root *root,
1414 unsigned long index, unsigned int tag)
1416 struct radix_tree_node *node, *parent;
1417 unsigned long maxindex;
1419 radix_tree_load_root(root, &node, &maxindex);
1420 BUG_ON(index > maxindex);
1422 while (radix_tree_is_internal_node(node)) {
1425 parent = entry_to_node(node);
1426 offset = radix_tree_descend(parent, &node, index);
1429 if (!tag_get(parent, tag, offset))
1430 tag_set(parent, tag, offset);
1433 /* set the root's tag bit */
1434 if (!root_tag_get(root, tag))
1435 root_tag_set(root, tag);
1439 EXPORT_SYMBOL(radix_tree_tag_set);
1442 * radix_tree_iter_tag_set - set a tag on the current iterator entry
1443 * @root: radix tree root
1444 * @iter: iterator state
1447 void radix_tree_iter_tag_set(struct radix_tree_root *root,
1448 const struct radix_tree_iter *iter, unsigned int tag)
1450 node_tag_set(root, iter->node, tag, iter_offset(iter));
1453 static void node_tag_clear(struct radix_tree_root *root,
1454 struct radix_tree_node *node,
1455 unsigned int tag, unsigned int offset)
1458 if (!tag_get(node, tag, offset))
1460 tag_clear(node, tag, offset);
1461 if (any_tag_set(node, tag))
1464 offset = node->offset;
1465 node = node->parent;
1468 /* clear the root's tag bit */
1469 if (root_tag_get(root, tag))
1470 root_tag_clear(root, tag);
1474 * radix_tree_tag_clear - clear a tag on a radix tree node
1475 * @root: radix tree root
1479 * Clear the search tag (which must be < RADIX_TREE_MAX_TAGS)
1480 * corresponding to @index in the radix tree. If this causes
1481 * the leaf node to have no tags set then clear the tag in the
1482 * next-to-leaf node, etc.
1484 * Returns the address of the tagged item on success, else NULL. ie:
1485 * has the same return value and semantics as radix_tree_lookup().
1487 void *radix_tree_tag_clear(struct radix_tree_root *root,
1488 unsigned long index, unsigned int tag)
1490 struct radix_tree_node *node, *parent;
1491 unsigned long maxindex;
1492 int uninitialized_var(offset);
1494 radix_tree_load_root(root, &node, &maxindex);
1495 if (index > maxindex)
1500 while (radix_tree_is_internal_node(node)) {
1501 parent = entry_to_node(node);
1502 offset = radix_tree_descend(parent, &node, index);
1506 node_tag_clear(root, parent, tag, offset);
1510 EXPORT_SYMBOL(radix_tree_tag_clear);
1513 * radix_tree_iter_tag_clear - clear a tag on the current iterator entry
1514 * @root: radix tree root
1515 * @iter: iterator state
1516 * @tag: tag to clear
1518 void radix_tree_iter_tag_clear(struct radix_tree_root *root,
1519 const struct radix_tree_iter *iter, unsigned int tag)
1521 node_tag_clear(root, iter->node, tag, iter_offset(iter));
1525 * radix_tree_tag_get - get a tag on a radix tree node
1526 * @root: radix tree root
1528 * @tag: tag index (< RADIX_TREE_MAX_TAGS)
1532 * 0: tag not present or not set
1535 * Note that the return value of this function may not be relied on, even if
1536 * the RCU lock is held, unless tag modification and node deletion are excluded
1539 int radix_tree_tag_get(const struct radix_tree_root *root,
1540 unsigned long index, unsigned int tag)
1542 struct radix_tree_node *node, *parent;
1543 unsigned long maxindex;
1545 if (!root_tag_get(root, tag))
1548 radix_tree_load_root(root, &node, &maxindex);
1549 if (index > maxindex)
1552 while (radix_tree_is_internal_node(node)) {
1555 parent = entry_to_node(node);
1556 offset = radix_tree_descend(parent, &node, index);
1558 if (!tag_get(parent, tag, offset))
1560 if (node == RADIX_TREE_RETRY)
1566 EXPORT_SYMBOL(radix_tree_tag_get);
1568 static inline void __set_iter_shift(struct radix_tree_iter *iter,
1571 #ifdef CONFIG_RADIX_TREE_MULTIORDER
1572 iter->shift = shift;
1576 /* Construct iter->tags bit-mask from node->tags[tag] array */
1577 static void set_iter_tags(struct radix_tree_iter *iter,
1578 struct radix_tree_node *node, unsigned offset,
1581 unsigned tag_long = offset / BITS_PER_LONG;
1582 unsigned tag_bit = offset % BITS_PER_LONG;
1589 iter->tags = node->tags[tag][tag_long] >> tag_bit;
1591 /* This never happens if RADIX_TREE_TAG_LONGS == 1 */
1592 if (tag_long < RADIX_TREE_TAG_LONGS - 1) {
1593 /* Pick tags from next element */
1595 iter->tags |= node->tags[tag][tag_long + 1] <<
1596 (BITS_PER_LONG - tag_bit);
1597 /* Clip chunk size, here only BITS_PER_LONG tags */
1598 iter->next_index = __radix_tree_iter_add(iter, BITS_PER_LONG);
1602 #ifdef CONFIG_RADIX_TREE_MULTIORDER
1603 static void **skip_siblings(struct radix_tree_node **nodep,
1604 void **slot, struct radix_tree_iter *iter)
1606 void *sib = node_to_entry(slot - 1);
1608 while (iter->index < iter->next_index) {
1609 *nodep = rcu_dereference_raw(*slot);
1610 if (*nodep && *nodep != sib)
1613 iter->index = __radix_tree_iter_add(iter, 1);
1621 void ** __radix_tree_next_slot(void **slot, struct radix_tree_iter *iter,
1624 unsigned tag = flags & RADIX_TREE_ITER_TAG_MASK;
1625 struct radix_tree_node *node = rcu_dereference_raw(*slot);
1627 slot = skip_siblings(&node, slot, iter);
1629 while (radix_tree_is_internal_node(node)) {
1631 unsigned long next_index;
1633 if (node == RADIX_TREE_RETRY)
1635 node = entry_to_node(node);
1637 iter->shift = node->shift;
1639 if (flags & RADIX_TREE_ITER_TAGGED) {
1640 offset = radix_tree_find_next_bit(node, tag, 0);
1641 if (offset == RADIX_TREE_MAP_SIZE)
1643 slot = &node->slots[offset];
1644 iter->index = __radix_tree_iter_add(iter, offset);
1645 set_iter_tags(iter, node, offset, tag);
1646 node = rcu_dereference_raw(*slot);
1649 slot = &node->slots[0];
1651 node = rcu_dereference_raw(*slot);
1656 if (offset == RADIX_TREE_MAP_SIZE)
1659 iter->index = __radix_tree_iter_add(iter, offset);
1661 if ((flags & RADIX_TREE_ITER_CONTIG) && (offset > 0))
1663 next_index = (iter->index | shift_maxindex(iter->shift)) + 1;
1664 if (next_index < iter->next_index)
1665 iter->next_index = next_index;
1670 iter->next_index = 0;
1673 EXPORT_SYMBOL(__radix_tree_next_slot);
1675 static void **skip_siblings(struct radix_tree_node **nodep,
1676 void **slot, struct radix_tree_iter *iter)
1682 void **radix_tree_iter_resume(void **slot, struct radix_tree_iter *iter)
1684 struct radix_tree_node *node;
1687 iter->index = __radix_tree_iter_add(iter, 1);
1688 skip_siblings(&node, slot, iter);
1689 iter->next_index = iter->index;
1693 EXPORT_SYMBOL(radix_tree_iter_resume);
1696 * radix_tree_next_chunk - find next chunk of slots for iteration
1698 * @root: radix tree root
1699 * @iter: iterator state
1700 * @flags: RADIX_TREE_ITER_* flags and tag index
1701 * Returns: pointer to chunk first slot, or NULL if iteration is over
1703 void **radix_tree_next_chunk(const struct radix_tree_root *root,
1704 struct radix_tree_iter *iter, unsigned flags)
1706 unsigned tag = flags & RADIX_TREE_ITER_TAG_MASK;
1707 struct radix_tree_node *node, *child;
1708 unsigned long index, offset, maxindex;
1710 if ((flags & RADIX_TREE_ITER_TAGGED) && !root_tag_get(root, tag))
1714 * Catch next_index overflow after ~0UL. iter->index never overflows
1715 * during iterating; it can be zero only at the beginning.
1716 * And we cannot overflow iter->next_index in a single step,
1717 * because RADIX_TREE_MAP_SHIFT < BITS_PER_LONG.
1719 * This condition also used by radix_tree_next_slot() to stop
1720 * contiguous iterating, and forbid switching to the next chunk.
1722 index = iter->next_index;
1723 if (!index && iter->index)
1727 radix_tree_load_root(root, &child, &maxindex);
1728 if (index > maxindex)
1733 if (!radix_tree_is_internal_node(child)) {
1734 /* Single-slot tree */
1735 iter->index = index;
1736 iter->next_index = maxindex + 1;
1739 __set_iter_shift(iter, 0);
1740 return (void **)&root->rnode;
1744 node = entry_to_node(child);
1745 offset = radix_tree_descend(node, &child, index);
1747 if ((flags & RADIX_TREE_ITER_TAGGED) ?
1748 !tag_get(node, tag, offset) : !child) {
1750 if (flags & RADIX_TREE_ITER_CONTIG)
1753 if (flags & RADIX_TREE_ITER_TAGGED)
1754 offset = radix_tree_find_next_bit(node, tag,
1757 while (++offset < RADIX_TREE_MAP_SIZE) {
1758 void *slot = node->slots[offset];
1759 if (is_sibling_entry(node, slot))
1764 index &= ~node_maxindex(node);
1765 index += offset << node->shift;
1766 /* Overflow after ~0UL */
1769 if (offset == RADIX_TREE_MAP_SIZE)
1771 child = rcu_dereference_raw(node->slots[offset]);
1776 if (child == RADIX_TREE_RETRY)
1778 } while (radix_tree_is_internal_node(child));
1780 /* Update the iterator state */
1781 iter->index = (index &~ node_maxindex(node)) | (offset << node->shift);
1782 iter->next_index = (index | node_maxindex(node)) + 1;
1784 __set_iter_shift(iter, node->shift);
1786 if (flags & RADIX_TREE_ITER_TAGGED)
1787 set_iter_tags(iter, node, offset, tag);
1789 return node->slots + offset;
1791 EXPORT_SYMBOL(radix_tree_next_chunk);
1794 * radix_tree_gang_lookup - perform multiple lookup on a radix tree
1795 * @root: radix tree root
1796 * @results: where the results of the lookup are placed
1797 * @first_index: start the lookup from this key
1798 * @max_items: place up to this many items at *results
1800 * Performs an index-ascending scan of the tree for present items. Places
1801 * them at *@results and returns the number of items which were placed at
1804 * The implementation is naive.
1806 * Like radix_tree_lookup, radix_tree_gang_lookup may be called under
1807 * rcu_read_lock. In this case, rather than the returned results being
1808 * an atomic snapshot of the tree at a single point in time, the
1809 * semantics of an RCU protected gang lookup are as though multiple
1810 * radix_tree_lookups have been issued in individual locks, and results
1811 * stored in 'results'.
1814 radix_tree_gang_lookup(const struct radix_tree_root *root, void **results,
1815 unsigned long first_index, unsigned int max_items)
1817 struct radix_tree_iter iter;
1819 unsigned int ret = 0;
1821 if (unlikely(!max_items))
1824 radix_tree_for_each_slot(slot, root, &iter, first_index) {
1825 results[ret] = rcu_dereference_raw(*slot);
1828 if (radix_tree_is_internal_node(results[ret])) {
1829 slot = radix_tree_iter_retry(&iter);
1832 if (++ret == max_items)
1838 EXPORT_SYMBOL(radix_tree_gang_lookup);
1841 * radix_tree_gang_lookup_slot - perform multiple slot lookup on radix tree
1842 * @root: radix tree root
1843 * @results: where the results of the lookup are placed
1844 * @indices: where their indices should be placed (but usually NULL)
1845 * @first_index: start the lookup from this key
1846 * @max_items: place up to this many items at *results
1848 * Performs an index-ascending scan of the tree for present items. Places
1849 * their slots at *@results and returns the number of items which were
1850 * placed at *@results.
1852 * The implementation is naive.
1854 * Like radix_tree_gang_lookup as far as RCU and locking goes. Slots must
1855 * be dereferenced with radix_tree_deref_slot, and if using only RCU
1856 * protection, radix_tree_deref_slot may fail requiring a retry.
1859 radix_tree_gang_lookup_slot(const struct radix_tree_root *root,
1860 void ***results, unsigned long *indices,
1861 unsigned long first_index, unsigned int max_items)
1863 struct radix_tree_iter iter;
1865 unsigned int ret = 0;
1867 if (unlikely(!max_items))
1870 radix_tree_for_each_slot(slot, root, &iter, first_index) {
1871 results[ret] = slot;
1873 indices[ret] = iter.index;
1874 if (++ret == max_items)
1880 EXPORT_SYMBOL(radix_tree_gang_lookup_slot);
1883 * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree
1885 * @root: radix tree root
1886 * @results: where the results of the lookup are placed
1887 * @first_index: start the lookup from this key
1888 * @max_items: place up to this many items at *results
1889 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
1891 * Performs an index-ascending scan of the tree for present items which
1892 * have the tag indexed by @tag set. Places the items at *@results and
1893 * returns the number of items which were placed at *@results.
1896 radix_tree_gang_lookup_tag(const struct radix_tree_root *root, void **results,
1897 unsigned long first_index, unsigned int max_items,
1900 struct radix_tree_iter iter;
1902 unsigned int ret = 0;
1904 if (unlikely(!max_items))
1907 radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) {
1908 results[ret] = rcu_dereference_raw(*slot);
1911 if (radix_tree_is_internal_node(results[ret])) {
1912 slot = radix_tree_iter_retry(&iter);
1915 if (++ret == max_items)
1921 EXPORT_SYMBOL(radix_tree_gang_lookup_tag);
1924 * radix_tree_gang_lookup_tag_slot - perform multiple slot lookup on a
1925 * radix tree based on a tag
1926 * @root: radix tree root
1927 * @results: where the results of the lookup are placed
1928 * @first_index: start the lookup from this key
1929 * @max_items: place up to this many items at *results
1930 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
1932 * Performs an index-ascending scan of the tree for present items which
1933 * have the tag indexed by @tag set. Places the slots at *@results and
1934 * returns the number of slots which were placed at *@results.
1937 radix_tree_gang_lookup_tag_slot(const struct radix_tree_root *root,
1938 void ***results, unsigned long first_index,
1939 unsigned int max_items, unsigned int tag)
1941 struct radix_tree_iter iter;
1943 unsigned int ret = 0;
1945 if (unlikely(!max_items))
1948 radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) {
1949 results[ret] = slot;
1950 if (++ret == max_items)
1956 EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot);
1959 * __radix_tree_delete_node - try to free node after clearing a slot
1960 * @root: radix tree root
1961 * @node: node containing @index
1962 * @update_node: callback for changing leaf nodes
1963 * @private: private data to pass to @update_node
1965 * After clearing the slot at @index in @node from radix tree
1966 * rooted at @root, call this function to attempt freeing the
1967 * node and shrinking the tree.
1969 void __radix_tree_delete_node(struct radix_tree_root *root,
1970 struct radix_tree_node *node,
1971 radix_tree_update_node_t update_node,
1974 delete_node(root, node, update_node, private);
1977 static bool __radix_tree_delete(struct radix_tree_root *root,
1978 struct radix_tree_node *node, void **slot)
1980 void *old = rcu_dereference_raw(*slot);
1981 int exceptional = radix_tree_exceptional_entry(old) ? -1 : 0;
1982 unsigned offset = get_slot_offset(node, slot);
1986 node_tag_set(root, node, IDR_FREE, offset);
1988 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
1989 node_tag_clear(root, node, tag, offset);
1991 replace_slot(slot, NULL, node, -1, exceptional);
1992 return node && delete_node(root, node, NULL, NULL);
1996 * radix_tree_iter_delete - delete the entry at this iterator position
1997 * @root: radix tree root
1998 * @iter: iterator state
1999 * @slot: pointer to slot
2001 * Delete the entry at the position currently pointed to by the iterator.
2002 * This may result in the current node being freed; if it is, the iterator
2003 * is advanced so that it will not reference the freed memory. This
2004 * function may be called without any locking if there are no other threads
2005 * which can access this tree.
2007 void radix_tree_iter_delete(struct radix_tree_root *root,
2008 struct radix_tree_iter *iter, void **slot)
2010 if (__radix_tree_delete(root, iter->node, slot))
2011 iter->index = iter->next_index;
2015 * radix_tree_delete_item - delete an item from a radix tree
2016 * @root: radix tree root
2018 * @item: expected item
2020 * Remove @item at @index from the radix tree rooted at @root.
2022 * Return: the deleted entry, or %NULL if it was not present
2023 * or the entry at the given @index was not @item.
2025 void *radix_tree_delete_item(struct radix_tree_root *root,
2026 unsigned long index, void *item)
2028 struct radix_tree_node *node = NULL;
2032 entry = __radix_tree_lookup(root, index, &node, &slot);
2033 if (!entry && (!is_idr(root) || node_tag_get(root, node, IDR_FREE,
2034 get_slot_offset(node, slot))))
2037 if (item && entry != item)
2040 __radix_tree_delete(root, node, slot);
2044 EXPORT_SYMBOL(radix_tree_delete_item);
2047 * radix_tree_delete - delete an entry from a radix tree
2048 * @root: radix tree root
2051 * Remove the entry at @index from the radix tree rooted at @root.
2053 * Return: The deleted entry, or %NULL if it was not present.
2055 void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
2057 return radix_tree_delete_item(root, index, NULL);
2059 EXPORT_SYMBOL(radix_tree_delete);
2061 void radix_tree_clear_tags(struct radix_tree_root *root,
2062 struct radix_tree_node *node,
2066 unsigned int tag, offset = get_slot_offset(node, slot);
2067 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
2068 node_tag_clear(root, node, tag, offset);
2070 root_tag_clear_all(root);
2075 * radix_tree_tagged - test whether any items in the tree are tagged
2076 * @root: radix tree root
2079 int radix_tree_tagged(const struct radix_tree_root *root, unsigned int tag)
2081 return root_tag_get(root, tag);
2083 EXPORT_SYMBOL(radix_tree_tagged);
2086 * idr_preload - preload for idr_alloc()
2087 * @gfp_mask: allocation mask to use for preloading
2089 * Preallocate memory to use for the next call to idr_alloc(). This function
2090 * returns with preemption disabled. It will be enabled by idr_preload_end().
2092 void idr_preload(gfp_t gfp_mask)
2094 __radix_tree_preload(gfp_mask, IDR_PRELOAD_SIZE);
2096 EXPORT_SYMBOL(idr_preload);
2099 * ida_pre_get - reserve resources for ida allocation
2101 * @gfp: memory allocation flags
2103 * This function should be called before calling ida_get_new_above(). If it
2104 * is unable to allocate memory, it will return %0. On success, it returns %1.
2106 int ida_pre_get(struct ida *ida, gfp_t gfp)
2108 __radix_tree_preload(gfp, IDA_PRELOAD_SIZE);
2110 * The IDA API has no preload_end() equivalent. Instead,
2111 * ida_get_new() can return -EAGAIN, prompting the caller
2112 * to return to the ida_pre_get() step.
2116 if (!this_cpu_read(ida_bitmap)) {
2117 struct ida_bitmap *bitmap = kmalloc(sizeof(*bitmap), gfp);
2120 bitmap = this_cpu_cmpxchg(ida_bitmap, NULL, bitmap);
2126 EXPORT_SYMBOL(ida_pre_get);
2128 void **idr_get_free(struct radix_tree_root *root,
2129 struct radix_tree_iter *iter, gfp_t gfp, int end)
2131 struct radix_tree_node *node = NULL, *child;
2132 void **slot = (void **)&root->rnode;
2133 unsigned long maxindex, start = iter->next_index;
2134 unsigned long max = end > 0 ? end - 1 : INT_MAX;
2135 unsigned int shift, offset = 0;
2138 shift = radix_tree_load_root(root, &child, &maxindex);
2139 if (!radix_tree_tagged(root, IDR_FREE))
2140 start = max(start, maxindex + 1);
2142 return ERR_PTR(-ENOSPC);
2144 if (start > maxindex) {
2145 int error = radix_tree_extend(root, gfp, start, shift);
2147 return ERR_PTR(error);
2149 child = rcu_dereference_raw(root->rnode);
2153 shift -= RADIX_TREE_MAP_SHIFT;
2154 if (child == NULL) {
2155 /* Have to add a child node. */
2156 child = radix_tree_node_alloc(gfp, node, root, shift,
2159 return ERR_PTR(-ENOMEM);
2160 all_tag_set(child, IDR_FREE);
2161 rcu_assign_pointer(*slot, node_to_entry(child));
2164 } else if (!radix_tree_is_internal_node(child))
2167 node = entry_to_node(child);
2168 offset = radix_tree_descend(node, &child, start);
2169 if (!tag_get(node, IDR_FREE, offset)) {
2170 offset = radix_tree_find_next_bit(node, IDR_FREE,
2172 start = next_index(start, node, offset);
2174 return ERR_PTR(-ENOSPC);
2175 while (offset == RADIX_TREE_MAP_SIZE) {
2176 offset = node->offset + 1;
2177 node = node->parent;
2180 shift = node->shift;
2182 child = rcu_dereference_raw(node->slots[offset]);
2184 slot = &node->slots[offset];
2187 iter->index = start;
2189 iter->next_index = 1 + min(max, (start | node_maxindex(node)));
2191 iter->next_index = 1;
2193 __set_iter_shift(iter, shift);
2194 set_iter_tags(iter, node, offset, IDR_FREE);
2200 * idr_destroy - release all internal memory from an IDR
2203 * After this function is called, the IDR is empty, and may be reused or
2204 * the data structure containing it may be freed.
2206 * A typical clean-up sequence for objects stored in an idr tree will use
2207 * idr_for_each() to free all objects, if necessary, then idr_destroy() to
2208 * free the memory used to keep track of those objects.
2210 void idr_destroy(struct idr *idr)
2212 struct radix_tree_node *node = rcu_dereference_raw(idr->idr_rt.rnode);
2213 if (radix_tree_is_internal_node(node))
2214 radix_tree_free_nodes(node);
2215 idr->idr_rt.rnode = NULL;
2216 root_tag_set(&idr->idr_rt, IDR_FREE);
2218 EXPORT_SYMBOL(idr_destroy);
2221 radix_tree_node_ctor(void *arg)
2223 struct radix_tree_node *node = arg;
2225 memset(node, 0, sizeof(*node));
2226 INIT_LIST_HEAD(&node->private_list);
2229 static __init unsigned long __maxindex(unsigned int height)
2231 unsigned int width = height * RADIX_TREE_MAP_SHIFT;
2232 int shift = RADIX_TREE_INDEX_BITS - width;
2236 if (shift >= BITS_PER_LONG)
2238 return ~0UL >> shift;
2241 static __init void radix_tree_init_maxnodes(void)
2243 unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH + 1];
2246 for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++)
2247 height_to_maxindex[i] = __maxindex(i);
2248 for (i = 0; i < ARRAY_SIZE(height_to_maxnodes); i++) {
2249 for (j = i; j > 0; j--)
2250 height_to_maxnodes[i] += height_to_maxindex[j - 1] + 1;
2254 static int radix_tree_cpu_dead(unsigned int cpu)
2256 struct radix_tree_preload *rtp;
2257 struct radix_tree_node *node;
2259 /* Free per-cpu pool of preloaded nodes */
2260 rtp = &per_cpu(radix_tree_preloads, cpu);
2263 rtp->nodes = node->parent;
2264 kmem_cache_free(radix_tree_node_cachep, node);
2267 kfree(per_cpu(ida_bitmap, cpu));
2268 per_cpu(ida_bitmap, cpu) = NULL;
2272 void __init radix_tree_init(void)
2275 radix_tree_node_cachep = kmem_cache_create("radix_tree_node",
2276 sizeof(struct radix_tree_node), 0,
2277 SLAB_PANIC | SLAB_RECLAIM_ACCOUNT,
2278 radix_tree_node_ctor);
2279 radix_tree_init_maxnodes();
2280 ret = cpuhp_setup_state_nocalls(CPUHP_RADIX_DEAD, "lib/radix:dead",
2281 NULL, radix_tree_cpu_dead);