Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0-or-later
2 : /*
3 : * Copyright (C) 2001 Momchil Velikov
4 : * Portions Copyright (C) 2001 Christoph Hellwig
5 : * Copyright (C) 2005 SGI, Christoph Lameter
6 : * Copyright (C) 2006 Nick Piggin
7 : * Copyright (C) 2012 Konstantin Khlebnikov
8 : * Copyright (C) 2016 Intel, Matthew Wilcox
9 : * Copyright (C) 2016 Intel, Ross Zwisler
10 : */
11 :
12 : #include <linux/bitmap.h>
13 : #include <linux/bitops.h>
14 : #include <linux/bug.h>
15 : #include <linux/cpu.h>
16 : #include <linux/errno.h>
17 : #include <linux/export.h>
18 : #include <linux/idr.h>
19 : #include <linux/init.h>
20 : #include <linux/kernel.h>
21 : #include <linux/kmemleak.h>
22 : #include <linux/percpu.h>
23 : #include <linux/preempt.h> /* in_interrupt() */
24 : #include <linux/radix-tree.h>
25 : #include <linux/rcupdate.h>
26 : #include <linux/slab.h>
27 : #include <linux/string.h>
28 : #include <linux/xarray.h>
29 :
30 : /*
31 : * Radix tree node cache.
32 : */
33 : struct kmem_cache *radix_tree_node_cachep;
34 :
35 : /*
36 : * The radix tree is variable-height, so an insert operation not only has
37 : * to build the branch to its corresponding item, it also has to build the
38 : * branch to existing items if the size has to be increased (by
39 : * radix_tree_extend).
40 : *
41 : * The worst case is a zero height tree with just a single item at index 0,
42 : * and then inserting an item at index ULONG_MAX. This requires 2 new branches
43 : * of RADIX_TREE_MAX_PATH size to be created, with only the root node shared.
44 : * Hence:
45 : */
46 : #define RADIX_TREE_PRELOAD_SIZE (RADIX_TREE_MAX_PATH * 2 - 1)
47 :
48 : /*
49 : * The IDR does not have to be as high as the radix tree since it uses
50 : * signed integers, not unsigned longs.
51 : */
52 : #define IDR_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(int) - 1)
53 : #define IDR_MAX_PATH (DIV_ROUND_UP(IDR_INDEX_BITS, \
54 : RADIX_TREE_MAP_SHIFT))
55 : #define IDR_PRELOAD_SIZE (IDR_MAX_PATH * 2 - 1)
56 :
57 : /*
58 : * Per-cpu pool of preloaded nodes
59 : */
60 : DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = {
61 : .lock = INIT_LOCAL_LOCK(lock),
62 : };
63 : EXPORT_PER_CPU_SYMBOL_GPL(radix_tree_preloads);
64 :
65 : static inline struct radix_tree_node *entry_to_node(void *ptr)
66 : {
67 41093 : return (void *)((unsigned long)ptr & ~RADIX_TREE_INTERNAL_NODE);
68 : }
69 :
70 : static inline void *node_to_entry(void *ptr)
71 : {
72 12061 : return (void *)((unsigned long)ptr | RADIX_TREE_INTERNAL_NODE);
73 : }
74 :
75 : #define RADIX_TREE_RETRY XA_RETRY_ENTRY
76 :
77 : static inline unsigned long
78 : get_slot_offset(const struct radix_tree_node *parent, void __rcu **slot)
79 : {
80 11377 : return parent ? slot - parent->slots : 0;
81 : }
82 :
83 : static unsigned int radix_tree_descend(const struct radix_tree_node *parent,
84 : struct radix_tree_node **nodep, unsigned long index)
85 : {
86 26829 : unsigned int offset = (index >> parent->shift) & RADIX_TREE_MAP_MASK;
87 26829 : void __rcu **entry = rcu_dereference_raw(parent->slots[offset]);
88 :
89 26829 : *nodep = (void *)entry;
90 : return offset;
91 : }
92 :
93 : static inline gfp_t root_gfp_mask(const struct radix_tree_root *root)
94 : {
95 0 : return root->xa_flags & (__GFP_BITS_MASK & ~GFP_ZONEMASK);
96 : }
97 :
98 : static inline void tag_set(struct radix_tree_node *node, unsigned int tag,
99 : int offset)
100 : {
101 2780 : __set_bit(offset, node->tags[tag]);
102 : }
103 :
104 : static inline void tag_clear(struct radix_tree_node *node, unsigned int tag,
105 : int offset)
106 : {
107 19484 : __clear_bit(offset, node->tags[tag]);
108 : }
109 :
110 45474 : static inline int tag_get(const struct radix_tree_node *node, unsigned int tag,
111 : int offset)
112 : {
113 91502 : return test_bit(offset, node->tags[tag]);
114 : }
115 :
116 : static inline void root_tag_set(struct radix_tree_root *root, unsigned tag)
117 : {
118 34 : root->xa_flags |= (__force gfp_t)(1 << (tag + ROOT_TAG_SHIFT));
119 : }
120 :
121 : static inline void root_tag_clear(struct radix_tree_root *root, unsigned tag)
122 : {
123 0 : root->xa_flags &= (__force gfp_t)~(1 << (tag + ROOT_TAG_SHIFT));
124 : }
125 :
126 : static inline void root_tag_clear_all(struct radix_tree_root *root)
127 : {
128 0 : root->xa_flags &= (__force gfp_t)((1 << ROOT_TAG_SHIFT) - 1);
129 : }
130 :
131 : static inline int root_tag_get(const struct radix_tree_root *root, unsigned tag)
132 : {
133 10918 : return (__force int)root->xa_flags & (1 << (tag + ROOT_TAG_SHIFT));
134 : }
135 :
136 : static inline unsigned root_tags_get(const struct radix_tree_root *root)
137 : {
138 0 : return (__force unsigned)root->xa_flags >> ROOT_TAG_SHIFT;
139 : }
140 :
141 : static inline bool is_idr(const struct radix_tree_root *root)
142 : {
143 11988 : return !!(root->xa_flags & ROOT_IS_IDR);
144 : }
145 :
146 : /*
147 : * Returns 1 if any slot in the node has this tag set.
148 : * Otherwise returns 0.
149 : */
150 : static inline int any_tag_set(const struct radix_tree_node *node,
151 : unsigned int tag)
152 : {
153 : unsigned idx;
154 125 : for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
155 9742 : if (node->tags[tag][idx])
156 : return 1;
157 : }
158 : return 0;
159 : }
160 :
161 : static inline void all_tag_set(struct radix_tree_node *node, unsigned int tag)
162 : {
163 1494 : bitmap_fill(node->tags[tag], RADIX_TREE_MAP_SIZE);
164 : }
165 :
166 : /**
167 : * radix_tree_find_next_bit - find the next set bit in a memory region
168 : *
169 : * @node: where to begin the search
170 : * @tag: the tag index
171 : * @offset: the bitnumber to start searching at
172 : *
173 : * Unrollable variant of find_next_bit() for constant size arrays.
174 : * Tail bits starting from size to roundup(size, BITS_PER_LONG) must be zero.
175 : * Returns next bit offset, or size if nothing found.
176 : */
177 : static __always_inline unsigned long
178 : radix_tree_find_next_bit(struct radix_tree_node *node, unsigned int tag,
179 : unsigned long offset)
180 : {
181 598 : const unsigned long *addr = node->tags[tag];
182 :
183 598 : if (offset < RADIX_TREE_MAP_SIZE) {
184 : unsigned long tmp;
185 :
186 598 : addr += offset / BITS_PER_LONG;
187 598 : tmp = *addr >> (offset % BITS_PER_LONG);
188 598 : if (tmp)
189 1196 : return __ffs(tmp) + offset;
190 0 : offset = (offset + BITS_PER_LONG) & ~(BITS_PER_LONG - 1);
191 0 : while (offset < RADIX_TREE_MAP_SIZE) {
192 0 : tmp = *++addr;
193 0 : if (tmp)
194 0 : return __ffs(tmp) + offset;
195 0 : offset += BITS_PER_LONG;
196 : }
197 : }
198 : return RADIX_TREE_MAP_SIZE;
199 : }
200 :
201 : static unsigned int iter_offset(const struct radix_tree_iter *iter)
202 : {
203 9617 : return iter->index & RADIX_TREE_MAP_MASK;
204 : }
205 :
206 : /*
207 : * The maximum index which can be stored in a radix tree
208 : */
209 : static inline unsigned long shift_maxindex(unsigned int shift)
210 : {
211 22182 : return (RADIX_TREE_MAP_SIZE << shift) - 1;
212 : }
213 :
214 : static inline unsigned long node_maxindex(const struct radix_tree_node *node)
215 : {
216 43802 : return shift_maxindex(node->shift);
217 : }
218 :
219 : static unsigned long next_index(unsigned long index,
220 : const struct radix_tree_node *node,
221 : unsigned long offset)
222 : {
223 1196 : return (index & ~node_maxindex(node)) + (offset << node->shift);
224 : }
225 :
226 : /*
227 : * This assumes that the caller has performed appropriate preallocation, and
228 : * that the caller has pinned this thread of control to the current CPU.
229 : */
230 : static struct radix_tree_node *
231 747 : radix_tree_node_alloc(gfp_t gfp_mask, struct radix_tree_node *parent,
232 : struct radix_tree_root *root,
233 : unsigned int shift, unsigned int offset,
234 : unsigned int count, unsigned int nr_values)
235 : {
236 747 : struct radix_tree_node *ret = NULL;
237 :
238 : /*
239 : * Preload code isn't irq safe and it doesn't make sense to use
240 : * preloading during an interrupt anyway as all the allocations have
241 : * to be atomic. So just do normal allocation when in interrupt.
242 : */
243 1476 : if (!gfpflags_allow_blocking(gfp_mask) && !in_interrupt()) {
244 : struct radix_tree_preload *rtp;
245 :
246 : /*
247 : * Even if the caller has preloaded, try to allocate from the
248 : * cache first for the new node to get accounted to the memory
249 : * cgroup.
250 : */
251 729 : ret = kmem_cache_alloc(radix_tree_node_cachep,
252 : gfp_mask | __GFP_NOWARN);
253 729 : if (ret)
254 : goto out;
255 :
256 : /*
257 : * Provided the caller has preloaded here, we will always
258 : * succeed in getting a node here (and never reach
259 : * kmem_cache_alloc)
260 : */
261 0 : rtp = this_cpu_ptr(&radix_tree_preloads);
262 0 : if (rtp->nr) {
263 0 : ret = rtp->nodes;
264 0 : rtp->nodes = ret->parent;
265 0 : rtp->nr--;
266 : }
267 : /*
268 : * Update the allocation stack trace as this is more useful
269 : * for debugging.
270 : */
271 : kmemleak_update_trace(ret);
272 : goto out;
273 : }
274 18 : ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
275 : out:
276 747 : BUG_ON(radix_tree_is_internal_node(ret));
277 747 : if (ret) {
278 747 : ret->shift = shift;
279 747 : ret->offset = offset;
280 747 : ret->count = count;
281 747 : ret->nr_values = nr_values;
282 747 : ret->parent = parent;
283 747 : ret->array = root;
284 : }
285 747 : return ret;
286 : }
287 :
288 608 : void radix_tree_node_rcu_free(struct rcu_head *head)
289 : {
290 608 : struct radix_tree_node *node =
291 608 : container_of(head, struct radix_tree_node, rcu_head);
292 :
293 : /*
294 : * Must only free zeroed nodes into the slab. We can be left with
295 : * non-NULL entries by radix_tree_free_nodes, so clear the entries
296 : * and tags here.
297 : */
298 608 : memset(node->slots, 0, sizeof(node->slots));
299 608 : memset(node->tags, 0, sizeof(node->tags));
300 1216 : INIT_LIST_HEAD(&node->private_list);
301 :
302 608 : kmem_cache_free(radix_tree_node_cachep, node);
303 608 : }
304 :
305 : static inline void
306 : radix_tree_node_free(struct radix_tree_node *node)
307 : {
308 610 : call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
309 : }
310 :
311 : /*
312 : * Load up this CPU's radix_tree_node buffer with sufficient objects to
313 : * ensure that the addition of a single element in the tree cannot fail. On
314 : * success, return zero, with preemption disabled. On error, return -ENOMEM
315 : * with preemption not disabled.
316 : *
317 : * To make use of this facility, the radix tree must be initialised without
318 : * __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE().
319 : */
320 9001 : static __must_check int __radix_tree_preload(gfp_t gfp_mask, unsigned nr)
321 : {
322 : struct radix_tree_preload *rtp;
323 : struct radix_tree_node *node;
324 9001 : int ret = -ENOMEM;
325 :
326 : /*
327 : * Nodes preloaded by one cgroup can be used by another cgroup, so
328 : * they should never be accounted to any particular memory cgroup.
329 : */
330 9001 : gfp_mask &= ~__GFP_ACCOUNT;
331 :
332 9001 : local_lock(&radix_tree_preloads.lock);
333 9001 : rtp = this_cpu_ptr(&radix_tree_preloads);
334 18013 : while (rtp->nr < nr) {
335 11 : local_unlock(&radix_tree_preloads.lock);
336 11 : node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
337 11 : if (node == NULL)
338 : goto out;
339 11 : local_lock(&radix_tree_preloads.lock);
340 11 : rtp = this_cpu_ptr(&radix_tree_preloads);
341 11 : if (rtp->nr < nr) {
342 11 : node->parent = rtp->nodes;
343 11 : rtp->nodes = node;
344 11 : rtp->nr++;
345 : } else {
346 0 : kmem_cache_free(radix_tree_node_cachep, node);
347 : }
348 : }
349 : ret = 0;
350 : out:
351 9001 : return ret;
352 : }
353 :
354 : /*
355 : * Load up this CPU's radix_tree_node buffer with sufficient objects to
356 : * ensure that the addition of a single element in the tree cannot fail. On
357 : * success, return zero, with preemption disabled. On error, return -ENOMEM
358 : * with preemption not disabled.
359 : *
360 : * To make use of this facility, the radix tree must be initialised without
361 : * __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE().
362 : */
363 0 : int radix_tree_preload(gfp_t gfp_mask)
364 : {
365 : /* Warn on non-sensical use... */
366 0 : WARN_ON_ONCE(!gfpflags_allow_blocking(gfp_mask));
367 0 : return __radix_tree_preload(gfp_mask, RADIX_TREE_PRELOAD_SIZE);
368 : }
369 : EXPORT_SYMBOL(radix_tree_preload);
370 :
371 : /*
372 : * The same as above function, except we don't guarantee preloading happens.
373 : * We do it, if we decide it helps. On success, return zero with preemption
374 : * disabled. On error, return -ENOMEM with preemption not disabled.
375 : */
376 0 : int radix_tree_maybe_preload(gfp_t gfp_mask)
377 : {
378 0 : if (gfpflags_allow_blocking(gfp_mask))
379 0 : return __radix_tree_preload(gfp_mask, RADIX_TREE_PRELOAD_SIZE);
380 : /* Preloading doesn't help anything with this gfp mask, skip it */
381 0 : local_lock(&radix_tree_preloads.lock);
382 0 : return 0;
383 : }
384 : EXPORT_SYMBOL(radix_tree_maybe_preload);
385 :
386 : static unsigned radix_tree_load_root(const struct radix_tree_root *root,
387 : struct radix_tree_node **nodep, unsigned long *maxindex)
388 : {
389 11723 : struct radix_tree_node *node = rcu_dereference_raw(root->xa_head);
390 :
391 11723 : *nodep = node;
392 :
393 11723 : if (likely(radix_tree_is_internal_node(node))) {
394 11686 : node = entry_to_node(node);
395 11686 : *maxindex = node_maxindex(node);
396 9580 : return node->shift + RADIX_TREE_MAP_SHIFT;
397 : }
398 :
399 : *maxindex = 0;
400 : return 0;
401 : }
402 :
403 : /*
404 : * Extend a radix tree so it can store key @index.
405 : */
406 281 : static int radix_tree_extend(struct radix_tree_root *root, gfp_t gfp,
407 : unsigned long index, unsigned int shift)
408 : {
409 : void *entry;
410 : unsigned int maxshift;
411 : int tag;
412 :
413 : /* Figure out what the shift should be. */
414 281 : maxshift = shift;
415 562 : while (index > shift_maxindex(maxshift))
416 0 : maxshift += RADIX_TREE_MAP_SHIFT;
417 :
418 281 : entry = rcu_dereference_raw(root->xa_head);
419 285 : if (!entry && (!is_idr(root) || root_tag_get(root, IDR_FREE)))
420 : goto out;
421 :
422 : do {
423 279 : struct radix_tree_node *node = radix_tree_node_alloc(gfp, NULL,
424 : root, shift, 0, 1, 0);
425 279 : if (!node)
426 : return -ENOMEM;
427 :
428 558 : if (is_idr(root)) {
429 279 : all_tag_set(node, IDR_FREE);
430 558 : if (!root_tag_get(root, IDR_FREE)) {
431 0 : tag_clear(node, IDR_FREE, 0);
432 0 : root_tag_set(root, IDR_FREE);
433 : }
434 : } else {
435 : /* Propagate the aggregated tag info to the new child */
436 0 : for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
437 0 : if (root_tag_get(root, tag))
438 0 : tag_set(node, tag, 0);
439 : }
440 : }
441 :
442 279 : BUG_ON(shift > BITS_PER_LONG);
443 279 : if (radix_tree_is_internal_node(entry)) {
444 279 : entry_to_node(entry)->parent = node;
445 0 : } else if (xa_is_value(entry)) {
446 : /* Moving a value entry root->xa_head to a node */
447 0 : node->nr_values = 1;
448 : }
449 : /*
450 : * entry was already in the radix tree, so we do not need
451 : * rcu_assign_pointer here
452 : */
453 279 : node->slots[0] = (void __rcu *)entry;
454 279 : entry = node_to_entry(node);
455 279 : rcu_assign_pointer(root->xa_head, entry);
456 279 : shift += RADIX_TREE_MAP_SHIFT;
457 279 : } while (shift <= maxshift);
458 : out:
459 281 : return maxshift + RADIX_TREE_MAP_SHIFT;
460 : }
461 :
462 : /**
463 : * radix_tree_shrink - shrink radix tree to minimum height
464 : * @root: radix tree root
465 : */
466 1745 : static inline bool radix_tree_shrink(struct radix_tree_root *root)
467 : {
468 1745 : bool shrunk = false;
469 :
470 277 : for (;;) {
471 2022 : struct radix_tree_node *node = rcu_dereference_raw(root->xa_head);
472 : struct radix_tree_node *child;
473 :
474 2022 : if (!radix_tree_is_internal_node(node))
475 : break;
476 2022 : node = entry_to_node(node);
477 :
478 : /*
479 : * The candidate node has more than one child, or its child
480 : * is not at the leftmost slot, we cannot shrink.
481 : */
482 2022 : if (node->count != 1)
483 : break;
484 334 : child = rcu_dereference_raw(node->slots[0]);
485 334 : if (!child)
486 : break;
487 :
488 : /*
489 : * For an IDR, we must not shrink entry 0 into the root in
490 : * case somebody calls idr_replace() with a pointer that
491 : * appears to be an internal entry
492 : */
493 315 : if (!node->shift && is_idr(root))
494 : break;
495 :
496 277 : if (radix_tree_is_internal_node(child))
497 277 : entry_to_node(child)->parent = NULL;
498 :
499 : /*
500 : * We don't need rcu_assign_pointer(), since we are simply
501 : * moving the node from one part of the tree to another: if it
502 : * was safe to dereference the old pointer to it
503 : * (node->slots[0]), it will be safe to dereference the new
504 : * one (root->xa_head) as far as dependent read barriers go.
505 : */
506 277 : root->xa_head = (void __rcu *)child;
507 831 : if (is_idr(root) && !tag_get(node, IDR_FREE, 0))
508 0 : root_tag_clear(root, IDR_FREE);
509 :
510 : /*
511 : * We have a dilemma here. The node's slot[0] must not be
512 : * NULLed in case there are concurrent lookups expecting to
513 : * find the item. However if this was a bottom-level node,
514 : * then it may be subject to the slot pointer being visible
515 : * to callers dereferencing it. If item corresponding to
516 : * slot[0] is subsequently deleted, these callers would expect
517 : * their slot to become empty sooner or later.
518 : *
519 : * For example, lockless pagecache will look up a slot, deref
520 : * the page pointer, and if the page has 0 refcount it means it
521 : * was concurrently deleted from pagecache so try the deref
522 : * again. Fortunately there is already a requirement for logic
523 : * to retry the entire slot lookup -- the indirect pointer
524 : * problem (replacing direct root node with an indirect pointer
525 : * also results in a stale slot). So tag the slot as indirect
526 : * to force callers to retry.
527 : */
528 277 : node->count = 0;
529 277 : if (!radix_tree_is_internal_node(child)) {
530 0 : node->slots[0] = (void __rcu *)RADIX_TREE_RETRY;
531 : }
532 :
533 554 : WARN_ON_ONCE(!list_empty(&node->private_list));
534 277 : radix_tree_node_free(node);
535 277 : shrunk = true;
536 : }
537 :
538 1745 : return shrunk;
539 : }
540 :
541 11348 : static bool delete_node(struct radix_tree_root *root,
542 : struct radix_tree_node *node)
543 : {
544 11348 : bool deleted = false;
545 :
546 : do {
547 : struct radix_tree_node *parent;
548 :
549 11647 : if (node->count) {
550 22628 : if (node_to_entry(node) ==
551 11314 : rcu_dereference_raw(root->xa_head))
552 1745 : deleted |= radix_tree_shrink(root);
553 : return deleted;
554 : }
555 :
556 333 : parent = node->parent;
557 333 : if (parent) {
558 299 : parent->slots[node->offset] = NULL;
559 299 : parent->count--;
560 : } else {
561 : /*
562 : * Shouldn't the tags already have all been cleared
563 : * by the caller?
564 : */
565 68 : if (!is_idr(root))
566 0 : root_tag_clear_all(root);
567 34 : root->xa_head = NULL;
568 : }
569 :
570 666 : WARN_ON_ONCE(!list_empty(&node->private_list));
571 333 : radix_tree_node_free(node);
572 333 : deleted = true;
573 :
574 333 : node = parent;
575 333 : } while (node);
576 :
577 : return deleted;
578 : }
579 :
580 : /**
581 : * __radix_tree_create - create a slot in a radix tree
582 : * @root: radix tree root
583 : * @index: index key
584 : * @nodep: returns node
585 : * @slotp: returns slot
586 : *
587 : * Create, if necessary, and return the node and slot for an item
588 : * at position @index in the radix tree @root.
589 : *
590 : * Until there is more than one item in the tree, no nodes are
591 : * allocated and @root->xa_head is used as a direct slot instead of
592 : * pointing to a node, in which case *@nodep will be NULL.
593 : *
594 : * Returns -ENOMEM, or 0 for success.
595 : */
596 0 : static int __radix_tree_create(struct radix_tree_root *root,
597 : unsigned long index, struct radix_tree_node **nodep,
598 : void __rcu ***slotp)
599 : {
600 0 : struct radix_tree_node *node = NULL, *child;
601 0 : void __rcu **slot = (void __rcu **)&root->xa_head;
602 : unsigned long maxindex;
603 0 : unsigned int shift, offset = 0;
604 0 : unsigned long max = index;
605 0 : gfp_t gfp = root_gfp_mask(root);
606 :
607 0 : shift = radix_tree_load_root(root, &child, &maxindex);
608 :
609 : /* Make sure the tree is high enough. */
610 0 : if (max > maxindex) {
611 0 : int error = radix_tree_extend(root, gfp, max, shift);
612 0 : if (error < 0)
613 : return error;
614 0 : shift = error;
615 0 : child = rcu_dereference_raw(root->xa_head);
616 : }
617 :
618 0 : while (shift > 0) {
619 0 : shift -= RADIX_TREE_MAP_SHIFT;
620 0 : if (child == NULL) {
621 : /* Have to add a child node. */
622 0 : child = radix_tree_node_alloc(gfp, node, root, shift,
623 : offset, 0, 0);
624 0 : if (!child)
625 : return -ENOMEM;
626 0 : rcu_assign_pointer(*slot, node_to_entry(child));
627 0 : if (node)
628 0 : node->count++;
629 0 : } else if (!radix_tree_is_internal_node(child))
630 : break;
631 :
632 : /* Go a level down */
633 0 : node = entry_to_node(child);
634 0 : offset = radix_tree_descend(node, &child, index);
635 0 : slot = &node->slots[offset];
636 : }
637 :
638 0 : if (nodep)
639 0 : *nodep = node;
640 0 : if (slotp)
641 0 : *slotp = slot;
642 : return 0;
643 : }
644 :
645 : /*
646 : * Free any nodes below this node. The tree is presumed to not need
647 : * shrinking, and any user data in the tree is presumed to not need a
648 : * destructor called on it. If we need to add a destructor, we can
649 : * add that functionality later. Note that we may not clear tags or
650 : * slots from the tree as an RCU walker may still have a pointer into
651 : * this subtree. We could replace the entries with RADIX_TREE_RETRY,
652 : * but we'll still have to clear those in rcu_free.
653 : */
654 0 : static void radix_tree_free_nodes(struct radix_tree_node *node)
655 : {
656 0 : unsigned offset = 0;
657 0 : struct radix_tree_node *child = entry_to_node(node);
658 :
659 : for (;;) {
660 0 : void *entry = rcu_dereference_raw(child->slots[offset]);
661 0 : if (xa_is_node(entry) && child->shift) {
662 0 : child = entry_to_node(entry);
663 0 : offset = 0;
664 0 : continue;
665 : }
666 0 : offset++;
667 0 : while (offset == RADIX_TREE_MAP_SIZE) {
668 0 : struct radix_tree_node *old = child;
669 0 : offset = child->offset + 1;
670 0 : child = child->parent;
671 0 : WARN_ON_ONCE(!list_empty(&old->private_list));
672 0 : radix_tree_node_free(old);
673 0 : if (old == entry_to_node(node))
674 0 : return;
675 : }
676 : }
677 : }
678 :
679 : static inline int insert_entries(struct radix_tree_node *node,
680 : void __rcu **slot, void *item)
681 : {
682 0 : if (*slot)
683 : return -EEXIST;
684 0 : rcu_assign_pointer(*slot, item);
685 0 : if (node) {
686 0 : node->count++;
687 0 : if (xa_is_value(item))
688 0 : node->nr_values++;
689 : }
690 : return 1;
691 : }
692 :
693 : /**
694 : * radix_tree_insert - insert into a radix tree
695 : * @root: radix tree root
696 : * @index: index key
697 : * @item: item to insert
698 : *
699 : * Insert an item into the radix tree at position @index.
700 : */
701 0 : int radix_tree_insert(struct radix_tree_root *root, unsigned long index,
702 : void *item)
703 : {
704 : struct radix_tree_node *node;
705 : void __rcu **slot;
706 : int error;
707 :
708 0 : BUG_ON(radix_tree_is_internal_node(item));
709 :
710 0 : error = __radix_tree_create(root, index, &node, &slot);
711 0 : if (error)
712 : return error;
713 :
714 0 : error = insert_entries(node, slot, item);
715 0 : if (error < 0)
716 : return error;
717 :
718 0 : if (node) {
719 0 : unsigned offset = get_slot_offset(node, slot);
720 0 : BUG_ON(tag_get(node, 0, offset));
721 0 : BUG_ON(tag_get(node, 1, offset));
722 0 : BUG_ON(tag_get(node, 2, offset));
723 : } else {
724 0 : BUG_ON(root_tags_get(root));
725 : }
726 :
727 : return 0;
728 : }
729 : EXPORT_SYMBOL(radix_tree_insert);
730 :
731 : /**
732 : * __radix_tree_lookup - lookup an item in a radix tree
733 : * @root: radix tree root
734 : * @index: index key
735 : * @nodep: returns node
736 : * @slotp: returns slot
737 : *
738 : * Lookup and return the item at position @index in the radix
739 : * tree @root.
740 : *
741 : * Until there is more than one item in the tree, no nodes are
742 : * allocated and @root->xa_head is used as a direct slot instead of
743 : * pointing to a node, in which case *@nodep will be NULL.
744 : */
745 1764 : void *__radix_tree_lookup(const struct radix_tree_root *root,
746 : unsigned long index, struct radix_tree_node **nodep,
747 : void __rcu ***slotp)
748 : {
749 : struct radix_tree_node *node, *parent;
750 : unsigned long maxindex;
751 : void __rcu **slot;
752 :
753 : restart:
754 1764 : parent = NULL;
755 1764 : slot = (void __rcu **)&root->xa_head;
756 1764 : radix_tree_load_root(root, &node, &maxindex);
757 1764 : if (index > maxindex)
758 : return NULL;
759 :
760 6372 : while (radix_tree_is_internal_node(node)) {
761 : unsigned offset;
762 :
763 6372 : parent = entry_to_node(node);
764 3186 : offset = radix_tree_descend(parent, &node, index);
765 3186 : slot = parent->slots + offset;
766 3186 : if (node == RADIX_TREE_RETRY)
767 : goto restart;
768 3186 : if (parent->shift == 0)
769 : break;
770 : }
771 :
772 1764 : if (nodep)
773 1731 : *nodep = parent;
774 1764 : if (slotp)
775 1731 : *slotp = slot;
776 : return node;
777 : }
778 :
779 : /**
780 : * radix_tree_lookup_slot - lookup a slot in a radix tree
781 : * @root: radix tree root
782 : * @index: index key
783 : *
784 : * Returns: the slot corresponding to the position @index in the
785 : * radix tree @root. This is useful for update-if-exists operations.
786 : *
787 : * This function can be called under rcu_read_lock iff the slot is not
788 : * modified by radix_tree_replace_slot, otherwise it must be called
789 : * exclusive from other writers. Any dereference of the slot must be done
790 : * using radix_tree_deref_slot.
791 : */
792 0 : void __rcu **radix_tree_lookup_slot(const struct radix_tree_root *root,
793 : unsigned long index)
794 : {
795 : void __rcu **slot;
796 :
797 0 : if (!__radix_tree_lookup(root, index, NULL, &slot))
798 : return NULL;
799 0 : return slot;
800 : }
801 : EXPORT_SYMBOL(radix_tree_lookup_slot);
802 :
803 : /**
804 : * radix_tree_lookup - perform lookup operation on a radix tree
805 : * @root: radix tree root
806 : * @index: index key
807 : *
808 : * Lookup the item at the position @index in the radix tree @root.
809 : *
810 : * This function can be called under rcu_read_lock, however the caller
811 : * must manage lifetimes of leaf nodes (eg. RCU may also be used to free
812 : * them safely). No RCU barriers are required to access or modify the
813 : * returned item, however.
814 : */
815 33 : void *radix_tree_lookup(const struct radix_tree_root *root, unsigned long index)
816 : {
817 33 : return __radix_tree_lookup(root, index, NULL, NULL);
818 : }
819 : EXPORT_SYMBOL(radix_tree_lookup);
820 :
821 : static void replace_slot(void __rcu **slot, void *item,
822 : struct radix_tree_node *node, int count, int values)
823 : {
824 11348 : if (node && (count || values)) {
825 11006 : node->count += count;
826 11006 : node->nr_values += values;
827 : }
828 :
829 11348 : rcu_assign_pointer(*slot, item);
830 : }
831 :
832 : static bool node_tag_get(const struct radix_tree_root *root,
833 : const struct radix_tree_node *node,
834 : unsigned int tag, unsigned int offset)
835 : {
836 9988 : if (node)
837 9988 : return tag_get(node, tag, offset);
838 0 : return root_tag_get(root, tag);
839 : }
840 :
841 : /*
842 : * IDR users want to be able to store NULL in the tree, so if the slot isn't
843 : * free, don't adjust the count, even if it's transitioning between NULL and
844 : * non-NULL. For the IDA, we mark slots as being IDR_FREE while they still
845 : * have empty bits, but it only stores NULL in slots when they're being
846 : * deleted.
847 : */
848 9959 : static int calculate_count(struct radix_tree_root *root,
849 : struct radix_tree_node *node, void __rcu **slot,
850 : void *item, void *old)
851 : {
852 19918 : if (is_idr(root)) {
853 9959 : unsigned offset = get_slot_offset(node, slot);
854 9959 : bool free = node_tag_get(root, node, IDR_FREE, offset);
855 9959 : if (!free)
856 : return 0;
857 9617 : if (!old)
858 : return 1;
859 : }
860 0 : return !!item - !!old;
861 : }
862 :
863 : /**
864 : * __radix_tree_replace - replace item in a slot
865 : * @root: radix tree root
866 : * @node: pointer to tree node
867 : * @slot: pointer to slot in @node
868 : * @item: new item to store in the slot.
869 : *
870 : * For use with __radix_tree_lookup(). Caller must hold tree write locked
871 : * across slot lookup and replacement.
872 : */
873 9959 : void __radix_tree_replace(struct radix_tree_root *root,
874 : struct radix_tree_node *node,
875 : void __rcu **slot, void *item)
876 : {
877 9959 : void *old = rcu_dereference_raw(*slot);
878 19918 : int values = !!xa_is_value(item) - !!xa_is_value(old);
879 9959 : int count = calculate_count(root, node, slot, item, old);
880 :
881 : /*
882 : * This function supports replacing value entries and
883 : * deleting entries, but that needs accounting against the
884 : * node unless the slot is root->xa_head.
885 : */
886 9959 : WARN_ON_ONCE(!node && (slot != (void __rcu **)&root->xa_head) &&
887 : (count || values));
888 9959 : replace_slot(slot, item, node, count, values);
889 :
890 9959 : if (!node)
891 : return;
892 :
893 9959 : delete_node(root, node);
894 : }
895 :
896 : /**
897 : * radix_tree_replace_slot - replace item in a slot
898 : * @root: radix tree root
899 : * @slot: pointer to slot
900 : * @item: new item to store in the slot.
901 : *
902 : * For use with radix_tree_lookup_slot() and
903 : * radix_tree_gang_lookup_tag_slot(). Caller must hold tree write locked
904 : * across slot lookup and replacement.
905 : *
906 : * NOTE: This cannot be used to switch between non-entries (empty slots),
907 : * regular entries, and value entries, as that requires accounting
908 : * inside the radix tree node. When switching from one type of entry or
909 : * deleting, use __radix_tree_lookup() and __radix_tree_replace() or
910 : * radix_tree_iter_replace().
911 : */
912 0 : void radix_tree_replace_slot(struct radix_tree_root *root,
913 : void __rcu **slot, void *item)
914 : {
915 0 : __radix_tree_replace(root, NULL, slot, item);
916 0 : }
917 : EXPORT_SYMBOL(radix_tree_replace_slot);
918 :
919 : /**
920 : * radix_tree_iter_replace - replace item in a slot
921 : * @root: radix tree root
922 : * @iter: iterator state
923 : * @slot: pointer to slot
924 : * @item: new item to store in the slot.
925 : *
926 : * For use with radix_tree_for_each_slot().
927 : * Caller must hold tree write locked.
928 : */
929 9617 : void radix_tree_iter_replace(struct radix_tree_root *root,
930 : const struct radix_tree_iter *iter,
931 : void __rcu **slot, void *item)
932 : {
933 9617 : __radix_tree_replace(root, iter->node, slot, item);
934 9617 : }
935 :
936 1389 : static void node_tag_set(struct radix_tree_root *root,
937 : struct radix_tree_node *node,
938 : unsigned int tag, unsigned int offset)
939 : {
940 4168 : while (node) {
941 2101 : if (tag_get(node, tag, offset))
942 : return;
943 2780 : tag_set(node, tag, offset);
944 1390 : offset = node->offset;
945 1390 : node = node->parent;
946 : }
947 :
948 1356 : if (!root_tag_get(root, tag))
949 0 : root_tag_set(root, tag);
950 : }
951 :
952 : /**
953 : * radix_tree_tag_set - set a tag on a radix tree node
954 : * @root: radix tree root
955 : * @index: index key
956 : * @tag: tag index
957 : *
958 : * Set the search tag (which must be < RADIX_TREE_MAX_TAGS)
959 : * corresponding to @index in the radix tree. From
960 : * the root all the way down to the leaf node.
961 : *
962 : * Returns the address of the tagged item. Setting a tag on a not-present
963 : * item is a bug.
964 : */
965 0 : void *radix_tree_tag_set(struct radix_tree_root *root,
966 : unsigned long index, unsigned int tag)
967 : {
968 : struct radix_tree_node *node, *parent;
969 : unsigned long maxindex;
970 :
971 0 : radix_tree_load_root(root, &node, &maxindex);
972 0 : BUG_ON(index > maxindex);
973 :
974 0 : while (radix_tree_is_internal_node(node)) {
975 : unsigned offset;
976 :
977 0 : parent = entry_to_node(node);
978 0 : offset = radix_tree_descend(parent, &node, index);
979 0 : BUG_ON(!node);
980 :
981 0 : if (!tag_get(parent, tag, offset))
982 0 : tag_set(parent, tag, offset);
983 : }
984 :
985 : /* set the root's tag bit */
986 0 : if (!root_tag_get(root, tag))
987 0 : root_tag_set(root, tag);
988 :
989 0 : return node;
990 : }
991 : EXPORT_SYMBOL(radix_tree_tag_set);
992 :
993 9617 : static void node_tag_clear(struct radix_tree_root *root,
994 : struct radix_tree_node *node,
995 : unsigned int tag, unsigned int offset)
996 : {
997 19359 : while (node) {
998 9742 : if (!tag_get(node, tag, offset))
999 : return;
1000 9742 : tag_clear(node, tag, offset);
1001 9742 : if (any_tag_set(node, tag))
1002 : return;
1003 :
1004 125 : offset = node->offset;
1005 125 : node = node->parent;
1006 : }
1007 :
1008 : /* clear the root's tag bit */
1009 0 : if (root_tag_get(root, tag))
1010 0 : root_tag_clear(root, tag);
1011 : }
1012 :
1013 : /**
1014 : * radix_tree_tag_clear - clear a tag on a radix tree node
1015 : * @root: radix tree root
1016 : * @index: index key
1017 : * @tag: tag index
1018 : *
1019 : * Clear the search tag (which must be < RADIX_TREE_MAX_TAGS)
1020 : * corresponding to @index in the radix tree. If this causes
1021 : * the leaf node to have no tags set then clear the tag in the
1022 : * next-to-leaf node, etc.
1023 : *
1024 : * Returns the address of the tagged item on success, else NULL. ie:
1025 : * has the same return value and semantics as radix_tree_lookup().
1026 : */
1027 0 : void *radix_tree_tag_clear(struct radix_tree_root *root,
1028 : unsigned long index, unsigned int tag)
1029 : {
1030 : struct radix_tree_node *node, *parent;
1031 : unsigned long maxindex;
1032 0 : int offset = 0;
1033 :
1034 0 : radix_tree_load_root(root, &node, &maxindex);
1035 0 : if (index > maxindex)
1036 : return NULL;
1037 :
1038 : parent = NULL;
1039 :
1040 0 : while (radix_tree_is_internal_node(node)) {
1041 0 : parent = entry_to_node(node);
1042 0 : offset = radix_tree_descend(parent, &node, index);
1043 : }
1044 :
1045 0 : if (node)
1046 0 : node_tag_clear(root, parent, tag, offset);
1047 :
1048 : return node;
1049 : }
1050 : EXPORT_SYMBOL(radix_tree_tag_clear);
1051 :
1052 : /**
1053 : * radix_tree_iter_tag_clear - clear a tag on the current iterator entry
1054 : * @root: radix tree root
1055 : * @iter: iterator state
1056 : * @tag: tag to clear
1057 : */
1058 9617 : void radix_tree_iter_tag_clear(struct radix_tree_root *root,
1059 : const struct radix_tree_iter *iter, unsigned int tag)
1060 : {
1061 19234 : node_tag_clear(root, iter->node, tag, iter_offset(iter));
1062 9617 : }
1063 :
1064 : /**
1065 : * radix_tree_tag_get - get a tag on a radix tree node
1066 : * @root: radix tree root
1067 : * @index: index key
1068 : * @tag: tag index (< RADIX_TREE_MAX_TAGS)
1069 : *
1070 : * Return values:
1071 : *
1072 : * 0: tag not present or not set
1073 : * 1: tag set
1074 : *
1075 : * Note that the return value of this function may not be relied on, even if
1076 : * the RCU lock is held, unless tag modification and node deletion are excluded
1077 : * from concurrency.
1078 : */
1079 342 : int radix_tree_tag_get(const struct radix_tree_root *root,
1080 : unsigned long index, unsigned int tag)
1081 : {
1082 : struct radix_tree_node *node, *parent;
1083 : unsigned long maxindex;
1084 :
1085 684 : if (!root_tag_get(root, tag))
1086 : return 0;
1087 :
1088 342 : radix_tree_load_root(root, &node, &maxindex);
1089 342 : if (index > maxindex)
1090 : return 0;
1091 :
1092 1238 : while (radix_tree_is_internal_node(node)) {
1093 : unsigned offset;
1094 :
1095 1238 : parent = entry_to_node(node);
1096 619 : offset = radix_tree_descend(parent, &node, index);
1097 :
1098 619 : if (!tag_get(parent, tag, offset))
1099 : return 0;
1100 277 : if (node == RADIX_TREE_RETRY)
1101 : break;
1102 : }
1103 :
1104 : return 1;
1105 : }
1106 : EXPORT_SYMBOL(radix_tree_tag_get);
1107 :
1108 : /* Construct iter->tags bit-mask from node->tags[tag] array */
1109 : static void set_iter_tags(struct radix_tree_iter *iter,
1110 : struct radix_tree_node *node, unsigned offset,
1111 : unsigned tag)
1112 : {
1113 9617 : unsigned tag_long = offset / BITS_PER_LONG;
1114 9617 : unsigned tag_bit = offset % BITS_PER_LONG;
1115 :
1116 9617 : if (!node) {
1117 0 : iter->tags = 1;
1118 : return;
1119 : }
1120 :
1121 9617 : iter->tags = node->tags[tag][tag_long] >> tag_bit;
1122 :
1123 : /* This never happens if RADIX_TREE_TAG_LONGS == 1 */
1124 : if (tag_long < RADIX_TREE_TAG_LONGS - 1) {
1125 : /* Pick tags from next element */
1126 : if (tag_bit)
1127 : iter->tags |= node->tags[tag][tag_long + 1] <<
1128 : (BITS_PER_LONG - tag_bit);
1129 : /* Clip chunk size, here only BITS_PER_LONG tags */
1130 : iter->next_index = __radix_tree_iter_add(iter, BITS_PER_LONG);
1131 : }
1132 : }
1133 :
1134 0 : void __rcu **radix_tree_iter_resume(void __rcu **slot,
1135 : struct radix_tree_iter *iter)
1136 : {
1137 0 : slot++;
1138 0 : iter->index = __radix_tree_iter_add(iter, 1);
1139 0 : iter->next_index = iter->index;
1140 0 : iter->tags = 0;
1141 0 : return NULL;
1142 : }
1143 : EXPORT_SYMBOL(radix_tree_iter_resume);
1144 :
1145 : /**
1146 : * radix_tree_next_chunk - find next chunk of slots for iteration
1147 : *
1148 : * @root: radix tree root
1149 : * @iter: iterator state
1150 : * @flags: RADIX_TREE_ITER_* flags and tag index
1151 : * Returns: pointer to chunk first slot, or NULL if iteration is over
1152 : */
1153 0 : void __rcu **radix_tree_next_chunk(const struct radix_tree_root *root,
1154 : struct radix_tree_iter *iter, unsigned flags)
1155 : {
1156 0 : unsigned tag = flags & RADIX_TREE_ITER_TAG_MASK;
1157 : struct radix_tree_node *node, *child;
1158 : unsigned long index, offset, maxindex;
1159 :
1160 0 : if ((flags & RADIX_TREE_ITER_TAGGED) && !root_tag_get(root, tag))
1161 : return NULL;
1162 :
1163 : /*
1164 : * Catch next_index overflow after ~0UL. iter->index never overflows
1165 : * during iterating; it can be zero only at the beginning.
1166 : * And we cannot overflow iter->next_index in a single step,
1167 : * because RADIX_TREE_MAP_SHIFT < BITS_PER_LONG.
1168 : *
1169 : * This condition also used by radix_tree_next_slot() to stop
1170 : * contiguous iterating, and forbid switching to the next chunk.
1171 : */
1172 0 : index = iter->next_index;
1173 0 : if (!index && iter->index)
1174 : return NULL;
1175 :
1176 : restart:
1177 0 : radix_tree_load_root(root, &child, &maxindex);
1178 0 : if (index > maxindex)
1179 : return NULL;
1180 0 : if (!child)
1181 : return NULL;
1182 :
1183 0 : if (!radix_tree_is_internal_node(child)) {
1184 : /* Single-slot tree */
1185 0 : iter->index = index;
1186 0 : iter->next_index = maxindex + 1;
1187 0 : iter->tags = 1;
1188 0 : iter->node = NULL;
1189 0 : return (void __rcu **)&root->xa_head;
1190 : }
1191 :
1192 : do {
1193 0 : node = entry_to_node(child);
1194 0 : offset = radix_tree_descend(node, &child, index);
1195 :
1196 0 : if ((flags & RADIX_TREE_ITER_TAGGED) ?
1197 0 : !tag_get(node, tag, offset) : !child) {
1198 : /* Hole detected */
1199 0 : if (flags & RADIX_TREE_ITER_CONTIG)
1200 : return NULL;
1201 :
1202 0 : if (flags & RADIX_TREE_ITER_TAGGED)
1203 0 : offset = radix_tree_find_next_bit(node, tag,
1204 : offset + 1);
1205 : else
1206 0 : while (++offset < RADIX_TREE_MAP_SIZE) {
1207 0 : void *slot = rcu_dereference_raw(
1208 : node->slots[offset]);
1209 0 : if (slot)
1210 : break;
1211 : }
1212 0 : index &= ~node_maxindex(node);
1213 0 : index += offset << node->shift;
1214 : /* Overflow after ~0UL */
1215 0 : if (!index)
1216 : return NULL;
1217 0 : if (offset == RADIX_TREE_MAP_SIZE)
1218 : goto restart;
1219 0 : child = rcu_dereference_raw(node->slots[offset]);
1220 : }
1221 :
1222 0 : if (!child)
1223 : goto restart;
1224 0 : if (child == RADIX_TREE_RETRY)
1225 : break;
1226 0 : } while (node->shift && radix_tree_is_internal_node(child));
1227 :
1228 : /* Update the iterator state */
1229 0 : iter->index = (index &~ node_maxindex(node)) | offset;
1230 0 : iter->next_index = (index | node_maxindex(node)) + 1;
1231 0 : iter->node = node;
1232 :
1233 0 : if (flags & RADIX_TREE_ITER_TAGGED)
1234 0 : set_iter_tags(iter, node, offset, tag);
1235 :
1236 0 : return node->slots + offset;
1237 : }
1238 : EXPORT_SYMBOL(radix_tree_next_chunk);
1239 :
1240 : /**
1241 : * radix_tree_gang_lookup - perform multiple lookup on a radix tree
1242 : * @root: radix tree root
1243 : * @results: where the results of the lookup are placed
1244 : * @first_index: start the lookup from this key
1245 : * @max_items: place up to this many items at *results
1246 : *
1247 : * Performs an index-ascending scan of the tree for present items. Places
1248 : * them at *@results and returns the number of items which were placed at
1249 : * *@results.
1250 : *
1251 : * The implementation is naive.
1252 : *
1253 : * Like radix_tree_lookup, radix_tree_gang_lookup may be called under
1254 : * rcu_read_lock. In this case, rather than the returned results being
1255 : * an atomic snapshot of the tree at a single point in time, the
1256 : * semantics of an RCU protected gang lookup are as though multiple
1257 : * radix_tree_lookups have been issued in individual locks, and results
1258 : * stored in 'results'.
1259 : */
1260 : unsigned int
1261 0 : radix_tree_gang_lookup(const struct radix_tree_root *root, void **results,
1262 : unsigned long first_index, unsigned int max_items)
1263 : {
1264 : struct radix_tree_iter iter;
1265 : void __rcu **slot;
1266 0 : unsigned int ret = 0;
1267 :
1268 0 : if (unlikely(!max_items))
1269 : return 0;
1270 :
1271 0 : radix_tree_for_each_slot(slot, root, &iter, first_index) {
1272 0 : results[ret] = rcu_dereference_raw(*slot);
1273 0 : if (!results[ret])
1274 0 : continue;
1275 0 : if (radix_tree_is_internal_node(results[ret])) {
1276 0 : slot = radix_tree_iter_retry(&iter);
1277 0 : continue;
1278 : }
1279 0 : if (++ret == max_items)
1280 : break;
1281 : }
1282 :
1283 : return ret;
1284 : }
1285 : EXPORT_SYMBOL(radix_tree_gang_lookup);
1286 :
1287 : /**
1288 : * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree
1289 : * based on a tag
1290 : * @root: radix tree root
1291 : * @results: where the results of the lookup are placed
1292 : * @first_index: start the lookup from this key
1293 : * @max_items: place up to this many items at *results
1294 : * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
1295 : *
1296 : * Performs an index-ascending scan of the tree for present items which
1297 : * have the tag indexed by @tag set. Places the items at *@results and
1298 : * returns the number of items which were placed at *@results.
1299 : */
1300 : unsigned int
1301 0 : radix_tree_gang_lookup_tag(const struct radix_tree_root *root, void **results,
1302 : unsigned long first_index, unsigned int max_items,
1303 : unsigned int tag)
1304 : {
1305 : struct radix_tree_iter iter;
1306 : void __rcu **slot;
1307 0 : unsigned int ret = 0;
1308 :
1309 0 : if (unlikely(!max_items))
1310 : return 0;
1311 :
1312 0 : radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) {
1313 0 : results[ret] = rcu_dereference_raw(*slot);
1314 0 : if (!results[ret])
1315 0 : continue;
1316 0 : if (radix_tree_is_internal_node(results[ret])) {
1317 0 : slot = radix_tree_iter_retry(&iter);
1318 0 : continue;
1319 : }
1320 0 : if (++ret == max_items)
1321 : break;
1322 : }
1323 :
1324 : return ret;
1325 : }
1326 : EXPORT_SYMBOL(radix_tree_gang_lookup_tag);
1327 :
1328 : /**
1329 : * radix_tree_gang_lookup_tag_slot - perform multiple slot lookup on a
1330 : * radix tree based on a tag
1331 : * @root: radix tree root
1332 : * @results: where the results of the lookup are placed
1333 : * @first_index: start the lookup from this key
1334 : * @max_items: place up to this many items at *results
1335 : * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
1336 : *
1337 : * Performs an index-ascending scan of the tree for present items which
1338 : * have the tag indexed by @tag set. Places the slots at *@results and
1339 : * returns the number of slots which were placed at *@results.
1340 : */
1341 : unsigned int
1342 0 : radix_tree_gang_lookup_tag_slot(const struct radix_tree_root *root,
1343 : void __rcu ***results, unsigned long first_index,
1344 : unsigned int max_items, unsigned int tag)
1345 : {
1346 : struct radix_tree_iter iter;
1347 : void __rcu **slot;
1348 0 : unsigned int ret = 0;
1349 :
1350 0 : if (unlikely(!max_items))
1351 : return 0;
1352 :
1353 0 : radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) {
1354 0 : results[ret] = slot;
1355 0 : if (++ret == max_items)
1356 : break;
1357 : }
1358 :
1359 : return ret;
1360 : }
1361 : EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot);
1362 :
1363 1389 : static bool __radix_tree_delete(struct radix_tree_root *root,
1364 : struct radix_tree_node *node, void __rcu **slot)
1365 : {
1366 1389 : void *old = rcu_dereference_raw(*slot);
1367 1389 : int values = xa_is_value(old) ? -1 : 0;
1368 1389 : unsigned offset = get_slot_offset(node, slot);
1369 : int tag;
1370 :
1371 2778 : if (is_idr(root))
1372 1389 : node_tag_set(root, node, IDR_FREE, offset);
1373 : else
1374 0 : for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
1375 0 : node_tag_clear(root, node, tag, offset);
1376 :
1377 1389 : replace_slot(slot, NULL, node, -1, values);
1378 1389 : return node && delete_node(root, node);
1379 : }
1380 :
1381 : /**
1382 : * radix_tree_iter_delete - delete the entry at this iterator position
1383 : * @root: radix tree root
1384 : * @iter: iterator state
1385 : * @slot: pointer to slot
1386 : *
1387 : * Delete the entry at the position currently pointed to by the iterator.
1388 : * This may result in the current node being freed; if it is, the iterator
1389 : * is advanced so that it will not reference the freed memory. This
1390 : * function may be called without any locking if there are no other threads
1391 : * which can access this tree.
1392 : */
1393 0 : void radix_tree_iter_delete(struct radix_tree_root *root,
1394 : struct radix_tree_iter *iter, void __rcu **slot)
1395 : {
1396 0 : if (__radix_tree_delete(root, iter->node, slot))
1397 0 : iter->index = iter->next_index;
1398 0 : }
1399 : EXPORT_SYMBOL(radix_tree_iter_delete);
1400 :
1401 : /**
1402 : * radix_tree_delete_item - delete an item from a radix tree
1403 : * @root: radix tree root
1404 : * @index: index key
1405 : * @item: expected item
1406 : *
1407 : * Remove @item at @index from the radix tree rooted at @root.
1408 : *
1409 : * Return: the deleted entry, or %NULL if it was not present
1410 : * or the entry at the given @index was not @item.
1411 : */
1412 1389 : void *radix_tree_delete_item(struct radix_tree_root *root,
1413 : unsigned long index, void *item)
1414 : {
1415 1389 : struct radix_tree_node *node = NULL;
1416 1389 : void __rcu **slot = NULL;
1417 : void *entry;
1418 :
1419 1389 : entry = __radix_tree_lookup(root, index, &node, &slot);
1420 1389 : if (!slot)
1421 : return NULL;
1422 1476 : if (!entry && (!is_idr(root) || node_tag_get(root, node, IDR_FREE,
1423 58 : get_slot_offset(node, slot))))
1424 : return NULL;
1425 :
1426 1389 : if (item && entry != item)
1427 : return NULL;
1428 :
1429 1389 : __radix_tree_delete(root, node, slot);
1430 :
1431 1389 : return entry;
1432 : }
1433 : EXPORT_SYMBOL(radix_tree_delete_item);
1434 :
1435 : /**
1436 : * radix_tree_delete - delete an entry from a radix tree
1437 : * @root: radix tree root
1438 : * @index: index key
1439 : *
1440 : * Remove the entry at @index from the radix tree rooted at @root.
1441 : *
1442 : * Return: The deleted entry, or %NULL if it was not present.
1443 : */
1444 0 : void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
1445 : {
1446 0 : return radix_tree_delete_item(root, index, NULL);
1447 : }
1448 : EXPORT_SYMBOL(radix_tree_delete);
1449 :
1450 : /**
1451 : * radix_tree_tagged - test whether any items in the tree are tagged
1452 : * @root: radix tree root
1453 : * @tag: tag to test
1454 : */
1455 0 : int radix_tree_tagged(const struct radix_tree_root *root, unsigned int tag)
1456 : {
1457 19234 : return root_tag_get(root, tag);
1458 : }
1459 : EXPORT_SYMBOL(radix_tree_tagged);
1460 :
1461 : /**
1462 : * idr_preload - preload for idr_alloc()
1463 : * @gfp_mask: allocation mask to use for preloading
1464 : *
1465 : * Preallocate memory to use for the next call to idr_alloc(). This function
1466 : * returns with preemption disabled. It will be enabled by idr_preload_end().
1467 : */
1468 9001 : void idr_preload(gfp_t gfp_mask)
1469 : {
1470 9001 : if (__radix_tree_preload(gfp_mask, IDR_PRELOAD_SIZE))
1471 0 : local_lock(&radix_tree_preloads.lock);
1472 9001 : }
1473 : EXPORT_SYMBOL(idr_preload);
1474 :
1475 9617 : void __rcu **idr_get_free(struct radix_tree_root *root,
1476 : struct radix_tree_iter *iter, gfp_t gfp,
1477 : unsigned long max)
1478 : {
1479 9617 : struct radix_tree_node *node = NULL, *child;
1480 9617 : void __rcu **slot = (void __rcu **)&root->xa_head;
1481 9617 : unsigned long maxindex, start = iter->next_index;
1482 9617 : unsigned int shift, offset = 0;
1483 :
1484 : grow:
1485 9617 : shift = radix_tree_load_root(root, &child, &maxindex);
1486 9617 : if (!radix_tree_tagged(root, IDR_FREE))
1487 0 : start = max(start, maxindex + 1);
1488 9617 : if (start > max)
1489 : return ERR_PTR(-ENOSPC);
1490 :
1491 9617 : if (start > maxindex) {
1492 281 : int error = radix_tree_extend(root, gfp, start, shift);
1493 281 : if (error < 0)
1494 0 : return ERR_PTR(error);
1495 281 : shift = error;
1496 281 : child = rcu_dereference_raw(root->xa_head);
1497 : }
1498 9617 : if (start == 0 && shift == 0)
1499 35 : shift = RADIX_TREE_MAP_SHIFT;
1500 :
1501 32641 : while (shift) {
1502 23024 : shift -= RADIX_TREE_MAP_SHIFT;
1503 23024 : if (child == NULL) {
1504 : /* Have to add a child node. */
1505 468 : child = radix_tree_node_alloc(gfp, node, root, shift,
1506 : offset, 0, 0);
1507 468 : if (!child)
1508 : return ERR_PTR(-ENOMEM);
1509 936 : all_tag_set(child, IDR_FREE);
1510 936 : rcu_assign_pointer(*slot, node_to_entry(child));
1511 468 : if (node)
1512 431 : node->count++;
1513 45112 : } else if (!radix_tree_is_internal_node(child))
1514 : break;
1515 :
1516 46048 : node = entry_to_node(child);
1517 23024 : offset = radix_tree_descend(node, &child, start);
1518 23024 : if (!tag_get(node, IDR_FREE, offset)) {
1519 1196 : offset = radix_tree_find_next_bit(node, IDR_FREE,
1520 598 : offset + 1);
1521 1196 : start = next_index(start, node, offset);
1522 598 : if (start > max || start == 0)
1523 : return ERR_PTR(-ENOSPC);
1524 598 : while (offset == RADIX_TREE_MAP_SIZE) {
1525 0 : offset = node->offset + 1;
1526 0 : node = node->parent;
1527 0 : if (!node)
1528 : goto grow;
1529 0 : shift = node->shift;
1530 : }
1531 598 : child = rcu_dereference_raw(node->slots[offset]);
1532 : }
1533 23024 : slot = &node->slots[offset];
1534 : }
1535 :
1536 9617 : iter->index = start;
1537 9617 : if (node)
1538 19234 : iter->next_index = 1 + min(max, (start | node_maxindex(node)));
1539 : else
1540 0 : iter->next_index = 1;
1541 9617 : iter->node = node;
1542 9617 : set_iter_tags(iter, node, offset, IDR_FREE);
1543 :
1544 : return slot;
1545 : }
1546 :
1547 : /**
1548 : * idr_destroy - release all internal memory from an IDR
1549 : * @idr: idr handle
1550 : *
1551 : * After this function is called, the IDR is empty, and may be reused or
1552 : * the data structure containing it may be freed.
1553 : *
1554 : * A typical clean-up sequence for objects stored in an idr tree will use
1555 : * idr_for_each() to free all objects, if necessary, then idr_destroy() to
1556 : * free the memory used to keep track of those objects.
1557 : */
1558 34 : void idr_destroy(struct idr *idr)
1559 : {
1560 34 : struct radix_tree_node *node = rcu_dereference_raw(idr->idr_rt.xa_head);
1561 34 : if (radix_tree_is_internal_node(node))
1562 0 : radix_tree_free_nodes(node);
1563 34 : idr->idr_rt.xa_head = NULL;
1564 68 : root_tag_set(&idr->idr_rt, IDR_FREE);
1565 34 : }
1566 : EXPORT_SYMBOL(idr_destroy);
1567 :
1568 : static void
1569 168 : radix_tree_node_ctor(void *arg)
1570 : {
1571 168 : struct radix_tree_node *node = arg;
1572 :
1573 168 : memset(node, 0, sizeof(*node));
1574 336 : INIT_LIST_HEAD(&node->private_list);
1575 168 : }
1576 :
1577 0 : static int radix_tree_cpu_dead(unsigned int cpu)
1578 : {
1579 : struct radix_tree_preload *rtp;
1580 : struct radix_tree_node *node;
1581 :
1582 : /* Free per-cpu pool of preloaded nodes */
1583 0 : rtp = &per_cpu(radix_tree_preloads, cpu);
1584 0 : while (rtp->nr) {
1585 0 : node = rtp->nodes;
1586 0 : rtp->nodes = node->parent;
1587 0 : kmem_cache_free(radix_tree_node_cachep, node);
1588 0 : rtp->nr--;
1589 : }
1590 0 : return 0;
1591 : }
1592 :
1593 1 : void __init radix_tree_init(void)
1594 : {
1595 : int ret;
1596 :
1597 : BUILD_BUG_ON(RADIX_TREE_MAX_TAGS + __GFP_BITS_SHIFT > 32);
1598 : BUILD_BUG_ON(ROOT_IS_IDR & ~GFP_ZONEMASK);
1599 : BUILD_BUG_ON(XA_CHUNK_SIZE > 255);
1600 1 : radix_tree_node_cachep = kmem_cache_create("radix_tree_node",
1601 : sizeof(struct radix_tree_node), 0,
1602 : SLAB_PANIC | SLAB_RECLAIM_ACCOUNT,
1603 : radix_tree_node_ctor);
1604 1 : ret = cpuhp_setup_state_nocalls(CPUHP_RADIX_DEAD, "lib/radix:dead",
1605 : NULL, radix_tree_cpu_dead);
1606 1 : WARN_ON(ret < 0);
1607 1 : }
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