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 : #include "radix-tree.h"
31 :
32 : /*
33 : * Radix tree node cache.
34 : */
35 : struct kmem_cache *radix_tree_node_cachep;
36 :
37 : /*
38 : * The radix tree is variable-height, so an insert operation not only has
39 : * to build the branch to its corresponding item, it also has to build the
40 : * branch to existing items if the size has to be increased (by
41 : * radix_tree_extend).
42 : *
43 : * The worst case is a zero height tree with just a single item at index 0,
44 : * and then inserting an item at index ULONG_MAX. This requires 2 new branches
45 : * of RADIX_TREE_MAX_PATH size to be created, with only the root node shared.
46 : * Hence:
47 : */
48 : #define RADIX_TREE_PRELOAD_SIZE (RADIX_TREE_MAX_PATH * 2 - 1)
49 :
50 : /*
51 : * The IDR does not have to be as high as the radix tree since it uses
52 : * signed integers, not unsigned longs.
53 : */
54 : #define IDR_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(int) - 1)
55 : #define IDR_MAX_PATH (DIV_ROUND_UP(IDR_INDEX_BITS, \
56 : RADIX_TREE_MAP_SHIFT))
57 : #define IDR_PRELOAD_SIZE (IDR_MAX_PATH * 2 - 1)
58 :
59 : /*
60 : * Per-cpu pool of preloaded nodes
61 : */
62 : DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = {
63 : .lock = INIT_LOCAL_LOCK(lock),
64 : };
65 : EXPORT_PER_CPU_SYMBOL_GPL(radix_tree_preloads);
66 :
67 : static inline struct radix_tree_node *entry_to_node(void *ptr)
68 : {
69 33891 : return (void *)((unsigned long)ptr & ~RADIX_TREE_INTERNAL_NODE);
70 : }
71 :
72 : static inline void *node_to_entry(void *ptr)
73 : {
74 9841 : return (void *)((unsigned long)ptr | RADIX_TREE_INTERNAL_NODE);
75 : }
76 :
77 : #define RADIX_TREE_RETRY XA_RETRY_ENTRY
78 :
79 : static inline unsigned long
80 : get_slot_offset(const struct radix_tree_node *parent, void __rcu **slot)
81 : {
82 9480 : return parent ? slot - parent->slots : 0;
83 : }
84 :
85 : static unsigned int radix_tree_descend(const struct radix_tree_node *parent,
86 : struct radix_tree_node **nodep, unsigned long index)
87 : {
88 23254 : unsigned int offset = (index >> parent->shift) & RADIX_TREE_MAP_MASK;
89 23254 : void __rcu **entry = rcu_dereference_raw(parent->slots[offset]);
90 :
91 23254 : *nodep = (void *)entry;
92 : return offset;
93 : }
94 :
95 : static inline gfp_t root_gfp_mask(const struct radix_tree_root *root)
96 : {
97 0 : return root->xa_flags & (__GFP_BITS_MASK & ~GFP_ZONEMASK);
98 : }
99 :
100 : static inline void tag_set(struct radix_tree_node *node, unsigned int tag,
101 : int offset)
102 : {
103 1058 : __set_bit(offset, node->tags[tag]);
104 : }
105 :
106 : static inline void tag_clear(struct radix_tree_node *node, unsigned int tag,
107 : int offset)
108 : {
109 17796 : __clear_bit(offset, node->tags[tag]);
110 : }
111 :
112 40598 : static inline int tag_get(const struct radix_tree_node *node, unsigned int tag,
113 : int offset)
114 : {
115 81420 : return test_bit(offset, node->tags[tag]);
116 : }
117 :
118 : static inline void root_tag_set(struct radix_tree_root *root, unsigned tag)
119 : {
120 10 : root->xa_flags |= (__force gfp_t)(1 << (tag + ROOT_TAG_SHIFT));
121 : }
122 :
123 : static inline void root_tag_clear(struct radix_tree_root *root, unsigned tag)
124 : {
125 0 : root->xa_flags &= (__force gfp_t)~(1 << (tag + ROOT_TAG_SHIFT));
126 : }
127 :
128 : static inline void root_tag_clear_all(struct radix_tree_root *root)
129 : {
130 0 : root->xa_flags &= (__force gfp_t)((1 << ROOT_TAG_SHIFT) - 1);
131 : }
132 :
133 : static inline int root_tag_get(const struct radix_tree_root *root, unsigned tag)
134 : {
135 9267 : return (__force int)root->xa_flags & (1 << (tag + ROOT_TAG_SHIFT));
136 : }
137 :
138 : static inline unsigned root_tags_get(const struct radix_tree_root *root)
139 : {
140 0 : return (__force unsigned)root->xa_flags >> ROOT_TAG_SHIFT;
141 : }
142 :
143 : static inline bool is_idr(const struct radix_tree_root *root)
144 : {
145 9724 : return !!(root->xa_flags & ROOT_IS_IDR);
146 : }
147 :
148 : /*
149 : * Returns 1 if any slot in the node has this tag set.
150 : * Otherwise returns 0.
151 : */
152 : static inline int any_tag_set(const struct radix_tree_node *node,
153 : unsigned int tag)
154 : {
155 : unsigned idx;
156 125 : for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
157 8898 : if (node->tags[tag][idx])
158 : return 1;
159 : }
160 : return 0;
161 : }
162 :
163 : static inline void all_tag_set(struct radix_tree_node *node, unsigned int tag)
164 : {
165 376 : bitmap_fill(node->tags[tag], RADIX_TREE_MAP_SIZE);
166 : }
167 :
168 : /**
169 : * radix_tree_find_next_bit - find the next set bit in a memory region
170 : *
171 : * @node: where to begin the search
172 : * @tag: the tag index
173 : * @offset: the bitnumber to start searching at
174 : *
175 : * Unrollable variant of find_next_bit() for constant size arrays.
176 : * Tail bits starting from size to roundup(size, BITS_PER_LONG) must be zero.
177 : * Returns next bit offset, or size if nothing found.
178 : */
179 : static __always_inline unsigned long
180 : radix_tree_find_next_bit(struct radix_tree_node *node, unsigned int tag,
181 : unsigned long offset)
182 : {
183 147 : const unsigned long *addr = node->tags[tag];
184 :
185 147 : if (offset < RADIX_TREE_MAP_SIZE) {
186 : unsigned long tmp;
187 :
188 147 : addr += offset / BITS_PER_LONG;
189 147 : tmp = *addr >> (offset % BITS_PER_LONG);
190 147 : if (tmp)
191 294 : return __ffs(tmp) + offset;
192 0 : offset = (offset + BITS_PER_LONG) & ~(BITS_PER_LONG - 1);
193 0 : while (offset < RADIX_TREE_MAP_SIZE) {
194 0 : tmp = *++addr;
195 0 : if (tmp)
196 0 : return __ffs(tmp) + offset;
197 0 : offset += BITS_PER_LONG;
198 : }
199 : }
200 : return RADIX_TREE_MAP_SIZE;
201 : }
202 :
203 : static unsigned int iter_offset(const struct radix_tree_iter *iter)
204 : {
205 8773 : return iter->index & RADIX_TREE_MAP_MASK;
206 : }
207 :
208 : /*
209 : * The maximum index which can be stored in a radix tree
210 : */
211 : static inline unsigned long shift_maxindex(unsigned int shift)
212 : {
213 18683 : return (RADIX_TREE_MAP_SIZE << shift) - 1;
214 : }
215 :
216 : static inline unsigned long node_maxindex(const struct radix_tree_node *node)
217 : {
218 37134 : return shift_maxindex(node->shift);
219 : }
220 :
221 : static unsigned long next_index(unsigned long index,
222 : const struct radix_tree_node *node,
223 : unsigned long offset)
224 : {
225 294 : return (index & ~node_maxindex(node)) + (offset << node->shift);
226 : }
227 :
228 : /*
229 : * This assumes that the caller has performed appropriate preallocation, and
230 : * that the caller has pinned this thread of control to the current CPU.
231 : */
232 : static struct radix_tree_node *
233 376 : radix_tree_node_alloc(gfp_t gfp_mask, struct radix_tree_node *parent,
234 : struct radix_tree_root *root,
235 : unsigned int shift, unsigned int offset,
236 : unsigned int count, unsigned int nr_values)
237 : {
238 376 : struct radix_tree_node *ret = NULL;
239 :
240 : /*
241 : * Preload code isn't irq safe and it doesn't make sense to use
242 : * preloading during an interrupt anyway as all the allocations have
243 : * to be atomic. So just do normal allocation when in interrupt.
244 : */
245 746 : if (!gfpflags_allow_blocking(gfp_mask) && !in_interrupt()) {
246 : struct radix_tree_preload *rtp;
247 :
248 : /*
249 : * Even if the caller has preloaded, try to allocate from the
250 : * cache first for the new node to get accounted to the memory
251 : * cgroup.
252 : */
253 370 : ret = kmem_cache_alloc(radix_tree_node_cachep,
254 : gfp_mask | __GFP_NOWARN);
255 370 : if (ret)
256 : goto out;
257 :
258 : /*
259 : * Provided the caller has preloaded here, we will always
260 : * succeed in getting a node here (and never reach
261 : * kmem_cache_alloc)
262 : */
263 0 : rtp = this_cpu_ptr(&radix_tree_preloads);
264 0 : if (rtp->nr) {
265 0 : ret = rtp->nodes;
266 0 : rtp->nodes = ret->parent;
267 0 : rtp->nr--;
268 : }
269 : /*
270 : * Update the allocation stack trace as this is more useful
271 : * for debugging.
272 : */
273 : kmemleak_update_trace(ret);
274 : goto out;
275 : }
276 6 : ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
277 : out:
278 376 : BUG_ON(radix_tree_is_internal_node(ret));
279 376 : if (ret) {
280 376 : ret->shift = shift;
281 376 : ret->offset = offset;
282 376 : ret->count = count;
283 376 : ret->nr_values = nr_values;
284 376 : ret->parent = parent;
285 376 : ret->array = root;
286 : }
287 376 : return ret;
288 : }
289 :
290 237 : void radix_tree_node_rcu_free(struct rcu_head *head)
291 : {
292 237 : struct radix_tree_node *node =
293 237 : container_of(head, struct radix_tree_node, rcu_head);
294 :
295 : /*
296 : * Must only free zeroed nodes into the slab. We can be left with
297 : * non-NULL entries by radix_tree_free_nodes, so clear the entries
298 : * and tags here.
299 : */
300 474 : memset(node->slots, 0, sizeof(node->slots));
301 474 : memset(node->tags, 0, sizeof(node->tags));
302 474 : INIT_LIST_HEAD(&node->private_list);
303 :
304 237 : kmem_cache_free(radix_tree_node_cachep, node);
305 237 : }
306 :
307 : static inline void
308 : radix_tree_node_free(struct radix_tree_node *node)
309 : {
310 239 : call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
311 : }
312 :
313 : /*
314 : * Load up this CPU's radix_tree_node buffer with sufficient objects to
315 : * ensure that the addition of a single element in the tree cannot fail. On
316 : * success, return zero, with preemption disabled. On error, return -ENOMEM
317 : * with preemption not disabled.
318 : *
319 : * To make use of this facility, the radix tree must be initialised without
320 : * __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE().
321 : */
322 8620 : static __must_check int __radix_tree_preload(gfp_t gfp_mask, unsigned nr)
323 : {
324 : struct radix_tree_preload *rtp;
325 : struct radix_tree_node *node;
326 8620 : int ret = -ENOMEM;
327 :
328 : /*
329 : * Nodes preloaded by one cgroup can be used by another cgroup, so
330 : * they should never be accounted to any particular memory cgroup.
331 : */
332 8620 : gfp_mask &= ~__GFP_ACCOUNT;
333 :
334 8620 : local_lock(&radix_tree_preloads.lock);
335 8620 : rtp = this_cpu_ptr(&radix_tree_preloads);
336 17251 : while (rtp->nr < nr) {
337 11 : local_unlock(&radix_tree_preloads.lock);
338 11 : node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
339 11 : if (node == NULL)
340 : goto out;
341 11 : local_lock(&radix_tree_preloads.lock);
342 11 : rtp = this_cpu_ptr(&radix_tree_preloads);
343 11 : if (rtp->nr < nr) {
344 11 : node->parent = rtp->nodes;
345 11 : rtp->nodes = node;
346 11 : rtp->nr++;
347 : } else {
348 0 : kmem_cache_free(radix_tree_node_cachep, node);
349 : }
350 : }
351 : ret = 0;
352 : out:
353 8620 : return ret;
354 : }
355 :
356 : /*
357 : * Load up this CPU's radix_tree_node buffer with sufficient objects to
358 : * ensure that the addition of a single element in the tree cannot fail. On
359 : * success, return zero, with preemption disabled. On error, return -ENOMEM
360 : * with preemption not disabled.
361 : *
362 : * To make use of this facility, the radix tree must be initialised without
363 : * __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE().
364 : */
365 0 : int radix_tree_preload(gfp_t gfp_mask)
366 : {
367 : /* Warn on non-sensical use... */
368 0 : WARN_ON_ONCE(!gfpflags_allow_blocking(gfp_mask));
369 0 : return __radix_tree_preload(gfp_mask, RADIX_TREE_PRELOAD_SIZE);
370 : }
371 : EXPORT_SYMBOL(radix_tree_preload);
372 :
373 : /*
374 : * The same as above function, except we don't guarantee preloading happens.
375 : * We do it, if we decide it helps. On success, return zero with preemption
376 : * disabled. On error, return -ENOMEM with preemption not disabled.
377 : */
378 0 : int radix_tree_maybe_preload(gfp_t gfp_mask)
379 : {
380 0 : if (gfpflags_allow_blocking(gfp_mask))
381 0 : return __radix_tree_preload(gfp_mask, RADIX_TREE_PRELOAD_SIZE);
382 : /* Preloading doesn't help anything with this gfp mask, skip it */
383 0 : local_lock(&radix_tree_preloads.lock);
384 0 : return 0;
385 : }
386 : EXPORT_SYMBOL(radix_tree_maybe_preload);
387 :
388 : static unsigned radix_tree_load_root(const struct radix_tree_root *root,
389 : struct radix_tree_node **nodep, unsigned long *maxindex)
390 : {
391 9660 : struct radix_tree_node *node = rcu_dereference_raw(root->xa_head);
392 :
393 9660 : *nodep = node;
394 :
395 9660 : if (likely(radix_tree_is_internal_node(node))) {
396 9647 : node = entry_to_node(node);
397 9647 : *maxindex = node_maxindex(node);
398 8760 : return node->shift + RADIX_TREE_MAP_SHIFT;
399 : }
400 :
401 : *maxindex = 0;
402 : return 0;
403 : }
404 :
405 : /*
406 : * Extend a radix tree so it can store key @index.
407 : */
408 116 : static int radix_tree_extend(struct radix_tree_root *root, gfp_t gfp,
409 : unsigned long index, unsigned int shift)
410 : {
411 : void *entry;
412 : unsigned int maxshift;
413 : int tag;
414 :
415 : /* Figure out what the shift should be. */
416 116 : maxshift = shift;
417 232 : while (index > shift_maxindex(maxshift))
418 0 : maxshift += RADIX_TREE_MAP_SHIFT;
419 :
420 116 : entry = rcu_dereference_raw(root->xa_head);
421 120 : if (!entry && (!is_idr(root) || root_tag_get(root, IDR_FREE)))
422 : goto out;
423 :
424 : do {
425 114 : struct radix_tree_node *node = radix_tree_node_alloc(gfp, NULL,
426 : root, shift, 0, 1, 0);
427 114 : if (!node)
428 : return -ENOMEM;
429 :
430 228 : if (is_idr(root)) {
431 114 : all_tag_set(node, IDR_FREE);
432 228 : if (!root_tag_get(root, IDR_FREE)) {
433 0 : tag_clear(node, IDR_FREE, 0);
434 0 : root_tag_set(root, IDR_FREE);
435 : }
436 : } else {
437 : /* Propagate the aggregated tag info to the new child */
438 0 : for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
439 0 : if (root_tag_get(root, tag))
440 0 : tag_set(node, tag, 0);
441 : }
442 : }
443 :
444 114 : BUG_ON(shift > BITS_PER_LONG);
445 114 : if (radix_tree_is_internal_node(entry)) {
446 114 : entry_to_node(entry)->parent = node;
447 0 : } else if (xa_is_value(entry)) {
448 : /* Moving a value entry root->xa_head to a node */
449 0 : node->nr_values = 1;
450 : }
451 : /*
452 : * entry was already in the radix tree, so we do not need
453 : * rcu_assign_pointer here
454 : */
455 114 : node->slots[0] = (void __rcu *)entry;
456 114 : entry = node_to_entry(node);
457 114 : rcu_assign_pointer(root->xa_head, entry);
458 114 : shift += RADIX_TREE_MAP_SHIFT;
459 114 : } while (shift <= maxshift);
460 : out:
461 116 : return maxshift + RADIX_TREE_MAP_SHIFT;
462 : }
463 :
464 : /**
465 : * radix_tree_shrink - shrink radix tree to minimum height
466 : * @root: radix tree root
467 : */
468 652 : static inline bool radix_tree_shrink(struct radix_tree_root *root)
469 : {
470 652 : bool shrunk = false;
471 :
472 112 : for (;;) {
473 764 : struct radix_tree_node *node = rcu_dereference_raw(root->xa_head);
474 : struct radix_tree_node *child;
475 :
476 764 : if (!radix_tree_is_internal_node(node))
477 : break;
478 764 : node = entry_to_node(node);
479 :
480 : /*
481 : * The candidate node has more than one child, or its child
482 : * is not at the leftmost slot, we cannot shrink.
483 : */
484 764 : if (node->count != 1)
485 : break;
486 131 : child = rcu_dereference_raw(node->slots[0]);
487 131 : if (!child)
488 : break;
489 :
490 : /*
491 : * For an IDR, we must not shrink entry 0 into the root in
492 : * case somebody calls idr_replace() with a pointer that
493 : * appears to be an internal entry
494 : */
495 124 : if (!node->shift && is_idr(root))
496 : break;
497 :
498 112 : if (radix_tree_is_internal_node(child))
499 112 : entry_to_node(child)->parent = NULL;
500 :
501 : /*
502 : * We don't need rcu_assign_pointer(), since we are simply
503 : * moving the node from one part of the tree to another: if it
504 : * was safe to dereference the old pointer to it
505 : * (node->slots[0]), it will be safe to dereference the new
506 : * one (root->xa_head) as far as dependent read barriers go.
507 : */
508 112 : root->xa_head = (void __rcu *)child;
509 336 : if (is_idr(root) && !tag_get(node, IDR_FREE, 0))
510 0 : root_tag_clear(root, IDR_FREE);
511 :
512 : /*
513 : * We have a dilemma here. The node's slot[0] must not be
514 : * NULLed in case there are concurrent lookups expecting to
515 : * find the item. However if this was a bottom-level node,
516 : * then it may be subject to the slot pointer being visible
517 : * to callers dereferencing it. If item corresponding to
518 : * slot[0] is subsequently deleted, these callers would expect
519 : * their slot to become empty sooner or later.
520 : *
521 : * For example, lockless pagecache will look up a slot, deref
522 : * the page pointer, and if the page has 0 refcount it means it
523 : * was concurrently deleted from pagecache so try the deref
524 : * again. Fortunately there is already a requirement for logic
525 : * to retry the entire slot lookup -- the indirect pointer
526 : * problem (replacing direct root node with an indirect pointer
527 : * also results in a stale slot). So tag the slot as indirect
528 : * to force callers to retry.
529 : */
530 112 : node->count = 0;
531 112 : if (!radix_tree_is_internal_node(child)) {
532 0 : node->slots[0] = (void __rcu *)RADIX_TREE_RETRY;
533 : }
534 :
535 224 : WARN_ON_ONCE(!list_empty(&node->private_list));
536 112 : radix_tree_node_free(node);
537 112 : shrunk = true;
538 : }
539 :
540 652 : return shrunk;
541 : }
542 :
543 9475 : static bool delete_node(struct radix_tree_root *root,
544 : struct radix_tree_node *node)
545 : {
546 9475 : bool deleted = false;
547 :
548 : do {
549 : struct radix_tree_node *parent;
550 :
551 9592 : if (node->count) {
552 18930 : if (node_to_entry(node) ==
553 9465 : rcu_dereference_raw(root->xa_head))
554 652 : deleted |= radix_tree_shrink(root);
555 : return deleted;
556 : }
557 :
558 127 : parent = node->parent;
559 127 : if (parent) {
560 117 : parent->slots[node->offset] = NULL;
561 117 : parent->count--;
562 : } else {
563 : /*
564 : * Shouldn't the tags already have all been cleared
565 : * by the caller?
566 : */
567 20 : if (!is_idr(root))
568 0 : root_tag_clear_all(root);
569 10 : root->xa_head = NULL;
570 : }
571 :
572 254 : WARN_ON_ONCE(!list_empty(&node->private_list));
573 127 : radix_tree_node_free(node);
574 127 : deleted = true;
575 :
576 127 : node = parent;
577 127 : } while (node);
578 :
579 : return deleted;
580 : }
581 :
582 : /**
583 : * __radix_tree_create - create a slot in a radix tree
584 : * @root: radix tree root
585 : * @index: index key
586 : * @nodep: returns node
587 : * @slotp: returns slot
588 : *
589 : * Create, if necessary, and return the node and slot for an item
590 : * at position @index in the radix tree @root.
591 : *
592 : * Until there is more than one item in the tree, no nodes are
593 : * allocated and @root->xa_head is used as a direct slot instead of
594 : * pointing to a node, in which case *@nodep will be NULL.
595 : *
596 : * Returns -ENOMEM, or 0 for success.
597 : */
598 0 : static int __radix_tree_create(struct radix_tree_root *root,
599 : unsigned long index, struct radix_tree_node **nodep,
600 : void __rcu ***slotp)
601 : {
602 0 : struct radix_tree_node *node = NULL, *child;
603 0 : void __rcu **slot = (void __rcu **)&root->xa_head;
604 : unsigned long maxindex;
605 0 : unsigned int shift, offset = 0;
606 0 : unsigned long max = index;
607 0 : gfp_t gfp = root_gfp_mask(root);
608 :
609 0 : shift = radix_tree_load_root(root, &child, &maxindex);
610 :
611 : /* Make sure the tree is high enough. */
612 0 : if (max > maxindex) {
613 0 : int error = radix_tree_extend(root, gfp, max, shift);
614 0 : if (error < 0)
615 : return error;
616 0 : shift = error;
617 0 : child = rcu_dereference_raw(root->xa_head);
618 : }
619 :
620 0 : while (shift > 0) {
621 0 : shift -= RADIX_TREE_MAP_SHIFT;
622 0 : if (child == NULL) {
623 : /* Have to add a child node. */
624 0 : child = radix_tree_node_alloc(gfp, node, root, shift,
625 : offset, 0, 0);
626 0 : if (!child)
627 : return -ENOMEM;
628 0 : rcu_assign_pointer(*slot, node_to_entry(child));
629 0 : if (node)
630 0 : node->count++;
631 0 : } else if (!radix_tree_is_internal_node(child))
632 : break;
633 :
634 : /* Go a level down */
635 0 : node = entry_to_node(child);
636 0 : offset = radix_tree_descend(node, &child, index);
637 0 : slot = &node->slots[offset];
638 : }
639 :
640 0 : if (nodep)
641 0 : *nodep = node;
642 0 : if (slotp)
643 0 : *slotp = slot;
644 : return 0;
645 : }
646 :
647 : /*
648 : * Free any nodes below this node. The tree is presumed to not need
649 : * shrinking, and any user data in the tree is presumed to not need a
650 : * destructor called on it. If we need to add a destructor, we can
651 : * add that functionality later. Note that we may not clear tags or
652 : * slots from the tree as an RCU walker may still have a pointer into
653 : * this subtree. We could replace the entries with RADIX_TREE_RETRY,
654 : * but we'll still have to clear those in rcu_free.
655 : */
656 0 : static void radix_tree_free_nodes(struct radix_tree_node *node)
657 : {
658 0 : unsigned offset = 0;
659 0 : struct radix_tree_node *child = entry_to_node(node);
660 :
661 : for (;;) {
662 0 : void *entry = rcu_dereference_raw(child->slots[offset]);
663 0 : if (xa_is_node(entry) && child->shift) {
664 0 : child = entry_to_node(entry);
665 0 : offset = 0;
666 0 : continue;
667 : }
668 0 : offset++;
669 0 : while (offset == RADIX_TREE_MAP_SIZE) {
670 0 : struct radix_tree_node *old = child;
671 0 : offset = child->offset + 1;
672 0 : child = child->parent;
673 0 : WARN_ON_ONCE(!list_empty(&old->private_list));
674 0 : radix_tree_node_free(old);
675 0 : if (old == entry_to_node(node))
676 0 : return;
677 : }
678 : }
679 : }
680 :
681 : static inline int insert_entries(struct radix_tree_node *node,
682 : void __rcu **slot, void *item)
683 : {
684 0 : if (*slot)
685 : return -EEXIST;
686 0 : rcu_assign_pointer(*slot, item);
687 0 : if (node) {
688 0 : node->count++;
689 0 : if (xa_is_value(item))
690 0 : node->nr_values++;
691 : }
692 : return 1;
693 : }
694 :
695 : /**
696 : * radix_tree_insert - insert into a radix tree
697 : * @root: radix tree root
698 : * @index: index key
699 : * @item: item to insert
700 : *
701 : * Insert an item into the radix tree at position @index.
702 : */
703 0 : int radix_tree_insert(struct radix_tree_root *root, unsigned long index,
704 : void *item)
705 : {
706 : struct radix_tree_node *node;
707 : void __rcu **slot;
708 : int error;
709 :
710 0 : BUG_ON(radix_tree_is_internal_node(item));
711 :
712 0 : error = __radix_tree_create(root, index, &node, &slot);
713 0 : if (error)
714 : return error;
715 :
716 0 : error = insert_entries(node, slot, item);
717 0 : if (error < 0)
718 : return error;
719 :
720 0 : if (node) {
721 0 : unsigned offset = get_slot_offset(node, slot);
722 0 : BUG_ON(tag_get(node, 0, offset));
723 0 : BUG_ON(tag_get(node, 1, offset));
724 0 : BUG_ON(tag_get(node, 2, offset));
725 : } else {
726 0 : BUG_ON(root_tags_get(root));
727 : }
728 :
729 : return 0;
730 : }
731 : EXPORT_SYMBOL(radix_tree_insert);
732 :
733 : /**
734 : * __radix_tree_lookup - lookup an item in a radix tree
735 : * @root: radix tree root
736 : * @index: index key
737 : * @nodep: returns node
738 : * @slotp: returns slot
739 : *
740 : * Lookup and return the item at position @index in the radix
741 : * tree @root.
742 : *
743 : * Until there is more than one item in the tree, no nodes are
744 : * allocated and @root->xa_head is used as a direct slot instead of
745 : * pointing to a node, in which case *@nodep will be NULL.
746 : */
747 712 : void *__radix_tree_lookup(const struct radix_tree_root *root,
748 : unsigned long index, struct radix_tree_node **nodep,
749 : void __rcu ***slotp)
750 : {
751 : struct radix_tree_node *node, *parent;
752 : unsigned long maxindex;
753 : void __rcu **slot;
754 :
755 : restart:
756 712 : parent = NULL;
757 712 : slot = (void __rcu **)&root->xa_head;
758 712 : radix_tree_load_root(root, &node, &maxindex);
759 712 : if (index > maxindex)
760 : return NULL;
761 :
762 2720 : while (radix_tree_is_internal_node(node)) {
763 : unsigned offset;
764 :
765 2720 : parent = entry_to_node(node);
766 1360 : offset = radix_tree_descend(parent, &node, index);
767 1360 : slot = parent->slots + offset;
768 1360 : if (node == RADIX_TREE_RETRY)
769 : goto restart;
770 1360 : if (parent->shift == 0)
771 : break;
772 : }
773 :
774 712 : if (nodep)
775 702 : *nodep = parent;
776 712 : if (slotp)
777 702 : *slotp = slot;
778 : return node;
779 : }
780 :
781 : /**
782 : * radix_tree_lookup_slot - lookup a slot in a radix tree
783 : * @root: radix tree root
784 : * @index: index key
785 : *
786 : * Returns: the slot corresponding to the position @index in the
787 : * radix tree @root. This is useful for update-if-exists operations.
788 : *
789 : * This function can be called under rcu_read_lock iff the slot is not
790 : * modified by radix_tree_replace_slot, otherwise it must be called
791 : * exclusive from other writers. Any dereference of the slot must be done
792 : * using radix_tree_deref_slot.
793 : */
794 0 : void __rcu **radix_tree_lookup_slot(const struct radix_tree_root *root,
795 : unsigned long index)
796 : {
797 : void __rcu **slot;
798 :
799 0 : if (!__radix_tree_lookup(root, index, NULL, &slot))
800 : return NULL;
801 0 : return slot;
802 : }
803 : EXPORT_SYMBOL(radix_tree_lookup_slot);
804 :
805 : /**
806 : * radix_tree_lookup - perform lookup operation on a radix tree
807 : * @root: radix tree root
808 : * @index: index key
809 : *
810 : * Lookup the item at the position @index in the radix tree @root.
811 : *
812 : * This function can be called under rcu_read_lock, however the caller
813 : * must manage lifetimes of leaf nodes (eg. RCU may also be used to free
814 : * them safely). No RCU barriers are required to access or modify the
815 : * returned item, however.
816 : */
817 10 : void *radix_tree_lookup(const struct radix_tree_root *root, unsigned long index)
818 : {
819 10 : return __radix_tree_lookup(root, index, NULL, NULL);
820 : }
821 : EXPORT_SYMBOL(radix_tree_lookup);
822 :
823 : static void replace_slot(void __rcu **slot, void *item,
824 : struct radix_tree_node *node, int count, int values)
825 : {
826 9475 : if (node && (count || values)) {
827 9300 : node->count += count;
828 9300 : node->nr_values += values;
829 : }
830 :
831 9475 : rcu_assign_pointer(*slot, item);
832 : }
833 :
834 : static bool node_tag_get(const struct radix_tree_root *root,
835 : const struct radix_tree_node *node,
836 : unsigned int tag, unsigned int offset)
837 : {
838 8953 : if (node)
839 8953 : return tag_get(node, tag, offset);
840 0 : return root_tag_get(root, tag);
841 : }
842 :
843 : /*
844 : * IDR users want to be able to store NULL in the tree, so if the slot isn't
845 : * free, don't adjust the count, even if it's transitioning between NULL and
846 : * non-NULL. For the IDA, we mark slots as being IDR_FREE while they still
847 : * have empty bits, but it only stores NULL in slots when they're being
848 : * deleted.
849 : */
850 8948 : static int calculate_count(struct radix_tree_root *root,
851 : struct radix_tree_node *node, void __rcu **slot,
852 : void *item, void *old)
853 : {
854 17896 : if (is_idr(root)) {
855 8948 : unsigned offset = get_slot_offset(node, slot);
856 8948 : bool free = node_tag_get(root, node, IDR_FREE, offset);
857 8948 : if (!free)
858 : return 0;
859 8773 : if (!old)
860 : return 1;
861 : }
862 0 : return !!item - !!old;
863 : }
864 :
865 : /**
866 : * __radix_tree_replace - replace item in a slot
867 : * @root: radix tree root
868 : * @node: pointer to tree node
869 : * @slot: pointer to slot in @node
870 : * @item: new item to store in the slot.
871 : *
872 : * For use with __radix_tree_lookup(). Caller must hold tree write locked
873 : * across slot lookup and replacement.
874 : */
875 8948 : void __radix_tree_replace(struct radix_tree_root *root,
876 : struct radix_tree_node *node,
877 : void __rcu **slot, void *item)
878 : {
879 8948 : void *old = rcu_dereference_raw(*slot);
880 17896 : int values = !!xa_is_value(item) - !!xa_is_value(old);
881 8948 : int count = calculate_count(root, node, slot, item, old);
882 :
883 : /*
884 : * This function supports replacing value entries and
885 : * deleting entries, but that needs accounting against the
886 : * node unless the slot is root->xa_head.
887 : */
888 8948 : WARN_ON_ONCE(!node && (slot != (void __rcu **)&root->xa_head) &&
889 : (count || values));
890 8948 : replace_slot(slot, item, node, count, values);
891 :
892 8948 : if (!node)
893 : return;
894 :
895 8948 : delete_node(root, node);
896 : }
897 :
898 : /**
899 : * radix_tree_replace_slot - replace item in a slot
900 : * @root: radix tree root
901 : * @slot: pointer to slot
902 : * @item: new item to store in the slot.
903 : *
904 : * For use with radix_tree_lookup_slot() and
905 : * radix_tree_gang_lookup_tag_slot(). Caller must hold tree write locked
906 : * across slot lookup and replacement.
907 : *
908 : * NOTE: This cannot be used to switch between non-entries (empty slots),
909 : * regular entries, and value entries, as that requires accounting
910 : * inside the radix tree node. When switching from one type of entry or
911 : * deleting, use __radix_tree_lookup() and __radix_tree_replace() or
912 : * radix_tree_iter_replace().
913 : */
914 0 : void radix_tree_replace_slot(struct radix_tree_root *root,
915 : void __rcu **slot, void *item)
916 : {
917 0 : __radix_tree_replace(root, NULL, slot, item);
918 0 : }
919 : EXPORT_SYMBOL(radix_tree_replace_slot);
920 :
921 : /**
922 : * radix_tree_iter_replace - replace item in a slot
923 : * @root: radix tree root
924 : * @iter: iterator state
925 : * @slot: pointer to slot
926 : * @item: new item to store in the slot.
927 : *
928 : * For use with radix_tree_for_each_slot().
929 : * Caller must hold tree write locked.
930 : */
931 8773 : void radix_tree_iter_replace(struct radix_tree_root *root,
932 : const struct radix_tree_iter *iter,
933 : void __rcu **slot, void *item)
934 : {
935 8773 : __radix_tree_replace(root, iter->node, slot, item);
936 8773 : }
937 :
938 527 : static void node_tag_set(struct radix_tree_root *root,
939 : struct radix_tree_node *node,
940 : unsigned int tag, unsigned int offset)
941 : {
942 1583 : while (node) {
943 853 : if (tag_get(node, tag, offset))
944 : return;
945 1058 : tag_set(node, tag, offset);
946 529 : offset = node->offset;
947 529 : node = node->parent;
948 : }
949 :
950 406 : if (!root_tag_get(root, tag))
951 0 : root_tag_set(root, tag);
952 : }
953 :
954 : /**
955 : * radix_tree_tag_set - set a tag on a radix tree node
956 : * @root: radix tree root
957 : * @index: index key
958 : * @tag: tag index
959 : *
960 : * Set the search tag (which must be < RADIX_TREE_MAX_TAGS)
961 : * corresponding to @index in the radix tree. From
962 : * the root all the way down to the leaf node.
963 : *
964 : * Returns the address of the tagged item. Setting a tag on a not-present
965 : * item is a bug.
966 : */
967 0 : void *radix_tree_tag_set(struct radix_tree_root *root,
968 : unsigned long index, unsigned int tag)
969 : {
970 : struct radix_tree_node *node, *parent;
971 : unsigned long maxindex;
972 :
973 0 : radix_tree_load_root(root, &node, &maxindex);
974 0 : BUG_ON(index > maxindex);
975 :
976 0 : while (radix_tree_is_internal_node(node)) {
977 : unsigned offset;
978 :
979 0 : parent = entry_to_node(node);
980 0 : offset = radix_tree_descend(parent, &node, index);
981 0 : BUG_ON(!node);
982 :
983 0 : if (!tag_get(parent, tag, offset))
984 0 : tag_set(parent, tag, offset);
985 : }
986 :
987 : /* set the root's tag bit */
988 0 : if (!root_tag_get(root, tag))
989 0 : root_tag_set(root, tag);
990 :
991 0 : return node;
992 : }
993 : EXPORT_SYMBOL(radix_tree_tag_set);
994 :
995 8773 : static void node_tag_clear(struct radix_tree_root *root,
996 : struct radix_tree_node *node,
997 : unsigned int tag, unsigned int offset)
998 : {
999 17671 : while (node) {
1000 8898 : if (!tag_get(node, tag, offset))
1001 : return;
1002 8898 : tag_clear(node, tag, offset);
1003 8898 : if (any_tag_set(node, tag))
1004 : return;
1005 :
1006 125 : offset = node->offset;
1007 125 : node = node->parent;
1008 : }
1009 :
1010 : /* clear the root's tag bit */
1011 0 : if (root_tag_get(root, tag))
1012 0 : root_tag_clear(root, tag);
1013 : }
1014 :
1015 : /**
1016 : * radix_tree_tag_clear - clear a tag on a radix tree node
1017 : * @root: radix tree root
1018 : * @index: index key
1019 : * @tag: tag index
1020 : *
1021 : * Clear the search tag (which must be < RADIX_TREE_MAX_TAGS)
1022 : * corresponding to @index in the radix tree. If this causes
1023 : * the leaf node to have no tags set then clear the tag in the
1024 : * next-to-leaf node, etc.
1025 : *
1026 : * Returns the address of the tagged item on success, else NULL. ie:
1027 : * has the same return value and semantics as radix_tree_lookup().
1028 : */
1029 0 : void *radix_tree_tag_clear(struct radix_tree_root *root,
1030 : unsigned long index, unsigned int tag)
1031 : {
1032 : struct radix_tree_node *node, *parent;
1033 : unsigned long maxindex;
1034 0 : int offset = 0;
1035 :
1036 0 : radix_tree_load_root(root, &node, &maxindex);
1037 0 : if (index > maxindex)
1038 : return NULL;
1039 :
1040 : parent = NULL;
1041 :
1042 0 : while (radix_tree_is_internal_node(node)) {
1043 0 : parent = entry_to_node(node);
1044 0 : offset = radix_tree_descend(parent, &node, index);
1045 : }
1046 :
1047 0 : if (node)
1048 0 : node_tag_clear(root, parent, tag, offset);
1049 :
1050 : return node;
1051 : }
1052 : EXPORT_SYMBOL(radix_tree_tag_clear);
1053 :
1054 : /**
1055 : * radix_tree_iter_tag_clear - clear a tag on the current iterator entry
1056 : * @root: radix tree root
1057 : * @iter: iterator state
1058 : * @tag: tag to clear
1059 : */
1060 8773 : void radix_tree_iter_tag_clear(struct radix_tree_root *root,
1061 : const struct radix_tree_iter *iter, unsigned int tag)
1062 : {
1063 17546 : node_tag_clear(root, iter->node, tag, iter_offset(iter));
1064 8773 : }
1065 :
1066 : /**
1067 : * radix_tree_tag_get - get a tag on a radix tree node
1068 : * @root: radix tree root
1069 : * @index: index key
1070 : * @tag: tag index (< RADIX_TREE_MAX_TAGS)
1071 : *
1072 : * Return values:
1073 : *
1074 : * 0: tag not present or not set
1075 : * 1: tag set
1076 : *
1077 : * Note that the return value of this function may not be relied on, even if
1078 : * the RCU lock is held, unless tag modification and node deletion are excluded
1079 : * from concurrency.
1080 : */
1081 175 : int radix_tree_tag_get(const struct radix_tree_root *root,
1082 : unsigned long index, unsigned int tag)
1083 : {
1084 : struct radix_tree_node *node, *parent;
1085 : unsigned long maxindex;
1086 :
1087 350 : if (!root_tag_get(root, tag))
1088 : return 0;
1089 :
1090 175 : radix_tree_load_root(root, &node, &maxindex);
1091 175 : if (index > maxindex)
1092 : return 0;
1093 :
1094 574 : while (radix_tree_is_internal_node(node)) {
1095 : unsigned offset;
1096 :
1097 574 : parent = entry_to_node(node);
1098 287 : offset = radix_tree_descend(parent, &node, index);
1099 :
1100 287 : if (!tag_get(parent, tag, offset))
1101 : return 0;
1102 112 : if (node == RADIX_TREE_RETRY)
1103 : break;
1104 : }
1105 :
1106 : return 1;
1107 : }
1108 : EXPORT_SYMBOL(radix_tree_tag_get);
1109 :
1110 : /* Construct iter->tags bit-mask from node->tags[tag] array */
1111 : static void set_iter_tags(struct radix_tree_iter *iter,
1112 : struct radix_tree_node *node, unsigned offset,
1113 : unsigned tag)
1114 : {
1115 8773 : unsigned tag_long = offset / BITS_PER_LONG;
1116 8773 : unsigned tag_bit = offset % BITS_PER_LONG;
1117 :
1118 8773 : if (!node) {
1119 0 : iter->tags = 1;
1120 : return;
1121 : }
1122 :
1123 8773 : iter->tags = node->tags[tag][tag_long] >> tag_bit;
1124 :
1125 : /* This never happens if RADIX_TREE_TAG_LONGS == 1 */
1126 : if (tag_long < RADIX_TREE_TAG_LONGS - 1) {
1127 : /* Pick tags from next element */
1128 : if (tag_bit)
1129 : iter->tags |= node->tags[tag][tag_long + 1] <<
1130 : (BITS_PER_LONG - tag_bit);
1131 : /* Clip chunk size, here only BITS_PER_LONG tags */
1132 : iter->next_index = __radix_tree_iter_add(iter, BITS_PER_LONG);
1133 : }
1134 : }
1135 :
1136 0 : void __rcu **radix_tree_iter_resume(void __rcu **slot,
1137 : struct radix_tree_iter *iter)
1138 : {
1139 0 : slot++;
1140 0 : iter->index = __radix_tree_iter_add(iter, 1);
1141 0 : iter->next_index = iter->index;
1142 0 : iter->tags = 0;
1143 0 : return NULL;
1144 : }
1145 : EXPORT_SYMBOL(radix_tree_iter_resume);
1146 :
1147 : /**
1148 : * radix_tree_next_chunk - find next chunk of slots for iteration
1149 : *
1150 : * @root: radix tree root
1151 : * @iter: iterator state
1152 : * @flags: RADIX_TREE_ITER_* flags and tag index
1153 : * Returns: pointer to chunk first slot, or NULL if iteration is over
1154 : */
1155 0 : void __rcu **radix_tree_next_chunk(const struct radix_tree_root *root,
1156 : struct radix_tree_iter *iter, unsigned flags)
1157 : {
1158 0 : unsigned tag = flags & RADIX_TREE_ITER_TAG_MASK;
1159 : struct radix_tree_node *node, *child;
1160 : unsigned long index, offset, maxindex;
1161 :
1162 0 : if ((flags & RADIX_TREE_ITER_TAGGED) && !root_tag_get(root, tag))
1163 : return NULL;
1164 :
1165 : /*
1166 : * Catch next_index overflow after ~0UL. iter->index never overflows
1167 : * during iterating; it can be zero only at the beginning.
1168 : * And we cannot overflow iter->next_index in a single step,
1169 : * because RADIX_TREE_MAP_SHIFT < BITS_PER_LONG.
1170 : *
1171 : * This condition also used by radix_tree_next_slot() to stop
1172 : * contiguous iterating, and forbid switching to the next chunk.
1173 : */
1174 0 : index = iter->next_index;
1175 0 : if (!index && iter->index)
1176 : return NULL;
1177 :
1178 : restart:
1179 0 : radix_tree_load_root(root, &child, &maxindex);
1180 0 : if (index > maxindex)
1181 : return NULL;
1182 0 : if (!child)
1183 : return NULL;
1184 :
1185 0 : if (!radix_tree_is_internal_node(child)) {
1186 : /* Single-slot tree */
1187 0 : iter->index = index;
1188 0 : iter->next_index = maxindex + 1;
1189 0 : iter->tags = 1;
1190 0 : iter->node = NULL;
1191 0 : return (void __rcu **)&root->xa_head;
1192 : }
1193 :
1194 : do {
1195 0 : node = entry_to_node(child);
1196 0 : offset = radix_tree_descend(node, &child, index);
1197 :
1198 0 : if ((flags & RADIX_TREE_ITER_TAGGED) ?
1199 0 : !tag_get(node, tag, offset) : !child) {
1200 : /* Hole detected */
1201 0 : if (flags & RADIX_TREE_ITER_CONTIG)
1202 : return NULL;
1203 :
1204 0 : if (flags & RADIX_TREE_ITER_TAGGED)
1205 0 : offset = radix_tree_find_next_bit(node, tag,
1206 : offset + 1);
1207 : else
1208 0 : while (++offset < RADIX_TREE_MAP_SIZE) {
1209 0 : void *slot = rcu_dereference_raw(
1210 : node->slots[offset]);
1211 0 : if (slot)
1212 : break;
1213 : }
1214 0 : index &= ~node_maxindex(node);
1215 0 : index += offset << node->shift;
1216 : /* Overflow after ~0UL */
1217 0 : if (!index)
1218 : return NULL;
1219 0 : if (offset == RADIX_TREE_MAP_SIZE)
1220 : goto restart;
1221 0 : child = rcu_dereference_raw(node->slots[offset]);
1222 : }
1223 :
1224 0 : if (!child)
1225 : goto restart;
1226 0 : if (child == RADIX_TREE_RETRY)
1227 : break;
1228 0 : } while (node->shift && radix_tree_is_internal_node(child));
1229 :
1230 : /* Update the iterator state */
1231 0 : iter->index = (index &~ node_maxindex(node)) | offset;
1232 0 : iter->next_index = (index | node_maxindex(node)) + 1;
1233 0 : iter->node = node;
1234 :
1235 0 : if (flags & RADIX_TREE_ITER_TAGGED)
1236 0 : set_iter_tags(iter, node, offset, tag);
1237 :
1238 0 : return node->slots + offset;
1239 : }
1240 : EXPORT_SYMBOL(radix_tree_next_chunk);
1241 :
1242 : /**
1243 : * radix_tree_gang_lookup - perform multiple lookup on a radix tree
1244 : * @root: radix tree root
1245 : * @results: where the results of the lookup are placed
1246 : * @first_index: start the lookup from this key
1247 : * @max_items: place up to this many items at *results
1248 : *
1249 : * Performs an index-ascending scan of the tree for present items. Places
1250 : * them at *@results and returns the number of items which were placed at
1251 : * *@results.
1252 : *
1253 : * The implementation is naive.
1254 : *
1255 : * Like radix_tree_lookup, radix_tree_gang_lookup may be called under
1256 : * rcu_read_lock. In this case, rather than the returned results being
1257 : * an atomic snapshot of the tree at a single point in time, the
1258 : * semantics of an RCU protected gang lookup are as though multiple
1259 : * radix_tree_lookups have been issued in individual locks, and results
1260 : * stored in 'results'.
1261 : */
1262 : unsigned int
1263 0 : radix_tree_gang_lookup(const struct radix_tree_root *root, void **results,
1264 : unsigned long first_index, unsigned int max_items)
1265 : {
1266 : struct radix_tree_iter iter;
1267 : void __rcu **slot;
1268 0 : unsigned int ret = 0;
1269 :
1270 0 : if (unlikely(!max_items))
1271 : return 0;
1272 :
1273 0 : radix_tree_for_each_slot(slot, root, &iter, first_index) {
1274 0 : results[ret] = rcu_dereference_raw(*slot);
1275 0 : if (!results[ret])
1276 0 : continue;
1277 0 : if (radix_tree_is_internal_node(results[ret])) {
1278 0 : slot = radix_tree_iter_retry(&iter);
1279 0 : continue;
1280 : }
1281 0 : if (++ret == max_items)
1282 : break;
1283 : }
1284 :
1285 : return ret;
1286 : }
1287 : EXPORT_SYMBOL(radix_tree_gang_lookup);
1288 :
1289 : /**
1290 : * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree
1291 : * based on a tag
1292 : * @root: radix tree root
1293 : * @results: where the results of the lookup are placed
1294 : * @first_index: start the lookup from this key
1295 : * @max_items: place up to this many items at *results
1296 : * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
1297 : *
1298 : * Performs an index-ascending scan of the tree for present items which
1299 : * have the tag indexed by @tag set. Places the items at *@results and
1300 : * returns the number of items which were placed at *@results.
1301 : */
1302 : unsigned int
1303 0 : radix_tree_gang_lookup_tag(const struct radix_tree_root *root, void **results,
1304 : unsigned long first_index, unsigned int max_items,
1305 : unsigned int tag)
1306 : {
1307 : struct radix_tree_iter iter;
1308 : void __rcu **slot;
1309 0 : unsigned int ret = 0;
1310 :
1311 0 : if (unlikely(!max_items))
1312 : return 0;
1313 :
1314 0 : radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) {
1315 0 : results[ret] = rcu_dereference_raw(*slot);
1316 0 : if (!results[ret])
1317 0 : continue;
1318 0 : if (radix_tree_is_internal_node(results[ret])) {
1319 0 : slot = radix_tree_iter_retry(&iter);
1320 0 : continue;
1321 : }
1322 0 : if (++ret == max_items)
1323 : break;
1324 : }
1325 :
1326 : return ret;
1327 : }
1328 : EXPORT_SYMBOL(radix_tree_gang_lookup_tag);
1329 :
1330 : /**
1331 : * radix_tree_gang_lookup_tag_slot - perform multiple slot lookup on a
1332 : * radix tree based on a tag
1333 : * @root: radix tree root
1334 : * @results: where the results of the lookup are placed
1335 : * @first_index: start the lookup from this key
1336 : * @max_items: place up to this many items at *results
1337 : * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
1338 : *
1339 : * Performs an index-ascending scan of the tree for present items which
1340 : * have the tag indexed by @tag set. Places the slots at *@results and
1341 : * returns the number of slots which were placed at *@results.
1342 : */
1343 : unsigned int
1344 0 : radix_tree_gang_lookup_tag_slot(const struct radix_tree_root *root,
1345 : void __rcu ***results, unsigned long first_index,
1346 : unsigned int max_items, unsigned int tag)
1347 : {
1348 : struct radix_tree_iter iter;
1349 : void __rcu **slot;
1350 0 : unsigned int ret = 0;
1351 :
1352 0 : if (unlikely(!max_items))
1353 : return 0;
1354 :
1355 0 : radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) {
1356 0 : results[ret] = slot;
1357 0 : if (++ret == max_items)
1358 : break;
1359 : }
1360 :
1361 : return ret;
1362 : }
1363 : EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot);
1364 :
1365 527 : static bool __radix_tree_delete(struct radix_tree_root *root,
1366 : struct radix_tree_node *node, void __rcu **slot)
1367 : {
1368 527 : void *old = rcu_dereference_raw(*slot);
1369 527 : int values = xa_is_value(old) ? -1 : 0;
1370 527 : unsigned offset = get_slot_offset(node, slot);
1371 : int tag;
1372 :
1373 1054 : if (is_idr(root))
1374 527 : node_tag_set(root, node, IDR_FREE, offset);
1375 : else
1376 0 : for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
1377 0 : node_tag_clear(root, node, tag, offset);
1378 :
1379 527 : replace_slot(slot, NULL, node, -1, values);
1380 527 : return node && delete_node(root, node);
1381 : }
1382 :
1383 : /**
1384 : * radix_tree_iter_delete - delete the entry at this iterator position
1385 : * @root: radix tree root
1386 : * @iter: iterator state
1387 : * @slot: pointer to slot
1388 : *
1389 : * Delete the entry at the position currently pointed to by the iterator.
1390 : * This may result in the current node being freed; if it is, the iterator
1391 : * is advanced so that it will not reference the freed memory. This
1392 : * function may be called without any locking if there are no other threads
1393 : * which can access this tree.
1394 : */
1395 0 : void radix_tree_iter_delete(struct radix_tree_root *root,
1396 : struct radix_tree_iter *iter, void __rcu **slot)
1397 : {
1398 0 : if (__radix_tree_delete(root, iter->node, slot))
1399 0 : iter->index = iter->next_index;
1400 0 : }
1401 : EXPORT_SYMBOL(radix_tree_iter_delete);
1402 :
1403 : /**
1404 : * radix_tree_delete_item - delete an item from a radix tree
1405 : * @root: radix tree root
1406 : * @index: index key
1407 : * @item: expected item
1408 : *
1409 : * Remove @item at @index from the radix tree rooted at @root.
1410 : *
1411 : * Return: the deleted entry, or %NULL if it was not present
1412 : * or the entry at the given @index was not @item.
1413 : */
1414 527 : void *radix_tree_delete_item(struct radix_tree_root *root,
1415 : unsigned long index, void *item)
1416 : {
1417 527 : struct radix_tree_node *node = NULL;
1418 527 : void __rcu **slot = NULL;
1419 : void *entry;
1420 :
1421 527 : entry = __radix_tree_lookup(root, index, &node, &slot);
1422 527 : if (!slot)
1423 : return NULL;
1424 542 : if (!entry && (!is_idr(root) || node_tag_get(root, node, IDR_FREE,
1425 10 : get_slot_offset(node, slot))))
1426 : return NULL;
1427 :
1428 527 : if (item && entry != item)
1429 : return NULL;
1430 :
1431 527 : __radix_tree_delete(root, node, slot);
1432 :
1433 527 : return entry;
1434 : }
1435 : EXPORT_SYMBOL(radix_tree_delete_item);
1436 :
1437 : /**
1438 : * radix_tree_delete - delete an entry from a radix tree
1439 : * @root: radix tree root
1440 : * @index: index key
1441 : *
1442 : * Remove the entry at @index from the radix tree rooted at @root.
1443 : *
1444 : * Return: The deleted entry, or %NULL if it was not present.
1445 : */
1446 0 : void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
1447 : {
1448 0 : return radix_tree_delete_item(root, index, NULL);
1449 : }
1450 : EXPORT_SYMBOL(radix_tree_delete);
1451 :
1452 : /**
1453 : * radix_tree_tagged - test whether any items in the tree are tagged
1454 : * @root: radix tree root
1455 : * @tag: tag to test
1456 : */
1457 0 : int radix_tree_tagged(const struct radix_tree_root *root, unsigned int tag)
1458 : {
1459 17546 : return root_tag_get(root, tag);
1460 : }
1461 : EXPORT_SYMBOL(radix_tree_tagged);
1462 :
1463 : /**
1464 : * idr_preload - preload for idr_alloc()
1465 : * @gfp_mask: allocation mask to use for preloading
1466 : *
1467 : * Preallocate memory to use for the next call to idr_alloc(). This function
1468 : * returns with preemption disabled. It will be enabled by idr_preload_end().
1469 : */
1470 8620 : void idr_preload(gfp_t gfp_mask)
1471 : {
1472 8620 : if (__radix_tree_preload(gfp_mask, IDR_PRELOAD_SIZE))
1473 0 : local_lock(&radix_tree_preloads.lock);
1474 8620 : }
1475 : EXPORT_SYMBOL(idr_preload);
1476 :
1477 8773 : void __rcu **idr_get_free(struct radix_tree_root *root,
1478 : struct radix_tree_iter *iter, gfp_t gfp,
1479 : unsigned long max)
1480 : {
1481 8773 : struct radix_tree_node *node = NULL, *child;
1482 8773 : void __rcu **slot = (void __rcu **)&root->xa_head;
1483 8773 : unsigned long maxindex, start = iter->next_index;
1484 8773 : unsigned int shift, offset = 0;
1485 :
1486 : grow:
1487 8773 : shift = radix_tree_load_root(root, &child, &maxindex);
1488 8773 : if (!radix_tree_tagged(root, IDR_FREE))
1489 0 : start = max(start, maxindex + 1);
1490 8773 : if (start > max)
1491 : return ERR_PTR(-ENOSPC);
1492 :
1493 8773 : if (start > maxindex) {
1494 116 : int error = radix_tree_extend(root, gfp, start, shift);
1495 116 : if (error < 0)
1496 0 : return ERR_PTR(error);
1497 116 : shift = error;
1498 116 : child = rcu_dereference_raw(root->xa_head);
1499 : }
1500 8773 : if (start == 0 && shift == 0)
1501 11 : shift = RADIX_TREE_MAP_SHIFT;
1502 :
1503 30380 : while (shift) {
1504 21607 : shift -= RADIX_TREE_MAP_SHIFT;
1505 21607 : if (child == NULL) {
1506 : /* Have to add a child node. */
1507 262 : child = radix_tree_node_alloc(gfp, node, root, shift,
1508 : offset, 0, 0);
1509 262 : if (!child)
1510 : return ERR_PTR(-ENOMEM);
1511 524 : all_tag_set(child, IDR_FREE);
1512 524 : rcu_assign_pointer(*slot, node_to_entry(child));
1513 262 : if (node)
1514 249 : node->count++;
1515 42690 : } else if (!radix_tree_is_internal_node(child))
1516 : break;
1517 :
1518 43214 : node = entry_to_node(child);
1519 21607 : offset = radix_tree_descend(node, &child, start);
1520 21607 : if (!tag_get(node, IDR_FREE, offset)) {
1521 294 : offset = radix_tree_find_next_bit(node, IDR_FREE,
1522 147 : offset + 1);
1523 294 : start = next_index(start, node, offset);
1524 147 : if (start > max || start == 0)
1525 : return ERR_PTR(-ENOSPC);
1526 147 : while (offset == RADIX_TREE_MAP_SIZE) {
1527 0 : offset = node->offset + 1;
1528 0 : node = node->parent;
1529 0 : if (!node)
1530 : goto grow;
1531 0 : shift = node->shift;
1532 : }
1533 147 : child = rcu_dereference_raw(node->slots[offset]);
1534 : }
1535 21607 : slot = &node->slots[offset];
1536 : }
1537 :
1538 8773 : iter->index = start;
1539 8773 : if (node)
1540 17546 : iter->next_index = 1 + min(max, (start | node_maxindex(node)));
1541 : else
1542 0 : iter->next_index = 1;
1543 8773 : iter->node = node;
1544 8773 : set_iter_tags(iter, node, offset, IDR_FREE);
1545 :
1546 : return slot;
1547 : }
1548 :
1549 : /**
1550 : * idr_destroy - release all internal memory from an IDR
1551 : * @idr: idr handle
1552 : *
1553 : * After this function is called, the IDR is empty, and may be reused or
1554 : * the data structure containing it may be freed.
1555 : *
1556 : * A typical clean-up sequence for objects stored in an idr tree will use
1557 : * idr_for_each() to free all objects, if necessary, then idr_destroy() to
1558 : * free the memory used to keep track of those objects.
1559 : */
1560 10 : void idr_destroy(struct idr *idr)
1561 : {
1562 10 : struct radix_tree_node *node = rcu_dereference_raw(idr->idr_rt.xa_head);
1563 10 : if (radix_tree_is_internal_node(node))
1564 0 : radix_tree_free_nodes(node);
1565 10 : idr->idr_rt.xa_head = NULL;
1566 20 : root_tag_set(&idr->idr_rt, IDR_FREE);
1567 10 : }
1568 : EXPORT_SYMBOL(idr_destroy);
1569 :
1570 : static void
1571 168 : radix_tree_node_ctor(void *arg)
1572 : {
1573 168 : struct radix_tree_node *node = arg;
1574 :
1575 336 : memset(node, 0, sizeof(*node));
1576 336 : INIT_LIST_HEAD(&node->private_list);
1577 168 : }
1578 :
1579 0 : static int radix_tree_cpu_dead(unsigned int cpu)
1580 : {
1581 : struct radix_tree_preload *rtp;
1582 : struct radix_tree_node *node;
1583 :
1584 : /* Free per-cpu pool of preloaded nodes */
1585 0 : rtp = &per_cpu(radix_tree_preloads, cpu);
1586 0 : while (rtp->nr) {
1587 0 : node = rtp->nodes;
1588 0 : rtp->nodes = node->parent;
1589 0 : kmem_cache_free(radix_tree_node_cachep, node);
1590 0 : rtp->nr--;
1591 : }
1592 0 : return 0;
1593 : }
1594 :
1595 1 : void __init radix_tree_init(void)
1596 : {
1597 : int ret;
1598 :
1599 : BUILD_BUG_ON(RADIX_TREE_MAX_TAGS + __GFP_BITS_SHIFT > 32);
1600 : BUILD_BUG_ON(ROOT_IS_IDR & ~GFP_ZONEMASK);
1601 : BUILD_BUG_ON(XA_CHUNK_SIZE > 255);
1602 1 : radix_tree_node_cachep = kmem_cache_create("radix_tree_node",
1603 : sizeof(struct radix_tree_node), 0,
1604 : SLAB_PANIC | SLAB_RECLAIM_ACCOUNT,
1605 : radix_tree_node_ctor);
1606 1 : ret = cpuhp_setup_state_nocalls(CPUHP_RADIX_DEAD, "lib/radix:dead",
1607 : NULL, radix_tree_cpu_dead);
1608 1 : WARN_ON(ret < 0);
1609 1 : }
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