arm/imx: let ARCH_MXC select COMMON_CLKDEV instead of each subfamily
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / lib / radix-tree.c
blob92cdd9936e3d2797f4d9b3804ad648b6bbec3c1b
1 /*
2 * Copyright (C) 2001 Momchil Velikov
3 * Portions Copyright (C) 2001 Christoph Hellwig
4 * Copyright (C) 2005 SGI, Christoph Lameter
5 * Copyright (C) 2006 Nick Piggin
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License as
9 * published by the Free Software Foundation; either version 2, or (at
10 * your option) any later version.
12 * This program is distributed in the hope that it will be useful, but
13 * WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
22 #include <linux/errno.h>
23 #include <linux/init.h>
24 #include <linux/kernel.h>
25 #include <linux/module.h>
26 #include <linux/radix-tree.h>
27 #include <linux/percpu.h>
28 #include <linux/slab.h>
29 #include <linux/notifier.h>
30 #include <linux/cpu.h>
31 #include <linux/gfp.h>
32 #include <linux/string.h>
33 #include <linux/bitops.h>
34 #include <linux/rcupdate.h>
37 #ifdef __KERNEL__
38 #define RADIX_TREE_MAP_SHIFT (CONFIG_BASE_SMALL ? 4 : 6)
39 #else
40 #define RADIX_TREE_MAP_SHIFT 3 /* For more stressful testing */
41 #endif
43 #define RADIX_TREE_MAP_SIZE (1UL << RADIX_TREE_MAP_SHIFT)
44 #define RADIX_TREE_MAP_MASK (RADIX_TREE_MAP_SIZE-1)
46 #define RADIX_TREE_TAG_LONGS \
47 ((RADIX_TREE_MAP_SIZE + BITS_PER_LONG - 1) / BITS_PER_LONG)
49 struct radix_tree_node {
50 unsigned int height; /* Height from the bottom */
51 unsigned int count;
52 struct rcu_head rcu_head;
53 void *slots[RADIX_TREE_MAP_SIZE];
54 unsigned long tags[RADIX_TREE_MAX_TAGS][RADIX_TREE_TAG_LONGS];
57 struct radix_tree_path {
58 struct radix_tree_node *node;
59 int offset;
62 #define RADIX_TREE_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(unsigned long))
63 #define RADIX_TREE_MAX_PATH (DIV_ROUND_UP(RADIX_TREE_INDEX_BITS, \
64 RADIX_TREE_MAP_SHIFT))
67 * The height_to_maxindex array needs to be one deeper than the maximum
68 * path as height 0 holds only 1 entry.
70 static unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH + 1] __read_mostly;
73 * Radix tree node cache.
75 static struct kmem_cache *radix_tree_node_cachep;
78 * Per-cpu pool of preloaded nodes
80 struct radix_tree_preload {
81 int nr;
82 struct radix_tree_node *nodes[RADIX_TREE_MAX_PATH];
84 static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, };
86 static inline gfp_t root_gfp_mask(struct radix_tree_root *root)
88 return root->gfp_mask & __GFP_BITS_MASK;
91 static inline void tag_set(struct radix_tree_node *node, unsigned int tag,
92 int offset)
94 __set_bit(offset, node->tags[tag]);
97 static inline void tag_clear(struct radix_tree_node *node, unsigned int tag,
98 int offset)
100 __clear_bit(offset, node->tags[tag]);
103 static inline int tag_get(struct radix_tree_node *node, unsigned int tag,
104 int offset)
106 return test_bit(offset, node->tags[tag]);
109 static inline void root_tag_set(struct radix_tree_root *root, unsigned int tag)
111 root->gfp_mask |= (__force gfp_t)(1 << (tag + __GFP_BITS_SHIFT));
114 static inline void root_tag_clear(struct radix_tree_root *root, unsigned int tag)
116 root->gfp_mask &= (__force gfp_t)~(1 << (tag + __GFP_BITS_SHIFT));
119 static inline void root_tag_clear_all(struct radix_tree_root *root)
121 root->gfp_mask &= __GFP_BITS_MASK;
124 static inline int root_tag_get(struct radix_tree_root *root, unsigned int tag)
126 return (__force unsigned)root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT));
130 * Returns 1 if any slot in the node has this tag set.
131 * Otherwise returns 0.
133 static inline int any_tag_set(struct radix_tree_node *node, unsigned int tag)
135 int idx;
136 for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
137 if (node->tags[tag][idx])
138 return 1;
140 return 0;
143 * This assumes that the caller has performed appropriate preallocation, and
144 * that the caller has pinned this thread of control to the current CPU.
146 static struct radix_tree_node *
147 radix_tree_node_alloc(struct radix_tree_root *root)
149 struct radix_tree_node *ret = NULL;
150 gfp_t gfp_mask = root_gfp_mask(root);
152 if (!(gfp_mask & __GFP_WAIT)) {
153 struct radix_tree_preload *rtp;
156 * Provided the caller has preloaded here, we will always
157 * succeed in getting a node here (and never reach
158 * kmem_cache_alloc)
160 rtp = &__get_cpu_var(radix_tree_preloads);
161 if (rtp->nr) {
162 ret = rtp->nodes[rtp->nr - 1];
163 rtp->nodes[rtp->nr - 1] = NULL;
164 rtp->nr--;
167 if (ret == NULL)
168 ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
170 BUG_ON(radix_tree_is_indirect_ptr(ret));
171 return ret;
174 static void radix_tree_node_rcu_free(struct rcu_head *head)
176 struct radix_tree_node *node =
177 container_of(head, struct radix_tree_node, rcu_head);
180 * must only free zeroed nodes into the slab. radix_tree_shrink
181 * can leave us with a non-NULL entry in the first slot, so clear
182 * that here to make sure.
184 tag_clear(node, 0, 0);
185 tag_clear(node, 1, 0);
186 node->slots[0] = NULL;
187 node->count = 0;
189 kmem_cache_free(radix_tree_node_cachep, node);
192 static inline void
193 radix_tree_node_free(struct radix_tree_node *node)
195 call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
199 * Load up this CPU's radix_tree_node buffer with sufficient objects to
200 * ensure that the addition of a single element in the tree cannot fail. On
201 * success, return zero, with preemption disabled. On error, return -ENOMEM
202 * with preemption not disabled.
204 * To make use of this facility, the radix tree must be initialised without
205 * __GFP_WAIT being passed to INIT_RADIX_TREE().
207 int radix_tree_preload(gfp_t gfp_mask)
209 struct radix_tree_preload *rtp;
210 struct radix_tree_node *node;
211 int ret = -ENOMEM;
213 preempt_disable();
214 rtp = &__get_cpu_var(radix_tree_preloads);
215 while (rtp->nr < ARRAY_SIZE(rtp->nodes)) {
216 preempt_enable();
217 node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
218 if (node == NULL)
219 goto out;
220 preempt_disable();
221 rtp = &__get_cpu_var(radix_tree_preloads);
222 if (rtp->nr < ARRAY_SIZE(rtp->nodes))
223 rtp->nodes[rtp->nr++] = node;
224 else
225 kmem_cache_free(radix_tree_node_cachep, node);
227 ret = 0;
228 out:
229 return ret;
231 EXPORT_SYMBOL(radix_tree_preload);
234 * Return the maximum key which can be store into a
235 * radix tree with height HEIGHT.
237 static inline unsigned long radix_tree_maxindex(unsigned int height)
239 return height_to_maxindex[height];
243 * Extend a radix tree so it can store key @index.
245 static int radix_tree_extend(struct radix_tree_root *root, unsigned long index)
247 struct radix_tree_node *node;
248 unsigned int height;
249 int tag;
251 /* Figure out what the height should be. */
252 height = root->height + 1;
253 while (index > radix_tree_maxindex(height))
254 height++;
256 if (root->rnode == NULL) {
257 root->height = height;
258 goto out;
261 do {
262 unsigned int newheight;
263 if (!(node = radix_tree_node_alloc(root)))
264 return -ENOMEM;
266 /* Increase the height. */
267 node->slots[0] = radix_tree_indirect_to_ptr(root->rnode);
269 /* Propagate the aggregated tag info into the new root */
270 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
271 if (root_tag_get(root, tag))
272 tag_set(node, tag, 0);
275 newheight = root->height+1;
276 node->height = newheight;
277 node->count = 1;
278 node = radix_tree_ptr_to_indirect(node);
279 rcu_assign_pointer(root->rnode, node);
280 root->height = newheight;
281 } while (height > root->height);
282 out:
283 return 0;
287 * radix_tree_insert - insert into a radix tree
288 * @root: radix tree root
289 * @index: index key
290 * @item: item to insert
292 * Insert an item into the radix tree at position @index.
294 int radix_tree_insert(struct radix_tree_root *root,
295 unsigned long index, void *item)
297 struct radix_tree_node *node = NULL, *slot;
298 unsigned int height, shift;
299 int offset;
300 int error;
302 BUG_ON(radix_tree_is_indirect_ptr(item));
304 /* Make sure the tree is high enough. */
305 if (index > radix_tree_maxindex(root->height)) {
306 error = radix_tree_extend(root, index);
307 if (error)
308 return error;
311 slot = radix_tree_indirect_to_ptr(root->rnode);
313 height = root->height;
314 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
316 offset = 0; /* uninitialised var warning */
317 while (height > 0) {
318 if (slot == NULL) {
319 /* Have to add a child node. */
320 if (!(slot = radix_tree_node_alloc(root)))
321 return -ENOMEM;
322 slot->height = height;
323 if (node) {
324 rcu_assign_pointer(node->slots[offset], slot);
325 node->count++;
326 } else
327 rcu_assign_pointer(root->rnode,
328 radix_tree_ptr_to_indirect(slot));
331 /* Go a level down */
332 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
333 node = slot;
334 slot = node->slots[offset];
335 shift -= RADIX_TREE_MAP_SHIFT;
336 height--;
339 if (slot != NULL)
340 return -EEXIST;
342 if (node) {
343 node->count++;
344 rcu_assign_pointer(node->slots[offset], item);
345 BUG_ON(tag_get(node, 0, offset));
346 BUG_ON(tag_get(node, 1, offset));
347 } else {
348 rcu_assign_pointer(root->rnode, item);
349 BUG_ON(root_tag_get(root, 0));
350 BUG_ON(root_tag_get(root, 1));
353 return 0;
355 EXPORT_SYMBOL(radix_tree_insert);
358 * is_slot == 1 : search for the slot.
359 * is_slot == 0 : search for the node.
361 static void *radix_tree_lookup_element(struct radix_tree_root *root,
362 unsigned long index, int is_slot)
364 unsigned int height, shift;
365 struct radix_tree_node *node, **slot;
367 node = rcu_dereference(root->rnode);
368 if (node == NULL)
369 return NULL;
371 if (!radix_tree_is_indirect_ptr(node)) {
372 if (index > 0)
373 return NULL;
374 return is_slot ? (void *)&root->rnode : node;
376 node = radix_tree_indirect_to_ptr(node);
378 height = node->height;
379 if (index > radix_tree_maxindex(height))
380 return NULL;
382 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
384 do {
385 slot = (struct radix_tree_node **)
386 (node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK));
387 node = rcu_dereference(*slot);
388 if (node == NULL)
389 return NULL;
391 shift -= RADIX_TREE_MAP_SHIFT;
392 height--;
393 } while (height > 0);
395 return is_slot ? (void *)slot:node;
399 * radix_tree_lookup_slot - lookup a slot in a radix tree
400 * @root: radix tree root
401 * @index: index key
403 * Returns: the slot corresponding to the position @index in the
404 * radix tree @root. This is useful for update-if-exists operations.
406 * This function can be called under rcu_read_lock iff the slot is not
407 * modified by radix_tree_replace_slot, otherwise it must be called
408 * exclusive from other writers. Any dereference of the slot must be done
409 * using radix_tree_deref_slot.
411 void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index)
413 return (void **)radix_tree_lookup_element(root, index, 1);
415 EXPORT_SYMBOL(radix_tree_lookup_slot);
418 * radix_tree_lookup - perform lookup operation on a radix tree
419 * @root: radix tree root
420 * @index: index key
422 * Lookup the item at the position @index in the radix tree @root.
424 * This function can be called under rcu_read_lock, however the caller
425 * must manage lifetimes of leaf nodes (eg. RCU may also be used to free
426 * them safely). No RCU barriers are required to access or modify the
427 * returned item, however.
429 void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
431 return radix_tree_lookup_element(root, index, 0);
433 EXPORT_SYMBOL(radix_tree_lookup);
436 * radix_tree_tag_set - set a tag on a radix tree node
437 * @root: radix tree root
438 * @index: index key
439 * @tag: tag index
441 * Set the search tag (which must be < RADIX_TREE_MAX_TAGS)
442 * corresponding to @index in the radix tree. From
443 * the root all the way down to the leaf node.
445 * Returns the address of the tagged item. Setting a tag on a not-present
446 * item is a bug.
448 void *radix_tree_tag_set(struct radix_tree_root *root,
449 unsigned long index, unsigned int tag)
451 unsigned int height, shift;
452 struct radix_tree_node *slot;
454 height = root->height;
455 BUG_ON(index > radix_tree_maxindex(height));
457 slot = radix_tree_indirect_to_ptr(root->rnode);
458 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
460 while (height > 0) {
461 int offset;
463 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
464 if (!tag_get(slot, tag, offset))
465 tag_set(slot, tag, offset);
466 slot = slot->slots[offset];
467 BUG_ON(slot == NULL);
468 shift -= RADIX_TREE_MAP_SHIFT;
469 height--;
472 /* set the root's tag bit */
473 if (slot && !root_tag_get(root, tag))
474 root_tag_set(root, tag);
476 return slot;
478 EXPORT_SYMBOL(radix_tree_tag_set);
481 * radix_tree_tag_clear - clear a tag on a radix tree node
482 * @root: radix tree root
483 * @index: index key
484 * @tag: tag index
486 * Clear the search tag (which must be < RADIX_TREE_MAX_TAGS)
487 * corresponding to @index in the radix tree. If
488 * this causes the leaf node to have no tags set then clear the tag in the
489 * next-to-leaf node, etc.
491 * Returns the address of the tagged item on success, else NULL. ie:
492 * has the same return value and semantics as radix_tree_lookup().
494 void *radix_tree_tag_clear(struct radix_tree_root *root,
495 unsigned long index, unsigned int tag)
498 * The radix tree path needs to be one longer than the maximum path
499 * since the "list" is null terminated.
501 struct radix_tree_path path[RADIX_TREE_MAX_PATH + 1], *pathp = path;
502 struct radix_tree_node *slot = NULL;
503 unsigned int height, shift;
505 height = root->height;
506 if (index > radix_tree_maxindex(height))
507 goto out;
509 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
510 pathp->node = NULL;
511 slot = radix_tree_indirect_to_ptr(root->rnode);
513 while (height > 0) {
514 int offset;
516 if (slot == NULL)
517 goto out;
519 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
520 pathp[1].offset = offset;
521 pathp[1].node = slot;
522 slot = slot->slots[offset];
523 pathp++;
524 shift -= RADIX_TREE_MAP_SHIFT;
525 height--;
528 if (slot == NULL)
529 goto out;
531 while (pathp->node) {
532 if (!tag_get(pathp->node, tag, pathp->offset))
533 goto out;
534 tag_clear(pathp->node, tag, pathp->offset);
535 if (any_tag_set(pathp->node, tag))
536 goto out;
537 pathp--;
540 /* clear the root's tag bit */
541 if (root_tag_get(root, tag))
542 root_tag_clear(root, tag);
544 out:
545 return slot;
547 EXPORT_SYMBOL(radix_tree_tag_clear);
550 * radix_tree_tag_get - get a tag on a radix tree node
551 * @root: radix tree root
552 * @index: index key
553 * @tag: tag index (< RADIX_TREE_MAX_TAGS)
555 * Return values:
557 * 0: tag not present or not set
558 * 1: tag set
560 int radix_tree_tag_get(struct radix_tree_root *root,
561 unsigned long index, unsigned int tag)
563 unsigned int height, shift;
564 struct radix_tree_node *node;
565 int saw_unset_tag = 0;
567 /* check the root's tag bit */
568 if (!root_tag_get(root, tag))
569 return 0;
571 node = rcu_dereference(root->rnode);
572 if (node == NULL)
573 return 0;
575 if (!radix_tree_is_indirect_ptr(node))
576 return (index == 0);
577 node = radix_tree_indirect_to_ptr(node);
579 height = node->height;
580 if (index > radix_tree_maxindex(height))
581 return 0;
583 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
585 for ( ; ; ) {
586 int offset;
588 if (node == NULL)
589 return 0;
591 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
594 * This is just a debug check. Later, we can bale as soon as
595 * we see an unset tag.
597 if (!tag_get(node, tag, offset))
598 saw_unset_tag = 1;
599 if (height == 1) {
600 int ret = tag_get(node, tag, offset);
602 BUG_ON(ret && saw_unset_tag);
603 return !!ret;
605 node = rcu_dereference(node->slots[offset]);
606 shift -= RADIX_TREE_MAP_SHIFT;
607 height--;
610 EXPORT_SYMBOL(radix_tree_tag_get);
613 * radix_tree_next_hole - find the next hole (not-present entry)
614 * @root: tree root
615 * @index: index key
616 * @max_scan: maximum range to search
618 * Search the set [index, min(index+max_scan-1, MAX_INDEX)] for the lowest
619 * indexed hole.
621 * Returns: the index of the hole if found, otherwise returns an index
622 * outside of the set specified (in which case 'return - index >= max_scan'
623 * will be true). In rare cases of index wrap-around, 0 will be returned.
625 * radix_tree_next_hole may be called under rcu_read_lock. However, like
626 * radix_tree_gang_lookup, this will not atomically search a snapshot of
627 * the tree at a single point in time. For example, if a hole is created
628 * at index 5, then subsequently a hole is created at index 10,
629 * radix_tree_next_hole covering both indexes may return 10 if called
630 * under rcu_read_lock.
632 unsigned long radix_tree_next_hole(struct radix_tree_root *root,
633 unsigned long index, unsigned long max_scan)
635 unsigned long i;
637 for (i = 0; i < max_scan; i++) {
638 if (!radix_tree_lookup(root, index))
639 break;
640 index++;
641 if (index == 0)
642 break;
645 return index;
647 EXPORT_SYMBOL(radix_tree_next_hole);
650 * radix_tree_prev_hole - find the prev hole (not-present entry)
651 * @root: tree root
652 * @index: index key
653 * @max_scan: maximum range to search
655 * Search backwards in the range [max(index-max_scan+1, 0), index]
656 * for the first hole.
658 * Returns: the index of the hole if found, otherwise returns an index
659 * outside of the set specified (in which case 'index - return >= max_scan'
660 * will be true). In rare cases of wrap-around, LONG_MAX will be returned.
662 * radix_tree_next_hole may be called under rcu_read_lock. However, like
663 * radix_tree_gang_lookup, this will not atomically search a snapshot of
664 * the tree at a single point in time. For example, if a hole is created
665 * at index 10, then subsequently a hole is created at index 5,
666 * radix_tree_prev_hole covering both indexes may return 5 if called under
667 * rcu_read_lock.
669 unsigned long radix_tree_prev_hole(struct radix_tree_root *root,
670 unsigned long index, unsigned long max_scan)
672 unsigned long i;
674 for (i = 0; i < max_scan; i++) {
675 if (!radix_tree_lookup(root, index))
676 break;
677 index--;
678 if (index == LONG_MAX)
679 break;
682 return index;
684 EXPORT_SYMBOL(radix_tree_prev_hole);
686 static unsigned int
687 __lookup(struct radix_tree_node *slot, void ***results, unsigned long index,
688 unsigned int max_items, unsigned long *next_index)
690 unsigned int nr_found = 0;
691 unsigned int shift, height;
692 unsigned long i;
694 height = slot->height;
695 if (height == 0)
696 goto out;
697 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
699 for ( ; height > 1; height--) {
700 i = (index >> shift) & RADIX_TREE_MAP_MASK;
701 for (;;) {
702 if (slot->slots[i] != NULL)
703 break;
704 index &= ~((1UL << shift) - 1);
705 index += 1UL << shift;
706 if (index == 0)
707 goto out; /* 32-bit wraparound */
708 i++;
709 if (i == RADIX_TREE_MAP_SIZE)
710 goto out;
713 shift -= RADIX_TREE_MAP_SHIFT;
714 slot = rcu_dereference(slot->slots[i]);
715 if (slot == NULL)
716 goto out;
719 /* Bottom level: grab some items */
720 for (i = index & RADIX_TREE_MAP_MASK; i < RADIX_TREE_MAP_SIZE; i++) {
721 index++;
722 if (slot->slots[i]) {
723 results[nr_found++] = &(slot->slots[i]);
724 if (nr_found == max_items)
725 goto out;
728 out:
729 *next_index = index;
730 return nr_found;
734 * radix_tree_gang_lookup - perform multiple lookup on a radix tree
735 * @root: radix tree root
736 * @results: where the results of the lookup are placed
737 * @first_index: start the lookup from this key
738 * @max_items: place up to this many items at *results
740 * Performs an index-ascending scan of the tree for present items. Places
741 * them at *@results and returns the number of items which were placed at
742 * *@results.
744 * The implementation is naive.
746 * Like radix_tree_lookup, radix_tree_gang_lookup may be called under
747 * rcu_read_lock. In this case, rather than the returned results being
748 * an atomic snapshot of the tree at a single point in time, the semantics
749 * of an RCU protected gang lookup are as though multiple radix_tree_lookups
750 * have been issued in individual locks, and results stored in 'results'.
752 unsigned int
753 radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
754 unsigned long first_index, unsigned int max_items)
756 unsigned long max_index;
757 struct radix_tree_node *node;
758 unsigned long cur_index = first_index;
759 unsigned int ret;
761 node = rcu_dereference(root->rnode);
762 if (!node)
763 return 0;
765 if (!radix_tree_is_indirect_ptr(node)) {
766 if (first_index > 0)
767 return 0;
768 results[0] = node;
769 return 1;
771 node = radix_tree_indirect_to_ptr(node);
773 max_index = radix_tree_maxindex(node->height);
775 ret = 0;
776 while (ret < max_items) {
777 unsigned int nr_found, slots_found, i;
778 unsigned long next_index; /* Index of next search */
780 if (cur_index > max_index)
781 break;
782 slots_found = __lookup(node, (void ***)results + ret, cur_index,
783 max_items - ret, &next_index);
784 nr_found = 0;
785 for (i = 0; i < slots_found; i++) {
786 struct radix_tree_node *slot;
787 slot = *(((void ***)results)[ret + i]);
788 if (!slot)
789 continue;
790 results[ret + nr_found] = rcu_dereference(slot);
791 nr_found++;
793 ret += nr_found;
794 if (next_index == 0)
795 break;
796 cur_index = next_index;
799 return ret;
801 EXPORT_SYMBOL(radix_tree_gang_lookup);
804 * radix_tree_gang_lookup_slot - perform multiple slot lookup on radix tree
805 * @root: radix tree root
806 * @results: where the results of the lookup are placed
807 * @first_index: start the lookup from this key
808 * @max_items: place up to this many items at *results
810 * Performs an index-ascending scan of the tree for present items. Places
811 * their slots at *@results and returns the number of items which were
812 * placed at *@results.
814 * The implementation is naive.
816 * Like radix_tree_gang_lookup as far as RCU and locking goes. Slots must
817 * be dereferenced with radix_tree_deref_slot, and if using only RCU
818 * protection, radix_tree_deref_slot may fail requiring a retry.
820 unsigned int
821 radix_tree_gang_lookup_slot(struct radix_tree_root *root, void ***results,
822 unsigned long first_index, unsigned int max_items)
824 unsigned long max_index;
825 struct radix_tree_node *node;
826 unsigned long cur_index = first_index;
827 unsigned int ret;
829 node = rcu_dereference(root->rnode);
830 if (!node)
831 return 0;
833 if (!radix_tree_is_indirect_ptr(node)) {
834 if (first_index > 0)
835 return 0;
836 results[0] = (void **)&root->rnode;
837 return 1;
839 node = radix_tree_indirect_to_ptr(node);
841 max_index = radix_tree_maxindex(node->height);
843 ret = 0;
844 while (ret < max_items) {
845 unsigned int slots_found;
846 unsigned long next_index; /* Index of next search */
848 if (cur_index > max_index)
849 break;
850 slots_found = __lookup(node, results + ret, cur_index,
851 max_items - ret, &next_index);
852 ret += slots_found;
853 if (next_index == 0)
854 break;
855 cur_index = next_index;
858 return ret;
860 EXPORT_SYMBOL(radix_tree_gang_lookup_slot);
863 * FIXME: the two tag_get()s here should use find_next_bit() instead of
864 * open-coding the search.
866 static unsigned int
867 __lookup_tag(struct radix_tree_node *slot, void ***results, unsigned long index,
868 unsigned int max_items, unsigned long *next_index, unsigned int tag)
870 unsigned int nr_found = 0;
871 unsigned int shift, height;
873 height = slot->height;
874 if (height == 0)
875 goto out;
876 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
878 while (height > 0) {
879 unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK ;
881 for (;;) {
882 if (tag_get(slot, tag, i))
883 break;
884 index &= ~((1UL << shift) - 1);
885 index += 1UL << shift;
886 if (index == 0)
887 goto out; /* 32-bit wraparound */
888 i++;
889 if (i == RADIX_TREE_MAP_SIZE)
890 goto out;
892 height--;
893 if (height == 0) { /* Bottom level: grab some items */
894 unsigned long j = index & RADIX_TREE_MAP_MASK;
896 for ( ; j < RADIX_TREE_MAP_SIZE; j++) {
897 index++;
898 if (!tag_get(slot, tag, j))
899 continue;
901 * Even though the tag was found set, we need to
902 * recheck that we have a non-NULL node, because
903 * if this lookup is lockless, it may have been
904 * subsequently deleted.
906 * Similar care must be taken in any place that
907 * lookup ->slots[x] without a lock (ie. can't
908 * rely on its value remaining the same).
910 if (slot->slots[j]) {
911 results[nr_found++] = &(slot->slots[j]);
912 if (nr_found == max_items)
913 goto out;
917 shift -= RADIX_TREE_MAP_SHIFT;
918 slot = rcu_dereference(slot->slots[i]);
919 if (slot == NULL)
920 break;
922 out:
923 *next_index = index;
924 return nr_found;
928 * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree
929 * based on a tag
930 * @root: radix tree root
931 * @results: where the results of the lookup are placed
932 * @first_index: start the lookup from this key
933 * @max_items: place up to this many items at *results
934 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
936 * Performs an index-ascending scan of the tree for present items which
937 * have the tag indexed by @tag set. Places the items at *@results and
938 * returns the number of items which were placed at *@results.
940 unsigned int
941 radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
942 unsigned long first_index, unsigned int max_items,
943 unsigned int tag)
945 struct radix_tree_node *node;
946 unsigned long max_index;
947 unsigned long cur_index = first_index;
948 unsigned int ret;
950 /* check the root's tag bit */
951 if (!root_tag_get(root, tag))
952 return 0;
954 node = rcu_dereference(root->rnode);
955 if (!node)
956 return 0;
958 if (!radix_tree_is_indirect_ptr(node)) {
959 if (first_index > 0)
960 return 0;
961 results[0] = node;
962 return 1;
964 node = radix_tree_indirect_to_ptr(node);
966 max_index = radix_tree_maxindex(node->height);
968 ret = 0;
969 while (ret < max_items) {
970 unsigned int nr_found, slots_found, i;
971 unsigned long next_index; /* Index of next search */
973 if (cur_index > max_index)
974 break;
975 slots_found = __lookup_tag(node, (void ***)results + ret,
976 cur_index, max_items - ret, &next_index, tag);
977 nr_found = 0;
978 for (i = 0; i < slots_found; i++) {
979 struct radix_tree_node *slot;
980 slot = *(((void ***)results)[ret + i]);
981 if (!slot)
982 continue;
983 results[ret + nr_found] = rcu_dereference(slot);
984 nr_found++;
986 ret += nr_found;
987 if (next_index == 0)
988 break;
989 cur_index = next_index;
992 return ret;
994 EXPORT_SYMBOL(radix_tree_gang_lookup_tag);
997 * radix_tree_gang_lookup_tag_slot - perform multiple slot lookup on a
998 * radix tree based on a tag
999 * @root: radix tree root
1000 * @results: where the results of the lookup are placed
1001 * @first_index: start the lookup from this key
1002 * @max_items: place up to this many items at *results
1003 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
1005 * Performs an index-ascending scan of the tree for present items which
1006 * have the tag indexed by @tag set. Places the slots at *@results and
1007 * returns the number of slots which were placed at *@results.
1009 unsigned int
1010 radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results,
1011 unsigned long first_index, unsigned int max_items,
1012 unsigned int tag)
1014 struct radix_tree_node *node;
1015 unsigned long max_index;
1016 unsigned long cur_index = first_index;
1017 unsigned int ret;
1019 /* check the root's tag bit */
1020 if (!root_tag_get(root, tag))
1021 return 0;
1023 node = rcu_dereference(root->rnode);
1024 if (!node)
1025 return 0;
1027 if (!radix_tree_is_indirect_ptr(node)) {
1028 if (first_index > 0)
1029 return 0;
1030 results[0] = (void **)&root->rnode;
1031 return 1;
1033 node = radix_tree_indirect_to_ptr(node);
1035 max_index = radix_tree_maxindex(node->height);
1037 ret = 0;
1038 while (ret < max_items) {
1039 unsigned int slots_found;
1040 unsigned long next_index; /* Index of next search */
1042 if (cur_index > max_index)
1043 break;
1044 slots_found = __lookup_tag(node, results + ret,
1045 cur_index, max_items - ret, &next_index, tag);
1046 ret += slots_found;
1047 if (next_index == 0)
1048 break;
1049 cur_index = next_index;
1052 return ret;
1054 EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot);
1058 * radix_tree_shrink - shrink height of a radix tree to minimal
1059 * @root radix tree root
1061 static inline void radix_tree_shrink(struct radix_tree_root *root)
1063 /* try to shrink tree height */
1064 while (root->height > 0) {
1065 struct radix_tree_node *to_free = root->rnode;
1066 void *newptr;
1068 BUG_ON(!radix_tree_is_indirect_ptr(to_free));
1069 to_free = radix_tree_indirect_to_ptr(to_free);
1072 * The candidate node has more than one child, or its child
1073 * is not at the leftmost slot, we cannot shrink.
1075 if (to_free->count != 1)
1076 break;
1077 if (!to_free->slots[0])
1078 break;
1081 * We don't need rcu_assign_pointer(), since we are simply
1082 * moving the node from one part of the tree to another. If
1083 * it was safe to dereference the old pointer to it
1084 * (to_free->slots[0]), it will be safe to dereference the new
1085 * one (root->rnode).
1087 newptr = to_free->slots[0];
1088 if (root->height > 1)
1089 newptr = radix_tree_ptr_to_indirect(newptr);
1090 root->rnode = newptr;
1091 root->height--;
1092 radix_tree_node_free(to_free);
1097 * radix_tree_delete - delete an item from a radix tree
1098 * @root: radix tree root
1099 * @index: index key
1101 * Remove the item at @index from the radix tree rooted at @root.
1103 * Returns the address of the deleted item, or NULL if it was not present.
1105 void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
1108 * The radix tree path needs to be one longer than the maximum path
1109 * since the "list" is null terminated.
1111 struct radix_tree_path path[RADIX_TREE_MAX_PATH + 1], *pathp = path;
1112 struct radix_tree_node *slot = NULL;
1113 struct radix_tree_node *to_free;
1114 unsigned int height, shift;
1115 int tag;
1116 int offset;
1118 height = root->height;
1119 if (index > radix_tree_maxindex(height))
1120 goto out;
1122 slot = root->rnode;
1123 if (height == 0) {
1124 root_tag_clear_all(root);
1125 root->rnode = NULL;
1126 goto out;
1128 slot = radix_tree_indirect_to_ptr(slot);
1130 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
1131 pathp->node = NULL;
1133 do {
1134 if (slot == NULL)
1135 goto out;
1137 pathp++;
1138 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
1139 pathp->offset = offset;
1140 pathp->node = slot;
1141 slot = slot->slots[offset];
1142 shift -= RADIX_TREE_MAP_SHIFT;
1143 height--;
1144 } while (height > 0);
1146 if (slot == NULL)
1147 goto out;
1150 * Clear all tags associated with the just-deleted item
1152 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
1153 if (tag_get(pathp->node, tag, pathp->offset))
1154 radix_tree_tag_clear(root, index, tag);
1157 to_free = NULL;
1158 /* Now free the nodes we do not need anymore */
1159 while (pathp->node) {
1160 pathp->node->slots[pathp->offset] = NULL;
1161 pathp->node->count--;
1163 * Queue the node for deferred freeing after the
1164 * last reference to it disappears (set NULL, above).
1166 if (to_free)
1167 radix_tree_node_free(to_free);
1169 if (pathp->node->count) {
1170 if (pathp->node ==
1171 radix_tree_indirect_to_ptr(root->rnode))
1172 radix_tree_shrink(root);
1173 goto out;
1176 /* Node with zero slots in use so free it */
1177 to_free = pathp->node;
1178 pathp--;
1181 root_tag_clear_all(root);
1182 root->height = 0;
1183 root->rnode = NULL;
1184 if (to_free)
1185 radix_tree_node_free(to_free);
1187 out:
1188 return slot;
1190 EXPORT_SYMBOL(radix_tree_delete);
1193 * radix_tree_tagged - test whether any items in the tree are tagged
1194 * @root: radix tree root
1195 * @tag: tag to test
1197 int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag)
1199 return root_tag_get(root, tag);
1201 EXPORT_SYMBOL(radix_tree_tagged);
1203 static void
1204 radix_tree_node_ctor(void *node)
1206 memset(node, 0, sizeof(struct radix_tree_node));
1209 static __init unsigned long __maxindex(unsigned int height)
1211 unsigned int width = height * RADIX_TREE_MAP_SHIFT;
1212 int shift = RADIX_TREE_INDEX_BITS - width;
1214 if (shift < 0)
1215 return ~0UL;
1216 if (shift >= BITS_PER_LONG)
1217 return 0UL;
1218 return ~0UL >> shift;
1221 static __init void radix_tree_init_maxindex(void)
1223 unsigned int i;
1225 for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++)
1226 height_to_maxindex[i] = __maxindex(i);
1229 static int radix_tree_callback(struct notifier_block *nfb,
1230 unsigned long action,
1231 void *hcpu)
1233 int cpu = (long)hcpu;
1234 struct radix_tree_preload *rtp;
1236 /* Free per-cpu pool of perloaded nodes */
1237 if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
1238 rtp = &per_cpu(radix_tree_preloads, cpu);
1239 while (rtp->nr) {
1240 kmem_cache_free(radix_tree_node_cachep,
1241 rtp->nodes[rtp->nr-1]);
1242 rtp->nodes[rtp->nr-1] = NULL;
1243 rtp->nr--;
1246 return NOTIFY_OK;
1249 void __init radix_tree_init(void)
1251 radix_tree_node_cachep = kmem_cache_create("radix_tree_node",
1252 sizeof(struct radix_tree_node), 0,
1253 SLAB_PANIC | SLAB_RECLAIM_ACCOUNT,
1254 radix_tree_node_ctor);
1255 radix_tree_init_maxindex();
1256 hotcpu_notifier(radix_tree_callback, 0);