xref: /netbsd-src/common/lib/libc/gen/ptree.c (revision b1c86f5f087524e68db12794ee9c3e3da1ab17a0)
1 /* $NetBSD: ptree.c,v 1.5 2009/06/07 03:12:40 yamt Exp $ */
2 
3 /*-
4  * Copyright (c) 2008 The NetBSD Foundation, Inc.
5  * All rights reserved.
6  *
7  * This code is derived from software contributed to The NetBSD Foundation
8  * by Matt Thomas <matt@3am-software.com>.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29  * POSSIBILITY OF SUCH DAMAGE.
30  */
31 
32 #define _PT_PRIVATE
33 
34 #if defined(PTCHECK) && !defined(PTDEBUG)
35 #define PTDEBUG
36 #endif
37 
38 #if defined(_KERNEL) || defined(_STANDALONE)
39 #include <sys/param.h>
40 #include <sys/types.h>
41 #include <sys/systm.h>
42 #include <lib/libkern/libkern.h>
43 __KERNEL_RCSID(0, "$NetBSD: ptree.c,v 1.5 2009/06/07 03:12:40 yamt Exp $");
44 #else
45 #include <stddef.h>
46 #include <stdint.h>
47 #include <limits.h>
48 #include <stdbool.h>
49 #include <string.h>
50 #ifdef PTDEBUG
51 #include <assert.h>
52 #define	KASSERT(e)	assert(e)
53 #else
54 #define	KASSERT(e)	do { } while (/*CONSTCOND*/ 0)
55 #endif
56 __RCSID("$NetBSD: ptree.c,v 1.5 2009/06/07 03:12:40 yamt Exp $");
57 #endif /* _KERNEL || _STANDALONE */
58 
59 #ifdef _LIBC
60 #include "namespace.h"
61 #endif
62 
63 #ifdef PTTEST
64 #include "ptree.h"
65 #else
66 #include <sys/ptree.h>
67 #endif
68 
69 /*
70  * This is an implementation of a radix / PATRICIA tree.  As in a traditional
71  * patricia tree, all the data is at the leaves of the tree.  An N-value
72  * tree would have N leaves, N-1 branching nodes, and a root pointer.  Each
73  * branching node would have left(0) and right(1) pointers that either point
74  * to another branching node or a leaf node.  The root pointer would also
75  * point to either the first branching node or a leaf node.  Leaf nodes
76  * have no need for pointers.
77  *
78  * However, allocation for these branching nodes is problematic since the
79  * allocation could fail.  This would cause insertions to fail for reasons
80  * beyond the users control.  So to prevent this, in this implementation
81  * each node has two identities: its leaf identity and its branch identity.
82  * Each is separate from the other.  Every branch is tagged as to whether
83  * it points to a leaf or a branch.  This is not an attribute of the object
84  * but of the pointer to the object.  The low bit of the pointer is used as
85  * the tag to determine whether it points to a leaf or branch identity, with
86  * branch identities having the low bit set.
87  *
88  * A node's branch identity has one rule: when traversing the tree from the
89  * root to the node's leaf identity, one of the branches traversed will be via
90  * the node's branch identity.  Of course, that has an exception: since to
91  * store N leaves, you need N-1 branches.  That one node whose branch identity
92  * isn't used is stored as "oddman"-out in the root.
93  *
94  * Branching nodes also has a bit offset and a bit length which determines
95  * which branch slot is used.  The bit length can be zero resulting in a
96  * one-way branch.  This is happens in two special cases: the root and
97  * interior mask nodes.
98  *
99  * To support longest match first lookups, when a mask node (one that only
100  * match the first N bits) has children who first N bits match the mask nodes,
101  * that mask node is converted from being a leaf node to being a one-way
102  * branch-node.  The mask becomes fixed in position in the tree.  The mask
103  * will always be the longest mask match for its descendants (unless they
104  * traverse an even longer match).
105  */
106 
107 #define	NODETOITEM(pt, ptn)	\
108 	((void *)((uintptr_t)(ptn) - (pt)->pt_node_offset))
109 #define	NODETOKEY(pt, ptn)	\
110 	((void *)((uintptr_t)(ptn) - (pt)->pt_node_offset + pt->pt_key_offset))
111 #define	ITEMTONODE(pt, ptn)	\
112 	((pt_node_t *)((uintptr_t)(ptn) + (pt)->pt_node_offset))
113 
114 bool ptree_check(const pt_tree_t *);
115 #if PTCHECK > 1
116 #define	PTREE_CHECK(pt)		ptree_check(pt)
117 #else
118 #define	PTREE_CHECK(pt)		do { } while (/*CONSTCOND*/ 0)
119 #endif
120 
121 static inline bool
122 ptree_matchnode(const pt_tree_t *pt, const pt_node_t *target,
123 	const pt_node_t *ptn, pt_bitoff_t max_bitoff,
124 	pt_bitoff_t *bitoff_p, pt_slot_t *slots_p)
125 {
126 	return (*pt->pt_ops->ptto_matchnode)(NODETOKEY(pt, target),
127 	    (ptn != NULL ? NODETOKEY(pt, ptn) : NULL), max_bitoff,
128 	    bitoff_p, slots_p);
129 }
130 
131 static inline pt_slot_t
132 ptree_testnode(const pt_tree_t *pt, const pt_node_t *target,
133 	const pt_node_t *ptn)
134 {
135 	const pt_bitlen_t bitlen = PTN_BRANCH_BITLEN(ptn);
136 	if (bitlen == 0)
137 		return PT_SLOT_ROOT;
138 	return (*pt->pt_ops->ptto_testnode)(NODETOKEY(pt, target),
139 	     PTN_BRANCH_BITOFF(ptn),
140 	     bitlen);
141 }
142 
143 static inline bool
144 ptree_matchkey(const pt_tree_t *pt, const void *key,
145 	const pt_node_t *ptn, pt_bitoff_t bitoff, pt_bitlen_t bitlen)
146 {
147 	return (*pt->pt_ops->ptto_matchkey)(key, NODETOKEY(pt, ptn),
148 	    bitoff, bitlen);
149 }
150 
151 static inline pt_slot_t
152 ptree_testkey(const pt_tree_t *pt, const void *key, const pt_node_t *ptn)
153 {
154 	return (*pt->pt_ops->ptto_testkey)(key,
155 	    PTN_BRANCH_BITOFF(ptn),
156 	    PTN_BRANCH_BITLEN(ptn));
157 }
158 
159 static inline void
160 ptree_set_position(uintptr_t node, pt_slot_t position)
161 {
162 	if (PT_LEAF_P(node))
163 		PTN_SET_LEAF_POSITION(PT_NODE(node), position);
164 	else
165 		PTN_SET_BRANCH_POSITION(PT_NODE(node), position);
166 }
167 
168 void
169 ptree_init(pt_tree_t *pt, const pt_tree_ops_t *ops, size_t node_offset,
170 	size_t key_offset)
171 {
172 	memset(pt, 0, sizeof(*pt));
173 	pt->pt_node_offset = node_offset;
174 	pt->pt_key_offset = key_offset;
175 	pt->pt_ops = ops;
176 }
177 
178 typedef struct {
179 	uintptr_t *id_insertp;
180 	pt_node_t *id_parent;
181 	uintptr_t id_node;
182 	pt_slot_t id_parent_slot;
183 	pt_bitoff_t id_bitoff;
184 	pt_slot_t id_slot;
185 } pt_insertdata_t;
186 
187 typedef bool (*pt_insertfunc_t)(pt_tree_t *, pt_node_t *, pt_insertdata_t *);
188 
189 /*
190  * Move a branch identify from src to dst.  The leaves don't care since
191  * nothing for them has changed.
192  */
193 /*ARGSUSED*/
194 static uintptr_t
195 ptree_move_branch(pt_tree_t * const pt, pt_node_t * const dst,
196 	const pt_node_t * const src)
197 {
198 	KASSERT(PTN_BRANCH_BITLEN(src) == 1);
199 	/* set branch bitlen and bitoff in one step.  */
200 	dst->ptn_branchdata = src->ptn_branchdata;
201 	PTN_SET_BRANCH_POSITION(dst, PTN_BRANCH_POSITION(src));
202 	PTN_COPY_BRANCH_SLOTS(dst, src);
203 	return PTN_BRANCH(dst);
204 }
205 
206 #ifndef PTNOMASK
207 static inline uintptr_t *
208 ptree_find_branch(pt_tree_t * const pt, uintptr_t branch_node)
209 {
210 	pt_node_t * const branch = PT_NODE(branch_node);
211 	pt_node_t *parent;
212 
213 	for (parent = &pt->pt_rootnode;;) {
214 		uintptr_t *nodep =
215 		    &PTN_BRANCH_SLOT(parent, ptree_testnode(pt, branch, parent));
216 		if (*nodep == branch_node)
217 			return nodep;
218 		if (PT_LEAF_P(*nodep))
219 			return NULL;
220 		parent = PT_NODE(*nodep);
221 	}
222 }
223 
224 static bool
225 ptree_insert_leaf_after_mask(pt_tree_t * const pt, pt_node_t * const target,
226 	pt_insertdata_t * const id)
227 {
228 	const uintptr_t target_node = PTN_LEAF(target);
229 	const uintptr_t mask_node = id->id_node;
230 	pt_node_t * const mask = PT_NODE(mask_node);
231 	const pt_bitlen_t mask_len = PTN_MASK_BITLEN(mask);
232 
233 	KASSERT(PT_LEAF_P(mask_node));
234 	KASSERT(PTN_LEAF_POSITION(mask) == id->id_parent_slot);
235 	KASSERT(mask_len <= id->id_bitoff);
236 	KASSERT(PTN_ISMASK_P(mask));
237 	KASSERT(!PTN_ISMASK_P(target) || mask_len < PTN_MASK_BITLEN(target));
238 
239 	if (mask_node == PTN_BRANCH_ODDMAN_SLOT(&pt->pt_rootnode)) {
240 		KASSERT(id->id_parent != mask);
241 		/*
242 		 * Nice, mask was an oddman.  So just set the oddman to target.
243 		 */
244 		PTN_BRANCH_ODDMAN_SLOT(&pt->pt_rootnode) = target_node;
245 	} else {
246 		/*
247 		 * We need to find out who's pointing to mask's branch
248 		 * identity.  We know that between root and the leaf identity,
249 		 * we must traverse the node's branch identity.
250 		 */
251 		uintptr_t * const mask_nodep = ptree_find_branch(pt, PTN_BRANCH(mask));
252 		KASSERT(mask_nodep != NULL);
253 		KASSERT(*mask_nodep == PTN_BRANCH(mask));
254 		KASSERT(PTN_BRANCH_BITLEN(mask) == 1);
255 
256 		/*
257 		 * Alas, mask was used as a branch.  Since the mask is becoming
258 		 * a one-way branch, we need make target take over mask's
259 		 * branching responsibilities.  Only then can we change it.
260 		 */
261 		*mask_nodep = ptree_move_branch(pt, target, mask);
262 
263 		/*
264 		 * However, it's possible that mask's parent is itself.  If
265 		 * that's true, update the insert point to use target since it
266 		 * has taken over mask's branching duties.
267 		 */
268 		if (id->id_parent == mask)
269 			id->id_insertp = &PTN_BRANCH_SLOT(target,
270 			    id->id_parent_slot);
271 	}
272 
273 	PTN_SET_BRANCH_BITLEN(mask, 0);
274 	PTN_SET_BRANCH_BITOFF(mask, mask_len);
275 
276 	PTN_BRANCH_ROOT_SLOT(mask) = target_node;
277 	PTN_BRANCH_ODDMAN_SLOT(mask) = PT_NULL;
278 	PTN_SET_LEAF_POSITION(target, PT_SLOT_ROOT);
279 	PTN_SET_BRANCH_POSITION(mask, id->id_parent_slot);
280 
281 	/*
282 	 * Now that everything is done, to make target visible we need to
283 	 * change mask from a leaf to a branch.
284 	 */
285 	*id->id_insertp = PTN_BRANCH(mask);
286 	PTREE_CHECK(pt);
287 	return true;
288 }
289 
290 /*ARGSUSED*/
291 static bool
292 ptree_insert_mask_before_node(pt_tree_t * const pt, pt_node_t * const target,
293 	pt_insertdata_t * const id)
294 {
295 	const uintptr_t node = id->id_node;
296 	pt_node_t * const ptn = PT_NODE(node);
297 	const pt_slot_t mask_len = PTN_MASK_BITLEN(target);
298 	const pt_bitlen_t node_mask_len = PTN_MASK_BITLEN(ptn);
299 
300 	KASSERT(PT_LEAF_P(node) || id->id_parent_slot == PTN_BRANCH_POSITION(ptn));
301 	KASSERT(PT_BRANCH_P(node) || id->id_parent_slot == PTN_LEAF_POSITION(ptn));
302 	KASSERT(PTN_ISMASK_P(target));
303 
304 	/*
305 	 * If the node we are placing ourself in front is a mask with the
306 	 * same mask length as us, return failure.
307 	 */
308 	if (PTN_ISMASK_P(ptn) && node_mask_len == mask_len)
309 		return false;
310 
311 	PTN_SET_BRANCH_BITLEN(target, 0);
312 	PTN_SET_BRANCH_BITOFF(target, mask_len);
313 
314 	PTN_BRANCH_SLOT(target, PT_SLOT_ROOT) = node;
315 	*id->id_insertp = PTN_BRANCH(target);
316 
317 	PTN_SET_BRANCH_POSITION(target, id->id_parent_slot);
318 	ptree_set_position(node, PT_SLOT_ROOT);
319 
320 	PTREE_CHECK(pt);
321 	return true;
322 }
323 #endif /* !PTNOMASK */
324 
325 /*ARGSUSED*/
326 static bool
327 ptree_insert_branch_at_node(pt_tree_t * const pt, pt_node_t * const target,
328 	pt_insertdata_t * const id)
329 {
330 	const uintptr_t target_node = PTN_LEAF(target);
331 	const uintptr_t node = id->id_node;
332 	const pt_slot_t other_slot = id->id_slot ^ PT_SLOT_OTHER;
333 
334 	KASSERT(PT_BRANCH_P(node) || id->id_parent_slot == PTN_LEAF_POSITION(PT_NODE(node)));
335 	KASSERT(PT_LEAF_P(node) || id->id_parent_slot == PTN_BRANCH_POSITION(PT_NODE(node)));
336 	KASSERT((node == pt->pt_root) == (id->id_parent == &pt->pt_rootnode));
337 #ifndef PTNOMASK
338 	KASSERT(!PTN_ISMASK_P(target) || id->id_bitoff <= PTN_MASK_BITLEN(target));
339 #endif
340 	KASSERT(node == pt->pt_root || PTN_BRANCH_BITOFF(id->id_parent) + PTN_BRANCH_BITLEN(id->id_parent) <= id->id_bitoff);
341 
342 	PTN_SET_BRANCH_BITOFF(target, id->id_bitoff);
343 	PTN_SET_BRANCH_BITLEN(target, 1);
344 
345 	PTN_BRANCH_SLOT(target, id->id_slot) = target_node;
346 	PTN_BRANCH_SLOT(target, other_slot) = node;
347 	*id->id_insertp = PTN_BRANCH(target);
348 
349 	PTN_SET_LEAF_POSITION(target, id->id_slot);
350 	ptree_set_position(node, other_slot);
351 
352 	PTN_SET_BRANCH_POSITION(target, id->id_parent_slot);
353 	PTREE_CHECK(pt);
354 	return true;
355 }
356 
357 static bool
358 ptree_insert_leaf(pt_tree_t * const pt, pt_node_t * const target,
359 	pt_insertdata_t * const id)
360 {
361 	const uintptr_t leaf_node = id->id_node;
362 	pt_node_t * const leaf = PT_NODE(leaf_node);
363 #ifdef PTNOMASK
364 	const bool inserting_mask = false;
365 	const bool at_mask = false;
366 #else
367 	const bool inserting_mask = PTN_ISMASK_P(target);
368 	const bool at_mask = PTN_ISMASK_P(leaf);
369 	const pt_bitlen_t leaf_masklen = PTN_MASK_BITLEN(leaf);
370 	const pt_bitlen_t target_masklen = PTN_MASK_BITLEN(target);
371 #endif
372 	pt_insertfunc_t insertfunc = ptree_insert_branch_at_node;
373 	bool matched;
374 
375 	/*
376 	 * In all likelyhood we are going simply going to insert a branch
377 	 * where this leaf is which will point to the old and new leaves.
378 	 */
379 	KASSERT(PT_LEAF_P(leaf_node));
380 	KASSERT(PTN_LEAF_POSITION(leaf) == id->id_parent_slot);
381 	matched = ptree_matchnode(pt, target, leaf, UINT_MAX,
382 	    &id->id_bitoff, &id->id_slot);
383 	if (__predict_false(!inserting_mask)) {
384 		/*
385 		 * We aren't inserting a mask nor is the leaf a mask, which
386 		 * means we are trying to insert a duplicate leaf.  Can't do
387 		 * that.
388 		 */
389 		if (!at_mask && matched)
390 			return false;
391 
392 #ifndef PTNOMASK
393 		/*
394 		 * We are at a mask and the leaf we are about to insert
395 		 * is at or beyond the mask, we need to convert the mask
396 		 * from a leaf to a one-way branch interior mask.
397 		 */
398 		if (at_mask && id->id_bitoff >= leaf_masklen)
399 			insertfunc = ptree_insert_leaf_after_mask;
400 #endif /* PTNOMASK */
401 	}
402 #ifndef PTNOMASK
403 	else {
404 		/*
405 		 * We are inserting a mask.
406 		 */
407 		if (matched) {
408 			/*
409 			 * If the leaf isn't a mask, we obviously have to
410 			 * insert the new mask before non-mask leaf.  If the
411 			 * leaf is a mask, and the new node has a LEQ mask
412 			 * length it too needs to inserted before leaf (*).
413 			 *
414 			 * In other cases, we place the new mask as leaf after
415 			 * leaf mask.  Which mask comes first will be a one-way
416 			 * branch interior mask node which has the other mask
417 			 * node as a child.
418 			 *
419 			 * (*) ptree_insert_mask_before_node can detect a
420 			 * duplicate mask and return failure if needed.
421 			 */
422 			if (!at_mask || target_masklen <= leaf_masklen)
423 				insertfunc = ptree_insert_mask_before_node;
424 			else
425 				insertfunc = ptree_insert_leaf_after_mask;
426 		} else if (at_mask && id->id_bitoff >= leaf_masklen) {
427 			/*
428 			 * If the new mask has a bit offset GEQ than the leaf's
429 			 * mask length, convert the left to a one-way branch
430 			 * interior mask and make that point to the new [leaf]
431 			 * mask.
432 			 */
433 			insertfunc = ptree_insert_leaf_after_mask;
434 		} else {
435 			/*
436 			 * The new mask has a bit offset less than the leaf's
437 			 * mask length or if the leaf isn't a mask at all, the
438 			 * new mask deserves to be its own leaf so we use the
439 			 * default insertfunc to do that.
440 			 */
441 		}
442 	}
443 #endif /* PTNOMASK */
444 
445 	return (*insertfunc)(pt, target, id);
446 }
447 
448 static bool
449 ptree_insert_node_common(pt_tree_t *pt, void *item)
450 {
451 	pt_node_t * const target = ITEMTONODE(pt, item);
452 #ifndef PTNOMASK
453 	const bool inserting_mask = PTN_ISMASK_P(target);
454 	const pt_bitlen_t target_masklen = PTN_MASK_BITLEN(target);
455 #endif
456 	pt_insertfunc_t insertfunc;
457 	pt_insertdata_t id;
458 
459 	/*
460 	 * We need a leaf so we can match against.  Until we get a leaf
461 	 * we having nothing to test against.
462 	 */
463 	if (__predict_false(PT_NULL_P(pt->pt_root))) {
464 		PTN_BRANCH_ROOT_SLOT(&pt->pt_rootnode) = PTN_LEAF(target);
465 		PTN_BRANCH_ODDMAN_SLOT(&pt->pt_rootnode) = PTN_LEAF(target);
466 		PTN_SET_LEAF_POSITION(target, PT_SLOT_ROOT);
467 		PTREE_CHECK(pt);
468 		return true;
469 	}
470 
471 	id.id_bitoff = 0;
472 	id.id_parent = &pt->pt_rootnode;
473 	id.id_parent_slot = PT_SLOT_ROOT;
474 	id.id_insertp = &PTN_BRANCH_ROOT_SLOT(id.id_parent);
475 	for (;;) {
476 		pt_bitoff_t branch_bitoff;
477 		pt_node_t * const ptn = PT_NODE(*id.id_insertp);
478 		id.id_node = *id.id_insertp;
479 
480 		/*
481 		 * If we hit a leaf, try to insert target at leaf.  We could
482 		 * have inlined ptree_insert_leaf here but that would have
483 		 * made this routine much harder to understand.  Trust the
484 		 * compiler to optimize this properly.
485 		 */
486 		if (PT_LEAF_P(id.id_node)) {
487 			KASSERT(PTN_LEAF_POSITION(ptn) == id.id_parent_slot);
488 			insertfunc = ptree_insert_leaf;
489 			break;
490 		}
491 
492 		/*
493 		 * If we aren't a leaf, we must be a branch.  Make sure we are
494 		 * in the slot we think we are.
495 		 */
496 		KASSERT(PT_BRANCH_P(id.id_node));
497 		KASSERT(PTN_BRANCH_POSITION(ptn) == id.id_parent_slot);
498 
499 		/*
500 		 * Where is this branch?
501 		 */
502 		branch_bitoff = PTN_BRANCH_BITOFF(ptn);
503 
504 #ifndef PTNOMASK
505 		/*
506 		 * If this is a one-way mask node, its offset must equal
507 		 * its mask's bitlen.
508 		 */
509 		KASSERT(!(PTN_ISMASK_P(ptn) && PTN_BRANCH_BITLEN(ptn) == 0) || PTN_MASK_BITLEN(ptn) == branch_bitoff);
510 
511 		/*
512 		 * If we are inserting a mask, and we know that at this point
513 		 * all bits before the current bit offset match both the target
514 		 * and the branch.  If the target's mask length is LEQ than
515 		 * this branch's bit offset, then this is where the mask needs
516 		 * to added to the tree.
517 		 */
518 		if (__predict_false(inserting_mask)
519 		    && (PTN_ISROOT_P(pt, id.id_parent)
520 			|| id.id_bitoff < target_masklen)
521 		    && target_masklen <= branch_bitoff) {
522 			/*
523 			 * We don't know about the bits (if any) between
524 			 * id.id_bitoff and the target's mask length match
525 			 * both the target and the branch.  If the target's
526 			 * mask length is greater than the current bit offset
527 			 * make sure the untested bits match both the target
528 			 * and the branch.
529 			 */
530 			if (target_masklen == id.id_bitoff
531 			    || ptree_matchnode(pt, target, ptn, target_masklen,
532 				    &id.id_bitoff, &id.id_slot)) {
533 				/*
534 				 * The bits matched, so insert the mask as a
535 				 * one-way branch.
536 				 */
537 				insertfunc = ptree_insert_mask_before_node;
538 				break;
539 			} else if (id.id_bitoff < branch_bitoff) {
540 				/*
541 				 * They didn't match, so create a normal branch
542 				 * because this mask needs to a be a new leaf.
543 				 */
544 				insertfunc = ptree_insert_branch_at_node;
545 				break;
546 			}
547 		}
548 #endif /* PTNOMASK */
549 
550 		/*
551 		 * If we are skipping some bits, verify they match the node.
552 		 * If they don't match, it means we have a leaf to insert.
553 		 * Note that if we are advancing bit by bit, we'll skip
554 		 * doing matchnode and walk the tree bit by bit via testnode.
555 		 */
556 		if (id.id_bitoff < branch_bitoff
557 		    && !ptree_matchnode(pt, target, ptn, branch_bitoff,
558 					&id.id_bitoff, &id.id_slot)) {
559 			KASSERT(id.id_bitoff < branch_bitoff);
560 			insertfunc = ptree_insert_branch_at_node;
561 			break;
562 		}
563 
564 		/*
565 		 * At this point, all bits before branch_bitoff are known
566 		 * to match the target.
567 		 */
568 		KASSERT(id.id_bitoff >= branch_bitoff);
569 
570 		/*
571 		 * Decend the tree one level.
572 		 */
573 		id.id_parent = ptn;
574 		id.id_parent_slot = ptree_testnode(pt, target, id.id_parent);
575 		id.id_bitoff += PTN_BRANCH_BITLEN(id.id_parent);
576 		id.id_insertp = &PTN_BRANCH_SLOT(id.id_parent, id.id_parent_slot);
577 	}
578 
579 	/*
580 	 * Do the actual insertion.
581 	 */
582 	return (*insertfunc)(pt, target, &id);
583 }
584 
585 bool
586 ptree_insert_node(pt_tree_t *pt, void *item)
587 {
588 	pt_node_t * const target = ITEMTONODE(pt, item);
589 
590 	memset(target, 0, sizeof(*target));
591 	return ptree_insert_node_common(pt, target);
592 }
593 
594 #ifndef PTNOMASK
595 bool
596 ptree_insert_mask_node(pt_tree_t *pt, void *item, pt_bitlen_t mask_len)
597 {
598 	pt_node_t * const target = ITEMTONODE(pt, item);
599 	pt_bitoff_t bitoff = mask_len;
600 	pt_slot_t slot;
601 
602 	memset(target, 0, sizeof(*target));
603 	KASSERT(mask_len == 0 || (~PT__MASK(PTN_MASK_BITLEN) & mask_len) == 0);
604 	/*
605 	 * Only the first <mask_len> bits can be non-zero.
606 	 * All other bits must be 0.
607 	 */
608 	if (!ptree_matchnode(pt, target, NULL, UINT_MAX, &bitoff, &slot))
609 		return false;
610 	PTN_SET_MASK_BITLEN(target, mask_len);
611 	PTN_MARK_MASK(target);
612 	return ptree_insert_node_common(pt, target);
613 }
614 #endif /* !PTNOMASH */
615 
616 void *
617 ptree_find_filtered_node(pt_tree_t *pt, void *key, pt_filter_t filter,
618 	void *filter_arg)
619 {
620 #ifndef PTNOMASK
621 	pt_node_t *mask = NULL;
622 #endif
623 	bool at_mask = false;
624 	pt_node_t *ptn, *parent;
625 	pt_bitoff_t bitoff;
626 	pt_slot_t parent_slot;
627 
628 	if (PT_NULL_P(PTN_BRANCH_ROOT_SLOT(&pt->pt_rootnode)))
629 		return NULL;
630 
631 	bitoff = 0;
632 	parent = &pt->pt_rootnode;
633 	parent_slot = PT_SLOT_ROOT;
634 	for (;;) {
635 		const uintptr_t node = PTN_BRANCH_SLOT(parent, parent_slot);
636 		const pt_slot_t branch_bitoff = PTN_BRANCH_BITOFF(PT_NODE(node));
637 		ptn = PT_NODE(node);
638 
639 		if (PT_LEAF_P(node)) {
640 #ifndef PTNOMASK
641 			at_mask = PTN_ISMASK_P(ptn);
642 #endif
643 			break;
644 		}
645 
646 		if (bitoff < branch_bitoff) {
647 			if (!ptree_matchkey(pt, key, ptn, bitoff, branch_bitoff - bitoff)) {
648 #ifndef PTNOMASK
649 				if (mask != NULL)
650 					return NODETOITEM(pt, mask);
651 #endif
652 				return NULL;
653 			}
654 			bitoff = branch_bitoff;
655 		}
656 
657 #ifndef PTNOMASK
658 		if (PTN_ISMASK_P(ptn) && PTN_BRANCH_BITLEN(ptn) == 0
659 		    && (!filter
660 		        || (*filter)(filter_arg, NODETOITEM(pt, ptn),
661 				     PT_FILTER_MASK)))
662 			mask = ptn;
663 #endif
664 
665 		parent = ptn;
666 		parent_slot = ptree_testkey(pt, key, parent);
667 		bitoff += PTN_BRANCH_BITLEN(parent);
668 	}
669 
670 	KASSERT(PTN_ISROOT_P(pt, parent) || PTN_BRANCH_BITOFF(parent) + PTN_BRANCH_BITLEN(parent) == bitoff);
671 	if (!filter || (*filter)(filter_arg, NODETOITEM(pt, ptn), at_mask ? PT_FILTER_MASK : 0)) {
672 #ifndef PTNOMASK
673 		if (PTN_ISMASK_P(ptn)) {
674 			const pt_bitlen_t mask_len = PTN_MASK_BITLEN(ptn);
675 			if (bitoff == PTN_MASK_BITLEN(ptn))
676 				return NODETOITEM(pt, ptn);
677 			if (ptree_matchkey(pt, key, ptn, bitoff, mask_len - bitoff))
678 				return NODETOITEM(pt, ptn);
679 		} else
680 #endif /* !PTNOMASK */
681 		if (ptree_matchkey(pt, key, ptn, bitoff, UINT_MAX))
682 			return NODETOITEM(pt, ptn);
683 	}
684 
685 #ifndef PTNOMASK
686 	/*
687 	 * By virtue of how the mask was placed in the tree,
688 	 * all nodes descended from it will match it.  But the bits
689 	 * before the mask still need to be checked and since the
690 	 * mask was a branch, that was done implicitly.
691 	 */
692 	if (mask != NULL) {
693 		KASSERT(ptree_matchkey(pt, key, mask, 0, PTN_MASK_BITLEN(mask)));
694 		return NODETOITEM(pt, mask);
695 	}
696 #endif /* !PTNOMASK */
697 
698 	/*
699 	 * Nothing matched.
700 	 */
701 	return NULL;
702 }
703 
704 void *
705 ptree_iterate(pt_tree_t *pt, const void *item, pt_direction_t direction)
706 {
707 	const pt_node_t * const target = ITEMTONODE(pt, item);
708 	uintptr_t node, next_node;
709 
710 	if (direction != PT_ASCENDING && direction != PT_DESCENDING)
711 		return NULL;
712 
713 	node = PTN_BRANCH_ROOT_SLOT(&pt->pt_rootnode);
714 	if (PT_NULL_P(node))
715 		return NULL;
716 
717 	if (item == NULL) {
718 		pt_node_t * const ptn = PT_NODE(node);
719 		if (direction == PT_ASCENDING
720 		    && PTN_ISMASK_P(ptn) && PTN_BRANCH_BITLEN(ptn) == 0)
721 			return NODETOITEM(pt, ptn);
722 		next_node = node;
723 	} else {
724 #ifndef PTNOMASK
725 		uintptr_t mask_node = PT_NULL;
726 #endif /* !PTNOMASK */
727 		next_node = PT_NULL;
728 		while (!PT_LEAF_P(node)) {
729 			pt_node_t * const ptn = PT_NODE(node);
730 			pt_slot_t slot;
731 #ifndef PTNOMASK
732 			if (PTN_ISMASK_P(ptn) && PTN_BRANCH_BITLEN(ptn) == 0) {
733 				if (ptn == target)
734 					break;
735 				if (direction == PT_DESCENDING) {
736 					mask_node = node;
737 					next_node = PT_NULL;
738 				}
739 			}
740 #endif /* !PTNOMASK */
741 			slot = ptree_testnode(pt, target, ptn);
742 			node = PTN_BRANCH_SLOT(ptn, slot);
743 			if (direction == PT_ASCENDING) {
744 				if (slot != (pt_slot_t)((1 << PTN_BRANCH_BITLEN(ptn)) - 1))
745 					next_node = PTN_BRANCH_SLOT(ptn, slot + 1);
746 			} else {
747 				if (slot > 0) {
748 #ifndef PTNOMASK
749 					mask_node = PT_NULL;
750 #endif /* !PTNOMASK */
751 					next_node = PTN_BRANCH_SLOT(ptn, slot - 1);
752 				}
753 			}
754 		}
755 		if (PT_NODE(node) != target)
756 			return NULL;
757 #ifndef PTNOMASK
758 		if (PT_BRANCH_P(node)) {
759 			pt_node_t *ptn = PT_NODE(node);
760 			KASSERT(PTN_ISMASK_P(PT_NODE(node)) && PTN_BRANCH_BITLEN(PT_NODE(node)) == 0);
761 			if (direction == PT_ASCENDING) {
762 				next_node = PTN_BRANCH_ROOT_SLOT(ptn);
763 				ptn = PT_NODE(next_node);
764 			}
765 		}
766 		/*
767 		 * When descending, if we countered a mask node then that's
768 		 * we want to return.
769 		 */
770 		if (direction == PT_DESCENDING && !PT_NULL_P(mask_node)) {
771 			KASSERT(PT_NULL_P(next_node));
772 			return NODETOITEM(pt, PT_NODE(mask_node));
773 		}
774 #endif /* !PTNOMASK */
775 	}
776 
777 	node = next_node;
778 	if (PT_NULL_P(node))
779 		return NULL;
780 
781 	while (!PT_LEAF_P(node)) {
782 		pt_node_t * const ptn = PT_NODE(node);
783 		pt_slot_t slot;
784 		if (direction == PT_ASCENDING) {
785 #ifndef PTNOMASK
786 			if (PT_BRANCH_P(node)
787 			    && PTN_ISMASK_P(ptn)
788 			    && PTN_BRANCH_BITLEN(ptn) == 0)
789 				return NODETOITEM(pt, ptn);
790 #endif /* !PTNOMASK */
791 			slot = PT_SLOT_LEFT;
792 		} else {
793 			slot = (1 << PTN_BRANCH_BITLEN(ptn)) - 1;
794 		}
795 		node = PTN_BRANCH_SLOT(ptn, slot);
796 	}
797 	return NODETOITEM(pt, PT_NODE(node));
798 }
799 
800 void
801 ptree_remove_node(pt_tree_t *pt, void *item)
802 {
803 	pt_node_t * const target = ITEMTONODE(pt, item);
804 	const pt_slot_t leaf_slot = PTN_LEAF_POSITION(target);
805 	const pt_slot_t branch_slot = PTN_BRANCH_POSITION(target);
806 	pt_node_t *ptn, *parent;
807 	uintptr_t node;
808 	uintptr_t *removep;
809 	uintptr_t *nodep;
810 	pt_bitoff_t bitoff;
811 	pt_slot_t parent_slot;
812 #ifndef PTNOMASK
813 	bool at_mask;
814 #endif
815 
816 	if (PT_NULL_P(PTN_BRANCH_ROOT_SLOT(&pt->pt_rootnode))) {
817 		KASSERT(!PT_NULL_P(PTN_BRANCH_ROOT_SLOT(&pt->pt_rootnode)));
818 		return;
819 	}
820 
821 	bitoff = 0;
822 	removep = NULL;
823 	nodep = NULL;
824 	parent = &pt->pt_rootnode;
825 	parent_slot = PT_SLOT_ROOT;
826 	for (;;) {
827 		node = PTN_BRANCH_SLOT(parent, parent_slot);
828 		ptn = PT_NODE(node);
829 #ifndef PTNOMASK
830 		at_mask = PTN_ISMASK_P(ptn);
831 #endif
832 
833 		if (PT_LEAF_P(node))
834 			break;
835 
836 		/*
837 		 * If we are at the target, then we are looking at its branch
838 		 * identity.  We need to remember who's pointing at it so we
839 		 * stop them from doing that.
840 		 */
841 		if (__predict_false(ptn == target)) {
842 			KASSERT(nodep == NULL);
843 #ifndef PTNOMASK
844 			/*
845 			 * Interior mask nodes are trivial to get rid of.
846 			 */
847 			if (at_mask && PTN_BRANCH_BITLEN(ptn) == 0) {
848 				PTN_BRANCH_SLOT(parent, parent_slot) =
849 				    PTN_BRANCH_ROOT_SLOT(ptn);
850 				KASSERT(PT_NULL_P(PTN_BRANCH_ODDMAN_SLOT(ptn)));
851 				PTREE_CHECK(pt);
852 				return;
853 			}
854 #endif /* !PTNOMASK */
855 			nodep = &PTN_BRANCH_SLOT(parent, parent_slot);
856 			KASSERT(*nodep == PTN_BRANCH(target));
857 		}
858 		/*
859 		 * We need also need to know who's pointing at our parent.
860 		 * After we remove ourselves from our parent, he'll only
861 		 * have one child and that's unacceptable.  So we replace
862 		 * the pointer to the parent with our abadoned sibling.
863 		 */
864 		removep = &PTN_BRANCH_SLOT(parent, parent_slot);
865 
866 		/*
867 		 * Descend into the tree.
868 		 */
869 		parent = ptn;
870 		parent_slot = ptree_testnode(pt, target, parent);
871 		bitoff += PTN_BRANCH_BITLEN(parent);
872 	}
873 
874 	/*
875 	 * We better have found that the leaf we are looking for is target.
876 	 */
877 	if (target != ptn) {
878 		KASSERT(target == ptn);
879 		return;
880 	}
881 
882 	/*
883 	 * If we didn't encounter target as branch, then target must be the
884 	 * oddman-out.
885 	 */
886 	if (nodep == NULL) {
887 		KASSERT(PTN_BRANCH_ODDMAN_SLOT(&pt->pt_rootnode) == PTN_LEAF(target));
888 		KASSERT(nodep == NULL);
889 		nodep = &PTN_BRANCH_ODDMAN_SLOT(&pt->pt_rootnode);
890 	}
891 
892 	KASSERT((removep == NULL) == (parent == &pt->pt_rootnode));
893 
894 	/*
895 	 * We have to special remove the last leaf from the root since
896 	 * the only time the tree can a PT_NULL node is when it's empty.
897 	 */
898 	if (__predict_false(PTN_ISROOT_P(pt, parent))) {
899 		KASSERT(removep == NULL);
900 		KASSERT(parent == &pt->pt_rootnode);
901 		KASSERT(nodep == &PTN_BRANCH_ODDMAN_SLOT(&pt->pt_rootnode));
902 		KASSERT(*nodep == PTN_LEAF(target));
903 		PTN_BRANCH_ROOT_SLOT(&pt->pt_rootnode) = PT_NULL;
904 		PTN_BRANCH_ODDMAN_SLOT(&pt->pt_rootnode) = PT_NULL;
905 		return;
906 	}
907 
908 	KASSERT((parent == target) == (removep == nodep));
909 	if (PTN_BRANCH(parent) == PTN_BRANCH_SLOT(target, PTN_BRANCH_POSITION(parent))) {
910 		/*
911 		 * The pointer to the parent actually lives in the target's
912 		 * branch identity.  We can't just move the target's branch
913 		 * identity since that would result in the parent pointing
914 		 * to its own branch identity and that's fobidden.
915 		 */
916 		const pt_slot_t slot = PTN_BRANCH_POSITION(parent);
917 		const pt_slot_t other_slot = slot ^ PT_SLOT_OTHER;
918 		const pt_bitlen_t parent_bitlen = PTN_BRANCH_BITLEN(parent);
919 
920 		KASSERT(PTN_BRANCH_BITOFF(target) < PTN_BRANCH_BITOFF(parent));
921 
922 		/*
923 		 * This gets so confusing.  The target's branch identity
924 		 * points to the branch identity of the parent of the target's
925 		 * leaf identity:
926 		 *
927 		 * 	TB = { X, PB = { TL, Y } }
928 		 *   or TB = { X, PB = { TL } }
929 		 *
930 		 * So we can't move the target's branch identity to the parent
931 		 * because that would corrupt the tree.
932 		 */
933 		if (__predict_true(parent_bitlen > 0)) {
934 			/*
935 			 * The parent is a two-way branch.  We have to have
936 			 * do to this chang in two steps to keep internally
937 			 * consistent.  First step is to copy our sibling from
938 			 * our parent to where we are pointing to parent's
939 			 * branch identiy.  This remove all references to his
940 			 * branch identity from the tree.  We then simply make
941 			 * the parent assume the target's branching duties.
942 			 *
943 			 *   TB = { X, PB = { Y, TL } } --> PB = { X, Y }.
944 			 *   TB = { X, PB = { TL, Y } } --> PB = { X, Y }.
945 			 *   TB = { PB = { Y, TL }, X } --> PB = { Y, X }.
946 			 *   TB = { PB = { TL, Y }, X } --> PB = { Y, X }.
947 			 */
948 			PTN_BRANCH_SLOT(target, slot) =
949 			    PTN_BRANCH_SLOT(parent, parent_slot ^ PT_SLOT_OTHER);
950 			*nodep = ptree_move_branch(pt, parent, target);
951 			PTREE_CHECK(pt);
952 			return;
953 		} else {
954 			/*
955 			 * If parent was a one-way branch, it must have been
956 			 * mask which pointed to a single leaf which we are
957 			 * removing.  This means we have to convert the
958 			 * parent back to a leaf node.  So in the same
959 			 * position that target pointed to parent, we place
960 			 * leaf pointer to parent.  In the other position,
961 			 * we just put the other node from target.
962 			 *
963 			 *   TB = { X, PB = { TL } } --> PB = { X, PL }
964 			 */
965 			KASSERT(PTN_ISMASK_P(parent));
966 			KASSERT(slot == ptree_testnode(pt, parent, target));
967 			PTN_BRANCH_SLOT(parent, slot) = PTN_LEAF(parent);
968 			PTN_BRANCH_SLOT(parent, other_slot) =
969 			   PTN_BRANCH_SLOT(target, other_slot);
970 			PTN_SET_LEAF_POSITION(parent,slot);
971 			PTN_SET_BRANCH_BITLEN(parent, 1);
972 		}
973 		PTN_SET_BRANCH_BITOFF(parent, PTN_BRANCH_BITOFF(target));
974 		PTN_SET_BRANCH_POSITION(parent, PTN_BRANCH_POSITION(target));
975 
976 		*nodep = PTN_BRANCH(parent);
977 		PTREE_CHECK(pt);
978 		return;
979 	}
980 
981 #ifndef PTNOMASK
982 	if (__predict_false(PTN_BRANCH_BITLEN(parent) == 0)) {
983 		/*
984 		 * Parent was a one-way branch which is changing back to a leaf.
985 		 * Since parent is no longer a one-way branch, it can take over
986 		 * target's branching duties.
987 		 *
988 		 *  GB = { PB = { TL } }	--> GB = { PL }
989 		 *  TB = { X, Y }		--> PB = { X, Y }
990 		 */
991 		KASSERT(PTN_ISMASK_P(parent));
992 		KASSERT(parent != target);
993 		*removep = PTN_LEAF(parent);
994 	} else
995 #endif /* !PTNOMASK */
996 	{
997 		/*
998 		 * Now we are the normal removal case.  Since after the
999 		 * target's leaf identity is removed from the its parent,
1000 		 * that parent will only have one decendent.  So we can
1001 		 * just as easily replace the node that has the parent's
1002 		 * branch identity with the surviving node.  This freeing
1003 		 * parent from its branching duties which means it can
1004 		 * take over target's branching duties.
1005 		 *
1006 		 *  GB = { PB = { X, TL } }	--> GB = { X }
1007 		 *  TB = { V, W }		--> PB = { V, W }
1008 		 */
1009 		const pt_slot_t other_slot = parent_slot ^ PT_SLOT_OTHER;
1010 		uintptr_t other_node = PTN_BRANCH_SLOT(parent, other_slot);
1011 		const pt_slot_t target_slot = (parent == target ? branch_slot : leaf_slot);
1012 
1013 		*removep = other_node;
1014 
1015 		ptree_set_position(other_node, target_slot);
1016 
1017 		/*
1018 		 * If target's branch identity contained its leaf identity, we
1019 		 * have nothing left to do.  We've already moved 'X' so there
1020 		 * is no longer anything in the target's branch identiy that
1021 		 * has to be preserved.
1022 		 */
1023 		if (parent == target) {
1024 			/*
1025 			 *  GB = { TB = { X, TL } }	--> GB = { X }
1026 			 *  TB = { X, TL }		--> don't care
1027 			 */
1028 			PTREE_CHECK(pt);
1029 			return;
1030 		}
1031 	}
1032 
1033 	/*
1034 	 * If target wasn't used as a branch, then it must have been the
1035 	 * oddman-out of the tree (the one node that doesn't have a branch
1036 	 * identity).  This makes parent the new oddman-out.
1037 	 */
1038 	if (*nodep == PTN_LEAF(target)) {
1039 		KASSERT(nodep == &PTN_BRANCH_ODDMAN_SLOT(&pt->pt_rootnode));
1040 		PTN_BRANCH_ODDMAN_SLOT(&pt->pt_rootnode) = PTN_LEAF(parent);
1041 		PTREE_CHECK(pt);
1042 		return;
1043 	}
1044 
1045 	/*
1046 	 * Finally move the target's branching duties to the parent.
1047 	 */
1048 	KASSERT(PTN_BRANCH_BITOFF(parent) > PTN_BRANCH_BITOFF(target));
1049 	*nodep = ptree_move_branch(pt, parent, target);
1050 	PTREE_CHECK(pt);
1051 }
1052 
1053 #ifdef PTCHECK
1054 static const pt_node_t *
1055 ptree_check_find_node2(const pt_tree_t *pt, const pt_node_t *parent,
1056 	uintptr_t target)
1057 {
1058 	const pt_bitlen_t slots = 1 << PTN_BRANCH_BITLEN(parent);
1059 	pt_slot_t slot;
1060 
1061 	for (slot = 0; slot < slots; slot++) {
1062 		const uintptr_t node = PTN_BRANCH_SLOT(parent, slot);
1063 		if (PTN_BRANCH_SLOT(parent, slot) == node)
1064 			return parent;
1065 	}
1066 	for (slot = 0; slot < slots; slot++) {
1067 		const uintptr_t node = PTN_BRANCH_SLOT(parent, slot);
1068 		const pt_node_t *branch;
1069 		if (!PT_BRANCH_P(node))
1070 			continue;
1071 		branch = ptree_check_find_node2(pt, PT_NODE(node), target);
1072 		if (branch != NULL)
1073 			return branch;
1074 	}
1075 
1076 	return NULL;
1077 }
1078 
1079 static bool
1080 ptree_check_leaf(const pt_tree_t *pt, const pt_node_t *parent,
1081 	const pt_node_t *ptn)
1082 {
1083 	const pt_bitoff_t leaf_position = PTN_LEAF_POSITION(ptn);
1084 	const pt_bitlen_t bitlen = PTN_BRANCH_BITLEN(ptn);
1085 	const pt_bitlen_t mask_len = PTN_MASK_BITLEN(ptn);
1086 	const uintptr_t leaf_node = PTN_LEAF(ptn);
1087 	const bool is_parent_root = (parent == &pt->pt_rootnode);
1088 	const bool is_mask = PTN_ISMASK_P(ptn);
1089 	bool ok = true;
1090 
1091 	if (is_parent_root) {
1092 		ok = ok && PTN_BRANCH_ODDMAN_SLOT(parent) == leaf_node;
1093 		KASSERT(ok);
1094 		return ok;
1095 	}
1096 
1097 	if (is_mask && PTN_ISMASK_P(parent) && PTN_BRANCH_BITLEN(parent) == 0) {
1098 		ok = ok && PTN_MASK_BITLEN(parent) < mask_len;
1099 		KASSERT(ok);
1100 		ok = ok && PTN_BRANCH_BITOFF(parent) < mask_len;
1101 		KASSERT(ok);
1102 	}
1103 	ok = ok && PTN_BRANCH_SLOT(parent, leaf_position) == leaf_node;
1104 	KASSERT(ok);
1105 	ok = ok && leaf_position == ptree_testnode(pt, ptn, parent);
1106 	KASSERT(ok);
1107 	if (PTN_BRANCH_ODDMAN_SLOT(&pt->pt_rootnode) != leaf_node) {
1108 		ok = ok && bitlen > 0;
1109 		KASSERT(ok);
1110 		ok = ok && ptn == ptree_check_find_node2(pt, ptn, PTN_LEAF(ptn));
1111 		KASSERT(ok);
1112 	}
1113 	return ok;
1114 }
1115 
1116 static bool
1117 ptree_check_branch(const pt_tree_t *pt, const pt_node_t *parent,
1118 	const pt_node_t *ptn)
1119 {
1120 	const bool is_parent_root = (parent == &pt->pt_rootnode);
1121 	const pt_slot_t branch_slot = PTN_BRANCH_POSITION(ptn);
1122 	const pt_bitoff_t bitoff = PTN_BRANCH_BITOFF(ptn);
1123 	const pt_bitoff_t bitlen = PTN_BRANCH_BITLEN(ptn);
1124 	const pt_bitoff_t parent_bitoff = PTN_BRANCH_BITOFF(parent);
1125 	const pt_bitoff_t parent_bitlen = PTN_BRANCH_BITLEN(parent);
1126 	const bool is_parent_mask = PTN_ISMASK_P(parent) && parent_bitlen == 0;
1127 	const bool is_mask = PTN_ISMASK_P(ptn) && bitlen == 0;
1128 	const pt_bitoff_t parent_mask_len = PTN_MASK_BITLEN(parent);
1129 	const pt_bitoff_t mask_len = PTN_MASK_BITLEN(ptn);
1130 	const pt_bitlen_t slots = 1 << bitlen;
1131 	pt_slot_t slot;
1132 	bool ok = true;
1133 
1134 	ok = ok && PTN_BRANCH_SLOT(parent, branch_slot) == PTN_BRANCH(ptn);
1135 	KASSERT(ok);
1136 	ok = ok && branch_slot == ptree_testnode(pt, ptn, parent);
1137 	KASSERT(ok);
1138 
1139 	if (is_mask) {
1140 		ok = ok && bitoff == mask_len;
1141 		KASSERT(ok);
1142 		if (is_parent_mask) {
1143 			ok = ok && parent_mask_len < mask_len;
1144 			KASSERT(ok);
1145 			ok = ok && parent_bitoff < bitoff;
1146 			KASSERT(ok);
1147 		}
1148 	} else {
1149 		if (is_parent_mask) {
1150 			ok = ok && parent_bitoff <= bitoff;
1151 		} else if (!is_parent_root) {
1152 			ok = ok && parent_bitoff < bitoff;
1153 		}
1154 		KASSERT(ok);
1155 	}
1156 
1157 	for (slot = 0; slot < slots; slot++) {
1158 		const uintptr_t node = PTN_BRANCH_SLOT(ptn, slot);
1159 		pt_bitoff_t tmp_bitoff = 0;
1160 		pt_slot_t tmp_slot;
1161 		ok = ok && node != PTN_BRANCH(ptn);
1162 		KASSERT(ok);
1163 		if (bitlen > 0) {
1164 			ok = ok && ptree_matchnode(pt, PT_NODE(node), ptn, bitoff, &tmp_bitoff, &tmp_slot);
1165 			KASSERT(ok);
1166 			tmp_slot = ptree_testnode(pt, PT_NODE(node), ptn);
1167 			ok = ok && slot == tmp_slot;
1168 			KASSERT(ok);
1169 		}
1170 		if (PT_LEAF_P(node))
1171 			ok = ok && ptree_check_leaf(pt, ptn, PT_NODE(node));
1172 		else
1173 			ok = ok && ptree_check_branch(pt, ptn, PT_NODE(node));
1174 	}
1175 
1176 	return ok;
1177 }
1178 #endif /* PTCHECK */
1179 
1180 /*ARGSUSED*/
1181 bool
1182 ptree_check(const pt_tree_t *pt)
1183 {
1184 	bool ok = true;
1185 #ifdef PTCHECK
1186 	const pt_node_t * const parent = &pt->pt_rootnode;
1187 	const uintptr_t node = pt->pt_root;
1188 	const pt_node_t * const ptn = PT_NODE(node);
1189 
1190 	ok = ok && PTN_BRANCH_BITOFF(parent) == 0;
1191 	ok = ok && !PTN_ISMASK_P(parent);
1192 
1193 	if (PT_NULL_P(node))
1194 		return ok;
1195 
1196 	if (PT_LEAF_P(node))
1197 		ok = ok && ptree_check_leaf(pt, parent, ptn);
1198 	else
1199 		ok = ok && ptree_check_branch(pt, parent, ptn);
1200 #endif
1201 	return ok;
1202 }
1203