summaryrefslogtreecommitdiff
path: root/ipc/ipc_entry.c
blob: 6cb1cfb6805939bcb3d430e4c1a694433c82ee33 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
/*
 * Mach Operating System
 * Copyright (c) 1991,1990,1989 Carnegie Mellon University.
 * Copyright (c) 1993,1994 The University of Utah and
 * the Computer Systems Laboratory (CSL).
 * All rights reserved.
 *
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 *
 * CARNEGIE MELLON, THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF
 * THIS SOFTWARE IN ITS "AS IS" CONDITION, AND DISCLAIM ANY LIABILITY
 * OF ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF
 * THIS SOFTWARE.
 *
 * Carnegie Mellon requests users of this software to return to
 *
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 *
 * any improvements or extensions that they make and grant Carnegie Mellon
 * the rights to redistribute these changes.
 */
/*
 *	File:	ipc/ipc_entry.c
 *	Author:	Rich Draves
 *	Date:	1989
 *
 *	Primitive functions to manipulate translation entries.
 */

#include <kern/printf.h>
#include <string.h>

#include <mach/kern_return.h>
#include <mach/port.h>
#include <kern/assert.h>
#include <kern/sched_prim.h>
#include <kern/slab.h>
#include <ipc/port.h>
#include <ipc/ipc_types.h>
#include <ipc/ipc_entry.h>
#include <ipc/ipc_space.h>
#include <ipc/ipc_splay.h>
#include <ipc/ipc_hash.h>
#include <ipc/ipc_table.h>
#include <ipc/ipc_object.h>

struct kmem_cache ipc_tree_entry_cache;

/*
 *	Routine:	ipc_entry_tree_collision
 *	Purpose:
 *		Checks if "name" collides with an allocated name
 *		in the space's tree.  That is, returns TRUE
 *		if the splay tree contains a name with the same
 *		index as "name".
 *	Conditions:
 *		The space is locked (read or write) and active.
 */

boolean_t
ipc_entry_tree_collision(
	ipc_space_t	space,
	mach_port_t	name)
{
	mach_port_index_t index;
	mach_port_t lower, upper;

	assert(space->is_active);

	/*
	 *	Check if we collide with the next smaller name
	 *	or the next larger name.
	 */

	ipc_splay_tree_bounds(&space->is_tree, name, &lower, &upper);

	index = MACH_PORT_INDEX(name);
	return (((lower != ~0) && (MACH_PORT_INDEX(lower) == index)) ||
		((upper != 0) && (MACH_PORT_INDEX(upper) == index)));
}

/*
 *	Routine:	ipc_entry_lookup
 *	Purpose:
 *		Searches for an entry, given its name.
 *	Conditions:
 *		The space must be read or write locked throughout.
 *		The space must be active.
 */

ipc_entry_t
ipc_entry_lookup(space, name)
	ipc_space_t space;
	mach_port_t name;
{
	mach_port_index_t index;
	ipc_entry_t entry;

	assert(space->is_active);

	index = MACH_PORT_INDEX(name);
	if (index < space->is_table_size) {
		entry = &space->is_table[index];
		if (IE_BITS_GEN(entry->ie_bits) != MACH_PORT_GEN(name))
			if (entry->ie_bits & IE_BITS_COLLISION) {
				assert(space->is_tree_total > 0);
				goto tree_lookup;
			} else
				entry = IE_NULL;
		else if (IE_BITS_TYPE(entry->ie_bits) == MACH_PORT_TYPE_NONE)
			entry = IE_NULL;
	} else if (space->is_tree_total == 0)
		entry = IE_NULL;
	else
	    tree_lookup:
		entry = (ipc_entry_t)
				ipc_splay_tree_lookup(&space->is_tree, name);

	assert((entry == IE_NULL) || IE_BITS_TYPE(entry->ie_bits));
	return entry;
}

/*
 *	Routine:	ipc_entry_get
 *	Purpose:
 *		Tries to allocate an entry out of the space.
 *	Conditions:
 *		The space is write-locked and active throughout.
 *		An object may be locked.  Will not allocate memory.
 *	Returns:
 *		KERN_SUCCESS		A free entry was found.
 *		KERN_NO_SPACE		No entry allocated.
 */

kern_return_t
ipc_entry_get(space, namep, entryp)
	ipc_space_t space;
	mach_port_t *namep;
	ipc_entry_t *entryp;
{
	ipc_entry_t table;
	mach_port_index_t first_free;
	mach_port_t new_name;
	ipc_entry_t free_entry;

	assert(space->is_active);

	table = space->is_table;
	first_free = table->ie_next;

	if (first_free == 0)
		return KERN_NO_SPACE;

	free_entry = &table[first_free];
	table->ie_next = free_entry->ie_next;

	/*
	 *	Initialize the new entry.  We need only
	 *	increment the generation number and clear ie_request.
	 */

    {
	mach_port_gen_t gen;

	assert((free_entry->ie_bits &~ IE_BITS_GEN_MASK) == 0);
	gen = free_entry->ie_bits + IE_BITS_GEN_ONE;
	free_entry->ie_bits = gen;
	free_entry->ie_request = 0;
	new_name = MACH_PORT_MAKE(first_free, gen);
    }

	/*
	 *	The new name can't be MACH_PORT_NULL because index
	 *	is non-zero.  It can't be MACH_PORT_DEAD because
	 *	the table isn't allowed to grow big enough.
	 *	(See comment in ipc/ipc_table.h.)
	 */

	assert(MACH_PORT_VALID(new_name));
	assert(free_entry->ie_object == IO_NULL);

	*namep = new_name;
	*entryp = free_entry;
	return KERN_SUCCESS;
}

/*
 *	Routine:	ipc_entry_alloc
 *	Purpose:
 *		Allocate an entry out of the space.
 *	Conditions:
 *		The space is not locked before, but it is write-locked after
 *		if the call is successful.  May allocate memory.
 *	Returns:
 *		KERN_SUCCESS		An entry was allocated.
 *		KERN_INVALID_TASK	The space is dead.
 *		KERN_NO_SPACE		No room for an entry in the space.
 *		KERN_RESOURCE_SHORTAGE	Couldn't allocate memory for an entry.
 */

kern_return_t
ipc_entry_alloc(
	ipc_space_t	space,
	mach_port_t	*namep,
	ipc_entry_t	*entryp)
{
	kern_return_t kr;

	is_write_lock(space);

	for (;;) {
		if (!space->is_active) {
			is_write_unlock(space);
			return KERN_INVALID_TASK;
		}

		kr = ipc_entry_get(space, namep, entryp);
		if (kr == KERN_SUCCESS)
			return kr;

		kr = ipc_entry_grow_table(space);
		if (kr != KERN_SUCCESS)
			return kr; /* space is unlocked */
	}
}

/*
 *	Routine:	ipc_entry_alloc_name
 *	Purpose:
 *		Allocates/finds an entry with a specific name.
 *		If an existing entry is returned, its type will be nonzero.
 *	Conditions:
 *		The space is not locked before, but it is write-locked after
 *		if the call is successful.  May allocate memory.
 *	Returns:
 *		KERN_SUCCESS		Found existing entry with same name.
 *		KERN_SUCCESS		Allocated a new entry.
 *		KERN_INVALID_TASK	The space is dead.
 *		KERN_RESOURCE_SHORTAGE	Couldn't allocate memory.
 */

kern_return_t
ipc_entry_alloc_name(
	ipc_space_t	space,
	mach_port_t	name,
	ipc_entry_t	*entryp)
{
	mach_port_index_t index = MACH_PORT_INDEX(name);
	mach_port_gen_t gen = MACH_PORT_GEN(name);
	ipc_tree_entry_t tree_entry = ITE_NULL;

	assert(MACH_PORT_VALID(name));


	is_write_lock(space);

	for (;;) {
		ipc_entry_t entry;
		ipc_tree_entry_t tentry;
		ipc_table_size_t its;

		if (!space->is_active) {
			is_write_unlock(space);
			if (tree_entry) ite_free(tree_entry);
			return KERN_INVALID_TASK;
		}

		/*
		 *	If we are under the table cutoff,
		 *	there are three cases:
		 *		1) The entry is inuse, for the same name
		 *		2) The entry is inuse, for a different name
		 *		3) The entry is free
		 */

		if ((0 < index) && (index < space->is_table_size)) {
			ipc_entry_t table = space->is_table;

			entry = &table[index];

			if (IE_BITS_TYPE(entry->ie_bits)) {
				if (IE_BITS_GEN(entry->ie_bits) == gen) {
					*entryp = entry;
					if (tree_entry) ite_free(tree_entry);
					return KERN_SUCCESS;
				}
			} else {
				mach_port_index_t free_index, next_index;

				/*
				 *	Rip the entry out of the free list.
				 */

				for (free_index = 0;
				     (next_index = table[free_index].ie_next)
							!= index;
				     free_index = next_index)
					continue;

				table[free_index].ie_next =
					table[next_index].ie_next;

				entry->ie_bits = gen;
				assert(entry->ie_object == IO_NULL);
				entry->ie_request = 0;

				*entryp = entry;
				if (tree_entry) ite_free(tree_entry);
				return KERN_SUCCESS;
			}
		}

		/*
		 *	Before trying to allocate any memory,
		 *	check if the entry already exists in the tree.
		 *	This avoids spurious resource errors.
		 *	The splay tree makes a subsequent lookup/insert
		 *	of the same name cheap, so this costs little.
		 */

		if ((space->is_tree_total > 0) &&
		    ((tentry = ipc_splay_tree_lookup(&space->is_tree, name))
							!= ITE_NULL)) {
			assert(tentry->ite_space == space);
			assert(IE_BITS_TYPE(tentry->ite_bits));

			*entryp = &tentry->ite_entry;
			if (tree_entry) ite_free(tree_entry);
			return KERN_SUCCESS;
		}

		its = space->is_table_next;

		/*
		 *	Check if the table should be grown.
		 *
		 *	Note that if space->is_table_size == its->its_size,
		 *	then we won't ever try to grow the table.
		 *
		 *	Note that we are optimistically assuming that name
		 *	doesn't collide with any existing names.  (So if
		 *	it were entered into the tree, is_tree_small would
		 *	be incremented.)  This is OK, because even in that
		 *	case, we don't lose memory by growing the table.
		 */

		if ((space->is_table_size <= index) &&
		    (index < its->its_size) &&
		    (((its->its_size - space->is_table_size) *
		      sizeof(struct ipc_entry)) <
		     ((space->is_tree_small + 1) *
		      sizeof(struct ipc_tree_entry)))) {
			kern_return_t kr;

			/*
			 *	Can save space by growing the table.
			 *	Because the space will be unlocked,
			 *	we must restart.
			 */

			kr = ipc_entry_grow_table(space);
			assert(kr != KERN_NO_SPACE);
			if (kr != KERN_SUCCESS) {
				/* space is unlocked */
				if (tree_entry) ite_free(tree_entry);
				return kr;
			}

			continue;
		}

		/*
		 *	If a splay-tree entry was allocated previously,
		 *	go ahead and insert it into the tree.
		 */

		if (tree_entry != ITE_NULL) {
			space->is_tree_total++;

			if (index < space->is_table_size)
				space->is_table[index].ie_bits |=
					IE_BITS_COLLISION;
			else if ((index < its->its_size) &&
				 !ipc_entry_tree_collision(space, name))
				space->is_tree_small++;

			ipc_splay_tree_insert(&space->is_tree,
					      name, tree_entry);

			tree_entry->ite_bits = 0;
			tree_entry->ite_object = IO_NULL;
			tree_entry->ite_request = 0;
			tree_entry->ite_space = space;
			*entryp = &tree_entry->ite_entry;
			return KERN_SUCCESS;
		}

		/*
		 *	Allocate a tree entry and try again.
		 */

		is_write_unlock(space);
		tree_entry = ite_alloc();
		if (tree_entry == ITE_NULL)
			return KERN_RESOURCE_SHORTAGE;
		is_write_lock(space);
	}
}

/*
 *	Routine:	ipc_entry_dealloc
 *	Purpose:
 *		Deallocates an entry from a space.
 *	Conditions:
 *		The space must be write-locked throughout.
 *		The space must be active.
 */

void
ipc_entry_dealloc(
	ipc_space_t	space,
	mach_port_t	name,
	ipc_entry_t	entry)
{
	ipc_entry_t table;
	ipc_entry_num_t size;
	mach_port_index_t index;

	assert(space->is_active);
	assert(entry->ie_object == IO_NULL);
	assert(entry->ie_request == 0);

	index = MACH_PORT_INDEX(name);
	table = space->is_table;
	size = space->is_table_size;

	if ((index < size) && (entry == &table[index])) {
		assert(IE_BITS_GEN(entry->ie_bits) == MACH_PORT_GEN(name));

		if (entry->ie_bits & IE_BITS_COLLISION) {
			struct ipc_splay_tree small, collisions;
			ipc_tree_entry_t tentry;
			mach_port_t tname;
			boolean_t pick;
			ipc_entry_bits_t bits;
			ipc_object_t obj;

			/* must move an entry from tree to table */

			ipc_splay_tree_split(&space->is_tree,
					     MACH_PORT_MAKE(index+1, 0),
					     &collisions);
			ipc_splay_tree_split(&collisions,
					     MACH_PORT_MAKE(index, 0),
					     &small);

			pick = ipc_splay_tree_pick(&collisions,
						   &tname, &tentry);
			assert(pick);
			assert(MACH_PORT_INDEX(tname) == index);

			bits = tentry->ite_bits;
			entry->ie_bits = bits | MACH_PORT_GEN(tname);
			entry->ie_object = obj = tentry->ite_object;
			entry->ie_request = tentry->ite_request;
			assert(tentry->ite_space == space);

			if (IE_BITS_TYPE(bits) == MACH_PORT_TYPE_SEND) {
				ipc_hash_global_delete(space, obj,
						       tname, tentry);
				ipc_hash_local_insert(space, obj,
						      index, entry);
			}

			ipc_splay_tree_delete(&collisions, tname, tentry);

			assert(space->is_tree_total > 0);
			space->is_tree_total--;

			/* check if collision bit should still be on */

			pick = ipc_splay_tree_pick(&collisions,
						   &tname, &tentry);
			if (pick) {
				entry->ie_bits |= IE_BITS_COLLISION;
				ipc_splay_tree_join(&space->is_tree,
						    &collisions);
			}

			ipc_splay_tree_join(&space->is_tree, &small);
		} else {
			entry->ie_bits &= IE_BITS_GEN_MASK;
			entry->ie_next = table->ie_next;
			table->ie_next = index;
		}
	} else {
		ipc_tree_entry_t tentry = (ipc_tree_entry_t) entry;

		assert(tentry->ite_space == space);

		ipc_splay_tree_delete(&space->is_tree, name, tentry);

		assert(space->is_tree_total > 0);
		space->is_tree_total--;

		if (index < size) {
			ipc_entry_t ientry = &table[index];

			assert(ientry->ie_bits & IE_BITS_COLLISION);

			if (!ipc_entry_tree_collision(space, name))
				ientry->ie_bits &= ~IE_BITS_COLLISION;
		} else if ((index < space->is_table_next->its_size) &&
			   !ipc_entry_tree_collision(space, name)) {
			assert(space->is_tree_small > 0);
			space->is_tree_small--;
		}
	}
}

/*
 *	Routine:	ipc_entry_grow_table
 *	Purpose:
 *		Grows the table in a space.
 *	Conditions:
 *		The space must be write-locked and active before.
 *		If successful, it is also returned locked.
 *		Allocates memory.
 *	Returns:
 *		KERN_SUCCESS		Grew the table.
 *		KERN_SUCCESS		Somebody else grew the table.
 *		KERN_SUCCESS		The space died.
 *		KERN_NO_SPACE		Table has maximum size already.
 *		KERN_RESOURCE_SHORTAGE	Couldn't allocate a new table.
 */

kern_return_t
ipc_entry_grow_table(space)
	ipc_space_t space;
{
	ipc_entry_num_t osize, size, nsize;

	do {
		ipc_entry_t otable, table;
		ipc_table_size_t oits, its, nits;
		mach_port_index_t i, free_index;

		assert(space->is_active);

		if (space->is_growing) {
			/*
			 *	Somebody else is growing the table.
			 *	We just wait for them to finish.
			 */

			assert_wait((event_t) space, FALSE);
			is_write_unlock(space);
			thread_block((void (*)()) 0);
			is_write_lock(space);
			return KERN_SUCCESS;
		}

		otable = space->is_table;
		its = space->is_table_next;
		size = its->its_size;
		oits = its - 1;
		osize = oits->its_size;
		nits = its + 1;
		nsize = nits->its_size;

		if (osize == size) {
			is_write_unlock(space);
			printf_once("no more room for ipc_entry_grow_table in space %p\n", space);
			return KERN_NO_SPACE;
		}

		assert((osize < size) && (size <= nsize));

		/*
		 *	OK, we'll attempt to grow the table.
		 *	The realloc requires that the old table
		 *	remain in existence.
		 */

		space->is_growing = TRUE;
		is_write_unlock(space);
		if (it_entries_reallocable(oits))
			table = it_entries_realloc(oits, otable, its);
		else
			table = it_entries_alloc(its);
		is_write_lock(space);
		space->is_growing = FALSE;

		/*
		 *	We need to do a wakeup on the space,
		 *	to rouse waiting threads.  We defer
		 *	this until the space is unlocked,
		 *	because we don't want them to spin.
		 */

		if (table == IE_NULL) {
			is_write_unlock(space);
			thread_wakeup((event_t) space);
			return KERN_RESOURCE_SHORTAGE;
		}

		if (!space->is_active) {
			/*
			 *	The space died while it was unlocked.
			 */

			is_write_unlock(space);
			thread_wakeup((event_t) space);
			it_entries_free(its, table);
			is_write_lock(space);
			return KERN_SUCCESS;
		}

		assert(space->is_table == otable);
		assert(space->is_table_next == its);
		assert(space->is_table_size == osize);

		space->is_table = table;
		space->is_table_size = size;
		space->is_table_next = nits;

		/*
		 *	If we did a realloc, it remapped the data.
		 *	Otherwise we copy by hand first.  Then we have
		 *	to clear the index fields in the old part and
		 *	zero the new part.
		 */

		if (!it_entries_reallocable(oits))
			memcpy(table, otable,
			      osize * sizeof(struct ipc_entry));

		for (i = 0; i < osize; i++)
			table[i].ie_index = 0;

		(void) memset((void *) (table + osize), 0,
		      (size - osize) * sizeof(struct ipc_entry));

		/*
		 *	Put old entries into the reverse hash table.
		 */

		for (i = 0; i < osize; i++) {
			ipc_entry_t entry = &table[i];

			if (IE_BITS_TYPE(entry->ie_bits) ==
						MACH_PORT_TYPE_SEND)
				ipc_hash_local_insert(space, entry->ie_object,
						      i, entry);
		}

		/*
		 *	If there are entries in the splay tree,
		 *	then we have work to do:
		 *		1) transfer entries to the table
		 *		2) update is_tree_small
		 */

		if (space->is_tree_total > 0) {
			mach_port_index_t index;
			boolean_t delete;
			struct ipc_splay_tree ignore;
			struct ipc_splay_tree move;
			struct ipc_splay_tree small;
			ipc_entry_num_t nosmall;
			ipc_tree_entry_t tentry;

			/*
			 *	The splay tree divides into four regions,
			 *	based on the index of the entries:
			 *		1) 0 <= index < osize
			 *		2) osize <= index < size
			 *		3) size <= index < nsize
			 *		4) nsize <= index
			 *
			 *	Entries in the first part are ignored.
			 *	Entries in the second part, that don't
			 *	collide, are moved into the table.
			 *	Entries in the third part, that don't
			 *	collide, are counted for is_tree_small.
			 *	Entries in the fourth part are ignored.
			 */

			ipc_splay_tree_split(&space->is_tree,
					     MACH_PORT_MAKE(nsize, 0),
					     &small);
			ipc_splay_tree_split(&small,
					     MACH_PORT_MAKE(size, 0),
					     &move);
			ipc_splay_tree_split(&move,
					     MACH_PORT_MAKE(osize, 0),
					     &ignore);

			/* move entries into the table */

			for (tentry = ipc_splay_traverse_start(&move);
			     tentry != ITE_NULL;
			     tentry = ipc_splay_traverse_next(&move, delete)) {
				mach_port_t name;
				mach_port_gen_t gen;
				mach_port_type_t type;
				ipc_entry_bits_t bits;
				ipc_object_t obj;
				ipc_entry_t entry;

				name = tentry->ite_name;
				gen = MACH_PORT_GEN(name);
				index = MACH_PORT_INDEX(name);

				assert(tentry->ite_space == space);
				assert((osize <= index) && (index < size));

				entry = &table[index];

				/* collision with previously moved entry? */

				bits = entry->ie_bits;
				if (bits != 0) {
					assert(IE_BITS_TYPE(bits));
					assert(IE_BITS_GEN(bits) != gen);

					entry->ie_bits =
						bits | IE_BITS_COLLISION;
					delete = FALSE;
					continue;
				}

				bits = tentry->ite_bits;
				type = IE_BITS_TYPE(bits);
				assert(type != MACH_PORT_TYPE_NONE);

				entry->ie_bits = bits | gen;
				entry->ie_object = obj = tentry->ite_object;
				entry->ie_request = tentry->ite_request;

				if (type == MACH_PORT_TYPE_SEND) {
					ipc_hash_global_delete(space, obj,
							       name, tentry);
					ipc_hash_local_insert(space, obj,
							      index, entry);
				}

				space->is_tree_total--;
				delete = TRUE;
			}
			ipc_splay_traverse_finish(&move);

			/* count entries for is_tree_small */

			nosmall = 0; index = 0;
			for (tentry = ipc_splay_traverse_start(&small);
			     tentry != ITE_NULL;
			     tentry = ipc_splay_traverse_next(&small, FALSE)) {
				mach_port_index_t nindex;

				nindex = MACH_PORT_INDEX(tentry->ite_name);

				if (nindex != index) {
					nosmall++;
					index = nindex;
				}
			}
			ipc_splay_traverse_finish(&small);

			assert(nosmall <= (nsize - size));
			assert(nosmall <= space->is_tree_total);
			space->is_tree_small = nosmall;

			/* put the splay tree back together */

			ipc_splay_tree_join(&space->is_tree, &small);
			ipc_splay_tree_join(&space->is_tree, &move);
			ipc_splay_tree_join(&space->is_tree, &ignore);
		}

		/*
		 *	Add entries in the new part which still aren't used
		 *	to the free list.  Add them in reverse order,
		 *	and set the generation number to -1, so that
		 *	early allocations produce "natural" names.
		 */

		free_index = table[0].ie_next;
		for (i = size-1; i >= osize; --i) {
			ipc_entry_t entry = &table[i];

			if (entry->ie_bits == 0) {
				entry->ie_bits = IE_BITS_GEN_MASK;
				entry->ie_next = free_index;
				free_index = i;
			}
		}
		table[0].ie_next = free_index;

		/*
		 *	Now we need to free the old table.
		 *	If the space dies or grows while unlocked,
		 *	then we can quit here.
		 */

		is_write_unlock(space);
		thread_wakeup((event_t) space);
		it_entries_free(oits, otable);
		is_write_lock(space);
		if (!space->is_active || (space->is_table_next != nits))
			return KERN_SUCCESS;

		/*
		 *	We might have moved enough entries from
		 *	the splay tree into the table that
		 *	the table can be profitably grown again.
		 *
		 *	Note that if size == nsize, then
		 *	space->is_tree_small == 0.
		 */
	} while ((space->is_tree_small > 0) &&
		 (((nsize - size) * sizeof(struct ipc_entry)) <
		  (space->is_tree_small * sizeof(struct ipc_tree_entry))));

	return KERN_SUCCESS;
}


#if	MACH_KDB
#include <ddb/db_output.h>
#include <kern/task.h>

#define	printf	kdbprintf

ipc_entry_t
db_ipc_object_by_name(
	task_t		task,
	mach_port_t	name)
{
        ipc_space_t space = task->itk_space;
        ipc_entry_t entry;
 
 
        entry = ipc_entry_lookup(space, name);
        if(entry != IE_NULL) {
                iprintf("(task 0x%x, name 0x%x) ==> object 0x%x",
			entry->ie_object);
                return (ipc_entry_t) entry->ie_object;
        }
        return entry;
}
#endif	/* MACH_KDB */