1/* $NetBSD: subr_extent.c,v 1.87 2017/12/31 09:25:19 skrll Exp $ */
2
3/*-
4 * Copyright (c) 1996, 1998, 2007 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Jason R. Thorpe and Matthias Drochner.
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/*
33 * General purpose extent manager.
34 */
35
36#include <sys/cdefs.h>
37__KERNEL_RCSID(0, "$NetBSD: subr_extent.c,v 1.87 2017/12/31 09:25:19 skrll Exp $");
38
39#ifdef _KERNEL
40#ifdef _KERNEL_OPT
41#include "opt_lockdebug.h"
42#endif
43
44#include <sys/param.h>
45#include <sys/extent.h>
46#include <sys/kmem.h>
47#include <sys/pool.h>
48#include <sys/time.h>
49#include <sys/systm.h>
50#include <sys/proc.h>
51
52#include <uvm/uvm_extern.h>
53
54#elif defined(_EXTENT_TESTING)
55
56/*
57 * user-land definitions, so it can fit into a testing harness.
58 */
59#include <sys/param.h>
60#include <sys/pool.h>
61#include <sys/extent.h>
62
63#include <errno.h>
64#include <stdlib.h>
65#include <stdio.h>
66#include <string.h>
67
68static inline void no_op(void) { return; }
69
70/*
71 * Use multi-line #defines to avoid screwing up the kernel tags file;
72 * without this, ctags produces a tags file where panic() shows up
73 * in subr_extent.c rather than subr_prf.c.
74 */
75#define \
76kmem_alloc(s, flags) malloc(s)
77#define \
78kmem_free(p, s) free(p)
79#define \
80cv_wait_sig(cv, lock) (EWOULDBLOCK)
81#define \
82pool_get(pool, flags) kmem_alloc((pool)->pr_size,0)
83#define \
84pool_put(pool, rp) kmem_free(rp,0)
85#define \
86panic(a ...) printf(a)
87#define mutex_init(a, b, c) no_op()
88#define mutex_destroy(a) no_op()
89#define mutex_enter(l) no_op()
90#define mutex_exit(l) no_op()
91#define cv_wait(cv, lock) no_op()
92#define cv_broadcast(cv) no_op()
93#define cv_init(a, b) no_op()
94#define cv_destroy(a) no_op()
95#define KMEM_IS_RUNNING (1)
96#define IPL_VM (0)
97#define MUTEX_DEFAULT (0)
98#define KASSERT(exp)
99#endif
100
101static struct pool expool;
102
103/*
104 * Macro to align to an arbitrary power-of-two boundary.
105 */
106#define EXTENT_ALIGN(_start, _align, _skew) \
107 (((((_start) - (_skew)) + ((_align) - 1)) & (-(_align))) + (_skew))
108
109/*
110 * Create the extent_region pool.
111 */
112void
113extent_init(void)
114{
115
116#if defined(_KERNEL)
117 pool_init(&expool, sizeof(struct extent_region), 0, 0, 0,
118 "extent", NULL, IPL_VM);
119#else
120 expool.pr_size = sizeof(struct extent_region);
121#endif
122}
123
124/*
125 * Allocate an extent region descriptor. EXTENT MUST NOT BE LOCKED.
126 * We will handle any locking we may need.
127 */
128static struct extent_region *
129extent_alloc_region_descriptor(struct extent *ex, int flags)
130{
131 struct extent_region *rp;
132 int error;
133
134 if (ex->ex_flags & EXF_FIXED) {
135 struct extent_fixed *fex = (struct extent_fixed *)ex;
136
137 if (!(ex->ex_flags & EXF_EARLY))
138 mutex_enter(&ex->ex_lock);
139 for (;;) {
140 if ((rp = LIST_FIRST(&fex->fex_freelist)) != NULL) {
141 /*
142 * Don't muck with flags after pulling it off
143 * the freelist; it may have been dynamically
144 * allocated, and kindly given to us. We
145 * need to remember that information.
146 */
147 LIST_REMOVE(rp, er_link);
148 if (!(ex->ex_flags & EXF_EARLY))
149 mutex_exit(&ex->ex_lock);
150 return (rp);
151 }
152 if (flags & EX_MALLOCOK) {
153 if (!(ex->ex_flags & EXF_EARLY))
154 mutex_exit(&ex->ex_lock);
155 goto alloc;
156 }
157 if ((flags & EX_WAITOK) == 0) {
158 if (!(ex->ex_flags & EXF_EARLY))
159 mutex_exit(&ex->ex_lock);
160 return (NULL);
161 }
162 KASSERT(mutex_owned(&ex->ex_lock));
163 ex->ex_flwanted = true;
164 if ((flags & EX_CATCH) != 0)
165 error = cv_wait_sig(&ex->ex_cv, &ex->ex_lock);
166 else {
167 cv_wait(&ex->ex_cv, &ex->ex_lock);
168 error = 0;
169 }
170 if (error != 0) {
171 mutex_exit(&ex->ex_lock);
172 return (NULL);
173 }
174 }
175 }
176
177 alloc:
178 rp = pool_get(&expool, (flags & EX_WAITOK) ? PR_WAITOK : PR_NOWAIT);
179
180 if (rp != NULL)
181 rp->er_flags = ER_ALLOC;
182
183 return (rp);
184}
185
186/*
187 * Free an extent region descriptor. EXTENT _MUST_ BE LOCKED!
188 */
189static void
190extent_free_region_descriptor(struct extent *ex, struct extent_region *rp)
191{
192
193 if (ex->ex_flags & EXF_FIXED) {
194 struct extent_fixed *fex = (struct extent_fixed *)ex;
195
196 /*
197 * If someone's waiting for a region descriptor,
198 * be nice and give them this one, rather than
199 * just free'ing it back to the system.
200 */
201 if (rp->er_flags & ER_ALLOC) {
202 if (ex->ex_flwanted) {
203 /* Clear all but ER_ALLOC flag. */
204 rp->er_flags = ER_ALLOC;
205 LIST_INSERT_HEAD(&fex->fex_freelist, rp,
206 er_link);
207 goto wake_em_up;
208 } else
209 pool_put(&expool, rp);
210 } else {
211 /* Clear all flags. */
212 rp->er_flags = 0;
213 LIST_INSERT_HEAD(&fex->fex_freelist, rp, er_link);
214 }
215
216 wake_em_up:
217 if (!(ex->ex_flags & EXF_EARLY)) {
218 ex->ex_flwanted = false;
219 cv_broadcast(&ex->ex_cv);
220 }
221 return;
222 }
223
224 /*
225 * We know it's dynamically allocated if we get here.
226 */
227 pool_put(&expool, rp);
228}
229
230/*
231 * Allocate and initialize an extent map.
232 */
233struct extent *
234extent_create(const char *name, u_long start, u_long end,
235 void *storage, size_t storagesize, int flags)
236{
237 struct extent *ex;
238 char *cp = storage;
239 size_t sz = storagesize;
240 struct extent_region *rp;
241 int fixed_extent = (storage != NULL);
242
243#ifndef _KERNEL
244 extent_init();
245#endif
246
247#ifdef DIAGNOSTIC
248 /* Check arguments. */
249 if (name == NULL)
250 panic("extent_create: name == NULL");
251 if (end < start) {
252 printf("extent_create: extent `%s', start 0x%lx, end 0x%lx\n",
253 name, start, end);
254 panic("extent_create: end < start");
255 }
256 if (fixed_extent && (storagesize < sizeof(struct extent_fixed)))
257 panic("extent_create: fixed extent, bad storagesize 0x%lx",
258 (u_long)storagesize);
259 if (fixed_extent == 0 && (storagesize != 0 || storage != NULL))
260 panic("extent_create: storage provided for non-fixed");
261#endif
262
263 /* Allocate extent descriptor. */
264 if (fixed_extent) {
265 struct extent_fixed *fex;
266
267 memset(storage, 0, storagesize);
268
269 /*
270 * Align all descriptors on "long" boundaries.
271 */
272 fex = (struct extent_fixed *)cp;
273 ex = (struct extent *)fex;
274 cp += ALIGN(sizeof(struct extent_fixed));
275 sz -= ALIGN(sizeof(struct extent_fixed));
276 fex->fex_storage = storage;
277 fex->fex_storagesize = storagesize;
278
279 /*
280 * In a fixed extent, we have to pre-allocate region
281 * descriptors and place them in the extent's freelist.
282 */
283 LIST_INIT(&fex->fex_freelist);
284 while (sz >= ALIGN(sizeof(struct extent_region))) {
285 rp = (struct extent_region *)cp;
286 cp += ALIGN(sizeof(struct extent_region));
287 sz -= ALIGN(sizeof(struct extent_region));
288 LIST_INSERT_HEAD(&fex->fex_freelist, rp, er_link);
289 }
290 } else {
291 ex = kmem_alloc(sizeof(*ex),
292 (flags & EX_WAITOK) ? KM_SLEEP : KM_NOSLEEP);
293 if (ex == NULL)
294 return (NULL);
295 }
296
297 /* Fill in the extent descriptor and return it to the caller. */
298 if ((flags & EX_EARLY) == 0) {
299 mutex_init(&ex->ex_lock, MUTEX_DEFAULT, IPL_VM);
300 cv_init(&ex->ex_cv, "extent");
301 }
302 LIST_INIT(&ex->ex_regions);
303 ex->ex_name = name;
304 ex->ex_start = start;
305 ex->ex_end = end;
306 ex->ex_flags = 0;
307 ex->ex_flwanted = false;
308 if (fixed_extent)
309 ex->ex_flags |= EXF_FIXED;
310 if (flags & EX_NOCOALESCE)
311 ex->ex_flags |= EXF_NOCOALESCE;
312 if (flags & EX_EARLY)
313 ex->ex_flags |= EXF_EARLY;
314 return (ex);
315}
316
317/*
318 * Destroy an extent map.
319 * Since we're freeing the data, there can't be any references
320 * so we don't need any locking.
321 */
322void
323extent_destroy(struct extent *ex)
324{
325 struct extent_region *rp, *orp;
326
327#ifdef DIAGNOSTIC
328 /* Check arguments. */
329 if (ex == NULL)
330 panic("extent_destroy: NULL extent");
331#endif
332
333 /* Free all region descriptors in extent. */
334 for (rp = LIST_FIRST(&ex->ex_regions); rp != NULL; ) {
335 orp = rp;
336 rp = LIST_NEXT(rp, er_link);
337 LIST_REMOVE(orp, er_link);
338 extent_free_region_descriptor(ex, orp);
339 }
340
341 cv_destroy(&ex->ex_cv);
342 mutex_destroy(&ex->ex_lock);
343
344 /* If we're not a fixed extent, free the extent descriptor itself. */
345 if ((ex->ex_flags & EXF_FIXED) == 0)
346 kmem_free(ex, sizeof(*ex));
347}
348
349/*
350 * Insert a region descriptor into the sorted region list after the
351 * entry "after" or at the head of the list (if "after" is NULL).
352 * The region descriptor we insert is passed in "rp". We must
353 * allocate the region descriptor before calling this function!
354 * If we don't need the region descriptor, it will be freed here.
355 */
356static void
357extent_insert_and_optimize(struct extent *ex, u_long start, u_long size,
358 int flags, struct extent_region *after, struct extent_region *rp)
359{
360 struct extent_region *nextr;
361 int appended = 0;
362
363 if (after == NULL) {
364 /*
365 * We're the first in the region list. If there's
366 * a region after us, attempt to coalesce to save
367 * descriptor overhead.
368 */
369 if (((ex->ex_flags & EXF_NOCOALESCE) == 0) &&
370 (LIST_FIRST(&ex->ex_regions) != NULL) &&
371 ((start + size) == LIST_FIRST(&ex->ex_regions)->er_start)) {
372 /*
373 * We can coalesce. Prepend us to the first region.
374 */
375 LIST_FIRST(&ex->ex_regions)->er_start = start;
376 extent_free_region_descriptor(ex, rp);
377 return;
378 }
379
380 /*
381 * Can't coalesce. Fill in the region descriptor
382 * in, and insert us at the head of the region list.
383 */
384 rp->er_start = start;
385 rp->er_end = start + (size - 1);
386 LIST_INSERT_HEAD(&ex->ex_regions, rp, er_link);
387 return;
388 }
389
390 /*
391 * If EXF_NOCOALESCE is set, coalescing is disallowed.
392 */
393 if (ex->ex_flags & EXF_NOCOALESCE)
394 goto cant_coalesce;
395
396 /*
397 * Attempt to coalesce with the region before us.
398 */
399 if ((after->er_end + 1) == start) {
400 /*
401 * We can coalesce. Append ourselves and make
402 * note of it.
403 */
404 after->er_end = start + (size - 1);
405 appended = 1;
406 }
407
408 /*
409 * Attempt to coalesce with the region after us.
410 */
411 if ((LIST_NEXT(after, er_link) != NULL) &&
412 ((start + size) == LIST_NEXT(after, er_link)->er_start)) {
413 /*
414 * We can coalesce. Note that if we appended ourselves
415 * to the previous region, we exactly fit the gap, and
416 * can free the "next" region descriptor.
417 */
418 if (appended) {
419 /*
420 * Yup, we can free it up.
421 */
422 after->er_end = LIST_NEXT(after, er_link)->er_end;
423 nextr = LIST_NEXT(after, er_link);
424 LIST_REMOVE(nextr, er_link);
425 extent_free_region_descriptor(ex, nextr);
426 } else {
427 /*
428 * Nope, just prepend us to the next region.
429 */
430 LIST_NEXT(after, er_link)->er_start = start;
431 }
432
433 extent_free_region_descriptor(ex, rp);
434 return;
435 }
436
437 /*
438 * We weren't able to coalesce with the next region, but
439 * we don't need to allocate a region descriptor if we
440 * appended ourselves to the previous region.
441 */
442 if (appended) {
443 extent_free_region_descriptor(ex, rp);
444 return;
445 }
446
447 cant_coalesce:
448
449 /*
450 * Fill in the region descriptor and insert ourselves
451 * into the region list.
452 */
453 rp->er_start = start;
454 rp->er_end = start + (size - 1);
455 LIST_INSERT_AFTER(after, rp, er_link);
456}
457
458/*
459 * Allocate a specific region in an extent map.
460 */
461int
462extent_alloc_region(struct extent *ex, u_long start, u_long size, int flags)
463{
464 struct extent_region *rp, *last, *myrp;
465 u_long end = start + (size - 1);
466 int error;
467
468#ifdef DIAGNOSTIC
469 /* Check arguments. */
470 if (ex == NULL)
471 panic("extent_alloc_region: NULL extent");
472 if (size < 1) {
473 printf("extent_alloc_region: extent `%s', size 0x%lx\n",
474 ex->ex_name, size);
475 panic("extent_alloc_region: bad size");
476 }
477 if (end < start) {
478 printf(
479 "extent_alloc_region: extent `%s', start 0x%lx, size 0x%lx\n",
480 ex->ex_name, start, size);
481 panic("extent_alloc_region: overflow");
482 }
483#endif
484#ifdef LOCKDEBUG
485 if (flags & EX_WAITSPACE) {
486 ASSERT_SLEEPABLE();
487 }
488#endif
489
490 /*
491 * Make sure the requested region lies within the
492 * extent.
493 *
494 * We don't lock to check the range, because those values
495 * are never modified, and if another thread deletes the
496 * extent, we're screwed anyway.
497 */
498 if ((start < ex->ex_start) || (end > ex->ex_end)) {
499#ifdef DIAGNOSTIC
500 printf("extent_alloc_region: extent `%s' (0x%lx - 0x%lx)\n",
501 ex->ex_name, ex->ex_start, ex->ex_end);
502 printf("extent_alloc_region: start 0x%lx, end 0x%lx\n",
503 start, end);
504 panic("extent_alloc_region: region lies outside extent");
505#else
506 return (EINVAL);
507#endif
508 }
509
510 /*
511 * Allocate the region descriptor. It will be freed later
512 * if we can coalesce with another region. Don't lock before
513 * here! This could block.
514 */
515 myrp = extent_alloc_region_descriptor(ex, flags);
516 if (myrp == NULL) {
517#ifdef DIAGNOSTIC
518 printf(
519 "extent_alloc_region: can't allocate region descriptor\n");
520#endif
521 return (ENOMEM);
522 }
523
524 if (!(ex->ex_flags & EXF_EARLY))
525 mutex_enter(&ex->ex_lock);
526 alloc_start:
527
528 /*
529 * Attempt to place ourselves in the desired area of the
530 * extent. We save ourselves some work by keeping the list sorted.
531 * In other words, if the start of the current region is greater
532 * than the end of our region, we don't have to search any further.
533 */
534
535 /*
536 * Keep a pointer to the last region we looked at so
537 * that we don't have to traverse the list again when
538 * we insert ourselves. If "last" is NULL when we
539 * finally insert ourselves, we go at the head of the
540 * list. See extent_insert_and_optimize() for details.
541 */
542 last = NULL;
543
544 LIST_FOREACH(rp, &ex->ex_regions, er_link) {
545 if (rp->er_start > end) {
546 /*
547 * We lie before this region and don't
548 * conflict.
549 */
550 break;
551 }
552
553 /*
554 * The current region begins before we end.
555 * Check for a conflict.
556 */
557 if (rp->er_end >= start) {
558 /*
559 * We conflict. If we can (and want to) wait,
560 * do so.
561 */
562 if (flags & EX_WAITSPACE) {
563 KASSERT(!(ex->ex_flags & EXF_EARLY));
564 if ((flags & EX_CATCH) != 0)
565 error = cv_wait_sig(&ex->ex_cv,
566 &ex->ex_lock);
567 else {
568 cv_wait(&ex->ex_cv, &ex->ex_lock);
569 error = 0;
570 }
571 if (error == 0)
572 goto alloc_start;
573 mutex_exit(&ex->ex_lock);
574 } else {
575 if (!(ex->ex_flags & EXF_EARLY))
576 mutex_exit(&ex->ex_lock);
577 error = EAGAIN;
578 }
579 extent_free_region_descriptor(ex, myrp);
580 return error;
581 }
582 /*
583 * We don't conflict, but this region lies before
584 * us. Keep a pointer to this region, and keep
585 * trying.
586 */
587 last = rp;
588 }
589
590 /*
591 * We don't conflict with any regions. "last" points
592 * to the region we fall after, or is NULL if we belong
593 * at the beginning of the region list. Insert ourselves.
594 */
595 extent_insert_and_optimize(ex, start, size, flags, last, myrp);
596 if (!(ex->ex_flags & EXF_EARLY))
597 mutex_exit(&ex->ex_lock);
598 return (0);
599}
600
601/*
602 * Macro to check (x + y) <= z. This check is designed to fail
603 * if an overflow occurs.
604 */
605#define LE_OV(x, y, z) ((((x) + (y)) >= (x)) && (((x) + (y)) <= (z)))
606
607/*
608 * Allocate a region in an extent map subregion.
609 *
610 * If EX_FAST is specified, we return the first fit in the map.
611 * Otherwise, we try to minimize fragmentation by finding the
612 * smallest gap that will hold the request.
613 *
614 * The allocated region is aligned to "alignment", which must be
615 * a power of 2.
616 */
617int
618extent_alloc_subregion1(struct extent *ex, u_long substart, u_long subend,
619 u_long size, u_long alignment, u_long skew, u_long boundary,
620 int flags, u_long *result)
621{
622 struct extent_region *rp, *myrp, *last, *bestlast;
623 u_long newstart, newend, exend, beststart, bestovh, ovh;
624 u_long dontcross;
625 int error;
626
627#ifdef DIAGNOSTIC
628 /*
629 * Check arguments.
630 *
631 * We don't lock to check these, because these values
632 * are never modified, and if another thread deletes the
633 * extent, we're screwed anyway.
634 */
635 if (ex == NULL)
636 panic("extent_alloc_subregion: NULL extent");
637 if (result == NULL)
638 panic("extent_alloc_subregion: NULL result pointer");
639 if ((substart < ex->ex_start) || (substart > ex->ex_end) ||
640 (subend > ex->ex_end) || (subend < ex->ex_start)) {
641 printf("extent_alloc_subregion: extent `%s', ex_start 0x%lx, ex_end 0x%lx\n",
642 ex->ex_name, ex->ex_start, ex->ex_end);
643 printf("extent_alloc_subregion: substart 0x%lx, subend 0x%lx\n",
644 substart, subend);
645 panic("extent_alloc_subregion: bad subregion");
646 }
647 if ((size < 1) || ((size - 1) > (subend - substart))) {
648 printf("extent_alloc_subregion: extent `%s', size 0x%lx\n",
649 ex->ex_name, size);
650 panic("extent_alloc_subregion: bad size");
651 }
652 if (alignment == 0)
653 panic("extent_alloc_subregion: bad alignment");
654 if (boundary && (boundary < size)) {
655 printf(
656 "extent_alloc_subregion: extent `%s', size 0x%lx, "
657 "boundary 0x%lx\n", ex->ex_name, size, boundary);
658 panic("extent_alloc_subregion: bad boundary");
659 }
660#endif
661#ifdef LOCKDEBUG
662 if (flags & EX_WAITSPACE) {
663 ASSERT_SLEEPABLE();
664 }
665#endif
666
667 /*
668 * Allocate the region descriptor. It will be freed later
669 * if we can coalesce with another region. Don't lock before
670 * here! This could block.
671 */
672 myrp = extent_alloc_region_descriptor(ex, flags);
673 if (myrp == NULL) {
674#ifdef DIAGNOSTIC
675 printf(
676 "extent_alloc_subregion: can't allocate region descriptor\n");
677#endif
678 return (ENOMEM);
679 }
680
681 alloc_start:
682 mutex_enter(&ex->ex_lock);
683
684 /*
685 * Keep a pointer to the last region we looked at so
686 * that we don't have to traverse the list again when
687 * we insert ourselves. If "last" is NULL when we
688 * finally insert ourselves, we go at the head of the
689 * list. See extent_insert_and_optimize() for deatails.
690 */
691 last = NULL;
692
693 /*
694 * Keep track of size and location of the smallest
695 * chunk we fit in.
696 *
697 * Since the extent can be as large as the numeric range
698 * of the CPU (0 - 0xffffffff for 32-bit systems), the
699 * best overhead value can be the maximum unsigned integer.
700 * Thus, we initialize "bestovh" to 0, since we insert ourselves
701 * into the region list immediately on an exact match (which
702 * is the only case where "bestovh" would be set to 0).
703 */
704 bestovh = 0;
705 beststart = 0;
706 bestlast = NULL;
707
708 /*
709 * Keep track of end of free region. This is either the end of extent
710 * or the start of a region past the subend.
711 */
712 exend = ex->ex_end;
713
714 /*
715 * For N allocated regions, we must make (N + 1)
716 * checks for unallocated space. The first chunk we
717 * check is the area from the beginning of the subregion
718 * to the first allocated region after that point.
719 */
720 newstart = EXTENT_ALIGN(substart, alignment, skew);
721 if (newstart < ex->ex_start) {
722#ifdef DIAGNOSTIC
723 printf(
724 "extent_alloc_subregion: extent `%s' (0x%lx - 0x%lx), alignment 0x%lx\n",
725 ex->ex_name, ex->ex_start, ex->ex_end, alignment);
726 mutex_exit(&ex->ex_lock);
727 panic("extent_alloc_subregion: overflow after alignment");
728#else
729 extent_free_region_descriptor(ex, myrp);
730 mutex_exit(&ex->ex_lock);
731 return (EINVAL);
732#endif
733 }
734
735 /*
736 * Find the first allocated region that begins on or after
737 * the subregion start, advancing the "last" pointer along
738 * the way.
739 */
740 LIST_FOREACH(rp, &ex->ex_regions, er_link) {
741 if (rp->er_start >= newstart)
742 break;
743 last = rp;
744 }
745
746 /*
747 * Relocate the start of our candidate region to the end of
748 * the last allocated region (if there was one overlapping
749 * our subrange).
750 */
751 if (last != NULL && last->er_end >= newstart)
752 newstart = EXTENT_ALIGN((last->er_end + 1), alignment, skew);
753
754 for (; rp != NULL; rp = LIST_NEXT(rp, er_link)) {
755 /*
756 * If the region pasts the subend, bail out and see
757 * if we fit against the subend.
758 */
759 if (rp->er_start > subend) {
760 exend = rp->er_start;
761 break;
762 }
763
764 /*
765 * Check the chunk before "rp". Note that our
766 * comparison is safe from overflow conditions.
767 */
768 if (LE_OV(newstart, size, rp->er_start)) {
769 /*
770 * Do a boundary check, if necessary. Note
771 * that a region may *begin* on the boundary,
772 * but it must end before the boundary.
773 */
774 if (boundary) {
775 newend = newstart + (size - 1);
776
777 /*
778 * Calculate the next boundary after the start
779 * of this region.
780 */
781 dontcross = EXTENT_ALIGN(newstart+1, boundary,
782 (flags & EX_BOUNDZERO) ? 0 : ex->ex_start)
783 - 1;
784
785#if 0
786 printf("newstart=%lx newend=%lx ex_start=%lx ex_end=%lx boundary=%lx dontcross=%lx\n",
787 newstart, newend, ex->ex_start, ex->ex_end,
788 boundary, dontcross);
789#endif
790
791 /* Check for overflow */
792 if (dontcross < ex->ex_start)
793 dontcross = ex->ex_end;
794 else if (newend > dontcross) {
795 /*
796 * Candidate region crosses boundary.
797 * Throw away the leading part and see
798 * if we still fit.
799 */
800 newstart = dontcross + 1;
801 newend = newstart + (size - 1);
802 dontcross += boundary;
803 if (!LE_OV(newstart, size, rp->er_start))
804 goto skip;
805 }
806
807 /*
808 * If we run past the end of
809 * the extent or the boundary
810 * overflows, then the request
811 * can't fit.
812 */
813 if (newstart + size - 1 > ex->ex_end ||
814 dontcross < newstart)
815 goto fail;
816 }
817
818 /*
819 * We would fit into this space. Calculate
820 * the overhead (wasted space). If we exactly
821 * fit, or we're taking the first fit, insert
822 * ourselves into the region list.
823 */
824 ovh = rp->er_start - newstart - size;
825 if ((flags & EX_FAST) || (ovh == 0))
826 goto found;
827
828 /*
829 * Don't exactly fit, but check to see
830 * if we're better than any current choice.
831 */
832 if ((bestovh == 0) || (ovh < bestovh)) {
833 bestovh = ovh;
834 beststart = newstart;
835 bestlast = last;
836 }
837 }
838
839skip:
840 /*
841 * Skip past the current region and check again.
842 */
843 newstart = EXTENT_ALIGN((rp->er_end + 1), alignment, skew);
844 if (newstart < rp->er_end) {
845 /*
846 * Overflow condition. Don't error out, since
847 * we might have a chunk of space that we can
848 * use.
849 */
850 goto fail;
851 }
852
853 last = rp;
854 }
855
856 /*
857 * The final check is from the current starting point to the
858 * end of the subregion. If there were no allocated regions,
859 * "newstart" is set to the beginning of the subregion, or
860 * just past the end of the last allocated region, adjusted
861 * for alignment in either case.
862 */
863 if (LE_OV(newstart, (size - 1), subend)) {
864 /*
865 * Do a boundary check, if necessary. Note
866 * that a region may *begin* on the boundary,
867 * but it must end before the boundary.
868 */
869 if (boundary) {
870 newend = newstart + (size - 1);
871
872 /*
873 * Calculate the next boundary after the start
874 * of this region.
875 */
876 dontcross = EXTENT_ALIGN(newstart+1, boundary,
877 (flags & EX_BOUNDZERO) ? 0 : ex->ex_start)
878 - 1;
879
880#if 0
881 printf("newstart=%lx newend=%lx ex_start=%lx ex_end=%lx boundary=%lx dontcross=%lx\n",
882 newstart, newend, ex->ex_start, ex->ex_end,
883 boundary, dontcross);
884#endif
885
886 /* Check for overflow */
887 if (dontcross < ex->ex_start)
888 dontcross = ex->ex_end;
889 else if (newend > dontcross) {
890 /*
891 * Candidate region crosses boundary.
892 * Throw away the leading part and see
893 * if we still fit.
894 */
895 newstart = dontcross + 1;
896 newend = newstart + (size - 1);
897 dontcross += boundary;
898 if (!LE_OV(newstart, (size - 1), subend))
899 goto fail;
900 }
901
902 /*
903 * If we run past the end of
904 * the extent or the boundary
905 * overflows, then the request
906 * can't fit.
907 */
908 if (newstart + size - 1 > ex->ex_end ||
909 dontcross < newstart)
910 goto fail;
911 }
912
913 /*
914 * We would fit into this space. Calculate
915 * the overhead (wasted space). If we exactly
916 * fit, or we're taking the first fit, insert
917 * ourselves into the region list.
918 */
919 ovh = exend - newstart - (size - 1);
920 if ((flags & EX_FAST) || (ovh == 0))
921 goto found;
922
923 /*
924 * Don't exactly fit, but check to see
925 * if we're better than any current choice.
926 */
927 if ((bestovh == 0) || (ovh < bestovh)) {
928 bestovh = ovh;
929 beststart = newstart;
930 bestlast = last;
931 }
932 }
933
934 fail:
935 /*
936 * One of the following two conditions have
937 * occurred:
938 *
939 * There is no chunk large enough to hold the request.
940 *
941 * If EX_FAST was not specified, there is not an
942 * exact match for the request.
943 *
944 * Note that if we reach this point and EX_FAST is
945 * set, then we know there is no space in the extent for
946 * the request.
947 */
948 if (((flags & EX_FAST) == 0) && (bestovh != 0)) {
949 /*
950 * We have a match that's "good enough".
951 */
952 newstart = beststart;
953 last = bestlast;
954 goto found;
955 }
956
957 /*
958 * No space currently available. Wait for it to free up,
959 * if possible.
960 */
961 if (flags & EX_WAITSPACE) {
962 if ((flags & EX_CATCH) != 0) {
963 error = cv_wait_sig(&ex->ex_cv, &ex->ex_lock);
964 } else {
965 cv_wait(&ex->ex_cv, &ex->ex_lock);
966 error = 0;
967 }
968 if (error == 0)
969 goto alloc_start;
970 mutex_exit(&ex->ex_lock);
971 } else {
972 mutex_exit(&ex->ex_lock);
973 error = EAGAIN;
974 }
975
976 extent_free_region_descriptor(ex, myrp);
977 return error;
978
979 found:
980 /*
981 * Insert ourselves into the region list.
982 */
983 extent_insert_and_optimize(ex, newstart, size, flags, last, myrp);
984 mutex_exit(&ex->ex_lock);
985 *result = newstart;
986 return (0);
987}
988
989int
990extent_alloc_subregion(struct extent *ex, u_long start, u_long end, u_long size,
991 u_long alignment, u_long boundary, int flags, u_long *result)
992{
993
994 return (extent_alloc_subregion1(ex, start, end, size, alignment,
995 0, boundary, flags, result));
996}
997
998int
999extent_alloc(struct extent *ex, u_long size, u_long alignment, u_long boundary,
1000 int flags, u_long *result)
1001{
1002
1003 return (extent_alloc_subregion1(ex, ex->ex_start, ex->ex_end,
1004 size, alignment, 0, boundary,
1005 flags, result));
1006}
1007
1008int
1009extent_alloc1(struct extent *ex, u_long size, u_long alignment, u_long skew,
1010 u_long boundary, int flags, u_long *result)
1011{
1012
1013 return (extent_alloc_subregion1(ex, ex->ex_start, ex->ex_end,
1014 size, alignment, skew, boundary,
1015 flags, result));
1016}
1017
1018int
1019extent_free(struct extent *ex, u_long start, u_long size, int flags)
1020{
1021 struct extent_region *rp, *nrp = NULL;
1022 u_long end = start + (size - 1);
1023
1024#ifdef DIAGNOSTIC
1025 /*
1026 * Check arguments.
1027 *
1028 * We don't lock to check these, because these values
1029 * are never modified, and if another thread deletes the
1030 * extent, we're screwed anyway.
1031 */
1032 if (ex == NULL)
1033 panic("extent_free: NULL extent");
1034 if ((start < ex->ex_start) || (end > ex->ex_end)) {
1035 extent_print(ex);
1036 printf("extent_free: extent `%s', start 0x%lx, size 0x%lx\n",
1037 ex->ex_name, start, size);
1038 panic("extent_free: extent `%s', region not within extent",
1039 ex->ex_name);
1040 }
1041 /* Check for an overflow. */
1042 if (end < start) {
1043 extent_print(ex);
1044 printf("extent_free: extent `%s', start 0x%lx, size 0x%lx\n",
1045 ex->ex_name, start, size);
1046 panic("extent_free: overflow");
1047 }
1048#endif
1049
1050 /*
1051 * If we're allowing coalescing, we must allocate a region
1052 * descriptor now, since it might block.
1053 */
1054 const bool coalesce = (ex->ex_flags & EXF_NOCOALESCE) == 0;
1055
1056 if (coalesce) {
1057 /* Allocate a region descriptor. */
1058 nrp = extent_alloc_region_descriptor(ex, flags);
1059 if (nrp == NULL)
1060 return (ENOMEM);
1061 }
1062
1063 if (!(ex->ex_flags & EXF_EARLY))
1064 mutex_enter(&ex->ex_lock);
1065
1066 /*
1067 * Find region and deallocate. Several possibilities:
1068 *
1069 * 1. (start == er_start) && (end == er_end):
1070 * Free descriptor.
1071 *
1072 * 2. (start == er_start) && (end < er_end):
1073 * Adjust er_start.
1074 *
1075 * 3. (start > er_start) && (end == er_end):
1076 * Adjust er_end.
1077 *
1078 * 4. (start > er_start) && (end < er_end):
1079 * Fragment region. Requires descriptor alloc.
1080 *
1081 * Cases 2, 3, and 4 require that the EXF_NOCOALESCE flag
1082 * is not set.
1083 */
1084 LIST_FOREACH(rp, &ex->ex_regions, er_link) {
1085 /*
1086 * Save ourselves some comparisons; does the current
1087 * region end before chunk to be freed begins? If so,
1088 * then we haven't found the appropriate region descriptor.
1089 */
1090 if (rp->er_end < start)
1091 continue;
1092
1093 /*
1094 * Save ourselves some traversal; does the current
1095 * region begin after the chunk to be freed ends? If so,
1096 * then we've already passed any possible region descriptors
1097 * that might have contained the chunk to be freed.
1098 */
1099 if (rp->er_start > end)
1100 break;
1101
1102 /* Case 1. */
1103 if ((start == rp->er_start) && (end == rp->er_end)) {
1104 LIST_REMOVE(rp, er_link);
1105 extent_free_region_descriptor(ex, rp);
1106 goto done;
1107 }
1108
1109 /*
1110 * The following cases all require that EXF_NOCOALESCE
1111 * is not set.
1112 */
1113 if (!coalesce)
1114 continue;
1115
1116 /* Case 2. */
1117 if ((start == rp->er_start) && (end < rp->er_end)) {
1118 rp->er_start = (end + 1);
1119 goto done;
1120 }
1121
1122 /* Case 3. */
1123 if ((start > rp->er_start) && (end == rp->er_end)) {
1124 rp->er_end = (start - 1);
1125 goto done;
1126 }
1127
1128 /* Case 4. */
1129 if ((start > rp->er_start) && (end < rp->er_end)) {
1130 /* Fill in new descriptor. */
1131 nrp->er_start = end + 1;
1132 nrp->er_end = rp->er_end;
1133
1134 /* Adjust current descriptor. */
1135 rp->er_end = start - 1;
1136
1137 /* Insert new descriptor after current. */
1138 LIST_INSERT_AFTER(rp, nrp, er_link);
1139
1140 /* We used the new descriptor, so don't free it below */
1141 nrp = NULL;
1142 goto done;
1143 }
1144 }
1145
1146 /* Region not found, or request otherwise invalid. */
1147 if (!(ex->ex_flags & EXF_EARLY))
1148 mutex_exit(&ex->ex_lock);
1149 extent_print(ex);
1150 printf("extent_free: start 0x%lx, end 0x%lx\n", start, end);
1151 panic("extent_free: region not found");
1152
1153 done:
1154 if (nrp != NULL)
1155 extent_free_region_descriptor(ex, nrp);
1156 if (!(ex->ex_flags & EXF_EARLY)) {
1157 cv_broadcast(&ex->ex_cv);
1158 mutex_exit(&ex->ex_lock);
1159 }
1160 return (0);
1161}
1162
1163void
1164extent_print(struct extent *ex)
1165{
1166 struct extent_region *rp;
1167
1168 if (ex == NULL)
1169 panic("extent_print: NULL extent");
1170
1171 if (!(ex->ex_flags & EXF_EARLY))
1172 mutex_enter(&ex->ex_lock);
1173
1174 printf("extent `%s' (0x%lx - 0x%lx), flags = 0x%x\n", ex->ex_name,
1175 ex->ex_start, ex->ex_end, ex->ex_flags);
1176
1177 LIST_FOREACH(rp, &ex->ex_regions, er_link)
1178 printf(" 0x%lx - 0x%lx\n", rp->er_start, rp->er_end);
1179
1180 if (!(ex->ex_flags & EXF_EARLY))
1181 mutex_exit(&ex->ex_lock);
1182}
1183