Disallow writes to filesystems mounted read-only via NULLFS. In this case
[dragonfly.git] / sys / kern / subr_rman.c
CommitLineData
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1/*
2 * Copyright 1998 Massachusetts Institute of Technology
3 *
4 * Permission to use, copy, modify, and distribute this software and
5 * its documentation for any purpose and without fee is hereby
6 * granted, provided that both the above copyright notice and this
7 * permission notice appear in all copies, that both the above
8 * copyright notice and this permission notice appear in all
9 * supporting documentation, and that the name of M.I.T. not be used
10 * in advertising or publicity pertaining to distribution of the
11 * software without specific, written prior permission. M.I.T. makes
12 * no representations about the suitability of this software for any
13 * purpose. It is provided "as is" without express or implied
14 * warranty.
15 *
16 * THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''. M.I.T. DISCLAIMS
17 * ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE,
18 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
19 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT
20 * SHALL M.I.T. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
23 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
24 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
25 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
26 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * $FreeBSD: src/sys/kern/subr_rman.c,v 1.10.2.1 2001/06/05 08:06:08 imp Exp $
77652cad 30 * $DragonFly: src/sys/kern/subr_rman.c,v 1.9 2006/09/05 03:48:12 dillon Exp $
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31 */
32
33/*
34 * The kernel resource manager. This code is responsible for keeping track
35 * of hardware resources which are apportioned out to various drivers.
36 * It does not actually assign those resources, and it is not expected
37 * that end-device drivers will call into this code directly. Rather,
38 * the code which implements the buses that those devices are attached to,
39 * and the code which manages CPU resources, will call this code, and the
40 * end-device drivers will make upcalls to that code to actually perform
41 * the allocation.
42 *
43 * There are two sorts of resources managed by this code. The first is
44 * the more familiar array (RMAN_ARRAY) type; resources in this class
45 * consist of a sequence of individually-allocatable objects which have
46 * been numbered in some well-defined order. Most of the resources
47 * are of this type, as it is the most familiar. The second type is
48 * called a gauge (RMAN_GAUGE), and models fungible resources (i.e.,
49 * resources in which each instance is indistinguishable from every
50 * other instance). The principal anticipated application of gauges
51 * is in the context of power consumption, where a bus may have a specific
52 * power budget which all attached devices share. RMAN_GAUGE is not
53 * implemented yet.
54 *
55 * For array resources, we make one simplifying assumption: two clients
56 * sharing the same resource must use the same range of indices. That
57 * is to say, sharing of overlapping-but-not-identical regions is not
58 * permitted.
59 */
60
61#include <sys/param.h>
62#include <sys/systm.h>
63#include <sys/kernel.h>
64#include <sys/lock.h>
65#include <sys/malloc.h>
66#include <sys/bus.h> /* XXX debugging */
67#include <machine/bus.h>
68#include <sys/rman.h>
69
70static MALLOC_DEFINE(M_RMAN, "rman", "Resource manager");
71
72struct rman_head rman_head;
8a8d5d85 73static struct lwkt_token rman_tok; /* mutex to protect rman_head */
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74static int int_rman_activate_resource(struct rman *rm, struct resource *r,
75 struct resource **whohas);
76static int int_rman_deactivate_resource(struct resource *r);
77static int int_rman_release_resource(struct rman *rm, struct resource *r);
78
79#define CIRCLEQ_TERMCOND(var, head) (var == (void *)&(head))
80
81int
82rman_init(struct rman *rm)
83{
84 static int once;
41a01a4d 85 lwkt_tokref ilock;
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86
87 if (once == 0) {
88 once = 1;
89 TAILQ_INIT(&rman_head);
41a01a4d 90 lwkt_token_init(&rman_tok);
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91 }
92
93 if (rm->rm_type == RMAN_UNINIT)
94 panic("rman_init");
95 if (rm->rm_type == RMAN_GAUGE)
96 panic("implement RMAN_GAUGE");
97
98 CIRCLEQ_INIT(&rm->rm_list);
efda3bd0 99 rm->rm_slock = kmalloc(sizeof *rm->rm_slock, M_RMAN, M_NOWAIT);
8a8d5d85 100 if (rm->rm_slock == NULL)
984263bc 101 return ENOMEM;
41a01a4d 102 lwkt_token_init(rm->rm_slock);
984263bc 103
41a01a4d 104 lwkt_gettoken(&ilock, &rman_tok);
984263bc 105 TAILQ_INSERT_TAIL(&rman_head, rm, rm_link);
41a01a4d 106 lwkt_reltoken(&ilock);
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107 return 0;
108}
109
110/*
111 * NB: this interface is not robust against programming errors which
112 * add multiple copies of the same region.
113 */
114int
115rman_manage_region(struct rman *rm, u_long start, u_long end)
116{
117 struct resource *r, *s;
41a01a4d 118 lwkt_tokref ilock;
984263bc 119
efda3bd0 120 r = kmalloc(sizeof *r, M_RMAN, M_NOWAIT);
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121 if (r == 0)
122 return ENOMEM;
123 bzero(r, sizeof *r);
124 r->r_sharehead = 0;
125 r->r_start = start;
126 r->r_end = end;
127 r->r_flags = 0;
128 r->r_dev = 0;
129 r->r_rm = rm;
130
41a01a4d 131 lwkt_gettoken(&ilock, rm->rm_slock);
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132 for (s = CIRCLEQ_FIRST(&rm->rm_list);
133 !CIRCLEQ_TERMCOND(s, rm->rm_list) && s->r_end < r->r_start;
134 s = CIRCLEQ_NEXT(s, r_link))
135 ;
136
137 if (CIRCLEQ_TERMCOND(s, rm->rm_list)) {
138 CIRCLEQ_INSERT_TAIL(&rm->rm_list, r, r_link);
139 } else {
140 CIRCLEQ_INSERT_BEFORE(&rm->rm_list, s, r, r_link);
141 }
142
41a01a4d 143 lwkt_reltoken(&ilock);
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144 return 0;
145}
146
147int
148rman_fini(struct rman *rm)
149{
150 struct resource *r;
41a01a4d 151 lwkt_tokref ilock;
984263bc 152
41a01a4d 153 lwkt_gettoken(&ilock, rm->rm_slock);
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154 CIRCLEQ_FOREACH(r, &rm->rm_list, r_link) {
155 if (r->r_flags & RF_ALLOCATED) {
41a01a4d 156 lwkt_reltoken(&ilock);
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157 return EBUSY;
158 }
159 }
160
161 /*
162 * There really should only be one of these if we are in this
163 * state and the code is working properly, but it can't hurt.
164 */
165 while (!CIRCLEQ_EMPTY(&rm->rm_list)) {
166 r = CIRCLEQ_FIRST(&rm->rm_list);
167 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
efda3bd0 168 kfree(r, M_RMAN);
984263bc 169 }
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170 lwkt_reltoken(&ilock);
171 /* XXX what's the point of this if we are going to free the struct? */
172 lwkt_gettoken(&ilock, &rman_tok);
984263bc 173 TAILQ_REMOVE(&rman_head, rm, rm_link);
41a01a4d 174 lwkt_reltoken(&ilock);
efda3bd0 175 kfree(rm->rm_slock, M_RMAN);
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176
177 return 0;
178}
179
180struct resource *
181rman_reserve_resource(struct rman *rm, u_long start, u_long end, u_long count,
182 u_int flags, struct device *dev)
183{
184 u_int want_activate;
185 struct resource *r, *s, *rv;
186 u_long rstart, rend;
41a01a4d 187 lwkt_tokref ilock;
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188
189 rv = 0;
190
191#ifdef RMAN_DEBUG
192 printf("rman_reserve_resource: <%s> request: [%#lx, %#lx], length "
193 "%#lx, flags %u, device %s%d\n", rm->rm_descr, start, end,
194 count, flags, device_get_name(dev), device_get_unit(dev));
195#endif /* RMAN_DEBUG */
196 want_activate = (flags & RF_ACTIVE);
197 flags &= ~RF_ACTIVE;
198
41a01a4d 199 lwkt_gettoken(&ilock, rm->rm_slock);
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200
201 for (r = CIRCLEQ_FIRST(&rm->rm_list);
202 !CIRCLEQ_TERMCOND(r, rm->rm_list) && r->r_end < start;
203 r = CIRCLEQ_NEXT(r, r_link))
204 ;
205
206 if (CIRCLEQ_TERMCOND(r, rm->rm_list)) {
207#ifdef RMAN_DEBUG
208 printf("could not find a region\n");
6b08710e 209#endif
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210 goto out;
211 }
212
213 /*
214 * First try to find an acceptable totally-unshared region.
215 */
216 for (s = r; !CIRCLEQ_TERMCOND(s, rm->rm_list);
217 s = CIRCLEQ_NEXT(s, r_link)) {
218#ifdef RMAN_DEBUG
219 printf("considering [%#lx, %#lx]\n", s->r_start, s->r_end);
220#endif /* RMAN_DEBUG */
221 if (s->r_start > end) {
222#ifdef RMAN_DEBUG
223 printf("s->r_start (%#lx) > end (%#lx)\n", s->r_start, end);
224#endif /* RMAN_DEBUG */
225 break;
226 }
227 if (s->r_flags & RF_ALLOCATED) {
228#ifdef RMAN_DEBUG
229 printf("region is allocated\n");
230#endif /* RMAN_DEBUG */
231 continue;
232 }
233 rstart = max(s->r_start, start);
234 rstart = (rstart + ((1ul << RF_ALIGNMENT(flags))) - 1) &
235 ~((1ul << RF_ALIGNMENT(flags)) - 1);
236 rend = min(s->r_end, max(start + count, end));
237#ifdef RMAN_DEBUG
238 printf("truncated region: [%#lx, %#lx]; size %#lx (requested %#lx)\n",
239 rstart, rend, (rend - rstart + 1), count);
240#endif /* RMAN_DEBUG */
241
242 if ((rend - rstart + 1) >= count) {
243#ifdef RMAN_DEBUG
244 printf("candidate region: [%#lx, %#lx], size %#lx\n",
245 rend, rstart, (rend - rstart + 1));
246#endif /* RMAN_DEBUG */
247 if ((s->r_end - s->r_start + 1) == count) {
248#ifdef RMAN_DEBUG
249 printf("candidate region is entire chunk\n");
250#endif /* RMAN_DEBUG */
251 rv = s;
252 rv->r_flags |= RF_ALLOCATED | flags;
253 rv->r_dev = dev;
254 goto out;
255 }
256
257 /*
258 * If s->r_start < rstart and
259 * s->r_end > rstart + count - 1, then
260 * we need to split the region into three pieces
261 * (the middle one will get returned to the user).
262 * Otherwise, we are allocating at either the
263 * beginning or the end of s, so we only need to
264 * split it in two. The first case requires
265 * two new allocations; the second requires but one.
266 */
efda3bd0 267 rv = kmalloc(sizeof *rv, M_RMAN, M_NOWAIT);
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268 if (rv == 0)
269 goto out;
270 bzero(rv, sizeof *rv);
271 rv->r_start = rstart;
272 rv->r_end = rstart + count - 1;
273 rv->r_flags = flags | RF_ALLOCATED;
274 rv->r_dev = dev;
275 rv->r_sharehead = 0;
276 rv->r_rm = rm;
277
278 if (s->r_start < rv->r_start && s->r_end > rv->r_end) {
279#ifdef RMAN_DEBUG
280 printf("splitting region in three parts: "
281 "[%#lx, %#lx]; [%#lx, %#lx]; [%#lx, %#lx]\n",
282 s->r_start, rv->r_start - 1,
283 rv->r_start, rv->r_end,
284 rv->r_end + 1, s->r_end);
285#endif /* RMAN_DEBUG */
286 /*
287 * We are allocating in the middle.
288 */
efda3bd0 289 r = kmalloc(sizeof *r, M_RMAN, M_NOWAIT);
984263bc 290 if (r == 0) {
efda3bd0 291 kfree(rv, M_RMAN);
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292 rv = 0;
293 goto out;
294 }
295 bzero(r, sizeof *r);
296 r->r_start = rv->r_end + 1;
297 r->r_end = s->r_end;
298 r->r_flags = s->r_flags;
299 r->r_dev = 0;
300 r->r_sharehead = 0;
301 r->r_rm = rm;
302 s->r_end = rv->r_start - 1;
303 CIRCLEQ_INSERT_AFTER(&rm->rm_list, s, rv,
304 r_link);
305 CIRCLEQ_INSERT_AFTER(&rm->rm_list, rv, r,
306 r_link);
307 } else if (s->r_start == rv->r_start) {
308#ifdef RMAN_DEBUG
309 printf("allocating from the beginning\n");
310#endif /* RMAN_DEBUG */
311 /*
312 * We are allocating at the beginning.
313 */
314 s->r_start = rv->r_end + 1;
315 CIRCLEQ_INSERT_BEFORE(&rm->rm_list, s, rv,
316 r_link);
317 } else {
318#ifdef RMAN_DEBUG
319 printf("allocating at the end\n");
320#endif /* RMAN_DEBUG */
321 /*
322 * We are allocating at the end.
323 */
324 s->r_end = rv->r_start - 1;
325 CIRCLEQ_INSERT_AFTER(&rm->rm_list, s, rv,
326 r_link);
327 }
328 goto out;
329 }
330 }
331
332 /*
333 * Now find an acceptable shared region, if the client's requirements
334 * allow sharing. By our implementation restriction, a candidate
335 * region must match exactly by both size and sharing type in order
336 * to be considered compatible with the client's request. (The
337 * former restriction could probably be lifted without too much
338 * additional work, but this does not seem warranted.)
339 */
340#ifdef RMAN_DEBUG
341 printf("no unshared regions found\n");
342#endif /* RMAN_DEBUG */
343 if ((flags & (RF_SHAREABLE | RF_TIMESHARE)) == 0)
344 goto out;
345
346 for (s = r; !CIRCLEQ_TERMCOND(s, rm->rm_list);
347 s = CIRCLEQ_NEXT(s, r_link)) {
348 if (s->r_start > end)
349 break;
350 if ((s->r_flags & flags) != flags)
351 continue;
352 rstart = max(s->r_start, start);
353 rend = min(s->r_end, max(start + count, end));
354 if (s->r_start >= start && s->r_end <= end
355 && (s->r_end - s->r_start + 1) == count) {
efda3bd0 356 rv = kmalloc(sizeof *rv, M_RMAN, M_NOWAIT);
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357 if (rv == 0)
358 goto out;
359 bzero(rv, sizeof *rv);
360 rv->r_start = s->r_start;
361 rv->r_end = s->r_end;
362 rv->r_flags = s->r_flags &
363 (RF_ALLOCATED | RF_SHAREABLE | RF_TIMESHARE);
364 rv->r_dev = dev;
365 rv->r_rm = rm;
366 if (s->r_sharehead == 0) {
77652cad 367 s->r_sharehead = kmalloc(sizeof *s->r_sharehead,
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368 M_RMAN, M_NOWAIT);
369 if (s->r_sharehead == 0) {
efda3bd0 370 kfree(rv, M_RMAN);
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371 rv = 0;
372 goto out;
373 }
374 bzero(s->r_sharehead, sizeof *s->r_sharehead);
375 LIST_INIT(s->r_sharehead);
376 LIST_INSERT_HEAD(s->r_sharehead, s,
377 r_sharelink);
378 s->r_flags |= RF_FIRSTSHARE;
379 }
380 rv->r_sharehead = s->r_sharehead;
381 LIST_INSERT_HEAD(s->r_sharehead, rv, r_sharelink);
382 goto out;
383 }
384 }
385
386 /*
387 * We couldn't find anything.
388 */
389out:
390 /*
391 * If the user specified RF_ACTIVE in the initial flags,
392 * which is reflected in `want_activate', we attempt to atomically
393 * activate the resource. If this fails, we release the resource
394 * and indicate overall failure. (This behavior probably doesn't
395 * make sense for RF_TIMESHARE-type resources.)
396 */
397 if (rv && want_activate) {
398 struct resource *whohas;
399 if (int_rman_activate_resource(rm, rv, &whohas)) {
400 int_rman_release_resource(rm, rv);
401 rv = 0;
402 }
403 }
41a01a4d 404 lwkt_reltoken(&ilock);
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405 return (rv);
406}
407
408static int
409int_rman_activate_resource(struct rman *rm, struct resource *r,
410 struct resource **whohas)
411{
412 struct resource *s;
413 int ok;
414
415 /*
416 * If we are not timesharing, then there is nothing much to do.
417 * If we already have the resource, then there is nothing at all to do.
418 * If we are not on a sharing list with anybody else, then there is
419 * little to do.
420 */
421 if ((r->r_flags & RF_TIMESHARE) == 0
422 || (r->r_flags & RF_ACTIVE) != 0
423 || r->r_sharehead == 0) {
424 r->r_flags |= RF_ACTIVE;
425 return 0;
426 }
427
428 ok = 1;
429 for (s = LIST_FIRST(r->r_sharehead); s && ok;
430 s = LIST_NEXT(s, r_sharelink)) {
431 if ((s->r_flags & RF_ACTIVE) != 0) {
432 ok = 0;
433 *whohas = s;
434 }
435 }
436 if (ok) {
437 r->r_flags |= RF_ACTIVE;
438 return 0;
439 }
440 return EBUSY;
441}
442
443int
444rman_activate_resource(struct resource *r)
445{
446 int rv;
447 struct resource *whohas;
41a01a4d 448 lwkt_tokref ilock;
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449 struct rman *rm;
450
451 rm = r->r_rm;
41a01a4d 452 lwkt_gettoken(&ilock, rm->rm_slock);
984263bc 453 rv = int_rman_activate_resource(rm, r, &whohas);
41a01a4d 454 lwkt_reltoken(&ilock);
984263bc
MD
455 return rv;
456}
457
41a01a4d
MD
458#if 0
459
460/* XXX */
984263bc 461int
41a01a4d 462rman_await_resource(struct resource *r, lwkt_tokref_t ilock, int slpflags, int timo)
984263bc 463{
e43a034f 464 int rv;
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MD
465 struct resource *whohas;
466 struct rman *rm;
467
468 rm = r->r_rm;
469 for (;;) {
41a01a4d 470 lwkt_gettoken(ilock, rm->rm_slock);
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471 rv = int_rman_activate_resource(rm, r, &whohas);
472 if (rv != EBUSY)
41a01a4d 473 return (rv); /* returns with ilock held */
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474
475 if (r->r_sharehead == 0)
476 panic("rman_await_resource");
477 /*
e43a034f
MD
478 * A critical section will hopefully will prevent a race
479 * between lwkt_reltoken and tsleep where a process
984263bc 480 * could conceivably get in and release the resource
8a8d5d85 481 * before we have a chance to sleep on it. YYY
984263bc 482 */
e43a034f 483 crit_enter();
984263bc 484 whohas->r_flags |= RF_WANTED;
377d4740 485 rv = tsleep(r->r_sharehead, slpflags, "rmwait", timo);
984263bc 486 if (rv) {
41a01a4d 487 lwkt_reltoken(ilock);
e43a034f 488 crit_exit();
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489 return rv;
490 }
e43a034f 491 crit_exit();
984263bc
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492 }
493}
494
41a01a4d
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495#endif
496
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497static int
498int_rman_deactivate_resource(struct resource *r)
499{
500 struct rman *rm;
501
502 rm = r->r_rm;
503 r->r_flags &= ~RF_ACTIVE;
504 if (r->r_flags & RF_WANTED) {
505 r->r_flags &= ~RF_WANTED;
506 wakeup(r->r_sharehead);
507 }
508 return 0;
509}
510
511int
512rman_deactivate_resource(struct resource *r)
513{
41a01a4d
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514 lwkt_tokref ilock;
515 struct rman *rm;
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516
517 rm = r->r_rm;
41a01a4d 518 lwkt_gettoken(&ilock, rm->rm_slock);
984263bc 519 int_rman_deactivate_resource(r);
41a01a4d 520 lwkt_reltoken(&ilock);
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521 return 0;
522}
523
524static int
525int_rman_release_resource(struct rman *rm, struct resource *r)
526{
527 struct resource *s, *t;
528
529 if (r->r_flags & RF_ACTIVE)
530 int_rman_deactivate_resource(r);
531
532 /*
533 * Check for a sharing list first. If there is one, then we don't
534 * have to think as hard.
535 */
536 if (r->r_sharehead) {
537 /*
538 * If a sharing list exists, then we know there are at
539 * least two sharers.
540 *
541 * If we are in the main circleq, appoint someone else.
542 */
543 LIST_REMOVE(r, r_sharelink);
544 s = LIST_FIRST(r->r_sharehead);
545 if (r->r_flags & RF_FIRSTSHARE) {
546 s->r_flags |= RF_FIRSTSHARE;
547 CIRCLEQ_INSERT_BEFORE(&rm->rm_list, r, s, r_link);
548 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
549 }
550
551 /*
552 * Make sure that the sharing list goes away completely
553 * if the resource is no longer being shared at all.
554 */
555 if (LIST_NEXT(s, r_sharelink) == 0) {
efda3bd0 556 kfree(s->r_sharehead, M_RMAN);
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557 s->r_sharehead = 0;
558 s->r_flags &= ~RF_FIRSTSHARE;
559 }
560 goto out;
561 }
562
563 /*
564 * Look at the adjacent resources in the list and see if our
565 * segment can be merged with any of them.
566 */
567 s = CIRCLEQ_PREV(r, r_link);
568 t = CIRCLEQ_NEXT(r, r_link);
569
570 if (s != (void *)&rm->rm_list && (s->r_flags & RF_ALLOCATED) == 0
571 && t != (void *)&rm->rm_list && (t->r_flags & RF_ALLOCATED) == 0) {
572 /*
573 * Merge all three segments.
574 */
575 s->r_end = t->r_end;
576 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
577 CIRCLEQ_REMOVE(&rm->rm_list, t, r_link);
efda3bd0 578 kfree(t, M_RMAN);
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579 } else if (s != (void *)&rm->rm_list
580 && (s->r_flags & RF_ALLOCATED) == 0) {
581 /*
582 * Merge previous segment with ours.
583 */
584 s->r_end = r->r_end;
585 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
586 } else if (t != (void *)&rm->rm_list
587 && (t->r_flags & RF_ALLOCATED) == 0) {
588 /*
589 * Merge next segment with ours.
590 */
591 t->r_start = r->r_start;
592 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
593 } else {
594 /*
595 * At this point, we know there is nothing we
596 * can potentially merge with, because on each
597 * side, there is either nothing there or what is
598 * there is still allocated. In that case, we don't
599 * want to remove r from the list; we simply want to
600 * change it to an unallocated region and return
601 * without freeing anything.
602 */
603 r->r_flags &= ~RF_ALLOCATED;
604 return 0;
605 }
606
607out:
efda3bd0 608 kfree(r, M_RMAN);
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609 return 0;
610}
611
612int
613rman_release_resource(struct resource *r)
614{
984263bc 615 struct rman *rm = r->r_rm;
41a01a4d
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616 lwkt_tokref ilock;
617 int rv;
984263bc 618
41a01a4d 619 lwkt_gettoken(&ilock, rm->rm_slock);
984263bc 620 rv = int_rman_release_resource(rm, r);
41a01a4d 621 lwkt_reltoken(&ilock);
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MD
622 return (rv);
623}
624
625uint32_t
626rman_make_alignment_flags(uint32_t size)
627{
628 int i;
629
630 /*
631 * Find the hightest bit set, and add one if more than one bit
632 * set. We're effectively computing the ceil(log2(size)) here.
633 */
634 for (i = 32; i > 0; i--)
635 if ((1 << i) & size)
636 break;
637 if (~(1 << i) & size)
638 i++;
639
640 return(RF_ALIGNMENT_LOG2(i));
641}