sys/kern/subr_rman.c

   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 $
  30  * $DragonFly: src/sys/kern/subr_rman.c,v 1.4 2003/07/19 21:14:38 dillon Exp $
  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
  70 static MALLOC_DEFINE(M_RMAN, "rman", "Resource manager");
  71
  72 struct  rman_head rman_head;
  73 static  struct lwkt_token rman_tok; /* mutex to protect rman_head */
  74 static  int int_rman_activate_resource(struct rman *rm, struct resource *r,
  75                                        struct resource **whohas);
  76 static  int int_rman_deactivate_resource(struct resource *r);
  77 static  int int_rman_release_resource(struct rman *rm, struct resource *r);
  78
  79 #define CIRCLEQ_TERMCOND(var, head)     (var == (void *)&(head))
  80
  81 int
  82 rman_init(struct rman *rm)
  83 {
  84         static int once;
  85
  86         if (once == 0) {
  87                 once = 1;
  88                 TAILQ_INIT(&rman_head);
  89                 lwkt_inittoken(&rman_tok);
  90         }
  91
  92         if (rm->rm_type == RMAN_UNINIT)
  93                 panic("rman_init");
  94         if (rm->rm_type == RMAN_GAUGE)
  95                 panic("implement RMAN_GAUGE");
  96
  97         CIRCLEQ_INIT(&rm->rm_list);
  98         rm->rm_slock = malloc(sizeof *rm->rm_slock, M_RMAN, M_NOWAIT);
  99         if (rm->rm_slock == NULL)
 100                 return ENOMEM;
 101         lwkt_inittoken(rm->rm_slock);
 102
 103         lwkt_gettoken(&rman_tok);
 104         TAILQ_INSERT_TAIL(&rman_head, rm, rm_link);
 105         lwkt_reltoken(&rman_tok);
 106         return 0;
 107 }
 108
 109 /*
 110  * NB: this interface is not robust against programming errors which
 111  * add multiple copies of the same region.
 112  */
 113 int
 114 rman_manage_region(struct rman *rm, u_long start, u_long end)
 115 {
 116         struct resource *r, *s;
 117
 118         r = malloc(sizeof *r, M_RMAN, M_NOWAIT);
 119         if (r == 0)
 120                 return ENOMEM;
 121         bzero(r, sizeof *r);
 122         r->r_sharehead = 0;
 123         r->r_start = start;
 124         r->r_end = end;
 125         r->r_flags = 0;
 126         r->r_dev = 0;
 127         r->r_rm = rm;
 128
 129         lwkt_gettoken(rm->rm_slock);
 130         for (s = CIRCLEQ_FIRST(&rm->rm_list);
 131              !CIRCLEQ_TERMCOND(s, rm->rm_list) && s->r_end < r->r_start;
 132              s = CIRCLEQ_NEXT(s, r_link))
 133                 ;
 134
 135         if (CIRCLEQ_TERMCOND(s, rm->rm_list)) {
 136                 CIRCLEQ_INSERT_TAIL(&rm->rm_list, r, r_link);
 137         } else {
 138                 CIRCLEQ_INSERT_BEFORE(&rm->rm_list, s, r, r_link);
 139         }
 140
 141         lwkt_reltoken(rm->rm_slock);
 142         return 0;
 143 }
 144
 145 int
 146 rman_fini(struct rman *rm)
 147 {
 148         struct resource *r;
 149
 150         lwkt_gettoken(rm->rm_slock);
 151         CIRCLEQ_FOREACH(r, &rm->rm_list, r_link) {
 152                 if (r->r_flags & RF_ALLOCATED) {
 153                         lwkt_reltoken(rm->rm_slock);
 154                         return EBUSY;
 155                 }
 156         }
 157
 158         /*
 159          * There really should only be one of these if we are in this
 160          * state and the code is working properly, but it can't hurt.
 161          */
 162         while (!CIRCLEQ_EMPTY(&rm->rm_list)) {
 163                 r = CIRCLEQ_FIRST(&rm->rm_list);
 164                 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
 165                 free(r, M_RMAN);
 166         }
 167         lwkt_reltoken(rm->rm_slock);
 168         lwkt_gettoken(&rman_tok);
 169         TAILQ_REMOVE(&rman_head, rm, rm_link);
 170         lwkt_reltoken(&rman_tok);
 171         free(rm->rm_slock, M_RMAN);
 172
 173         return 0;
 174 }
 175
 176 struct resource *
 177 rman_reserve_resource(struct rman *rm, u_long start, u_long end, u_long count,
 178                       u_int flags, struct device *dev)
 179 {
 180         u_int   want_activate;
 181         struct  resource *r, *s, *rv;
 182         u_long  rstart, rend;
 183
 184         rv = 0;
 185
 186 #ifdef RMAN_DEBUG
 187         printf("rman_reserve_resource: <%s> request: [%#lx, %#lx], length "
 188                "%#lx, flags %u, device %s%d\n", rm->rm_descr, start, end,
 189                count, flags, device_get_name(dev), device_get_unit(dev));
 190 #endif /* RMAN_DEBUG */
 191         want_activate = (flags & RF_ACTIVE);
 192         flags &= ~RF_ACTIVE;
 193
 194         lwkt_gettoken(rm->rm_slock);
 195
 196         for (r = CIRCLEQ_FIRST(&rm->rm_list);
 197              !CIRCLEQ_TERMCOND(r, rm->rm_list) && r->r_end < start;
 198              r = CIRCLEQ_NEXT(r, r_link))
 199                 ;
 200
 201         if (CIRCLEQ_TERMCOND(r, rm->rm_list)) {
 202 #ifdef RMAN_DEBUG
 203                 printf("could not find a region\n");
 204 #endif RMAN_DEBUG
 205                 goto out;
 206         }
 207
 208         /*
 209          * First try to find an acceptable totally-unshared region.
 210          */
 211         for (s = r; !CIRCLEQ_TERMCOND(s, rm->rm_list);
 212              s = CIRCLEQ_NEXT(s, r_link)) {
 213 #ifdef RMAN_DEBUG
 214                 printf("considering [%#lx, %#lx]\n", s->r_start, s->r_end);
 215 #endif /* RMAN_DEBUG */
 216                 if (s->r_start > end) {
 217 #ifdef RMAN_DEBUG
 218                         printf("s->r_start (%#lx) > end (%#lx)\n", s->r_start, end);
 219 #endif /* RMAN_DEBUG */
 220                         break;
 221                 }
 222                 if (s->r_flags & RF_ALLOCATED) {
 223 #ifdef RMAN_DEBUG
 224                         printf("region is allocated\n");
 225 #endif /* RMAN_DEBUG */
 226                         continue;
 227                 }
 228                 rstart = max(s->r_start, start);
 229                 rstart = (rstart + ((1ul << RF_ALIGNMENT(flags))) - 1) &
 230                     ~((1ul << RF_ALIGNMENT(flags)) - 1);
 231                 rend = min(s->r_end, max(start + count, end));
 232 #ifdef RMAN_DEBUG
 233                 printf("truncated region: [%#lx, %#lx]; size %#lx (requested %#lx)\n",
 234                        rstart, rend, (rend - rstart + 1), count);
 235 #endif /* RMAN_DEBUG */
 236
 237                 if ((rend - rstart + 1) >= count) {
 238 #ifdef RMAN_DEBUG
 239                         printf("candidate region: [%#lx, %#lx], size %#lx\n",
 240                                rend, rstart, (rend - rstart + 1));
 241 #endif /* RMAN_DEBUG */
 242                         if ((s->r_end - s->r_start + 1) == count) {
 243 #ifdef RMAN_DEBUG
 244                                 printf("candidate region is entire chunk\n");
 245 #endif /* RMAN_DEBUG */
 246                                 rv = s;
 247                                 rv->r_flags |= RF_ALLOCATED | flags;
 248                                 rv->r_dev = dev;
 249                                 goto out;
 250                         }
 251
 252                         /*
 253                          * If s->r_start < rstart and
 254                          *    s->r_end > rstart + count - 1, then
 255                          * we need to split the region into three pieces
 256                          * (the middle one will get returned to the user).
 257                          * Otherwise, we are allocating at either the
 258                          * beginning or the end of s, so we only need to
 259                          * split it in two.  The first case requires
 260                          * two new allocations; the second requires but one.
 261                          */
 262                         rv = malloc(sizeof *rv, M_RMAN, M_NOWAIT);
 263                         if (rv == 0)
 264                                 goto out;
 265                         bzero(rv, sizeof *rv);
 266                         rv->r_start = rstart;
 267                         rv->r_end = rstart + count - 1;
 268                         rv->r_flags = flags | RF_ALLOCATED;
 269                         rv->r_dev = dev;
 270                         rv->r_sharehead = 0;
 271                         rv->r_rm = rm;
 272
 273                         if (s->r_start < rv->r_start && s->r_end > rv->r_end) {
 274 #ifdef RMAN_DEBUG
 275                                 printf("splitting region in three parts: "
 276                                        "[%#lx, %#lx]; [%#lx, %#lx]; [%#lx, %#lx]\n",
 277                                        s->r_start, rv->r_start - 1,
 278                                        rv->r_start, rv->r_end,
 279                                        rv->r_end + 1, s->r_end);
 280 #endif /* RMAN_DEBUG */
 281                                 /*
 282                                  * We are allocating in the middle.
 283                                  */
 284                                 r = malloc(sizeof *r, M_RMAN, M_NOWAIT);
 285                                 if (r == 0) {
 286                                         free(rv, M_RMAN);
 287                                         rv = 0;
 288                                         goto out;
 289                                 }
 290                                 bzero(r, sizeof *r);
 291                                 r->r_start = rv->r_end + 1;
 292                                 r->r_end = s->r_end;
 293                                 r->r_flags = s->r_flags;
 294                                 r->r_dev = 0;
 295                                 r->r_sharehead = 0;
 296                                 r->r_rm = rm;
 297                                 s->r_end = rv->r_start - 1;
 298                                 CIRCLEQ_INSERT_AFTER(&rm->rm_list, s, rv,
 299                                                      r_link);
 300                                 CIRCLEQ_INSERT_AFTER(&rm->rm_list, rv, r,
 301                                                      r_link);
 302                         } else if (s->r_start == rv->r_start) {
 303 #ifdef RMAN_DEBUG
 304                                 printf("allocating from the beginning\n");
 305 #endif /* RMAN_DEBUG */
 306                                 /*
 307                                  * We are allocating at the beginning.
 308                                  */
 309                                 s->r_start = rv->r_end + 1;
 310                                 CIRCLEQ_INSERT_BEFORE(&rm->rm_list, s, rv,
 311                                                       r_link);
 312                         } else {
 313 #ifdef RMAN_DEBUG
 314                                 printf("allocating at the end\n");
 315 #endif /* RMAN_DEBUG */
 316                                 /*
 317                                  * We are allocating at the end.
 318                                  */
 319                                 s->r_end = rv->r_start - 1;
 320                                 CIRCLEQ_INSERT_AFTER(&rm->rm_list, s, rv,
 321                                                      r_link);
 322                         }
 323                         goto out;
 324                 }
 325         }
 326
 327         /*
 328          * Now find an acceptable shared region, if the client's requirements
 329          * allow sharing.  By our implementation restriction, a candidate
 330          * region must match exactly by both size and sharing type in order
 331          * to be considered compatible with the client's request.  (The
 332          * former restriction could probably be lifted without too much
 333          * additional work, but this does not seem warranted.)
 334          */
 335 #ifdef RMAN_DEBUG
 336         printf("no unshared regions found\n");
 337 #endif /* RMAN_DEBUG */
 338         if ((flags & (RF_SHAREABLE | RF_TIMESHARE)) == 0)
 339                 goto out;
 340
 341         for (s = r; !CIRCLEQ_TERMCOND(s, rm->rm_list);
 342              s = CIRCLEQ_NEXT(s, r_link)) {
 343                 if (s->r_start > end)
 344                         break;
 345                 if ((s->r_flags & flags) != flags)
 346                         continue;
 347                 rstart = max(s->r_start, start);
 348                 rend = min(s->r_end, max(start + count, end));
 349                 if (s->r_start >= start && s->r_end <= end
 350                     && (s->r_end - s->r_start + 1) == count) {
 351                         rv = malloc(sizeof *rv, M_RMAN, M_NOWAIT);
 352                         if (rv == 0)
 353                                 goto out;
 354                         bzero(rv, sizeof *rv);
 355                         rv->r_start = s->r_start;
 356                         rv->r_end = s->r_end;
 357                         rv->r_flags = s->r_flags &
 358                                 (RF_ALLOCATED | RF_SHAREABLE | RF_TIMESHARE);
 359                         rv->r_dev = dev;
 360                         rv->r_rm = rm;
 361                         if (s->r_sharehead == 0) {
 362                                 s->r_sharehead = malloc(sizeof *s->r_sharehead,
 363                                                         M_RMAN, M_NOWAIT);
 364                                 if (s->r_sharehead == 0) {
 365                                         free(rv, M_RMAN);
 366                                         rv = 0;
 367                                         goto out;
 368                                 }
 369                                 bzero(s->r_sharehead, sizeof *s->r_sharehead);
 370                                 LIST_INIT(s->r_sharehead);
 371                                 LIST_INSERT_HEAD(s->r_sharehead, s,
 372                                                  r_sharelink);
 373                                 s->r_flags |= RF_FIRSTSHARE;
 374                         }
 375                         rv->r_sharehead = s->r_sharehead;
 376                         LIST_INSERT_HEAD(s->r_sharehead, rv, r_sharelink);
 377                         goto out;
 378                 }
 379         }
 380
 381         /*
 382          * We couldn't find anything.
 383          */
 384 out:
 385         /*
 386          * If the user specified RF_ACTIVE in the initial flags,
 387          * which is reflected in `want_activate', we attempt to atomically
 388          * activate the resource.  If this fails, we release the resource
 389          * and indicate overall failure.  (This behavior probably doesn't
 390          * make sense for RF_TIMESHARE-type resources.)
 391          */
 392         if (rv && want_activate) {
 393                 struct resource *whohas;
 394                 if (int_rman_activate_resource(rm, rv, &whohas)) {
 395                         int_rman_release_resource(rm, rv);
 396                         rv = 0;
 397                 }
 398         }
 399
 400         lwkt_reltoken(rm->rm_slock);
 401         return (rv);
 402 }
 403
 404 static int
 405 int_rman_activate_resource(struct rman *rm, struct resource *r,
 406                            struct resource **whohas)
 407 {
 408         struct resource *s;
 409         int ok;
 410
 411         /*
 412          * If we are not timesharing, then there is nothing much to do.
 413          * If we already have the resource, then there is nothing at all to do.
 414          * If we are not on a sharing list with anybody else, then there is
 415          * little to do.
 416          */
 417         if ((r->r_flags & RF_TIMESHARE) == 0
 418             || (r->r_flags & RF_ACTIVE) != 0
 419             || r->r_sharehead == 0) {
 420                 r->r_flags |= RF_ACTIVE;
 421                 return 0;
 422         }
 423
 424         ok = 1;
 425         for (s = LIST_FIRST(r->r_sharehead); s && ok;
 426              s = LIST_NEXT(s, r_sharelink)) {
 427                 if ((s->r_flags & RF_ACTIVE) != 0) {
 428                         ok = 0;
 429                         *whohas = s;
 430                 }
 431         }
 432         if (ok) {
 433                 r->r_flags |= RF_ACTIVE;
 434                 return 0;
 435         }
 436         return EBUSY;
 437 }
 438
 439 int
 440 rman_activate_resource(struct resource *r)
 441 {
 442         int rv;
 443         struct resource *whohas;
 444         struct rman *rm;
 445
 446         rm = r->r_rm;
 447         lwkt_gettoken(rm->rm_slock);
 448         rv = int_rman_activate_resource(rm, r, &whohas);
 449         lwkt_reltoken(rm->rm_slock);
 450         return rv;
 451 }
 452
 453 int
 454 rman_await_resource(struct resource *r, int slpflags, int timo)
 455 {
 456         int     rv, s;
 457         struct  resource *whohas;
 458         struct  rman *rm;
 459
 460         rm = r->r_rm;
 461         for (;;) {
 462                 lwkt_gettoken(rm->rm_slock);
 463                 rv = int_rman_activate_resource(rm, r, &whohas);
 464                 if (rv != EBUSY)
 465                         return (rv);    /* returns with simple token */
 466
 467                 if (r->r_sharehead == 0)
 468                         panic("rman_await_resource");
 469                 /*
 470                  * splhigh hopefully will prevent a race between
 471                  * lwkt_reltoken and tsleep where a process
 472                  * could conceivably get in and release the resource
 473                  * before we have a chance to sleep on it. YYY
 474                  */
 475                 s = splhigh();
 476                 whohas->r_flags |= RF_WANTED;
 477                 lwkt_reltoken(rm->rm_slock);    /* YYY */
 478                 rv = tsleep(r->r_sharehead, slpflags, "rmwait", timo);
 479                 if (rv) {
 480                         splx(s);
 481                         return rv;
 482                 }
 483                 lwkt_gettoken(rm->rm_slock);
 484                 splx(s);
 485         }
 486 }
 487
 488 static int
 489 int_rman_deactivate_resource(struct resource *r)
 490 {
 491         struct  rman *rm;
 492
 493         rm = r->r_rm;
 494         r->r_flags &= ~RF_ACTIVE;
 495         if (r->r_flags & RF_WANTED) {
 496                 r->r_flags &= ~RF_WANTED;
 497                 wakeup(r->r_sharehead);
 498         }
 499         return 0;
 500 }
 501
 502 int
 503 rman_deactivate_resource(struct resource *r)
 504 {
 505         struct  rman *rm;
 506
 507         rm = r->r_rm;
 508         lwkt_gettoken(rm->rm_slock);
 509         int_rman_deactivate_resource(r);
 510         lwkt_reltoken(rm->rm_slock);
 511         return 0;
 512 }
 513
 514 static int
 515 int_rman_release_resource(struct rman *rm, struct resource *r)
 516 {
 517         struct  resource *s, *t;
 518
 519         if (r->r_flags & RF_ACTIVE)
 520                 int_rman_deactivate_resource(r);
 521
 522         /*
 523          * Check for a sharing list first.  If there is one, then we don't
 524          * have to think as hard.
 525          */
 526         if (r->r_sharehead) {
 527                 /*
 528                  * If a sharing list exists, then we know there are at
 529                  * least two sharers.
 530                  *
 531                  * If we are in the main circleq, appoint someone else.
 532                  */
 533                 LIST_REMOVE(r, r_sharelink);
 534                 s = LIST_FIRST(r->r_sharehead);
 535                 if (r->r_flags & RF_FIRSTSHARE) {
 536                         s->r_flags |= RF_FIRSTSHARE;
 537                         CIRCLEQ_INSERT_BEFORE(&rm->rm_list, r, s, r_link);
 538                         CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
 539                 }
 540
 541                 /*
 542                  * Make sure that the sharing list goes away completely
 543                  * if the resource is no longer being shared at all.
 544                  */
 545                 if (LIST_NEXT(s, r_sharelink) == 0) {
 546                         free(s->r_sharehead, M_RMAN);
 547                         s->r_sharehead = 0;
 548                         s->r_flags &= ~RF_FIRSTSHARE;
 549                 }
 550                 goto out;
 551         }
 552
 553         /*
 554          * Look at the adjacent resources in the list and see if our
 555          * segment can be merged with any of them.
 556          */
 557         s = CIRCLEQ_PREV(r, r_link);
 558         t = CIRCLEQ_NEXT(r, r_link);
 559
 560         if (s != (void *)&rm->rm_list && (s->r_flags & RF_ALLOCATED) == 0
 561             && t != (void *)&rm->rm_list && (t->r_flags & RF_ALLOCATED) == 0) {
 562                 /*
 563                  * Merge all three segments.
 564                  */
 565                 s->r_end = t->r_end;
 566                 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
 567                 CIRCLEQ_REMOVE(&rm->rm_list, t, r_link);
 568                 free(t, M_RMAN);
 569         } else if (s != (void *)&rm->rm_list
 570                    && (s->r_flags & RF_ALLOCATED) == 0) {
 571                 /*
 572                  * Merge previous segment with ours.
 573                  */
 574                 s->r_end = r->r_end;
 575                 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
 576         } else if (t != (void *)&rm->rm_list
 577                    && (t->r_flags & RF_ALLOCATED) == 0) {
 578                 /*
 579                  * Merge next segment with ours.
 580                  */
 581                 t->r_start = r->r_start;
 582                 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
 583         } else {
 584                 /*
 585                  * At this point, we know there is nothing we
 586                  * can potentially merge with, because on each
 587                  * side, there is either nothing there or what is
 588                  * there is still allocated.  In that case, we don't
 589                  * want to remove r from the list; we simply want to
 590                  * change it to an unallocated region and return
 591                  * without freeing anything.
 592                  */
 593                 r->r_flags &= ~RF_ALLOCATED;
 594                 return 0;
 595         }
 596
 597 out:
 598         free(r, M_RMAN);
 599         return 0;
 600 }
 601
 602 int
 603 rman_release_resource(struct resource *r)
 604 {
 605         int     rv;
 606         struct  rman *rm = r->r_rm;
 607
 608         lwkt_gettoken(rm->rm_slock);
 609         rv = int_rman_release_resource(rm, r);
 610         lwkt_reltoken(rm->rm_slock);
 611         return (rv);
 612 }
 613
 614 uint32_t
 615 rman_make_alignment_flags(uint32_t size)
 616 {
 617         int     i;
 618
 619         /*
 620          * Find the hightest bit set, and add one if more than one bit
 621          * set.  We're effectively computing the ceil(log2(size)) here.
 622          */
 623         for (i = 32; i > 0; i--)
 624                 if ((1 << i) & size)
 625                         break;
 626         if (~(1 << i) & size)
 627                 i++;
 628
 629         return(RF_ALIGNMENT_LOG2(i));
 630 }