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 1.13 2007/09/21 02:28:00 y0netan1 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 <sys/rman.h>
  68 #include <sys/sysctl.h>
  69
  70 int     rman_debug = 0;
  71 TUNABLE_INT("debug.rman_debug", &rman_debug);
  72 SYSCTL_INT(_debug, OID_AUTO, rman_debug, CTLFLAG_RW,
  73     &rman_debug, 0, "rman debug");
  74
  75 #define DPRINTF(params) if (rman_debug) kprintf params
  76
  77 static MALLOC_DEFINE(M_RMAN, "rman", "Resource manager");
  78
  79 struct  rman_head rman_head;
  80 static  struct lwkt_token rman_tok; /* mutex to protect rman_head */
  81 static  int int_rman_activate_resource(struct rman *rm, struct resource *r,
  82                                        struct resource **whohas);
  83 static  int int_rman_deactivate_resource(struct resource *r);
  84 static  int int_rman_release_resource(struct rman *rm, struct resource *r);
  85
  86 #define CIRCLEQ_TERMCOND(var, head)     (var == (void *)&(head))
  87
  88 int
  89 rman_init(struct rman *rm)
  90 {
  91         static int once;
  92         lwkt_tokref ilock;
  93
  94         if (once == 0) {
  95                 once = 1;
  96                 TAILQ_INIT(&rman_head);
  97                 lwkt_token_init(&rman_tok);
  98         }
  99
 100         if (rm->rm_type == RMAN_UNINIT)
 101                 panic("rman_init");
 102         if (rm->rm_type == RMAN_GAUGE)
 103                 panic("implement RMAN_GAUGE");
 104
 105         CIRCLEQ_INIT(&rm->rm_list);
 106         rm->rm_slock = kmalloc(sizeof *rm->rm_slock, M_RMAN, M_NOWAIT);
 107         if (rm->rm_slock == NULL)
 108                 return ENOMEM;
 109         lwkt_token_init(rm->rm_slock);
 110
 111         lwkt_gettoken(&ilock, &rman_tok);
 112         TAILQ_INSERT_TAIL(&rman_head, rm, rm_link);
 113         lwkt_reltoken(&ilock);
 114         return 0;
 115 }
 116
 117 /*
 118  * NB: this interface is not robust against programming errors which
 119  * add multiple copies of the same region.
 120  */
 121 int
 122 rman_manage_region(struct rman *rm, u_long start, u_long end)
 123 {
 124         struct resource *r, *s;
 125         lwkt_tokref ilock;
 126
 127         DPRINTF(("rman_manage_region: <%s> request: start %#lx, end %#lx\n",
 128             rm->rm_descr, start, end));
 129         r = kmalloc(sizeof *r, M_RMAN, M_NOWAIT);
 130         if (r == 0)
 131                 return ENOMEM;
 132         bzero(r, sizeof *r);
 133         r->r_sharehead = 0;
 134         r->r_start = start;
 135         r->r_end = end;
 136         r->r_flags = 0;
 137         r->r_dev = 0;
 138         r->r_rm = rm;
 139
 140         lwkt_gettoken(&ilock, rm->rm_slock);
 141         for (s = CIRCLEQ_FIRST(&rm->rm_list);
 142              !CIRCLEQ_TERMCOND(s, rm->rm_list) && s->r_end < r->r_start;
 143              s = CIRCLEQ_NEXT(s, r_link))
 144                 ;
 145
 146         if (CIRCLEQ_TERMCOND(s, rm->rm_list)) {
 147                 CIRCLEQ_INSERT_TAIL(&rm->rm_list, r, r_link);
 148         } else {
 149                 CIRCLEQ_INSERT_BEFORE(&rm->rm_list, s, r, r_link);
 150         }
 151
 152         lwkt_reltoken(&ilock);
 153         return 0;
 154 }
 155
 156 int
 157 rman_fini(struct rman *rm)
 158 {
 159         struct resource *r;
 160         lwkt_tokref ilock;
 161
 162         lwkt_gettoken(&ilock, rm->rm_slock);
 163         CIRCLEQ_FOREACH(r, &rm->rm_list, r_link) {
 164                 if (r->r_flags & RF_ALLOCATED) {
 165                         lwkt_reltoken(&ilock);
 166                         return EBUSY;
 167                 }
 168         }
 169
 170         /*
 171          * There really should only be one of these if we are in this
 172          * state and the code is working properly, but it can't hurt.
 173          */
 174         while (!CIRCLEQ_EMPTY(&rm->rm_list)) {
 175                 r = CIRCLEQ_FIRST(&rm->rm_list);
 176                 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
 177                 kfree(r, M_RMAN);
 178         }
 179         lwkt_reltoken(&ilock);
 180         /* XXX what's the point of this if we are going to free the struct? */
 181         lwkt_gettoken(&ilock, &rman_tok);
 182         TAILQ_REMOVE(&rman_head, rm, rm_link);
 183         lwkt_reltoken(&ilock);
 184         kfree(rm->rm_slock, M_RMAN);
 185
 186         return 0;
 187 }
 188
 189 struct resource *
 190 rman_reserve_resource(struct rman *rm, u_long start, u_long end, u_long count,
 191                       u_int flags, struct device *dev)
 192 {
 193         u_int   want_activate;
 194         struct  resource *r, *s, *rv;
 195         u_long  rstart, rend;
 196         lwkt_tokref ilock;
 197
 198         rv = 0;
 199
 200         DPRINTF(("rman_reserve_resource: <%s> request: [%#lx, %#lx], length "
 201                "%#lx, flags %u, device %s\n", rm->rm_descr, start, end,
 202                count, flags,
 203                dev == NULL ? "<null>" : device_get_nameunit(dev)));
 204         want_activate = (flags & RF_ACTIVE);
 205         flags &= ~RF_ACTIVE;
 206
 207         lwkt_gettoken(&ilock, rm->rm_slock);
 208
 209         for (r = CIRCLEQ_FIRST(&rm->rm_list);
 210              !CIRCLEQ_TERMCOND(r, rm->rm_list) && r->r_end < start;
 211              r = CIRCLEQ_NEXT(r, r_link))
 212                 ;
 213
 214         if (CIRCLEQ_TERMCOND(r, rm->rm_list)) {
 215                 DPRINTF(("could not find a region\n"));
 216                 goto out;
 217         }
 218
 219         /*
 220          * First try to find an acceptable totally-unshared region.
 221          */
 222         for (s = r; !CIRCLEQ_TERMCOND(s, rm->rm_list);
 223              s = CIRCLEQ_NEXT(s, r_link)) {
 224                 DPRINTF(("considering [%#lx, %#lx]\n", s->r_start, s->r_end));
 225                 if (s->r_start > end) {
 226                         DPRINTF(("s->r_start (%#lx) > end (%#lx)\n",
 227                             s->r_start, end));
 228                         break;
 229                 }
 230                 if (s->r_flags & RF_ALLOCATED) {
 231                         DPRINTF(("region is allocated\n"));
 232                         continue;
 233                 }
 234                 rstart = max(s->r_start, start);
 235                 rstart = (rstart + ((1ul << RF_ALIGNMENT(flags))) - 1) &
 236                     ~((1ul << RF_ALIGNMENT(flags)) - 1);
 237                 rend = min(s->r_end, max(start + count, end));
 238                 DPRINTF(("truncated region: [%#lx, %#lx]; size %#lx (requested %#lx)\n",
 239                        rstart, rend, (rend - rstart + 1), count));
 240
 241                 if ((rend - rstart + 1) >= count) {
 242                         DPRINTF(("candidate region: [%#lx, %#lx], size %#lx\n",
 243                                rstart, rend, (rend - rstart + 1)));
 244                         if ((s->r_end - s->r_start + 1) == count) {
 245                                 DPRINTF(("candidate region is entire chunk\n"));
 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 = kmalloc(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                                 DPRINTF(("splitting region in three parts: "
 275                                        "[%#lx, %#lx]; [%#lx, %#lx]; [%#lx, %#lx]\n",
 276                                        s->r_start, rv->r_start - 1,
 277                                        rv->r_start, rv->r_end,
 278                                        rv->r_end + 1, s->r_end));
 279                                 /*
 280                                  * We are allocating in the middle.
 281                                  */
 282                                 r = kmalloc(sizeof *r, M_RMAN, M_NOWAIT);
 283                                 if (r == 0) {
 284                                         kfree(rv, M_RMAN);
 285                                         rv = 0;
 286                                         goto out;
 287                                 }
 288                                 bzero(r, sizeof *r);
 289                                 r->r_start = rv->r_end + 1;
 290                                 r->r_end = s->r_end;
 291                                 r->r_flags = s->r_flags;
 292                                 r->r_dev = 0;
 293                                 r->r_sharehead = 0;
 294                                 r->r_rm = rm;
 295                                 s->r_end = rv->r_start - 1;
 296                                 CIRCLEQ_INSERT_AFTER(&rm->rm_list, s, rv,
 297                                                      r_link);
 298                                 CIRCLEQ_INSERT_AFTER(&rm->rm_list, rv, r,
 299                                                      r_link);
 300                         } else if (s->r_start == rv->r_start) {
 301                                 DPRINTF(("allocating from the beginning\n"));
 302                                 /*
 303                                  * We are allocating at the beginning.
 304                                  */
 305                                 s->r_start = rv->r_end + 1;
 306                                 CIRCLEQ_INSERT_BEFORE(&rm->rm_list, s, rv,
 307                                                       r_link);
 308                         } else {
 309                                 DPRINTF(("allocating at the end\n"));
 310                                 /*
 311                                  * We are allocating at the end.
 312                                  */
 313                                 s->r_end = rv->r_start - 1;
 314                                 CIRCLEQ_INSERT_AFTER(&rm->rm_list, s, rv,
 315                                                      r_link);
 316                         }
 317                         goto out;
 318                 }
 319         }
 320
 321         /*
 322          * Now find an acceptable shared region, if the client's requirements
 323          * allow sharing.  By our implementation restriction, a candidate
 324          * region must match exactly by both size and sharing type in order
 325          * to be considered compatible with the client's request.  (The
 326          * former restriction could probably be lifted without too much
 327          * additional work, but this does not seem warranted.)
 328          */
 329         DPRINTF(("no unshared regions found\n"));
 330         if ((flags & (RF_SHAREABLE | RF_TIMESHARE)) == 0)
 331                 goto out;
 332
 333         for (s = r; !CIRCLEQ_TERMCOND(s, rm->rm_list);
 334              s = CIRCLEQ_NEXT(s, r_link)) {
 335                 if (s->r_start > end)
 336                         break;
 337                 if ((s->r_flags & flags) != flags)
 338                         continue;
 339                 rstart = max(s->r_start, start);
 340                 rend = min(s->r_end, max(start + count, end));
 341                 if (s->r_start >= start && s->r_end <= end
 342                     && (s->r_end - s->r_start + 1) == count) {
 343                         rv = kmalloc(sizeof *rv, M_RMAN, M_NOWAIT);
 344                         if (rv == 0)
 345                                 goto out;
 346                         bzero(rv, sizeof *rv);
 347                         rv->r_start = s->r_start;
 348                         rv->r_end = s->r_end;
 349                         rv->r_flags = s->r_flags &
 350                                 (RF_ALLOCATED | RF_SHAREABLE | RF_TIMESHARE);
 351                         rv->r_dev = dev;
 352                         rv->r_rm = rm;
 353                         if (s->r_sharehead == 0) {
 354                                 s->r_sharehead = kmalloc(sizeof *s->r_sharehead,
 355                                                         M_RMAN, M_NOWAIT);
 356                                 if (s->r_sharehead == 0) {
 357                                         kfree(rv, M_RMAN);
 358                                         rv = 0;
 359                                         goto out;
 360                                 }
 361                                 bzero(s->r_sharehead, sizeof *s->r_sharehead);
 362                                 LIST_INIT(s->r_sharehead);
 363                                 LIST_INSERT_HEAD(s->r_sharehead, s,
 364                                                  r_sharelink);
 365                                 s->r_flags |= RF_FIRSTSHARE;
 366                         }
 367                         rv->r_sharehead = s->r_sharehead;
 368                         LIST_INSERT_HEAD(s->r_sharehead, rv, r_sharelink);
 369                         goto out;
 370                 }
 371         }
 372
 373         /*
 374          * We couldn't find anything.
 375          */
 376 out:
 377         /*
 378          * If the user specified RF_ACTIVE in the initial flags,
 379          * which is reflected in `want_activate', we attempt to atomically
 380          * activate the resource.  If this fails, we release the resource
 381          * and indicate overall failure.  (This behavior probably doesn't
 382          * make sense for RF_TIMESHARE-type resources.)
 383          */
 384         if (rv && want_activate) {
 385                 struct resource *whohas;
 386                 if (int_rman_activate_resource(rm, rv, &whohas)) {
 387                         int_rman_release_resource(rm, rv);
 388                         rv = 0;
 389                 }
 390         }
 391         lwkt_reltoken(&ilock);
 392         return (rv);
 393 }
 394
 395 static int
 396 int_rman_activate_resource(struct rman *rm, struct resource *r,
 397                            struct resource **whohas)
 398 {
 399         struct resource *s;
 400         int ok;
 401
 402         /*
 403          * If we are not timesharing, then there is nothing much to do.
 404          * If we already have the resource, then there is nothing at all to do.
 405          * If we are not on a sharing list with anybody else, then there is
 406          * little to do.
 407          */
 408         if ((r->r_flags & RF_TIMESHARE) == 0
 409             || (r->r_flags & RF_ACTIVE) != 0
 410             || r->r_sharehead == 0) {
 411                 r->r_flags |= RF_ACTIVE;
 412                 return 0;
 413         }
 414
 415         ok = 1;
 416         for (s = LIST_FIRST(r->r_sharehead); s && ok;
 417              s = LIST_NEXT(s, r_sharelink)) {
 418                 if ((s->r_flags & RF_ACTIVE) != 0) {
 419                         ok = 0;
 420                         *whohas = s;
 421                 }
 422         }
 423         if (ok) {
 424                 r->r_flags |= RF_ACTIVE;
 425                 return 0;
 426         }
 427         return EBUSY;
 428 }
 429
 430 int
 431 rman_activate_resource(struct resource *r)
 432 {
 433         int rv;
 434         struct resource *whohas;
 435         lwkt_tokref ilock;
 436         struct rman *rm;
 437
 438         rm = r->r_rm;
 439         lwkt_gettoken(&ilock, rm->rm_slock);
 440         rv = int_rman_activate_resource(rm, r, &whohas);
 441         lwkt_reltoken(&ilock);
 442         return rv;
 443 }
 444
 445 #if 0
 446
 447 /* XXX */
 448 int
 449 rman_await_resource(struct resource *r, lwkt_tokref_t ilock, int slpflags, int timo)
 450 {
 451         int     rv;
 452         struct  resource *whohas;
 453         struct  rman *rm;
 454
 455         rm = r->r_rm;
 456         for (;;) {
 457                 lwkt_gettoken(ilock, rm->rm_slock);
 458                 rv = int_rman_activate_resource(rm, r, &whohas);
 459                 if (rv != EBUSY)
 460                         return (rv);    /* returns with ilock held */
 461
 462                 if (r->r_sharehead == 0)
 463                         panic("rman_await_resource");
 464                 /*
 465                  * A critical section will hopefully will prevent a race
 466                  * between lwkt_reltoken and tsleep where a process
 467                  * could conceivably get in and release the resource
 468                  * before we have a chance to sleep on it. YYY
 469                  */
 470                 crit_enter();
 471                 whohas->r_flags |= RF_WANTED;
 472                 rv = tsleep(r->r_sharehead, slpflags, "rmwait", timo);
 473                 if (rv) {
 474                         lwkt_reltoken(ilock);
 475                         crit_exit();
 476                         return rv;
 477                 }
 478                 crit_exit();
 479         }
 480 }
 481
 482 #endif
 483
 484 static int
 485 int_rman_deactivate_resource(struct resource *r)
 486 {
 487         struct  rman *rm;
 488
 489         rm = r->r_rm;
 490         r->r_flags &= ~RF_ACTIVE;
 491         if (r->r_flags & RF_WANTED) {
 492                 r->r_flags &= ~RF_WANTED;
 493                 wakeup(r->r_sharehead);
 494         }
 495         return 0;
 496 }
 497
 498 int
 499 rman_deactivate_resource(struct resource *r)
 500 {
 501         lwkt_tokref ilock;
 502         struct rman *rm;
 503
 504         rm = r->r_rm;
 505         lwkt_gettoken(&ilock, rm->rm_slock);
 506         int_rman_deactivate_resource(r);
 507         lwkt_reltoken(&ilock);
 508         return 0;
 509 }
 510
 511 static int
 512 int_rman_release_resource(struct rman *rm, struct resource *r)
 513 {
 514         struct  resource *s, *t;
 515
 516         if (r->r_flags & RF_ACTIVE)
 517                 int_rman_deactivate_resource(r);
 518
 519         /*
 520          * Check for a sharing list first.  If there is one, then we don't
 521          * have to think as hard.
 522          */
 523         if (r->r_sharehead) {
 524                 /*
 525                  * If a sharing list exists, then we know there are at
 526                  * least two sharers.
 527                  *
 528                  * If we are in the main circleq, appoint someone else.
 529                  */
 530                 LIST_REMOVE(r, r_sharelink);
 531                 s = LIST_FIRST(r->r_sharehead);
 532                 if (r->r_flags & RF_FIRSTSHARE) {
 533                         s->r_flags |= RF_FIRSTSHARE;
 534                         CIRCLEQ_INSERT_BEFORE(&rm->rm_list, r, s, r_link);
 535                         CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
 536                 }
 537
 538                 /*
 539                  * Make sure that the sharing list goes away completely
 540                  * if the resource is no longer being shared at all.
 541                  */
 542                 if (LIST_NEXT(s, r_sharelink) == 0) {
 543                         kfree(s->r_sharehead, M_RMAN);
 544                         s->r_sharehead = 0;
 545                         s->r_flags &= ~RF_FIRSTSHARE;
 546                 }
 547                 goto out;
 548         }
 549
 550         /*
 551          * Look at the adjacent resources in the list and see if our
 552          * segment can be merged with any of them.
 553          */
 554         s = CIRCLEQ_PREV(r, r_link);
 555         t = CIRCLEQ_NEXT(r, r_link);
 556
 557         if (s != (void *)&rm->rm_list && (s->r_flags & RF_ALLOCATED) == 0
 558             && t != (void *)&rm->rm_list && (t->r_flags & RF_ALLOCATED) == 0) {
 559                 /*
 560                  * Merge all three segments.
 561                  */
 562                 s->r_end = t->r_end;
 563                 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
 564                 CIRCLEQ_REMOVE(&rm->rm_list, t, r_link);
 565                 kfree(t, M_RMAN);
 566         } else if (s != (void *)&rm->rm_list
 567                    && (s->r_flags & RF_ALLOCATED) == 0) {
 568                 /*
 569                  * Merge previous segment with ours.
 570                  */
 571                 s->r_end = r->r_end;
 572                 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
 573         } else if (t != (void *)&rm->rm_list
 574                    && (t->r_flags & RF_ALLOCATED) == 0) {
 575                 /*
 576                  * Merge next segment with ours.
 577                  */
 578                 t->r_start = r->r_start;
 579                 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
 580         } else {
 581                 /*
 582                  * At this point, we know there is nothing we
 583                  * can potentially merge with, because on each
 584                  * side, there is either nothing there or what is
 585                  * there is still allocated.  In that case, we don't
 586                  * want to remove r from the list; we simply want to
 587                  * change it to an unallocated region and return
 588                  * without freeing anything.
 589                  */
 590                 r->r_flags &= ~RF_ALLOCATED;
 591                 return 0;
 592         }
 593
 594 out:
 595         kfree(r, M_RMAN);
 596         return 0;
 597 }
 598
 599 int
 600 rman_release_resource(struct resource *r)
 601 {
 602         struct  rman *rm = r->r_rm;
 603         lwkt_tokref ilock;
 604         int     rv;
 605
 606         lwkt_gettoken(&ilock, rm->rm_slock);
 607         rv = int_rman_release_resource(rm, r);
 608         lwkt_reltoken(&ilock);
 609         return (rv);
 610 }
 611
 612 uint32_t
 613 rman_make_alignment_flags(uint32_t size)
 614 {
 615         int     i;
 616
 617         /*
 618          * Find the hightest bit set, and add one if more than one bit
 619          * set.  We're effectively computing the ceil(log2(size)) here.
 620          */
 621         for (i = 32; i > 0; i--)
 622                 if ((1 << i) & size)
 623                         break;
 624         if (~(1 << i) & size)
 625                 i++;
 626
 627         return(RF_ALIGNMENT_LOG2(i));
 628 }