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 1.6 2004/03/01 06:33:17 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         lwkt_tokref ilock;
  86
  87         if (once == 0) {
  88                 once = 1;
  89                 TAILQ_INIT(&rman_head);
  90                 lwkt_token_init(&rman_tok);
  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);
  99         rm->rm_slock = malloc(sizeof *rm->rm_slock, M_RMAN, M_NOWAIT);
 100         if (rm->rm_slock == NULL)
 101                 return ENOMEM;
 102         lwkt_token_init(rm->rm_slock);
 103
 104         lwkt_gettoken(&ilock, &rman_tok);
 105         TAILQ_INSERT_TAIL(&rman_head, rm, rm_link);
 106         lwkt_reltoken(&ilock);
 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  */
 114 int
 115 rman_manage_region(struct rman *rm, u_long start, u_long end)
 116 {
 117         struct resource *r, *s;
 118         lwkt_tokref ilock;
 119
 120         r = malloc(sizeof *r, M_RMAN, M_NOWAIT);
 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
 131         lwkt_gettoken(&ilock, rm->rm_slock);
 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
 143         lwkt_reltoken(&ilock);
 144         return 0;
 145 }
 146
 147 int
 148 rman_fini(struct rman *rm)
 149 {
 150         struct resource *r;
 151         lwkt_tokref ilock;
 152
 153         lwkt_gettoken(&ilock, rm->rm_slock);
 154         CIRCLEQ_FOREACH(r, &rm->rm_list, r_link) {
 155                 if (r->r_flags & RF_ALLOCATED) {
 156                         lwkt_reltoken(&ilock);
 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);
 168                 free(r, M_RMAN);
 169         }
 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);
 173         TAILQ_REMOVE(&rman_head, rm, rm_link);
 174         lwkt_reltoken(&ilock);
 175         free(rm->rm_slock, M_RMAN);
 176
 177         return 0;
 178 }
 179
 180 struct resource *
 181 rman_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;
 187         lwkt_tokref ilock;
 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
 199         lwkt_gettoken(&ilock, rm->rm_slock);
 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");
 209 #endif
 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                          */
 267                         rv = malloc(sizeof *rv, M_RMAN, M_NOWAIT);
 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                                  */
 289                                 r = malloc(sizeof *r, M_RMAN, M_NOWAIT);
 290                                 if (r == 0) {
 291                                         free(rv, M_RMAN);
 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) {
 356                         rv = malloc(sizeof *rv, M_RMAN, M_NOWAIT);
 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) {
 367                                 s->r_sharehead = malloc(sizeof *s->r_sharehead,
 368                                                         M_RMAN, M_NOWAIT);
 369                                 if (s->r_sharehead == 0) {
 370                                         free(rv, M_RMAN);
 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          */
 389 out:
 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         }
 404         lwkt_reltoken(&ilock);
 405         return (rv);
 406 }
 407
 408 static int
 409 int_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
 443 int
 444 rman_activate_resource(struct resource *r)
 445 {
 446         int rv;
 447         struct resource *whohas;
 448         lwkt_tokref ilock;
 449         struct rman *rm;
 450
 451         rm = r->r_rm;
 452         lwkt_gettoken(&ilock, rm->rm_slock);
 453         rv = int_rman_activate_resource(rm, r, &whohas);
 454         lwkt_reltoken(&ilock);
 455         return rv;
 456 }
 457
 458 #if 0
 459
 460 /* XXX */
 461 int
 462 rman_await_resource(struct resource *r, lwkt_tokref_t ilock, int slpflags, int timo)
 463 {
 464         int     rv, s;
 465         struct  resource *whohas;
 466         struct  rman *rm;
 467
 468         rm = r->r_rm;
 469         for (;;) {
 470                 lwkt_gettoken(ilock, rm->rm_slock);
 471                 rv = int_rman_activate_resource(rm, r, &whohas);
 472                 if (rv != EBUSY)
 473                         return (rv);    /* returns with ilock held */
 474
 475                 if (r->r_sharehead == 0)
 476                         panic("rman_await_resource");
 477                 /*
 478                  * splhigh hopefully will prevent a race between
 479                  * lwkt_reltoken and tsleep where a process
 480                  * could conceivably get in and release the resource
 481                  * before we have a chance to sleep on it. YYY
 482                  */
 483                 s = splhigh();
 484                 whohas->r_flags |= RF_WANTED;
 485                 rv = tsleep(r->r_sharehead, slpflags, "rmwait", timo);
 486                 if (rv) {
 487                         lwkt_reltoken(ilock);
 488                         splx(s);
 489                         return rv;
 490                 }
 491                 splx(s);
 492         }
 493 }
 494
 495 #endif
 496
 497 static int
 498 int_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
 511 int
 512 rman_deactivate_resource(struct resource *r)
 513 {
 514         lwkt_tokref ilock;
 515         struct rman *rm;
 516
 517         rm = r->r_rm;
 518         lwkt_gettoken(&ilock, rm->rm_slock);
 519         int_rman_deactivate_resource(r);
 520         lwkt_reltoken(&ilock);
 521         return 0;
 522 }
 523
 524 static int
 525 int_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) {
 556                         free(s->r_sharehead, M_RMAN);
 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);
 578                 free(t, M_RMAN);
 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
 607 out:
 608         free(r, M_RMAN);
 609         return 0;
 610 }
 611
 612 int
 613 rman_release_resource(struct resource *r)
 614 {
 615         struct  rman *rm = r->r_rm;
 616         lwkt_tokref ilock;
 617         int     rv;
 618
 619         lwkt_gettoken(&ilock, rm->rm_slock);
 620         rv = int_rman_release_resource(rm, r);
 621         lwkt_reltoken(&ilock);
 622         return (rv);
 623 }
 624
 625 uint32_t
 626 rman_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 }