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 1.10 2006/10/25 20:56:02 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 <sys/rman.h>
  68
  69 static MALLOC_DEFINE(M_RMAN, "rman", "Resource manager");
  70
  71 struct  rman_head rman_head;
  72 static  struct lwkt_token rman_tok; /* mutex to protect rman_head */
  73 static  int int_rman_activate_resource(struct rman *rm, struct resource *r,
  74                                        struct resource **whohas);
  75 static  int int_rman_deactivate_resource(struct resource *r);
  76 static  int int_rman_release_resource(struct rman *rm, struct resource *r);
  77
  78 #define CIRCLEQ_TERMCOND(var, head)     (var == (void *)&(head))
  79
  80 int
  81 rman_init(struct rman *rm)
  82 {
  83         static int once;
  84         lwkt_tokref ilock;
  85
  86         if (once == 0) {
  87                 once = 1;
  88                 TAILQ_INIT(&rman_head);
  89                 lwkt_token_init(&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 = kmalloc(sizeof *rm->rm_slock, M_RMAN, M_NOWAIT);
  99         if (rm->rm_slock == NULL)
 100                 return ENOMEM;
 101         lwkt_token_init(rm->rm_slock);
 102
 103         lwkt_gettoken(&ilock, &rman_tok);
 104         TAILQ_INSERT_TAIL(&rman_head, rm, rm_link);
 105         lwkt_reltoken(&ilock);
 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         lwkt_tokref ilock;
 118
 119         r = kmalloc(sizeof *r, M_RMAN, M_NOWAIT);
 120         if (r == 0)
 121                 return ENOMEM;
 122         bzero(r, sizeof *r);
 123         r->r_sharehead = 0;
 124         r->r_start = start;
 125         r->r_end = end;
 126         r->r_flags = 0;
 127         r->r_dev = 0;
 128         r->r_rm = rm;
 129
 130         lwkt_gettoken(&ilock, rm->rm_slock);
 131         for (s = CIRCLEQ_FIRST(&rm->rm_list);
 132              !CIRCLEQ_TERMCOND(s, rm->rm_list) && s->r_end < r->r_start;
 133              s = CIRCLEQ_NEXT(s, r_link))
 134                 ;
 135
 136         if (CIRCLEQ_TERMCOND(s, rm->rm_list)) {
 137                 CIRCLEQ_INSERT_TAIL(&rm->rm_list, r, r_link);
 138         } else {
 139                 CIRCLEQ_INSERT_BEFORE(&rm->rm_list, s, r, r_link);
 140         }
 141
 142         lwkt_reltoken(&ilock);
 143         return 0;
 144 }
 145
 146 int
 147 rman_fini(struct rman *rm)
 148 {
 149         struct resource *r;
 150         lwkt_tokref ilock;
 151
 152         lwkt_gettoken(&ilock, rm->rm_slock);
 153         CIRCLEQ_FOREACH(r, &rm->rm_list, r_link) {
 154                 if (r->r_flags & RF_ALLOCATED) {
 155                         lwkt_reltoken(&ilock);
 156                         return EBUSY;
 157                 }
 158         }
 159
 160         /*
 161          * There really should only be one of these if we are in this
 162          * state and the code is working properly, but it can't hurt.
 163          */
 164         while (!CIRCLEQ_EMPTY(&rm->rm_list)) {
 165                 r = CIRCLEQ_FIRST(&rm->rm_list);
 166                 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
 167                 kfree(r, M_RMAN);
 168         }
 169         lwkt_reltoken(&ilock);
 170         /* XXX what's the point of this if we are going to free the struct? */
 171         lwkt_gettoken(&ilock, &rman_tok);
 172         TAILQ_REMOVE(&rman_head, rm, rm_link);
 173         lwkt_reltoken(&ilock);
 174         kfree(rm->rm_slock, M_RMAN);
 175
 176         return 0;
 177 }
 178
 179 struct resource *
 180 rman_reserve_resource(struct rman *rm, u_long start, u_long end, u_long count,
 181                       u_int flags, struct device *dev)
 182 {
 183         u_int   want_activate;
 184         struct  resource *r, *s, *rv;
 185         u_long  rstart, rend;
 186         lwkt_tokref ilock;
 187
 188         rv = 0;
 189
 190 #ifdef RMAN_DEBUG
 191         printf("rman_reserve_resource: <%s> request: [%#lx, %#lx], length "
 192                "%#lx, flags %u, device %s%d\n", rm->rm_descr, start, end,
 193                count, flags, device_get_name(dev), device_get_unit(dev));
 194 #endif /* RMAN_DEBUG */
 195         want_activate = (flags & RF_ACTIVE);
 196         flags &= ~RF_ACTIVE;
 197
 198         lwkt_gettoken(&ilock, rm->rm_slock);
 199
 200         for (r = CIRCLEQ_FIRST(&rm->rm_list);
 201              !CIRCLEQ_TERMCOND(r, rm->rm_list) && r->r_end < start;
 202              r = CIRCLEQ_NEXT(r, r_link))
 203                 ;
 204
 205         if (CIRCLEQ_TERMCOND(r, rm->rm_list)) {
 206 #ifdef RMAN_DEBUG
 207                 printf("could not find a region\n");
 208 #endif
 209                 goto out;
 210         }
 211
 212         /*
 213          * First try to find an acceptable totally-unshared region.
 214          */
 215         for (s = r; !CIRCLEQ_TERMCOND(s, rm->rm_list);
 216              s = CIRCLEQ_NEXT(s, r_link)) {
 217 #ifdef RMAN_DEBUG
 218                 printf("considering [%#lx, %#lx]\n", s->r_start, s->r_end);
 219 #endif /* RMAN_DEBUG */
 220                 if (s->r_start > end) {
 221 #ifdef RMAN_DEBUG
 222                         printf("s->r_start (%#lx) > end (%#lx)\n", s->r_start, end);
 223 #endif /* RMAN_DEBUG */
 224                         break;
 225                 }
 226                 if (s->r_flags & RF_ALLOCATED) {
 227 #ifdef RMAN_DEBUG
 228                         printf("region is allocated\n");
 229 #endif /* RMAN_DEBUG */
 230                         continue;
 231                 }
 232                 rstart = max(s->r_start, start);
 233                 rstart = (rstart + ((1ul << RF_ALIGNMENT(flags))) - 1) &
 234                     ~((1ul << RF_ALIGNMENT(flags)) - 1);
 235                 rend = min(s->r_end, max(start + count, end));
 236 #ifdef RMAN_DEBUG
 237                 printf("truncated region: [%#lx, %#lx]; size %#lx (requested %#lx)\n",
 238                        rstart, rend, (rend - rstart + 1), count);
 239 #endif /* RMAN_DEBUG */
 240
 241                 if ((rend - rstart + 1) >= count) {
 242 #ifdef RMAN_DEBUG
 243                         printf("candidate region: [%#lx, %#lx], size %#lx\n",
 244                                rend, rstart, (rend - rstart + 1));
 245 #endif /* RMAN_DEBUG */
 246                         if ((s->r_end - s->r_start + 1) == count) {
 247 #ifdef RMAN_DEBUG
 248                                 printf("candidate region is entire chunk\n");
 249 #endif /* RMAN_DEBUG */
 250                                 rv = s;
 251                                 rv->r_flags |= RF_ALLOCATED | flags;
 252                                 rv->r_dev = dev;
 253                                 goto out;
 254                         }
 255
 256                         /*
 257                          * If s->r_start < rstart and
 258                          *    s->r_end > rstart + count - 1, then
 259                          * we need to split the region into three pieces
 260                          * (the middle one will get returned to the user).
 261                          * Otherwise, we are allocating at either the
 262                          * beginning or the end of s, so we only need to
 263                          * split it in two.  The first case requires
 264                          * two new allocations; the second requires but one.
 265                          */
 266                         rv = kmalloc(sizeof *rv, M_RMAN, M_NOWAIT);
 267                         if (rv == 0)
 268                                 goto out;
 269                         bzero(rv, sizeof *rv);
 270                         rv->r_start = rstart;
 271                         rv->r_end = rstart + count - 1;
 272                         rv->r_flags = flags | RF_ALLOCATED;
 273                         rv->r_dev = dev;
 274                         rv->r_sharehead = 0;
 275                         rv->r_rm = rm;
 276
 277                         if (s->r_start < rv->r_start && s->r_end > rv->r_end) {
 278 #ifdef RMAN_DEBUG
 279                                 printf("splitting region in three parts: "
 280                                        "[%#lx, %#lx]; [%#lx, %#lx]; [%#lx, %#lx]\n",
 281                                        s->r_start, rv->r_start - 1,
 282                                        rv->r_start, rv->r_end,
 283                                        rv->r_end + 1, s->r_end);
 284 #endif /* RMAN_DEBUG */
 285                                 /*
 286                                  * We are allocating in the middle.
 287                                  */
 288                                 r = kmalloc(sizeof *r, M_RMAN, M_NOWAIT);
 289                                 if (r == 0) {
 290                                         kfree(rv, M_RMAN);
 291                                         rv = 0;
 292                                         goto out;
 293                                 }
 294                                 bzero(r, sizeof *r);
 295                                 r->r_start = rv->r_end + 1;
 296                                 r->r_end = s->r_end;
 297                                 r->r_flags = s->r_flags;
 298                                 r->r_dev = 0;
 299                                 r->r_sharehead = 0;
 300                                 r->r_rm = rm;
 301                                 s->r_end = rv->r_start - 1;
 302                                 CIRCLEQ_INSERT_AFTER(&rm->rm_list, s, rv,
 303                                                      r_link);
 304                                 CIRCLEQ_INSERT_AFTER(&rm->rm_list, rv, r,
 305                                                      r_link);
 306                         } else if (s->r_start == rv->r_start) {
 307 #ifdef RMAN_DEBUG
 308                                 printf("allocating from the beginning\n");
 309 #endif /* RMAN_DEBUG */
 310                                 /*
 311                                  * We are allocating at the beginning.
 312                                  */
 313                                 s->r_start = rv->r_end + 1;
 314                                 CIRCLEQ_INSERT_BEFORE(&rm->rm_list, s, rv,
 315                                                       r_link);
 316                         } else {
 317 #ifdef RMAN_DEBUG
 318                                 printf("allocating at the end\n");
 319 #endif /* RMAN_DEBUG */
 320                                 /*
 321                                  * We are allocating at the end.
 322                                  */
 323                                 s->r_end = rv->r_start - 1;
 324                                 CIRCLEQ_INSERT_AFTER(&rm->rm_list, s, rv,
 325                                                      r_link);
 326                         }
 327                         goto out;
 328                 }
 329         }
 330
 331         /*
 332          * Now find an acceptable shared region, if the client's requirements
 333          * allow sharing.  By our implementation restriction, a candidate
 334          * region must match exactly by both size and sharing type in order
 335          * to be considered compatible with the client's request.  (The
 336          * former restriction could probably be lifted without too much
 337          * additional work, but this does not seem warranted.)
 338          */
 339 #ifdef RMAN_DEBUG
 340         printf("no unshared regions found\n");
 341 #endif /* RMAN_DEBUG */
 342         if ((flags & (RF_SHAREABLE | RF_TIMESHARE)) == 0)
 343                 goto out;
 344
 345         for (s = r; !CIRCLEQ_TERMCOND(s, rm->rm_list);
 346              s = CIRCLEQ_NEXT(s, r_link)) {
 347                 if (s->r_start > end)
 348                         break;
 349                 if ((s->r_flags & flags) != flags)
 350                         continue;
 351                 rstart = max(s->r_start, start);
 352                 rend = min(s->r_end, max(start + count, end));
 353                 if (s->r_start >= start && s->r_end <= end
 354                     && (s->r_end - s->r_start + 1) == count) {
 355                         rv = kmalloc(sizeof *rv, M_RMAN, M_NOWAIT);
 356                         if (rv == 0)
 357                                 goto out;
 358                         bzero(rv, sizeof *rv);
 359                         rv->r_start = s->r_start;
 360                         rv->r_end = s->r_end;
 361                         rv->r_flags = s->r_flags &
 362                                 (RF_ALLOCATED | RF_SHAREABLE | RF_TIMESHARE);
 363                         rv->r_dev = dev;
 364                         rv->r_rm = rm;
 365                         if (s->r_sharehead == 0) {
 366                                 s->r_sharehead = kmalloc(sizeof *s->r_sharehead,
 367                                                         M_RMAN, M_NOWAIT);
 368                                 if (s->r_sharehead == 0) {
 369                                         kfree(rv, M_RMAN);
 370                                         rv = 0;
 371                                         goto out;
 372                                 }
 373                                 bzero(s->r_sharehead, sizeof *s->r_sharehead);
 374                                 LIST_INIT(s->r_sharehead);
 375                                 LIST_INSERT_HEAD(s->r_sharehead, s,
 376                                                  r_sharelink);
 377                                 s->r_flags |= RF_FIRSTSHARE;
 378                         }
 379                         rv->r_sharehead = s->r_sharehead;
 380                         LIST_INSERT_HEAD(s->r_sharehead, rv, r_sharelink);
 381                         goto out;
 382                 }
 383         }
 384
 385         /*
 386          * We couldn't find anything.
 387          */
 388 out:
 389         /*
 390          * If the user specified RF_ACTIVE in the initial flags,
 391          * which is reflected in `want_activate', we attempt to atomically
 392          * activate the resource.  If this fails, we release the resource
 393          * and indicate overall failure.  (This behavior probably doesn't
 394          * make sense for RF_TIMESHARE-type resources.)
 395          */
 396         if (rv && want_activate) {
 397                 struct resource *whohas;
 398                 if (int_rman_activate_resource(rm, rv, &whohas)) {
 399                         int_rman_release_resource(rm, rv);
 400                         rv = 0;
 401                 }
 402         }
 403         lwkt_reltoken(&ilock);
 404         return (rv);
 405 }
 406
 407 static int
 408 int_rman_activate_resource(struct rman *rm, struct resource *r,
 409                            struct resource **whohas)
 410 {
 411         struct resource *s;
 412         int ok;
 413
 414         /*
 415          * If we are not timesharing, then there is nothing much to do.
 416          * If we already have the resource, then there is nothing at all to do.
 417          * If we are not on a sharing list with anybody else, then there is
 418          * little to do.
 419          */
 420         if ((r->r_flags & RF_TIMESHARE) == 0
 421             || (r->r_flags & RF_ACTIVE) != 0
 422             || r->r_sharehead == 0) {
 423                 r->r_flags |= RF_ACTIVE;
 424                 return 0;
 425         }
 426
 427         ok = 1;
 428         for (s = LIST_FIRST(r->r_sharehead); s && ok;
 429              s = LIST_NEXT(s, r_sharelink)) {
 430                 if ((s->r_flags & RF_ACTIVE) != 0) {
 431                         ok = 0;
 432                         *whohas = s;
 433                 }
 434         }
 435         if (ok) {
 436                 r->r_flags |= RF_ACTIVE;
 437                 return 0;
 438         }
 439         return EBUSY;
 440 }
 441
 442 int
 443 rman_activate_resource(struct resource *r)
 444 {
 445         int rv;
 446         struct resource *whohas;
 447         lwkt_tokref ilock;
 448         struct rman *rm;
 449
 450         rm = r->r_rm;
 451         lwkt_gettoken(&ilock, rm->rm_slock);
 452         rv = int_rman_activate_resource(rm, r, &whohas);
 453         lwkt_reltoken(&ilock);
 454         return rv;
 455 }
 456
 457 #if 0
 458
 459 /* XXX */
 460 int
 461 rman_await_resource(struct resource *r, lwkt_tokref_t ilock, int slpflags, int timo)
 462 {
 463         int     rv;
 464         struct  resource *whohas;
 465         struct  rman *rm;
 466
 467         rm = r->r_rm;
 468         for (;;) {
 469                 lwkt_gettoken(ilock, rm->rm_slock);
 470                 rv = int_rman_activate_resource(rm, r, &whohas);
 471                 if (rv != EBUSY)
 472                         return (rv);    /* returns with ilock held */
 473
 474                 if (r->r_sharehead == 0)
 475                         panic("rman_await_resource");
 476                 /*
 477                  * A critical section will hopefully will prevent a race
 478                  * between lwkt_reltoken and tsleep where a process
 479                  * could conceivably get in and release the resource
 480                  * before we have a chance to sleep on it. YYY
 481                  */
 482                 crit_enter();
 483                 whohas->r_flags |= RF_WANTED;
 484                 rv = tsleep(r->r_sharehead, slpflags, "rmwait", timo);
 485                 if (rv) {
 486                         lwkt_reltoken(ilock);
 487                         crit_exit();
 488                         return rv;
 489                 }
 490                 crit_exit();
 491         }
 492 }
 493
 494 #endif
 495
 496 static int
 497 int_rman_deactivate_resource(struct resource *r)
 498 {
 499         struct  rman *rm;
 500
 501         rm = r->r_rm;
 502         r->r_flags &= ~RF_ACTIVE;
 503         if (r->r_flags & RF_WANTED) {
 504                 r->r_flags &= ~RF_WANTED;
 505                 wakeup(r->r_sharehead);
 506         }
 507         return 0;
 508 }
 509
 510 int
 511 rman_deactivate_resource(struct resource *r)
 512 {
 513         lwkt_tokref ilock;
 514         struct rman *rm;
 515
 516         rm = r->r_rm;
 517         lwkt_gettoken(&ilock, rm->rm_slock);
 518         int_rman_deactivate_resource(r);
 519         lwkt_reltoken(&ilock);
 520         return 0;
 521 }
 522
 523 static int
 524 int_rman_release_resource(struct rman *rm, struct resource *r)
 525 {
 526         struct  resource *s, *t;
 527
 528         if (r->r_flags & RF_ACTIVE)
 529                 int_rman_deactivate_resource(r);
 530
 531         /*
 532          * Check for a sharing list first.  If there is one, then we don't
 533          * have to think as hard.
 534          */
 535         if (r->r_sharehead) {
 536                 /*
 537                  * If a sharing list exists, then we know there are at
 538                  * least two sharers.
 539                  *
 540                  * If we are in the main circleq, appoint someone else.
 541                  */
 542                 LIST_REMOVE(r, r_sharelink);
 543                 s = LIST_FIRST(r->r_sharehead);
 544                 if (r->r_flags & RF_FIRSTSHARE) {
 545                         s->r_flags |= RF_FIRSTSHARE;
 546                         CIRCLEQ_INSERT_BEFORE(&rm->rm_list, r, s, r_link);
 547                         CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
 548                 }
 549
 550                 /*
 551                  * Make sure that the sharing list goes away completely
 552                  * if the resource is no longer being shared at all.
 553                  */
 554                 if (LIST_NEXT(s, r_sharelink) == 0) {
 555                         kfree(s->r_sharehead, M_RMAN);
 556                         s->r_sharehead = 0;
 557                         s->r_flags &= ~RF_FIRSTSHARE;
 558                 }
 559                 goto out;
 560         }
 561
 562         /*
 563          * Look at the adjacent resources in the list and see if our
 564          * segment can be merged with any of them.
 565          */
 566         s = CIRCLEQ_PREV(r, r_link);
 567         t = CIRCLEQ_NEXT(r, r_link);
 568
 569         if (s != (void *)&rm->rm_list && (s->r_flags & RF_ALLOCATED) == 0
 570             && t != (void *)&rm->rm_list && (t->r_flags & RF_ALLOCATED) == 0) {
 571                 /*
 572                  * Merge all three segments.
 573                  */
 574                 s->r_end = t->r_end;
 575                 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
 576                 CIRCLEQ_REMOVE(&rm->rm_list, t, r_link);
 577                 kfree(t, M_RMAN);
 578         } else if (s != (void *)&rm->rm_list
 579                    && (s->r_flags & RF_ALLOCATED) == 0) {
 580                 /*
 581                  * Merge previous segment with ours.
 582                  */
 583                 s->r_end = r->r_end;
 584                 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
 585         } else if (t != (void *)&rm->rm_list
 586                    && (t->r_flags & RF_ALLOCATED) == 0) {
 587                 /*
 588                  * Merge next segment with ours.
 589                  */
 590                 t->r_start = r->r_start;
 591                 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
 592         } else {
 593                 /*
 594                  * At this point, we know there is nothing we
 595                  * can potentially merge with, because on each
 596                  * side, there is either nothing there or what is
 597                  * there is still allocated.  In that case, we don't
 598                  * want to remove r from the list; we simply want to
 599                  * change it to an unallocated region and return
 600                  * without freeing anything.
 601                  */
 602                 r->r_flags &= ~RF_ALLOCATED;
 603                 return 0;
 604         }
 605
 606 out:
 607         kfree(r, M_RMAN);
 608         return 0;
 609 }
 610
 611 int
 612 rman_release_resource(struct resource *r)
 613 {
 614         struct  rman *rm = r->r_rm;
 615         lwkt_tokref ilock;
 616         int     rv;
 617
 618         lwkt_gettoken(&ilock, rm->rm_slock);
 619         rv = int_rman_release_resource(rm, r);
 620         lwkt_reltoken(&ilock);
 621         return (rv);
 622 }
 623
 624 uint32_t
 625 rman_make_alignment_flags(uint32_t size)
 626 {
 627         int     i;
 628
 629         /*
 630          * Find the hightest bit set, and add one if more than one bit
 631          * set.  We're effectively computing the ceil(log2(size)) here.
 632          */
 633         for (i = 32; i > 0; i--)
 634                 if ((1 << i) & size)
 635                         break;
 636         if (~(1 << i) & size)
 637                 i++;
 638
 639         return(RF_ALIGNMENT_LOG2(i));
 640 }