The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_rman.c

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

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