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/kern_osd.c

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    1 /*-
    2  * Copyright (c) 2007 Pawel Jakub Dawidek <pjd@FreeBSD.org>
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  *
   14  * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
   15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
   18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   24  * SUCH DAMAGE.
   25  */
   26 
   27 #include <sys/cdefs.h>
   28 __FBSDID("$FreeBSD$");
   29 
   30 #include <sys/param.h>
   31 #include <sys/kernel.h>
   32 #include <sys/systm.h>
   33 #include <sys/sysctl.h>
   34 #include <sys/errno.h>
   35 #include <sys/jail.h>
   36 #include <sys/malloc.h>
   37 #include <sys/lock.h>
   38 #include <sys/mutex.h>
   39 #include <sys/rmlock.h>
   40 #include <sys/sx.h>
   41 #include <sys/queue.h>
   42 #include <sys/proc.h>
   43 #include <sys/osd.h>
   44 
   45 /* OSD (Object Specific Data) */
   46 
   47 /*
   48  * Lock key:
   49  *  (m) osd_module_lock
   50  *  (o) osd_object_lock
   51  *  (l) osd_list_lock
   52  */
   53 struct osd_master {
   54         struct sx                osd_module_lock;
   55         struct rmlock            osd_object_lock;
   56         struct mtx               osd_list_lock;
   57         LIST_HEAD(, osd)         osd_list;              /* (l) */
   58         osd_destructor_t        *osd_destructors;       /* (o) */
   59         osd_method_t            *osd_methods;           /* (m) */
   60         u_int                    osd_ntslots;           /* (m) */
   61         const u_int              osd_nmethods;
   62 };
   63 
   64 static MALLOC_DEFINE(M_OSD, "osd", "Object Specific Data");
   65 
   66 static int osd_debug = 0;
   67 SYSCTL_INT(_debug, OID_AUTO, osd, CTLFLAG_RWTUN, &osd_debug, 0, "OSD debug level");
   68 
   69 #define OSD_DEBUG(...)  do {                                            \
   70         if (osd_debug) {                                                \
   71                 printf("OSD (%s:%u): ", __func__, __LINE__);            \
   72                 printf(__VA_ARGS__);                                    \
   73                 printf("\n");                                           \
   74         }                                                               \
   75 } while (0)
   76 
   77 static void do_osd_del(u_int type, struct osd *osd, u_int slot,
   78     int list_locked);
   79 
   80 /*
   81  * List of objects with OSD.
   82  */
   83 struct osd_master osdm[OSD_LAST + 1] = {
   84         [OSD_JAIL] = { .osd_nmethods = PR_MAXMETHOD },
   85 };
   86 
   87 static void
   88 osd_default_destructor(void *value __unused)
   89 {
   90         /* Do nothing. */
   91 }
   92 
   93 int
   94 osd_register(u_int type, osd_destructor_t destructor, osd_method_t *methods)
   95 {
   96         void *newptr;
   97         u_int i, m;
   98 
   99         KASSERT(type >= OSD_FIRST && type <= OSD_LAST, ("Invalid type."));
  100 
  101         /*
  102          * If no destructor is given, use default one. We need to use some
  103          * destructor, because NULL destructor means unused slot.
  104          */
  105         if (destructor == NULL)
  106                 destructor = osd_default_destructor;
  107 
  108         sx_xlock(&osdm[type].osd_module_lock);
  109         /*
  110          * First, we try to find unused slot.
  111          */
  112         for (i = 0; i < osdm[type].osd_ntslots; i++) {
  113                 if (osdm[type].osd_destructors[i] == NULL) {
  114                         OSD_DEBUG("Unused slot found (type=%u, slot=%u).",
  115                             type, i);
  116                         break;
  117                 }
  118         }
  119         /*
  120          * If no unused slot was found, allocate one.
  121          */
  122         if (i == osdm[type].osd_ntslots) {
  123                 osdm[type].osd_ntslots++;
  124                 if (osdm[type].osd_nmethods != 0)
  125                         osdm[type].osd_methods = realloc(osdm[type].osd_methods,
  126                             sizeof(osd_method_t) * osdm[type].osd_ntslots *
  127                             osdm[type].osd_nmethods, M_OSD, M_WAITOK);
  128                 newptr = malloc(sizeof(osd_destructor_t) *
  129                     osdm[type].osd_ntslots, M_OSD, M_WAITOK);
  130                 rm_wlock(&osdm[type].osd_object_lock);
  131                 bcopy(osdm[type].osd_destructors, newptr,
  132                     sizeof(osd_destructor_t) * i);
  133                 free(osdm[type].osd_destructors, M_OSD);
  134                 osdm[type].osd_destructors = newptr;
  135                 rm_wunlock(&osdm[type].osd_object_lock);
  136                 OSD_DEBUG("New slot allocated (type=%u, slot=%u).",
  137                     type, i + 1);
  138         }
  139 
  140         osdm[type].osd_destructors[i] = destructor;
  141         if (osdm[type].osd_nmethods != 0) {
  142                 for (m = 0; m < osdm[type].osd_nmethods; m++)
  143                         osdm[type].osd_methods[i * osdm[type].osd_nmethods + m]
  144                             = methods != NULL ? methods[m] : NULL;
  145         }
  146         sx_xunlock(&osdm[type].osd_module_lock);
  147         return (i + 1);
  148 }
  149 
  150 void
  151 osd_deregister(u_int type, u_int slot)
  152 {
  153         struct osd *osd, *tosd;
  154 
  155         KASSERT(type >= OSD_FIRST && type <= OSD_LAST, ("Invalid type."));
  156         KASSERT(slot > 0, ("Invalid slot."));
  157         KASSERT(osdm[type].osd_destructors[slot - 1] != NULL, ("Unused slot."));
  158 
  159         sx_xlock(&osdm[type].osd_module_lock);
  160         rm_wlock(&osdm[type].osd_object_lock);
  161         /*
  162          * Free all OSD for the given slot.
  163          */
  164         mtx_lock(&osdm[type].osd_list_lock);
  165         LIST_FOREACH_SAFE(osd, &osdm[type].osd_list, osd_next, tosd)
  166                 do_osd_del(type, osd, slot, 1);
  167         mtx_unlock(&osdm[type].osd_list_lock);
  168         /*
  169          * Set destructor to NULL to free the slot.
  170          */
  171         osdm[type].osd_destructors[slot - 1] = NULL;
  172         if (slot == osdm[type].osd_ntslots) {
  173                 osdm[type].osd_ntslots--;
  174                 osdm[type].osd_destructors = realloc(osdm[type].osd_destructors,
  175                     sizeof(osd_destructor_t) * osdm[type].osd_ntslots, M_OSD,
  176                     M_NOWAIT | M_ZERO);
  177                 if (osdm[type].osd_nmethods != 0)
  178                         osdm[type].osd_methods = realloc(osdm[type].osd_methods,
  179                             sizeof(osd_method_t) * osdm[type].osd_ntslots *
  180                             osdm[type].osd_nmethods, M_OSD, M_NOWAIT | M_ZERO);
  181                 /*
  182                  * We always reallocate to smaller size, so we assume it will
  183                  * always succeed.
  184                  */
  185                 KASSERT(osdm[type].osd_destructors != NULL &&
  186                     (osdm[type].osd_nmethods == 0 ||
  187                      osdm[type].osd_methods != NULL), ("realloc() failed"));
  188                 OSD_DEBUG("Deregistration of the last slot (type=%u, slot=%u).",
  189                     type, slot);
  190         } else {
  191                 OSD_DEBUG("Slot deregistration (type=%u, slot=%u).",
  192                     type, slot);
  193         }
  194         rm_wunlock(&osdm[type].osd_object_lock);
  195         sx_xunlock(&osdm[type].osd_module_lock);
  196 }
  197 
  198 int
  199 osd_set(u_int type, struct osd *osd, u_int slot, void *value)
  200 {
  201 
  202         return (osd_set_reserved(type, osd, slot, NULL, value));
  203 }
  204 
  205 void **
  206 osd_reserve(u_int slot)
  207 {
  208 
  209         KASSERT(slot > 0, ("Invalid slot."));
  210 
  211         OSD_DEBUG("Reserving slot array (slot=%u).", slot);
  212         return (malloc(sizeof(void *) * slot, M_OSD, M_WAITOK | M_ZERO));
  213 }
  214 
  215 int
  216 osd_set_reserved(u_int type, struct osd *osd, u_int slot, void **rsv,
  217     void *value)
  218 {
  219         struct rm_priotracker tracker;
  220 
  221         KASSERT(type >= OSD_FIRST && type <= OSD_LAST, ("Invalid type."));
  222         KASSERT(slot > 0, ("Invalid slot."));
  223         KASSERT(osdm[type].osd_destructors[slot - 1] != NULL, ("Unused slot."));
  224 
  225         rm_rlock(&osdm[type].osd_object_lock, &tracker);
  226         if (slot > osd->osd_nslots) {
  227                 void **newptr;
  228 
  229                 if (value == NULL) {
  230                         OSD_DEBUG(
  231                             "Not allocating null slot (type=%u, slot=%u).",
  232                             type, slot);
  233                         rm_runlock(&osdm[type].osd_object_lock, &tracker);
  234                         if (rsv)
  235                                 osd_free_reserved(rsv);
  236                         return (0);
  237                 }
  238 
  239                 /*
  240                  * Too few slots allocated here, so we need to extend or create
  241                  * the array.
  242                  */
  243                 if (rsv) {
  244                         /*
  245                          * Use the reserve passed in (assumed to be
  246                          * the right size).
  247                          */
  248                         newptr = rsv;
  249                         if (osd->osd_nslots != 0) {
  250                                 memcpy(newptr, osd->osd_slots,
  251                                     sizeof(void *) * osd->osd_nslots);
  252                                 free(osd->osd_slots, M_OSD);
  253                         }
  254                 } else {
  255                         newptr = realloc(osd->osd_slots, sizeof(void *) * slot,
  256                             M_OSD, M_NOWAIT | M_ZERO);
  257                         if (newptr == NULL) {
  258                                 rm_runlock(&osdm[type].osd_object_lock,
  259                                     &tracker);
  260                                 return (ENOMEM);
  261                         }
  262                 }
  263                 if (osd->osd_nslots == 0) {
  264                         /*
  265                          * First OSD for this object, so we need to put it
  266                          * onto the list.
  267                          */
  268                         mtx_lock(&osdm[type].osd_list_lock);
  269                         LIST_INSERT_HEAD(&osdm[type].osd_list, osd, osd_next);
  270                         mtx_unlock(&osdm[type].osd_list_lock);
  271                         OSD_DEBUG("Setting first slot (type=%u).", type);
  272                 } else
  273                         OSD_DEBUG("Growing slots array (type=%u).", type);
  274                 osd->osd_slots = newptr;
  275                 osd->osd_nslots = slot;
  276         } else if (rsv)
  277                 osd_free_reserved(rsv);
  278         OSD_DEBUG("Setting slot value (type=%u, slot=%u, value=%p).", type,
  279             slot, value);
  280         osd->osd_slots[slot - 1] = value;
  281         rm_runlock(&osdm[type].osd_object_lock, &tracker);
  282         return (0);
  283 }
  284 
  285 void
  286 osd_free_reserved(void **rsv)
  287 {
  288 
  289         OSD_DEBUG("Discarding reserved slot array.");
  290         free(rsv, M_OSD);
  291 }
  292 
  293 void *
  294 osd_get(u_int type, struct osd *osd, u_int slot)
  295 {
  296         struct rm_priotracker tracker;
  297         void *value;
  298 
  299         KASSERT(type >= OSD_FIRST && type <= OSD_LAST, ("Invalid type."));
  300         KASSERT(slot > 0, ("Invalid slot."));
  301         KASSERT(osdm[type].osd_destructors[slot - 1] != NULL, ("Unused slot."));
  302 
  303         rm_rlock(&osdm[type].osd_object_lock, &tracker);
  304         if (slot > osd->osd_nslots) {
  305                 value = NULL;
  306                 OSD_DEBUG("Slot doesn't exist (type=%u, slot=%u).", type, slot);
  307         } else {
  308                 value = osd->osd_slots[slot - 1];
  309                 OSD_DEBUG("Returning slot value (type=%u, slot=%u, value=%p).",
  310                     type, slot, value);
  311         }
  312         rm_runlock(&osdm[type].osd_object_lock, &tracker);
  313         return (value);
  314 }
  315 
  316 void
  317 osd_del(u_int type, struct osd *osd, u_int slot)
  318 {
  319         struct rm_priotracker tracker;
  320 
  321         rm_rlock(&osdm[type].osd_object_lock, &tracker);
  322         do_osd_del(type, osd, slot, 0);
  323         rm_runlock(&osdm[type].osd_object_lock, &tracker);
  324 }
  325 
  326 static void
  327 do_osd_del(u_int type, struct osd *osd, u_int slot, int list_locked)
  328 {
  329         int i;
  330 
  331         KASSERT(type >= OSD_FIRST && type <= OSD_LAST, ("Invalid type."));
  332         KASSERT(slot > 0, ("Invalid slot."));
  333         KASSERT(osdm[type].osd_destructors[slot - 1] != NULL, ("Unused slot."));
  334 
  335         OSD_DEBUG("Deleting slot (type=%u, slot=%u).", type, slot);
  336 
  337         if (slot > osd->osd_nslots) {
  338                 OSD_DEBUG("Slot doesn't exist (type=%u, slot=%u).", type, slot);
  339                 return;
  340         }
  341         if (osd->osd_slots[slot - 1] != NULL) {
  342                 osdm[type].osd_destructors[slot - 1](osd->osd_slots[slot - 1]);
  343                 osd->osd_slots[slot - 1] = NULL;
  344         }
  345         for (i = osd->osd_nslots - 1; i >= 0; i--) {
  346                 if (osd->osd_slots[i] != NULL) {
  347                         OSD_DEBUG("Slot still has a value (type=%u, slot=%u).",
  348                             type, i + 1);
  349                         break;
  350                 }
  351         }
  352         if (i == -1) {
  353                 /* No values left for this object. */
  354                 OSD_DEBUG("No more slots left (type=%u).", type);
  355                 if (!list_locked)
  356                         mtx_lock(&osdm[type].osd_list_lock);
  357                 LIST_REMOVE(osd, osd_next);
  358                 if (!list_locked)
  359                         mtx_unlock(&osdm[type].osd_list_lock);
  360                 free(osd->osd_slots, M_OSD);
  361                 osd->osd_slots = NULL;
  362                 osd->osd_nslots = 0;
  363         } else if (slot == osd->osd_nslots) {
  364                 /* This was the last slot. */
  365                 osd->osd_slots = realloc(osd->osd_slots,
  366                     sizeof(void *) * (i + 1), M_OSD, M_NOWAIT | M_ZERO);
  367                 /*
  368                  * We always reallocate to smaller size, so we assume it will
  369                  * always succeed.
  370                  */
  371                 KASSERT(osd->osd_slots != NULL, ("realloc() failed"));
  372                 osd->osd_nslots = i + 1;
  373                 OSD_DEBUG("Reducing slots array to %u (type=%u).",
  374                     osd->osd_nslots, type);
  375         }
  376 }
  377 
  378 int
  379 osd_call(u_int type, u_int method, void *obj, void *data)
  380 {
  381         osd_method_t methodfun;
  382         int error, i;
  383 
  384         KASSERT(type >= OSD_FIRST && type <= OSD_LAST, ("Invalid type."));
  385         KASSERT(method < osdm[type].osd_nmethods, ("Invalid method."));
  386 
  387         /*
  388          * Call this method for every slot that defines it, stopping if an
  389          * error is encountered.
  390          */
  391         error = 0;
  392         sx_slock(&osdm[type].osd_module_lock);
  393         for (i = 0; i < osdm[type].osd_ntslots; i++) {
  394                 methodfun = osdm[type].osd_methods[i * osdm[type].osd_nmethods +
  395                     method];
  396                 if (methodfun != NULL && (error = methodfun(obj, data)) != 0)
  397                         break;
  398         }
  399         sx_sunlock(&osdm[type].osd_module_lock);
  400         return (error);
  401 }
  402 
  403 void
  404 osd_exit(u_int type, struct osd *osd)
  405 {
  406         struct rm_priotracker tracker;
  407         u_int i;
  408 
  409         KASSERT(type >= OSD_FIRST && type <= OSD_LAST, ("Invalid type."));
  410 
  411         if (osd->osd_nslots == 0) {
  412                 KASSERT(osd->osd_slots == NULL, ("Non-null osd_slots."));
  413                 /* No OSD attached, just leave. */
  414                 return;
  415         }
  416 
  417         rm_rlock(&osdm[type].osd_object_lock, &tracker);
  418         for (i = 1; i <= osd->osd_nslots; i++) {
  419                 if (osdm[type].osd_destructors[i - 1] != NULL)
  420                         do_osd_del(type, osd, i, 0);
  421                 else
  422                         OSD_DEBUG("Unused slot (type=%u, slot=%u).", type, i);
  423         }
  424         rm_runlock(&osdm[type].osd_object_lock, &tracker);
  425         OSD_DEBUG("Object exit (type=%u).", type);
  426 }
  427 
  428 static void
  429 osd_init(void *arg __unused)
  430 {
  431         u_int i;
  432 
  433         for (i = OSD_FIRST; i <= OSD_LAST; i++) {
  434                 sx_init(&osdm[i].osd_module_lock, "osd_module");
  435                 rm_init(&osdm[i].osd_object_lock, "osd_object");
  436                 mtx_init(&osdm[i].osd_list_lock, "osd_list", NULL, MTX_DEF);
  437                 LIST_INIT(&osdm[i].osd_list);
  438                 osdm[i].osd_destructors = NULL;
  439                 osdm[i].osd_ntslots = 0;
  440                 osdm[i].osd_methods = NULL;
  441         }
  442 }
  443 SYSINIT(osd, SI_SUB_LOCK, SI_ORDER_ANY, osd_init, NULL);

Cache object: 42a6f50cd31f99c030c7b6cf0a52608d


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