bsd/kern/subr_eventhandler.c

   1 /*
   2  * Copyright (c) 2016-2019 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 /*-
  29  * Copyright (c) 1999 Michael Smith <msmith@freebsd.org>
  30  * All rights reserved.
  31  *
  32  * Redistribution and use in source and binary forms, with or without
  33  * modification, are permitted provided that the following conditions
  34  * are met:
  35  * 1. Redistributions of source code must retain the above copyright
  36  *    notice, this list of conditions and the following disclaimer.
  37  * 2. Redistributions in binary form must reproduce the above copyright
  38  *    notice, this list of conditions and the following disclaimer in the
  39  *    documentation and/or other materials provided with the distribution.
  40  *
  41  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  42  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  43  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  44  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  45  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  46  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  47  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  48  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  49  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  50  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  51  * SUCH DAMAGE.
  52  */
  53
  54 #include <sys/cdefs.h>
  55 #include <sys/param.h>
  56 #include <sys/kernel.h>
  57 #include <kern/queue.h>
  58 #include <kern/locks.h>
  59 #include <sys/malloc.h>
  60 #include <sys/proc.h>
  61 #include <sys/systm.h>
  62 #include <sys/mcache.h>
  63 #include <sys/eventhandler.h>
  64 #include <sys/sysctl.h>
  65
  66 int evh_debug = 0;
  67
  68 SYSCTL_NODE(_kern, OID_AUTO, eventhandler, CTLFLAG_RW | CTLFLAG_LOCKED,
  69     0, "Eventhandler");
  70 SYSCTL_INT(_kern_eventhandler, OID_AUTO, debug, CTLFLAG_RW | CTLFLAG_LOCKED,
  71     &evh_debug, 0, "Eventhandler debug mode");
  72
  73 struct eventhandler_entry_arg eventhandler_entry_dummy_arg = { .ee_fm_uuid = { 0 }, .ee_fr_uuid = { 0 } };
  74
  75 /* List of 'slow' lists */
  76 static struct eventhandler_lists_ctxt evthdlr_lists_ctxt_glb;
  77 static LCK_GRP_DECLARE(eventhandler_mutex_grp, "eventhandler");
  78
  79 static unsigned int eg_size;    /* size of eventhandler_entry_generic */
  80 static struct mcache *eg_cache; /* mcache for eventhandler_entry_generic */
  81
  82 static unsigned int el_size;    /* size of eventhandler_list */
  83 static struct mcache *el_cache; /* mcache for eventhandler_list */
  84
  85 LCK_GRP_DECLARE(el_lock_grp, "eventhandler list");
  86 LCK_ATTR_DECLARE(el_lock_attr, 0, 0);
  87
  88 struct eventhandler_entry_generic {
  89         struct eventhandler_entry       ee;
  90         void                           *func;
  91 };
  92
  93 static struct eventhandler_list *_eventhandler_find_list(
  94         struct eventhandler_lists_ctxt *evthdlr_lists_ctxt, const char *name);
  95
  96 void
  97 eventhandler_lists_ctxt_init(struct eventhandler_lists_ctxt *evthdlr_lists_ctxt)
  98 {
  99         VERIFY(evthdlr_lists_ctxt != NULL);
 100
 101         TAILQ_INIT(&evthdlr_lists_ctxt->eventhandler_lists);
 102         evthdlr_lists_ctxt->eventhandler_lists_initted = 1;
 103         lck_mtx_init(&evthdlr_lists_ctxt->eventhandler_mutex,
 104             &eventhandler_mutex_grp, LCK_ATTR_NULL);
 105 }
 106
 107 /*
 108  * Initialize the eventhandler mutex and list.
 109  */
 110 void
 111 eventhandler_init(void)
 112 {
 113         eventhandler_lists_ctxt_init(&evthdlr_lists_ctxt_glb);
 114
 115         eg_size = sizeof(struct eventhandler_entry_generic);
 116         eg_cache = mcache_create("eventhdlr_generic", eg_size,
 117             sizeof(uint64_t), 0, MCR_SLEEP);
 118
 119         el_size = sizeof(struct eventhandler_list);
 120         el_cache = mcache_create("eventhdlr_list", el_size,
 121             sizeof(uint64_t), 0, MCR_SLEEP);
 122 }
 123
 124 void
 125 eventhandler_reap_caches(boolean_t purge)
 126 {
 127         mcache_reap_now(eg_cache, purge);
 128         mcache_reap_now(el_cache, purge);
 129 }
 130
 131 /*
 132  * Insertion is O(n) due to the priority scan, but optimises to O(1)
 133  * if all priorities are identical.
 134  */
 135 static eventhandler_tag
 136 eventhandler_register_internal(
 137         struct eventhandler_lists_ctxt *evthdlr_lists_ctxt,
 138         struct eventhandler_list *list,
 139         const char *name, eventhandler_tag epn)
 140 {
 141         struct eventhandler_list                *new_list;
 142         struct eventhandler_entry               *ep;
 143
 144         VERIFY(strlen(name) <= (sizeof(new_list->el_name) - 1));
 145
 146         if (evthdlr_lists_ctxt == NULL) {
 147                 evthdlr_lists_ctxt = &evthdlr_lists_ctxt_glb;
 148         }
 149
 150         VERIFY(evthdlr_lists_ctxt->eventhandler_lists_initted); /* eventhandler registered too early */
 151         VERIFY(epn != NULL); /* cannot register NULL event */
 152
 153         /* lock the eventhandler lists */
 154         lck_mtx_lock_spin(&evthdlr_lists_ctxt->eventhandler_mutex);
 155
 156         /* Do we need to find/create the (slow) list? */
 157         if (list == NULL) {
 158                 /* look for a matching, existing list */
 159                 list = _eventhandler_find_list(evthdlr_lists_ctxt, name);
 160
 161                 /* Do we need to create the list? */
 162                 if (list == NULL) {
 163                         lck_mtx_convert_spin(&evthdlr_lists_ctxt->eventhandler_mutex);
 164                         new_list = mcache_alloc(el_cache, MCR_SLEEP);
 165                         if (new_list == NULL) {
 166                                 evhlog((LOG_DEBUG, "%s: Can't allocate list \"%s\"", __func__, name));
 167                                 lck_mtx_unlock(&evthdlr_lists_ctxt->eventhandler_mutex);
 168                                 return NULL;
 169                         }
 170                         bzero(new_list, el_size);
 171                         evhlog((LOG_DEBUG, "%s: creating list \"%s\"", __func__, name));
 172                         list = new_list;
 173                         list->el_flags = 0;
 174                         list->el_runcount = 0;
 175                         bzero(&list->el_lock, sizeof(list->el_lock));
 176                         (void) snprintf(list->el_name, sizeof(list->el_name), "%s", name);
 177                         TAILQ_INSERT_HEAD(&evthdlr_lists_ctxt->eventhandler_lists, list, el_link);
 178                 }
 179         }
 180         if (!(list->el_flags & EHL_INITTED)) {
 181                 TAILQ_INIT(&list->el_entries);
 182                 EHL_LOCK_INIT(list);
 183                 list->el_flags |= EHL_INITTED;
 184         }
 185         lck_mtx_unlock(&evthdlr_lists_ctxt->eventhandler_mutex);
 186
 187         KASSERT(epn->ee_priority != EHE_DEAD_PRIORITY,
 188             ("%s: handler for %s registered with dead priority", __func__, name));
 189
 190         /* sort it into the list */
 191         evhlog((LOG_DEBUG, "%s: adding item %p (function %p to \"%s\"", __func__, (void *)VM_KERNEL_ADDRPERM(epn),
 192             (void *)VM_KERNEL_UNSLIDE(((struct eventhandler_entry_generic *)epn)->func), name));
 193         EHL_LOCK(list);
 194         TAILQ_FOREACH(ep, &list->el_entries, ee_link) {
 195                 if (ep->ee_priority != EHE_DEAD_PRIORITY &&
 196                     epn->ee_priority < ep->ee_priority) {
 197                         TAILQ_INSERT_BEFORE(ep, epn, ee_link);
 198                         break;
 199                 }
 200         }
 201         if (ep == NULL) {
 202                 TAILQ_INSERT_TAIL(&list->el_entries, epn, ee_link);
 203         }
 204         EHL_UNLOCK(list);
 205         return epn;
 206 }
 207
 208 eventhandler_tag
 209 eventhandler_register(struct eventhandler_lists_ctxt *evthdlr_lists_ctxt,
 210     struct eventhandler_list *list, const char *name,
 211     void *func, struct eventhandler_entry_arg arg, int priority)
 212 {
 213         struct eventhandler_entry_generic       *eg;
 214
 215         /* allocate an entry for this handler, populate it */
 216         eg = mcache_alloc(eg_cache, MCR_SLEEP);
 217         if (eg == NULL) {
 218                 evhlog((LOG_DEBUG, "%s: Can't allocate entry to register for event list "
 219                     "\"%s\"", __func__, name));
 220                 return NULL;
 221         }
 222         bzero(eg, eg_size);
 223         eg->func = func;
 224         eg->ee.ee_arg = arg;
 225         eg->ee.ee_priority = priority;
 226
 227         return eventhandler_register_internal(evthdlr_lists_ctxt, list, name, &eg->ee);
 228 }
 229
 230 void
 231 eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag)
 232 {
 233         struct eventhandler_entry       *ep = tag;
 234
 235         EHL_LOCK_ASSERT(list, LCK_MTX_ASSERT_OWNED);
 236         if (ep != NULL) {
 237                 /* remove just this entry */
 238                 if (list->el_runcount == 0) {
 239                         evhlog((LOG_DEBUG, "%s: removing item %p from \"%s\"", __func__, (void *)VM_KERNEL_ADDRPERM(ep),
 240                             list->el_name));
 241                         /*
 242                          * We may have purged the list because of certain events.
 243                          * Make sure that is not the case when a specific entry
 244                          * is being removed.
 245                          */
 246                         if (!TAILQ_EMPTY(&list->el_entries)) {
 247                                 TAILQ_REMOVE(&list->el_entries, ep, ee_link);
 248                         }
 249                         EHL_LOCK_CONVERT(list);
 250                         mcache_free(eg_cache, ep);
 251                 } else {
 252                         evhlog((LOG_DEBUG, "%s: marking item %p from \"%s\" as dead", __func__,
 253                             (void *)VM_KERNEL_ADDRPERM(ep), list->el_name));
 254                         ep->ee_priority = EHE_DEAD_PRIORITY;
 255                 }
 256         } else {
 257                 /* remove entire list */
 258                 if (list->el_runcount == 0) {
 259                         evhlog((LOG_DEBUG, "%s: removing all items from \"%s\"", __func__,
 260                             list->el_name));
 261                         EHL_LOCK_CONVERT(list);
 262                         while (!TAILQ_EMPTY(&list->el_entries)) {
 263                                 ep = TAILQ_FIRST(&list->el_entries);
 264                                 TAILQ_REMOVE(&list->el_entries, ep, ee_link);
 265                                 mcache_free(eg_cache, ep);
 266                         }
 267                 } else {
 268                         evhlog((LOG_DEBUG, "%s: marking all items from \"%s\" as dead",
 269                             __func__, list->el_name));
 270                         TAILQ_FOREACH(ep, &list->el_entries, ee_link)
 271                         ep->ee_priority = EHE_DEAD_PRIORITY;
 272                 }
 273         }
 274         while (list->el_runcount > 0) {
 275                 msleep((caddr_t)list, &list->el_lock, PSPIN, "evhrm", 0);
 276         }
 277         EHL_UNLOCK(list);
 278 }
 279
 280 /*
 281  * Internal version for use when eventhandler list is already locked.
 282  */
 283 static struct eventhandler_list *
 284 _eventhandler_find_list(struct eventhandler_lists_ctxt *evthdlr_lists_ctxt,
 285     const char *name)
 286 {
 287         struct eventhandler_list        *list;
 288
 289         VERIFY(evthdlr_lists_ctxt != NULL);
 290
 291         LCK_MTX_ASSERT(&evthdlr_lists_ctxt->eventhandler_mutex, LCK_MTX_ASSERT_OWNED);
 292         TAILQ_FOREACH(list, &evthdlr_lists_ctxt->eventhandler_lists, el_link) {
 293                 if (!strcmp(name, list->el_name)) {
 294                         break;
 295                 }
 296         }
 297         return list;
 298 }
 299
 300 /*
 301  * Lookup a "slow" list by name.  Returns with the list locked.
 302  */
 303 struct eventhandler_list *
 304 eventhandler_find_list(struct eventhandler_lists_ctxt *evthdlr_lists_ctxt,
 305     const char *name)
 306 {
 307         struct eventhandler_list        *list;
 308
 309         if (evthdlr_lists_ctxt == NULL) {
 310                 evthdlr_lists_ctxt = &evthdlr_lists_ctxt_glb;
 311         }
 312
 313         if (!evthdlr_lists_ctxt->eventhandler_lists_initted) {
 314                 return NULL;
 315         }
 316
 317         /* scan looking for the requested list */
 318         lck_mtx_lock_spin(&evthdlr_lists_ctxt->eventhandler_mutex);
 319         list = _eventhandler_find_list(evthdlr_lists_ctxt, name);
 320         if (list != NULL) {
 321                 lck_mtx_convert_spin(&evthdlr_lists_ctxt->eventhandler_mutex);
 322                 EHL_LOCK_SPIN(list);
 323         }
 324         lck_mtx_unlock(&evthdlr_lists_ctxt->eventhandler_mutex);
 325
 326         return list;
 327 }
 328
 329 /*
 330  * Prune "dead" entries from an eventhandler list.
 331  */
 332 void
 333 eventhandler_prune_list(struct eventhandler_list *list)
 334 {
 335         struct eventhandler_entry *ep, *en;
 336         int pruned = 0;
 337
 338         evhlog((LOG_DEBUG, "%s: pruning list \"%s\"", __func__, list->el_name));
 339         EHL_LOCK_ASSERT(list, LCK_MTX_ASSERT_OWNED);
 340         TAILQ_FOREACH_SAFE(ep, &list->el_entries, ee_link, en) {
 341                 if (ep->ee_priority == EHE_DEAD_PRIORITY) {
 342                         TAILQ_REMOVE(&list->el_entries, ep, ee_link);
 343                         mcache_free(eg_cache, ep);
 344                         pruned++;
 345                 }
 346         }
 347         if (pruned > 0) {
 348                 wakeup(list);
 349         }
 350 }
 351
 352 /*
 353  * This should be called when last reference to an object
 354  * is being released.
 355  * The individual event type lists must be purged when the object
 356  * becomes defunct.
 357  */
 358 void
 359 eventhandler_lists_ctxt_destroy(struct eventhandler_lists_ctxt *evthdlr_lists_ctxt)
 360 {
 361         struct eventhandler_list        *list = NULL;
 362         struct eventhandler_list        *list_next = NULL;
 363
 364         lck_mtx_lock(&evthdlr_lists_ctxt->eventhandler_mutex);
 365         TAILQ_FOREACH_SAFE(list, &evthdlr_lists_ctxt->eventhandler_lists,
 366             el_link, list_next) {
 367                 VERIFY(TAILQ_EMPTY(&list->el_entries));
 368                 EHL_LOCK_DESTROY(list);
 369                 mcache_free(el_cache, list);
 370         }
 371         lck_mtx_unlock(&evthdlr_lists_ctxt->eventhandler_mutex);
 372         lck_mtx_destroy(&evthdlr_lists_ctxt->eventhandler_mutex,
 373             &eventhandler_mutex_grp);
 374         return;
 375 }