bsd/kern/subr_eventhandler.c

   1 /*
   2  * Copyright (c) 2016-2017 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 MALLOC_DEFINE(M_EVENTHANDLER, "eventhandler", "Event handler records");
  69
  70 SYSCTL_NODE(_kern, OID_AUTO, eventhandler, CTLFLAG_RW | CTLFLAG_LOCKED,
  71     0, "Eventhandler");
  72 SYSCTL_INT(_kern_eventhandler, OID_AUTO, debug, CTLFLAG_RW | CTLFLAG_LOCKED,
  73     &evh_debug, 0, "Eventhandler debug mode");
  74
  75 struct eventhandler_entry_arg eventhandler_entry_dummy_arg = { { 0 }, { 0 } };
  76
  77 /* List of 'slow' lists */
  78 static struct eventhandler_lists_ctxt evthdlr_lists_ctxt_glb;
  79 static lck_grp_attr_t   *eventhandler_mutex_grp_attr;
  80 static lck_grp_t        *eventhandler_mutex_grp;
  81 static lck_attr_t       *eventhandler_mutex_attr;
  82
  83 static unsigned int eg_size;    /* size of eventhandler_entry_generic */
  84 static struct mcache *eg_cache; /* mcache for eventhandler_entry_generic */
  85
  86 static unsigned int el_size;    /* size of eventhandler_list */
  87 static struct mcache *el_cache; /* mcache for eventhandler_list */
  88
  89 static lck_grp_attr_t   *el_lock_grp_attr;
  90 lck_grp_t        *el_lock_grp;
  91 lck_attr_t       *el_lock_attr;
  92
  93 struct eventhandler_entry_generic {
  94         struct eventhandler_entry       ee;
  95         void                    (* func)(void);
  96 };
  97
  98 static struct eventhandler_list *_eventhandler_find_list(
  99         struct eventhandler_lists_ctxt *evthdlr_lists_ctxt, const char *name);
 100
 101 void
 102 eventhandler_lists_ctxt_init(struct eventhandler_lists_ctxt *evthdlr_lists_ctxt)
 103 {
 104         VERIFY(evthdlr_lists_ctxt != NULL);
 105
 106         TAILQ_INIT(&evthdlr_lists_ctxt->eventhandler_lists);
 107         evthdlr_lists_ctxt->eventhandler_lists_initted = 1;
 108         lck_mtx_init(&evthdlr_lists_ctxt->eventhandler_mutex,
 109             eventhandler_mutex_grp, eventhandler_mutex_attr);
 110 }
 111
 112 /*
 113  * Initialize the eventhandler mutex and list.
 114  */
 115 void
 116 eventhandler_init(void)
 117 {
 118         eventhandler_mutex_grp_attr = lck_grp_attr_alloc_init();
 119         eventhandler_mutex_grp = lck_grp_alloc_init("eventhandler",
 120             eventhandler_mutex_grp_attr);
 121         eventhandler_mutex_attr = lck_attr_alloc_init();
 122
 123         el_lock_grp_attr = lck_grp_attr_alloc_init();
 124         el_lock_grp = lck_grp_alloc_init("eventhandler list",
 125             el_lock_grp_attr);
 126         el_lock_attr = lck_attr_alloc_init();
 127
 128         eventhandler_lists_ctxt_init(&evthdlr_lists_ctxt_glb);
 129
 130         eg_size = sizeof(struct eventhandler_entry_generic);
 131         eg_cache = mcache_create("eventhdlr_generic", eg_size,
 132             sizeof(uint64_t), 0, MCR_SLEEP);
 133
 134         el_size = sizeof(struct eventhandler_list);
 135         el_cache = mcache_create("eventhdlr_list", el_size,
 136             sizeof(uint64_t), 0, MCR_SLEEP);
 137 }
 138
 139 void
 140 eventhandler_reap_caches(boolean_t purge)
 141 {
 142         mcache_reap_now(eg_cache, purge);
 143         mcache_reap_now(el_cache, purge);
 144 }
 145
 146 /*
 147  * Insertion is O(n) due to the priority scan, but optimises to O(1)
 148  * if all priorities are identical.
 149  */
 150 static eventhandler_tag
 151 eventhandler_register_internal(
 152         struct eventhandler_lists_ctxt *evthdlr_lists_ctxt,
 153         struct eventhandler_list *list,
 154         const char *name, eventhandler_tag epn)
 155 {
 156         struct eventhandler_list                *new_list;
 157         struct eventhandler_entry               *ep;
 158
 159         VERIFY(strlen(name) <= (sizeof(new_list->el_name) - 1));
 160
 161         if (evthdlr_lists_ctxt == NULL) {
 162                 evthdlr_lists_ctxt = &evthdlr_lists_ctxt_glb;
 163         }
 164
 165         VERIFY(evthdlr_lists_ctxt->eventhandler_lists_initted); /* eventhandler registered too early */
 166         VERIFY(epn != NULL); /* cannot register NULL event */
 167
 168         /* lock the eventhandler lists */
 169         lck_mtx_lock_spin(&evthdlr_lists_ctxt->eventhandler_mutex);
 170
 171         /* Do we need to find/create the (slow) list? */
 172         if (list == NULL) {
 173                 /* look for a matching, existing list */
 174                 list = _eventhandler_find_list(evthdlr_lists_ctxt, name);
 175
 176                 /* Do we need to create the list? */
 177                 if (list == NULL) {
 178                         lck_mtx_convert_spin(&evthdlr_lists_ctxt->eventhandler_mutex);
 179                         new_list = mcache_alloc(el_cache, MCR_SLEEP);
 180                         bzero(new_list, el_size);
 181                         evhlog((LOG_DEBUG, "%s: creating list \"%s\"", __func__, name));
 182                         list = new_list;
 183                         list->el_flags = 0;
 184                         list->el_runcount = 0;
 185                         bzero(&list->el_lock, sizeof(list->el_lock));
 186                         (void) snprintf(list->el_name, sizeof(list->el_name), "%s", name);
 187                         TAILQ_INSERT_HEAD(&evthdlr_lists_ctxt->eventhandler_lists, list, el_link);
 188                 }
 189         }
 190         if (!(list->el_flags & EHL_INITTED)) {
 191                 TAILQ_INIT(&list->el_entries);
 192                 EHL_LOCK_INIT(list);
 193                 list->el_flags |= EHL_INITTED;
 194         }
 195         lck_mtx_unlock(&evthdlr_lists_ctxt->eventhandler_mutex);
 196
 197         KASSERT(epn->ee_priority != EHE_DEAD_PRIORITY,
 198             ("%s: handler for %s registered with dead priority", __func__, name));
 199
 200         /* sort it into the list */
 201         evhlog((LOG_DEBUG, "%s: adding item %p (function %p to \"%s\"", __func__, VM_KERNEL_ADDRPERM(epn),
 202             VM_KERNEL_UNSLIDE(((struct eventhandler_entry_generic *)epn)->func), name));
 203         EHL_LOCK(list);
 204         TAILQ_FOREACH(ep, &list->el_entries, ee_link) {
 205                 if (ep->ee_priority != EHE_DEAD_PRIORITY &&
 206                     epn->ee_priority < ep->ee_priority) {
 207                         TAILQ_INSERT_BEFORE(ep, epn, ee_link);
 208                         break;
 209                 }
 210         }
 211         if (ep == NULL) {
 212                 TAILQ_INSERT_TAIL(&list->el_entries, epn, ee_link);
 213         }
 214         EHL_UNLOCK(list);
 215         return epn;
 216 }
 217
 218 eventhandler_tag
 219 eventhandler_register(struct eventhandler_lists_ctxt *evthdlr_lists_ctxt,
 220     struct eventhandler_list *list, const char *name,
 221     void *func, struct eventhandler_entry_arg arg, int priority)
 222 {
 223         struct eventhandler_entry_generic       *eg;
 224
 225         /* allocate an entry for this handler, populate it */
 226         eg = mcache_alloc(eg_cache, MCR_SLEEP);
 227         bzero(eg, eg_size);
 228         eg->func = func;
 229         eg->ee.ee_arg = arg;
 230         eg->ee.ee_priority = priority;
 231
 232         return eventhandler_register_internal(evthdlr_lists_ctxt, list, name, &eg->ee);
 233 }
 234
 235 void
 236 eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag)
 237 {
 238         struct eventhandler_entry       *ep = tag;
 239
 240         EHL_LOCK_ASSERT(list, LCK_MTX_ASSERT_OWNED);
 241         if (ep != NULL) {
 242                 /* remove just this entry */
 243                 if (list->el_runcount == 0) {
 244                         evhlog((LOG_DEBUG, "%s: removing item %p from \"%s\"", __func__, VM_KERNEL_ADDRPERM(ep),
 245                             list->el_name));
 246                         /*
 247                          * We may have purged the list because of certain events.
 248                          * Make sure that is not the case when a specific entry
 249                          * is being removed.
 250                          */
 251                         if (!TAILQ_EMPTY(&list->el_entries)) {
 252                                 TAILQ_REMOVE(&list->el_entries, ep, ee_link);
 253                         }
 254                         EHL_LOCK_CONVERT(list);
 255                         mcache_free(eg_cache, ep);
 256                 } else {
 257                         evhlog((LOG_DEBUG, "%s: marking item %p from \"%s\" as dead", __func__,
 258                             VM_KERNEL_ADDRPERM(ep), list->el_name));
 259                         ep->ee_priority = EHE_DEAD_PRIORITY;
 260                 }
 261         } else {
 262                 /* remove entire list */
 263                 if (list->el_runcount == 0) {
 264                         evhlog((LOG_DEBUG, "%s: removing all items from \"%s\"", __func__,
 265                             list->el_name));
 266                         EHL_LOCK_CONVERT(list);
 267                         while (!TAILQ_EMPTY(&list->el_entries)) {
 268                                 ep = TAILQ_FIRST(&list->el_entries);
 269                                 TAILQ_REMOVE(&list->el_entries, ep, ee_link);
 270                                 mcache_free(eg_cache, ep);
 271                         }
 272                 } else {
 273                         evhlog((LOG_DEBUG, "%s: marking all items from \"%s\" as dead",
 274                             __func__, list->el_name));
 275                         TAILQ_FOREACH(ep, &list->el_entries, ee_link)
 276                         ep->ee_priority = EHE_DEAD_PRIORITY;
 277                 }
 278         }
 279         while (list->el_runcount > 0) {
 280                 msleep((caddr_t)list, &list->el_lock, PSPIN, "evhrm", 0);
 281         }
 282         EHL_UNLOCK(list);
 283 }
 284
 285 /*
 286  * Internal version for use when eventhandler list is already locked.
 287  */
 288 static struct eventhandler_list *
 289 _eventhandler_find_list(struct eventhandler_lists_ctxt *evthdlr_lists_ctxt,
 290     const char *name)
 291 {
 292         struct eventhandler_list        *list;
 293
 294         VERIFY(evthdlr_lists_ctxt != NULL);
 295
 296         LCK_MTX_ASSERT(&evthdlr_lists_ctxt->eventhandler_mutex, LCK_MTX_ASSERT_OWNED);
 297         TAILQ_FOREACH(list, &evthdlr_lists_ctxt->eventhandler_lists, el_link) {
 298                 if (!strcmp(name, list->el_name)) {
 299                         break;
 300                 }
 301         }
 302         return list;
 303 }
 304
 305 /*
 306  * Lookup a "slow" list by name.  Returns with the list locked.
 307  */
 308 struct eventhandler_list *
 309 eventhandler_find_list(struct eventhandler_lists_ctxt *evthdlr_lists_ctxt,
 310     const char *name)
 311 {
 312         struct eventhandler_list        *list;
 313
 314         if (evthdlr_lists_ctxt == NULL) {
 315                 evthdlr_lists_ctxt = &evthdlr_lists_ctxt_glb;
 316         }
 317
 318         if (!evthdlr_lists_ctxt->eventhandler_lists_initted) {
 319                 return NULL;
 320         }
 321
 322         /* scan looking for the requested list */
 323         lck_mtx_lock_spin(&evthdlr_lists_ctxt->eventhandler_mutex);
 324         list = _eventhandler_find_list(evthdlr_lists_ctxt, name);
 325         if (list != NULL) {
 326                 lck_mtx_convert_spin(&evthdlr_lists_ctxt->eventhandler_mutex);
 327                 EHL_LOCK_SPIN(list);
 328         }
 329         lck_mtx_unlock(&evthdlr_lists_ctxt->eventhandler_mutex);
 330
 331         return list;
 332 }
 333
 334 /*
 335  * Prune "dead" entries from an eventhandler list.
 336  */
 337 void
 338 eventhandler_prune_list(struct eventhandler_list *list)
 339 {
 340         struct eventhandler_entry *ep, *en;
 341         int pruned = 0;
 342
 343         evhlog((LOG_DEBUG, "%s: pruning list \"%s\"", __func__, list->el_name));
 344         EHL_LOCK_ASSERT(list, LCK_MTX_ASSERT_OWNED);
 345         TAILQ_FOREACH_SAFE(ep, &list->el_entries, ee_link, en) {
 346                 if (ep->ee_priority == EHE_DEAD_PRIORITY) {
 347                         TAILQ_REMOVE(&list->el_entries, ep, ee_link);
 348                         mcache_free(eg_cache, ep);
 349                         pruned++;
 350                 }
 351         }
 352         if (pruned > 0) {
 353                 wakeup(list);
 354         }
 355 }
 356
 357 /*
 358  * This should be called when last reference to an object
 359  * is being released.
 360  * The individual event type lists must be purged when the object
 361  * becomes defunct.
 362  */
 363 void
 364 eventhandler_lists_ctxt_destroy(struct eventhandler_lists_ctxt *evthdlr_lists_ctxt)
 365 {
 366         struct eventhandler_list        *list = NULL;
 367         struct eventhandler_list        *list_next = NULL;
 368
 369         lck_mtx_lock(&evthdlr_lists_ctxt->eventhandler_mutex);
 370         TAILQ_FOREACH_SAFE(list, &evthdlr_lists_ctxt->eventhandler_lists,
 371             el_link, list_next) {
 372                 VERIFY(TAILQ_EMPTY(&list->el_entries));
 373                 EHL_LOCK_DESTROY(list);
 374                 mcache_free(el_cache, list);
 375         }
 376         lck_mtx_unlock(&evthdlr_lists_ctxt->eventhandler_mutex);
 377         lck_mtx_destroy(&evthdlr_lists_ctxt->eventhandler_mutex,
 378             eventhandler_mutex_grp);
 379         return;
 380 }