1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 1999 Michael Smith <msmith@freebsd.org> 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include <sys/cdefs.h> 30 __FBSDID("$FreeBSD$"); 31 32 #include <sys/param.h> 33 #include <sys/kernel.h> 34 #include <sys/lock.h> 35 #include <sys/malloc.h> 36 #include <sys/mutex.h> 37 #include <sys/proc.h> 38 #include <sys/systm.h> 39 #include <sys/eventhandler.h> 40 41 static MALLOC_DEFINE(M_EVENTHANDLER, "eventhandler", "Event handler records"); 42 43 /* List of all eventhandler lists */ 44 static TAILQ_HEAD(, eventhandler_list) eventhandler_lists; 45 static int eventhandler_lists_initted = 0; 46 static struct mtx eventhandler_mutex; 47 48 struct eventhandler_entry_generic 49 { 50 struct eventhandler_entry ee; 51 void (* func)(void); 52 }; 53 54 static struct eventhandler_list *_eventhandler_find_list(const char *name); 55 56 /* 57 * Initialize the eventhandler mutex and list. 58 */ 59 static void 60 eventhandler_init(void *dummy __unused) 61 { 62 TAILQ_INIT(&eventhandler_lists); 63 mtx_init(&eventhandler_mutex, "eventhandler", NULL, MTX_DEF); 64 atomic_store_rel_int(&eventhandler_lists_initted, 1); 65 } 66 SYSINIT(eventhandlers, SI_SUB_EVENTHANDLER, SI_ORDER_FIRST, eventhandler_init, 67 NULL); 68 69 static struct eventhandler_list * 70 eventhandler_find_or_create_list(const char *name) 71 { 72 struct eventhandler_list *list, *new_list; 73 74 /* look for a matching, existing list */ 75 list = _eventhandler_find_list(name); 76 77 /* Do we need to create the list? */ 78 if (list == NULL) { 79 mtx_unlock(&eventhandler_mutex); 80 81 new_list = malloc(sizeof(*new_list) + strlen(name) + 1, 82 M_EVENTHANDLER, M_WAITOK | M_ZERO); 83 84 /* If someone else created it already, then use that one. */ 85 mtx_lock(&eventhandler_mutex); 86 list = _eventhandler_find_list(name); 87 if (list != NULL) { 88 free(new_list, M_EVENTHANDLER); 89 } else { 90 CTR2(KTR_EVH, "%s: creating list \"%s\"", __func__, name); 91 list = new_list; 92 TAILQ_INIT(&list->el_entries); 93 list->el_name = (char *)(list + 1); 94 strcpy(list->el_name, name); 95 mtx_init(&list->el_lock, list->el_name, "eventhandler list", 96 MTX_DEF); 97 TAILQ_INSERT_HEAD(&eventhandler_lists, list, el_link); 98 } 99 } 100 return (list); 101 } 102 103 /* 104 * Insertion is O(n) due to the priority scan, but optimises to O(1) 105 * if all priorities are identical. 106 */ 107 static eventhandler_tag 108 eventhandler_register_internal(struct eventhandler_list *list, 109 const char *name, eventhandler_tag epn) 110 { 111 struct eventhandler_entry *ep; 112 113 KASSERT(eventhandler_lists_initted, ("eventhandler registered too early")); 114 KASSERT(epn != NULL, ("%s: cannot register NULL event", __func__)); 115 116 /* Do we need to find/create the list? */ 117 if (list == NULL) { 118 mtx_lock(&eventhandler_mutex); 119 list = eventhandler_find_or_create_list(name); 120 mtx_unlock(&eventhandler_mutex); 121 } 122 123 KASSERT(epn->ee_priority != EHE_DEAD_PRIORITY, 124 ("%s: handler for %s registered with dead priority", __func__, name)); 125 126 /* sort it into the list */ 127 CTR4(KTR_EVH, "%s: adding item %p (function %p) to \"%s\"", __func__, epn, 128 ((struct eventhandler_entry_generic *)epn)->func, name); 129 EHL_LOCK(list); 130 TAILQ_FOREACH(ep, &list->el_entries, ee_link) { 131 if (ep->ee_priority != EHE_DEAD_PRIORITY && 132 epn->ee_priority < ep->ee_priority) { 133 TAILQ_INSERT_BEFORE(ep, epn, ee_link); 134 break; 135 } 136 } 137 if (ep == NULL) 138 TAILQ_INSERT_TAIL(&list->el_entries, epn, ee_link); 139 EHL_UNLOCK(list); 140 return(epn); 141 } 142 143 eventhandler_tag 144 eventhandler_register(struct eventhandler_list *list, const char *name, 145 void *func, void *arg, int priority) 146 { 147 struct eventhandler_entry_generic *eg; 148 149 /* allocate an entry for this handler, populate it */ 150 eg = malloc(sizeof(struct eventhandler_entry_generic), M_EVENTHANDLER, 151 M_WAITOK | M_ZERO); 152 eg->func = func; 153 eg->ee.ee_arg = arg; 154 eg->ee.ee_priority = priority; 155 156 return (eventhandler_register_internal(list, name, &eg->ee)); 157 } 158 159 #ifdef VIMAGE 160 struct eventhandler_entry_generic_vimage 161 { 162 struct eventhandler_entry ee; 163 vimage_iterator_func_t func; /* Vimage iterator function. */ 164 struct eventhandler_entry_vimage v_ee; /* Original func, arg. */ 165 }; 166 167 eventhandler_tag 168 vimage_eventhandler_register(struct eventhandler_list *list, const char *name, 169 void *func, void *arg, int priority, vimage_iterator_func_t iterfunc) 170 { 171 struct eventhandler_entry_generic_vimage *eg; 172 173 /* allocate an entry for this handler, populate it */ 174 eg = malloc(sizeof(struct eventhandler_entry_generic_vimage), 175 M_EVENTHANDLER, M_WAITOK | M_ZERO); 176 eg->func = iterfunc; 177 eg->v_ee.func = func; 178 eg->v_ee.ee_arg = arg; 179 eg->ee.ee_arg = &eg->v_ee; 180 eg->ee.ee_priority = priority; 181 182 return (eventhandler_register_internal(list, name, &eg->ee)); 183 } 184 #endif 185 186 static void 187 _eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag, 188 bool wait) 189 { 190 struct eventhandler_entry *ep = tag; 191 192 EHL_LOCK_ASSERT(list, MA_OWNED); 193 if (ep != NULL) { 194 /* remove just this entry */ 195 if (list->el_runcount == 0) { 196 CTR3(KTR_EVH, "%s: removing item %p from \"%s\"", __func__, ep, 197 list->el_name); 198 TAILQ_REMOVE(&list->el_entries, ep, ee_link); 199 free(ep, M_EVENTHANDLER); 200 } else { 201 CTR3(KTR_EVH, "%s: marking item %p from \"%s\" as dead", __func__, 202 ep, list->el_name); 203 ep->ee_priority = EHE_DEAD_PRIORITY; 204 } 205 } else { 206 /* remove entire list */ 207 if (list->el_runcount == 0) { 208 CTR2(KTR_EVH, "%s: removing all items from \"%s\"", __func__, 209 list->el_name); 210 while (!TAILQ_EMPTY(&list->el_entries)) { 211 ep = TAILQ_FIRST(&list->el_entries); 212 TAILQ_REMOVE(&list->el_entries, ep, ee_link); 213 free(ep, M_EVENTHANDLER); 214 } 215 } else { 216 CTR2(KTR_EVH, "%s: marking all items from \"%s\" as dead", 217 __func__, list->el_name); 218 TAILQ_FOREACH(ep, &list->el_entries, ee_link) 219 ep->ee_priority = EHE_DEAD_PRIORITY; 220 } 221 } 222 while (wait && list->el_runcount > 0) 223 mtx_sleep(list, &list->el_lock, 0, "evhrm", 0); 224 EHL_UNLOCK(list); 225 } 226 227 void 228 eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag) 229 { 230 231 _eventhandler_deregister(list, tag, true); 232 } 233 234 void 235 eventhandler_deregister_nowait(struct eventhandler_list *list, 236 eventhandler_tag tag) 237 { 238 239 _eventhandler_deregister(list, tag, false); 240 } 241 242 /* 243 * Internal version for use when eventhandler list is already locked. 244 */ 245 static struct eventhandler_list * 246 _eventhandler_find_list(const char *name) 247 { 248 struct eventhandler_list *list; 249 250 mtx_assert(&eventhandler_mutex, MA_OWNED); 251 TAILQ_FOREACH(list, &eventhandler_lists, el_link) { 252 if (!strcmp(name, list->el_name)) 253 break; 254 } 255 return (list); 256 } 257 258 /* 259 * Lookup a "slow" list by name. Returns with the list locked. 260 */ 261 struct eventhandler_list * 262 eventhandler_find_list(const char *name) 263 { 264 struct eventhandler_list *list; 265 266 if (!eventhandler_lists_initted) 267 return(NULL); 268 269 /* scan looking for the requested list */ 270 mtx_lock(&eventhandler_mutex); 271 list = _eventhandler_find_list(name); 272 if (list != NULL) 273 EHL_LOCK(list); 274 mtx_unlock(&eventhandler_mutex); 275 276 return(list); 277 } 278 279 /* 280 * Prune "dead" entries from an eventhandler list. 281 */ 282 void 283 eventhandler_prune_list(struct eventhandler_list *list) 284 { 285 struct eventhandler_entry *ep, *en; 286 int pruned = 0; 287 288 CTR2(KTR_EVH, "%s: pruning list \"%s\"", __func__, list->el_name); 289 EHL_LOCK_ASSERT(list, MA_OWNED); 290 TAILQ_FOREACH_SAFE(ep, &list->el_entries, ee_link, en) { 291 if (ep->ee_priority == EHE_DEAD_PRIORITY) { 292 TAILQ_REMOVE(&list->el_entries, ep, ee_link); 293 free(ep, M_EVENTHANDLER); 294 pruned++; 295 } 296 } 297 if (pruned > 0) 298 wakeup(list); 299 } 300 301 /* 302 * Create (or get the existing) list so the pointer can be stored by 303 * EVENTHANDLER_LIST_DEFINE. 304 */ 305 struct eventhandler_list * 306 eventhandler_create_list(const char *name) 307 { 308 struct eventhandler_list *list; 309 310 KASSERT(eventhandler_lists_initted, 311 ("eventhandler list created too early")); 312 313 mtx_lock(&eventhandler_mutex); 314 list = eventhandler_find_or_create_list(name); 315 mtx_unlock(&eventhandler_mutex); 316 317 return (list); 318 } 319