1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 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/ktr.h> 35 #include <sys/lock.h> 36 #include <sys/malloc.h> 37 #include <sys/mutex.h> 38 #include <sys/proc.h> 39 #include <sys/systm.h> 40 #include <sys/eventhandler.h> 41 42 static MALLOC_DEFINE(M_EVENTHANDLER, "eventhandler", "Event handler records"); 43 44 /* List of all eventhandler lists */ 45 static TAILQ_HEAD(, eventhandler_list) eventhandler_lists; 46 static int eventhandler_lists_initted = 0; 47 static struct mtx eventhandler_mutex; 48 49 struct eventhandler_entry_generic 50 { 51 struct eventhandler_entry ee; 52 void (* func)(void); 53 }; 54 55 static struct eventhandler_list *_eventhandler_find_list(const char *name); 56 57 /* 58 * Initialize the eventhandler mutex and list. 59 */ 60 static void 61 eventhandler_init(void *dummy __unused) 62 { 63 TAILQ_INIT(&eventhandler_lists); 64 mtx_init(&eventhandler_mutex, "eventhandler", NULL, MTX_DEF); 65 atomic_store_rel_int(&eventhandler_lists_initted, 1); 66 } 67 SYSINIT(eventhandlers, SI_SUB_EVENTHANDLER, SI_ORDER_FIRST, eventhandler_init, 68 NULL); 69 70 static struct eventhandler_list * 71 eventhandler_find_or_create_list(const char *name) 72 { 73 struct eventhandler_list *list, *new_list; 74 75 /* look for a matching, existing list */ 76 list = _eventhandler_find_list(name); 77 78 /* Do we need to create the list? */ 79 if (list == NULL) { 80 mtx_unlock(&eventhandler_mutex); 81 82 new_list = malloc(sizeof(*new_list) + strlen(name) + 1, 83 M_EVENTHANDLER, M_WAITOK | M_ZERO); 84 85 /* If someone else created it already, then use that one. */ 86 mtx_lock(&eventhandler_mutex); 87 list = _eventhandler_find_list(name); 88 if (list != NULL) { 89 free(new_list, M_EVENTHANDLER); 90 } else { 91 CTR2(KTR_EVH, "%s: creating list \"%s\"", __func__, name); 92 list = new_list; 93 TAILQ_INIT(&list->el_entries); 94 list->el_name = (char *)(list + 1); 95 strcpy(list->el_name, name); 96 mtx_init(&list->el_lock, list->el_name, "eventhandler list", 97 MTX_DEF); 98 TAILQ_INSERT_HEAD(&eventhandler_lists, list, el_link); 99 } 100 } 101 return (list); 102 } 103 104 /* 105 * Insertion is O(n) due to the priority scan, but optimises to O(1) 106 * if all priorities are identical. 107 */ 108 static eventhandler_tag 109 eventhandler_register_internal(struct eventhandler_list *list, 110 const char *name, eventhandler_tag epn) 111 { 112 struct eventhandler_entry *ep; 113 114 KASSERT(eventhandler_lists_initted, ("eventhandler registered too early")); 115 KASSERT(epn != NULL, ("%s: cannot register NULL event", __func__)); 116 117 /* Do we need to find/create the list? */ 118 if (list == NULL) { 119 mtx_lock(&eventhandler_mutex); 120 list = eventhandler_find_or_create_list(name); 121 mtx_unlock(&eventhandler_mutex); 122 } 123 124 KASSERT(epn->ee_priority != EHE_DEAD_PRIORITY, 125 ("%s: handler for %s registered with dead priority", __func__, name)); 126 127 /* sort it into the list */ 128 CTR4(KTR_EVH, "%s: adding item %p (function %p) to \"%s\"", __func__, epn, 129 ((struct eventhandler_entry_generic *)epn)->func, name); 130 EHL_LOCK(list); 131 TAILQ_FOREACH(ep, &list->el_entries, ee_link) { 132 if (ep->ee_priority != EHE_DEAD_PRIORITY && 133 epn->ee_priority < ep->ee_priority) { 134 TAILQ_INSERT_BEFORE(ep, epn, ee_link); 135 break; 136 } 137 } 138 if (ep == NULL) 139 TAILQ_INSERT_TAIL(&list->el_entries, epn, ee_link); 140 EHL_UNLOCK(list); 141 return(epn); 142 } 143 144 eventhandler_tag 145 eventhandler_register(struct eventhandler_list *list, const char *name, 146 void *func, void *arg, int priority) 147 { 148 struct eventhandler_entry_generic *eg; 149 150 /* allocate an entry for this handler, populate it */ 151 eg = malloc(sizeof(struct eventhandler_entry_generic), M_EVENTHANDLER, 152 M_WAITOK | M_ZERO); 153 eg->func = func; 154 eg->ee.ee_arg = arg; 155 eg->ee.ee_priority = priority; 156 157 return (eventhandler_register_internal(list, name, &eg->ee)); 158 } 159 160 #ifdef VIMAGE 161 struct eventhandler_entry_generic_vimage 162 { 163 struct eventhandler_entry ee; 164 vimage_iterator_func_t func; /* Vimage iterator function. */ 165 struct eventhandler_entry_vimage v_ee; /* Original func, arg. */ 166 }; 167 168 eventhandler_tag 169 vimage_eventhandler_register(struct eventhandler_list *list, const char *name, 170 void *func, void *arg, int priority, vimage_iterator_func_t iterfunc) 171 { 172 struct eventhandler_entry_generic_vimage *eg; 173 174 /* allocate an entry for this handler, populate it */ 175 eg = malloc(sizeof(struct eventhandler_entry_generic_vimage), 176 M_EVENTHANDLER, M_WAITOK | M_ZERO); 177 eg->func = iterfunc; 178 eg->v_ee.func = func; 179 eg->v_ee.ee_arg = arg; 180 eg->ee.ee_arg = &eg->v_ee; 181 eg->ee.ee_priority = priority; 182 183 return (eventhandler_register_internal(list, name, &eg->ee)); 184 } 185 #endif 186 187 static void 188 _eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag, 189 bool wait) 190 { 191 struct eventhandler_entry *ep = tag; 192 193 EHL_LOCK_ASSERT(list, MA_OWNED); 194 if (ep != NULL) { 195 /* remove just this entry */ 196 if (list->el_runcount == 0) { 197 CTR3(KTR_EVH, "%s: removing item %p from \"%s\"", __func__, ep, 198 list->el_name); 199 TAILQ_REMOVE(&list->el_entries, ep, ee_link); 200 free(ep, M_EVENTHANDLER); 201 } else { 202 CTR3(KTR_EVH, "%s: marking item %p from \"%s\" as dead", __func__, 203 ep, list->el_name); 204 ep->ee_priority = EHE_DEAD_PRIORITY; 205 } 206 } else { 207 /* remove entire list */ 208 if (list->el_runcount == 0) { 209 CTR2(KTR_EVH, "%s: removing all items from \"%s\"", __func__, 210 list->el_name); 211 while (!TAILQ_EMPTY(&list->el_entries)) { 212 ep = TAILQ_FIRST(&list->el_entries); 213 TAILQ_REMOVE(&list->el_entries, ep, ee_link); 214 free(ep, M_EVENTHANDLER); 215 } 216 } else { 217 CTR2(KTR_EVH, "%s: marking all items from \"%s\" as dead", 218 __func__, list->el_name); 219 TAILQ_FOREACH(ep, &list->el_entries, ee_link) 220 ep->ee_priority = EHE_DEAD_PRIORITY; 221 } 222 } 223 while (wait && list->el_runcount > 0) 224 mtx_sleep(list, &list->el_lock, 0, "evhrm", 0); 225 EHL_UNLOCK(list); 226 } 227 228 void 229 eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag) 230 { 231 232 _eventhandler_deregister(list, tag, true); 233 } 234 235 void 236 eventhandler_deregister_nowait(struct eventhandler_list *list, 237 eventhandler_tag tag) 238 { 239 240 _eventhandler_deregister(list, tag, false); 241 } 242 243 /* 244 * Internal version for use when eventhandler list is already locked. 245 */ 246 static struct eventhandler_list * 247 _eventhandler_find_list(const char *name) 248 { 249 struct eventhandler_list *list; 250 251 mtx_assert(&eventhandler_mutex, MA_OWNED); 252 TAILQ_FOREACH(list, &eventhandler_lists, el_link) { 253 if (!strcmp(name, list->el_name)) 254 break; 255 } 256 return (list); 257 } 258 259 /* 260 * Lookup a "slow" list by name. Returns with the list locked. 261 */ 262 struct eventhandler_list * 263 eventhandler_find_list(const char *name) 264 { 265 struct eventhandler_list *list; 266 267 if (!eventhandler_lists_initted) 268 return(NULL); 269 270 /* scan looking for the requested list */ 271 mtx_lock(&eventhandler_mutex); 272 list = _eventhandler_find_list(name); 273 if (list != NULL) 274 EHL_LOCK(list); 275 mtx_unlock(&eventhandler_mutex); 276 277 return(list); 278 } 279 280 /* 281 * Prune "dead" entries from an eventhandler list. 282 */ 283 void 284 eventhandler_prune_list(struct eventhandler_list *list) 285 { 286 struct eventhandler_entry *ep, *en; 287 int pruned = 0; 288 289 CTR2(KTR_EVH, "%s: pruning list \"%s\"", __func__, list->el_name); 290 EHL_LOCK_ASSERT(list, MA_OWNED); 291 TAILQ_FOREACH_SAFE(ep, &list->el_entries, ee_link, en) { 292 if (ep->ee_priority == EHE_DEAD_PRIORITY) { 293 TAILQ_REMOVE(&list->el_entries, ep, ee_link); 294 free(ep, M_EVENTHANDLER); 295 pruned++; 296 } 297 } 298 if (pruned > 0) 299 wakeup(list); 300 } 301 302 /* 303 * Create (or get the existing) list so the pointer can be stored by 304 * EVENTHANDLER_LIST_DEFINE. 305 */ 306 struct eventhandler_list * 307 eventhandler_create_list(const char *name) 308 { 309 struct eventhandler_list *list; 310 311 KASSERT(eventhandler_lists_initted, 312 ("eventhandler list created too early")); 313 314 mtx_lock(&eventhandler_mutex); 315 list = eventhandler_find_or_create_list(name); 316 mtx_unlock(&eventhandler_mutex); 317 318 return (list); 319 } 320