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 #include <sys/param.h> 31 #include <sys/kernel.h> 32 #include <sys/ktr.h> 33 #include <sys/lock.h> 34 #include <sys/malloc.h> 35 #include <sys/mutex.h> 36 #include <sys/proc.h> 37 #include <sys/systm.h> 38 #include <sys/eventhandler.h> 39 40 static MALLOC_DEFINE(M_EVENTHANDLER, "eventhandler", "Event handler records"); 41 42 /* List of all eventhandler lists */ 43 static TAILQ_HEAD(, eventhandler_list) eventhandler_lists; 44 static int eventhandler_lists_initted = 0; 45 static struct mtx eventhandler_mutex; 46 47 struct eventhandler_entry_generic 48 { 49 struct eventhandler_entry ee; 50 void (* func)(void); 51 }; 52 53 static struct eventhandler_list *_eventhandler_find_list(const char *name); 54 55 /* 56 * Initialize the eventhandler mutex and list. 57 */ 58 static void 59 eventhandler_init(void *dummy __unused) 60 { 61 TAILQ_INIT(&eventhandler_lists); 62 mtx_init(&eventhandler_mutex, "eventhandler", NULL, MTX_DEF); 63 atomic_store_rel_int(&eventhandler_lists_initted, 1); 64 } 65 SYSINIT(eventhandlers, SI_SUB_EVENTHANDLER, SI_ORDER_FIRST, eventhandler_init, 66 NULL); 67 68 static struct eventhandler_list * 69 eventhandler_find_or_create_list(const char *name) 70 { 71 struct eventhandler_list *list, *new_list; 72 73 /* look for a matching, existing list */ 74 list = _eventhandler_find_list(name); 75 76 /* Do we need to create the list? */ 77 if (list == NULL) { 78 mtx_unlock(&eventhandler_mutex); 79 80 new_list = malloc(sizeof(*new_list) + strlen(name) + 1, 81 M_EVENTHANDLER, M_WAITOK | M_ZERO); 82 83 /* If someone else created it already, then use that one. */ 84 mtx_lock(&eventhandler_mutex); 85 list = _eventhandler_find_list(name); 86 if (list != NULL) { 87 free(new_list, M_EVENTHANDLER); 88 } else { 89 CTR2(KTR_EVH, "%s: creating list \"%s\"", __func__, name); 90 list = new_list; 91 TAILQ_INIT(&list->el_entries); 92 list->el_name = (char *)(list + 1); 93 strcpy(list->el_name, name); 94 mtx_init(&list->el_lock, list->el_name, "eventhandler list", 95 MTX_DEF); 96 TAILQ_INSERT_HEAD(&eventhandler_lists, list, el_link); 97 } 98 } 99 return (list); 100 } 101 102 /* 103 * Insertion is O(n) due to the priority scan, but optimises to O(1) 104 * if all priorities are identical. 105 */ 106 static eventhandler_tag 107 eventhandler_register_internal(struct eventhandler_list *list, 108 const char *name, eventhandler_tag epn) 109 { 110 struct eventhandler_entry *ep; 111 112 KASSERT(eventhandler_lists_initted, ("eventhandler registered too early")); 113 KASSERT(epn != NULL, ("%s: cannot register NULL event", __func__)); 114 115 /* Do we need to find/create the list? */ 116 if (list == NULL) { 117 mtx_lock(&eventhandler_mutex); 118 list = eventhandler_find_or_create_list(name); 119 mtx_unlock(&eventhandler_mutex); 120 } 121 122 KASSERT(epn->ee_priority != EHE_DEAD_PRIORITY, 123 ("%s: handler for %s registered with dead priority", __func__, name)); 124 125 /* sort it into the list */ 126 CTR4(KTR_EVH, "%s: adding item %p (function %p) to \"%s\"", __func__, epn, 127 ((struct eventhandler_entry_generic *)epn)->func, name); 128 EHL_LOCK(list); 129 TAILQ_FOREACH(ep, &list->el_entries, ee_link) { 130 if (ep->ee_priority != EHE_DEAD_PRIORITY && 131 epn->ee_priority < ep->ee_priority) { 132 TAILQ_INSERT_BEFORE(ep, epn, ee_link); 133 break; 134 } 135 } 136 if (ep == NULL) 137 TAILQ_INSERT_TAIL(&list->el_entries, epn, ee_link); 138 EHL_UNLOCK(list); 139 return(epn); 140 } 141 142 eventhandler_tag 143 eventhandler_register(struct eventhandler_list *list, const char *name, 144 void *func, void *arg, int priority) 145 { 146 struct eventhandler_entry_generic *eg; 147 148 /* allocate an entry for this handler, populate it */ 149 eg = malloc(sizeof(struct eventhandler_entry_generic), M_EVENTHANDLER, 150 M_WAITOK | M_ZERO); 151 eg->func = func; 152 eg->ee.ee_arg = arg; 153 eg->ee.ee_priority = priority; 154 155 return (eventhandler_register_internal(list, name, &eg->ee)); 156 } 157 158 #ifdef VIMAGE 159 struct eventhandler_entry_generic_vimage 160 { 161 struct eventhandler_entry ee; 162 vimage_iterator_func_t func; /* Vimage iterator function. */ 163 struct eventhandler_entry_vimage v_ee; /* Original func, arg. */ 164 }; 165 166 eventhandler_tag 167 vimage_eventhandler_register(struct eventhandler_list *list, const char *name, 168 void *func, void *arg, int priority, vimage_iterator_func_t iterfunc) 169 { 170 struct eventhandler_entry_generic_vimage *eg; 171 172 /* allocate an entry for this handler, populate it */ 173 eg = malloc(sizeof(struct eventhandler_entry_generic_vimage), 174 M_EVENTHANDLER, M_WAITOK | M_ZERO); 175 eg->func = iterfunc; 176 eg->v_ee.func = func; 177 eg->v_ee.ee_arg = arg; 178 eg->ee.ee_arg = &eg->v_ee; 179 eg->ee.ee_priority = priority; 180 181 return (eventhandler_register_internal(list, name, &eg->ee)); 182 } 183 #endif 184 185 static void 186 _eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag, 187 bool wait) 188 { 189 struct eventhandler_entry *ep = tag; 190 191 EHL_LOCK_ASSERT(list, MA_OWNED); 192 if (ep != NULL) { 193 /* remove just this entry */ 194 if (list->el_runcount == 0) { 195 CTR3(KTR_EVH, "%s: removing item %p from \"%s\"", __func__, ep, 196 list->el_name); 197 TAILQ_REMOVE(&list->el_entries, ep, ee_link); 198 free(ep, M_EVENTHANDLER); 199 } else { 200 CTR3(KTR_EVH, "%s: marking item %p from \"%s\" as dead", __func__, 201 ep, list->el_name); 202 ep->ee_priority = EHE_DEAD_PRIORITY; 203 } 204 } else { 205 /* remove entire list */ 206 if (list->el_runcount == 0) { 207 CTR2(KTR_EVH, "%s: removing all items from \"%s\"", __func__, 208 list->el_name); 209 while (!TAILQ_EMPTY(&list->el_entries)) { 210 ep = TAILQ_FIRST(&list->el_entries); 211 TAILQ_REMOVE(&list->el_entries, ep, ee_link); 212 free(ep, M_EVENTHANDLER); 213 } 214 } else { 215 CTR2(KTR_EVH, "%s: marking all items from \"%s\" as dead", 216 __func__, list->el_name); 217 TAILQ_FOREACH(ep, &list->el_entries, ee_link) 218 ep->ee_priority = EHE_DEAD_PRIORITY; 219 } 220 } 221 while (wait && list->el_runcount > 0) 222 mtx_sleep(list, &list->el_lock, 0, "evhrm", 0); 223 EHL_UNLOCK(list); 224 } 225 226 void 227 eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag) 228 { 229 230 _eventhandler_deregister(list, tag, true); 231 } 232 233 void 234 eventhandler_deregister_nowait(struct eventhandler_list *list, 235 eventhandler_tag tag) 236 { 237 238 _eventhandler_deregister(list, tag, false); 239 } 240 241 /* 242 * Internal version for use when eventhandler list is already locked. 243 */ 244 static struct eventhandler_list * 245 _eventhandler_find_list(const char *name) 246 { 247 struct eventhandler_list *list; 248 249 mtx_assert(&eventhandler_mutex, MA_OWNED); 250 TAILQ_FOREACH(list, &eventhandler_lists, el_link) { 251 if (!strcmp(name, list->el_name)) 252 break; 253 } 254 return (list); 255 } 256 257 /* 258 * Lookup a "slow" list by name. Returns with the list locked. 259 */ 260 struct eventhandler_list * 261 eventhandler_find_list(const char *name) 262 { 263 struct eventhandler_list *list; 264 265 if (!eventhandler_lists_initted) 266 return(NULL); 267 268 /* scan looking for the requested list */ 269 mtx_lock(&eventhandler_mutex); 270 list = _eventhandler_find_list(name); 271 if (list != NULL) 272 EHL_LOCK(list); 273 mtx_unlock(&eventhandler_mutex); 274 275 return(list); 276 } 277 278 /* 279 * Prune "dead" entries from an eventhandler list. 280 */ 281 void 282 eventhandler_prune_list(struct eventhandler_list *list) 283 { 284 struct eventhandler_entry *ep, *en; 285 int pruned = 0; 286 287 CTR2(KTR_EVH, "%s: pruning list \"%s\"", __func__, list->el_name); 288 EHL_LOCK_ASSERT(list, MA_OWNED); 289 TAILQ_FOREACH_SAFE(ep, &list->el_entries, ee_link, en) { 290 if (ep->ee_priority == EHE_DEAD_PRIORITY) { 291 TAILQ_REMOVE(&list->el_entries, ep, ee_link); 292 free(ep, M_EVENTHANDLER); 293 pruned++; 294 } 295 } 296 if (pruned > 0) 297 wakeup(list); 298 } 299 300 /* 301 * Create (or get the existing) list so the pointer can be stored by 302 * EVENTHANDLER_LIST_DEFINE. 303 */ 304 struct eventhandler_list * 305 eventhandler_create_list(const char *name) 306 { 307 struct eventhandler_list *list; 308 309 KASSERT(eventhandler_lists_initted, 310 ("eventhandler list created too early")); 311 312 mtx_lock(&eventhandler_mutex); 313 list = eventhandler_find_or_create_list(name); 314 mtx_unlock(&eventhandler_mutex); 315 316 return (list); 317 } 318