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/param.h> 30 #include <sys/kernel.h> 31 #include <sys/ktr.h> 32 #include <sys/lock.h> 33 #include <sys/malloc.h> 34 #include <sys/mutex.h> 35 #include <sys/proc.h> 36 #include <sys/systm.h> 37 #include <sys/eventhandler.h> 38 39 static MALLOC_DEFINE(M_EVENTHANDLER, "eventhandler", "Event handler records"); 40 41 /* List of all eventhandler lists */ 42 static TAILQ_HEAD(, eventhandler_list) eventhandler_lists; 43 static int eventhandler_lists_initted = 0; 44 static struct mtx eventhandler_mutex; 45 46 struct eventhandler_entry_generic 47 { 48 struct eventhandler_entry ee; 49 void (* func)(void); 50 }; 51 52 static struct eventhandler_list *_eventhandler_find_list(const char *name); 53 54 /* 55 * Initialize the eventhandler mutex and list. 56 */ 57 static void 58 eventhandler_init(void *dummy __unused) 59 { 60 TAILQ_INIT(&eventhandler_lists); 61 mtx_init(&eventhandler_mutex, "eventhandler", NULL, MTX_DEF); 62 atomic_store_rel_int(&eventhandler_lists_initted, 1); 63 } 64 SYSINIT(eventhandlers, SI_SUB_EVENTHANDLER, SI_ORDER_FIRST, eventhandler_init, 65 NULL); 66 67 static struct eventhandler_list * 68 eventhandler_find_or_create_list(const char *name) 69 { 70 struct eventhandler_list *list, *new_list; 71 72 /* look for a matching, existing list */ 73 list = _eventhandler_find_list(name); 74 75 /* Do we need to create the list? */ 76 if (list == NULL) { 77 mtx_unlock(&eventhandler_mutex); 78 79 new_list = malloc(sizeof(*new_list) + strlen(name) + 1, 80 M_EVENTHANDLER, M_WAITOK | M_ZERO); 81 82 /* If someone else created it already, then use that one. */ 83 mtx_lock(&eventhandler_mutex); 84 list = _eventhandler_find_list(name); 85 if (list != NULL) { 86 free(new_list, M_EVENTHANDLER); 87 } else { 88 CTR2(KTR_EVH, "%s: creating list \"%s\"", __func__, name); 89 list = new_list; 90 TAILQ_INIT(&list->el_entries); 91 list->el_name = (char *)(list + 1); 92 strcpy(list->el_name, name); 93 mtx_init(&list->el_lock, list->el_name, "eventhandler list", 94 MTX_DEF); 95 TAILQ_INSERT_HEAD(&eventhandler_lists, list, el_link); 96 } 97 } 98 return (list); 99 } 100 101 /* 102 * Insertion is O(n) due to the priority scan, but optimises to O(1) 103 * if all priorities are identical. 104 */ 105 static eventhandler_tag 106 eventhandler_register_internal(struct eventhandler_list *list, 107 const char *name, eventhandler_tag epn) 108 { 109 struct eventhandler_entry *ep; 110 111 KASSERT(eventhandler_lists_initted, ("eventhandler registered too early")); 112 KASSERT(epn != NULL, ("%s: cannot register NULL event", __func__)); 113 114 /* Do we need to find/create the list? */ 115 if (list == NULL) { 116 mtx_lock(&eventhandler_mutex); 117 list = eventhandler_find_or_create_list(name); 118 mtx_unlock(&eventhandler_mutex); 119 } 120 121 KASSERT(epn->ee_priority != EHE_DEAD_PRIORITY, 122 ("%s: handler for %s registered with dead priority", __func__, name)); 123 124 /* sort it into the list */ 125 CTR4(KTR_EVH, "%s: adding item %p (function %p) to \"%s\"", __func__, epn, 126 ((struct eventhandler_entry_generic *)epn)->func, name); 127 EHL_LOCK(list); 128 TAILQ_FOREACH(ep, &list->el_entries, ee_link) { 129 if (ep->ee_priority != EHE_DEAD_PRIORITY && 130 epn->ee_priority < ep->ee_priority) { 131 TAILQ_INSERT_BEFORE(ep, epn, ee_link); 132 break; 133 } 134 } 135 if (ep == NULL) 136 TAILQ_INSERT_TAIL(&list->el_entries, epn, ee_link); 137 EHL_UNLOCK(list); 138 return(epn); 139 } 140 141 eventhandler_tag 142 eventhandler_register(struct eventhandler_list *list, const char *name, 143 void *func, void *arg, int priority) 144 { 145 struct eventhandler_entry_generic *eg; 146 147 /* allocate an entry for this handler, populate it */ 148 eg = malloc(sizeof(struct eventhandler_entry_generic), M_EVENTHANDLER, 149 M_WAITOK | M_ZERO); 150 eg->func = func; 151 eg->ee.ee_arg = arg; 152 eg->ee.ee_priority = priority; 153 154 return (eventhandler_register_internal(list, name, &eg->ee)); 155 } 156 157 #ifdef VIMAGE 158 struct eventhandler_entry_generic_vimage 159 { 160 struct eventhandler_entry ee; 161 vimage_iterator_func_t func; /* Vimage iterator function. */ 162 struct eventhandler_entry_vimage v_ee; /* Original func, arg. */ 163 }; 164 165 eventhandler_tag 166 vimage_eventhandler_register(struct eventhandler_list *list, const char *name, 167 void *func, void *arg, int priority, vimage_iterator_func_t iterfunc) 168 { 169 struct eventhandler_entry_generic_vimage *eg; 170 171 /* allocate an entry for this handler, populate it */ 172 eg = malloc(sizeof(struct eventhandler_entry_generic_vimage), 173 M_EVENTHANDLER, M_WAITOK | M_ZERO); 174 eg->func = iterfunc; 175 eg->v_ee.func = func; 176 eg->v_ee.ee_arg = arg; 177 eg->ee.ee_arg = &eg->v_ee; 178 eg->ee.ee_priority = priority; 179 180 return (eventhandler_register_internal(list, name, &eg->ee)); 181 } 182 #endif 183 184 static void 185 _eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag, 186 bool wait) 187 { 188 struct eventhandler_entry *ep = tag; 189 190 EHL_LOCK_ASSERT(list, MA_OWNED); 191 if (ep != NULL) { 192 /* remove just this entry */ 193 if (list->el_runcount == 0) { 194 CTR3(KTR_EVH, "%s: removing item %p from \"%s\"", __func__, ep, 195 list->el_name); 196 TAILQ_REMOVE(&list->el_entries, ep, ee_link); 197 free(ep, M_EVENTHANDLER); 198 } else { 199 CTR3(KTR_EVH, "%s: marking item %p from \"%s\" as dead", __func__, 200 ep, list->el_name); 201 ep->ee_priority = EHE_DEAD_PRIORITY; 202 } 203 } else { 204 /* remove entire list */ 205 if (list->el_runcount == 0) { 206 CTR2(KTR_EVH, "%s: removing all items from \"%s\"", __func__, 207 list->el_name); 208 while (!TAILQ_EMPTY(&list->el_entries)) { 209 ep = TAILQ_FIRST(&list->el_entries); 210 TAILQ_REMOVE(&list->el_entries, ep, ee_link); 211 free(ep, M_EVENTHANDLER); 212 } 213 } else { 214 CTR2(KTR_EVH, "%s: marking all items from \"%s\" as dead", 215 __func__, list->el_name); 216 TAILQ_FOREACH(ep, &list->el_entries, ee_link) 217 ep->ee_priority = EHE_DEAD_PRIORITY; 218 } 219 } 220 while (wait && list->el_runcount > 0) 221 mtx_sleep(list, &list->el_lock, 0, "evhrm", 0); 222 EHL_UNLOCK(list); 223 } 224 225 void 226 eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag) 227 { 228 229 _eventhandler_deregister(list, tag, true); 230 } 231 232 void 233 eventhandler_deregister_nowait(struct eventhandler_list *list, 234 eventhandler_tag tag) 235 { 236 237 _eventhandler_deregister(list, tag, false); 238 } 239 240 /* 241 * Internal version for use when eventhandler list is already locked. 242 */ 243 static struct eventhandler_list * 244 _eventhandler_find_list(const char *name) 245 { 246 struct eventhandler_list *list; 247 248 mtx_assert(&eventhandler_mutex, MA_OWNED); 249 TAILQ_FOREACH(list, &eventhandler_lists, el_link) { 250 if (!strcmp(name, list->el_name)) 251 break; 252 } 253 return (list); 254 } 255 256 /* 257 * Lookup a "slow" list by name. Returns with the list locked. 258 */ 259 struct eventhandler_list * 260 eventhandler_find_list(const char *name) 261 { 262 struct eventhandler_list *list; 263 264 if (!eventhandler_lists_initted) 265 return(NULL); 266 267 /* scan looking for the requested list */ 268 mtx_lock(&eventhandler_mutex); 269 list = _eventhandler_find_list(name); 270 if (list != NULL) 271 EHL_LOCK(list); 272 mtx_unlock(&eventhandler_mutex); 273 274 return(list); 275 } 276 277 /* 278 * Prune "dead" entries from an eventhandler list. 279 */ 280 void 281 eventhandler_prune_list(struct eventhandler_list *list) 282 { 283 struct eventhandler_entry *ep, *en; 284 int pruned = 0; 285 286 CTR2(KTR_EVH, "%s: pruning list \"%s\"", __func__, list->el_name); 287 EHL_LOCK_ASSERT(list, MA_OWNED); 288 TAILQ_FOREACH_SAFE(ep, &list->el_entries, ee_link, en) { 289 if (ep->ee_priority == EHE_DEAD_PRIORITY) { 290 TAILQ_REMOVE(&list->el_entries, ep, ee_link); 291 free(ep, M_EVENTHANDLER); 292 pruned++; 293 } 294 } 295 if (pruned > 0) 296 wakeup(list); 297 } 298 299 /* 300 * Create (or get the existing) list so the pointer can be stored by 301 * EVENTHANDLER_LIST_DEFINE. 302 */ 303 struct eventhandler_list * 304 eventhandler_create_list(const char *name) 305 { 306 struct eventhandler_list *list; 307 308 KASSERT(eventhandler_lists_initted, 309 ("eventhandler list created too early")); 310 311 mtx_lock(&eventhandler_mutex); 312 list = eventhandler_find_or_create_list(name); 313 mtx_unlock(&eventhandler_mutex); 314 315 return (list); 316 } 317