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