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 * $FreeBSD$ 27 */ 28 29 #include <sys/param.h> 30 #include <sys/kernel.h> 31 #include <sys/lock.h> 32 #include <sys/malloc.h> 33 #include <sys/mutex.h> 34 #include <sys/proc.h> 35 #include <sys/systm.h> 36 #include <sys/eventhandler.h> 37 38 static MALLOC_DEFINE(M_EVENTHANDLER, "eventhandler", "Event handler records"); 39 40 /* List of 'slow' lists */ 41 static TAILQ_HEAD(, eventhandler_list) eventhandler_lists; 42 static int eventhandler_lists_initted = 0; 43 static struct mtx eventhandler_mutex; 44 45 struct eventhandler_entry_generic 46 { 47 struct eventhandler_entry ee; 48 void (* func)(void); 49 }; 50 51 static struct eventhandler_list *_eventhandler_find_list(char *name); 52 53 /* 54 * Initialize the eventhandler mutex and list. 55 */ 56 static void 57 eventhandler_init(void *dummy __unused) 58 { 59 TAILQ_INIT(&eventhandler_lists); 60 mtx_init(&eventhandler_mutex, "eventhandler", NULL, MTX_DEF); 61 atomic_store_rel_int(&eventhandler_lists_initted, 1); 62 } 63 SYSINIT(eventhandlers, SI_SUB_EVENTHANDLER, SI_ORDER_FIRST, eventhandler_init, 64 NULL) 65 66 /* 67 * Insertion is O(n) due to the priority scan, but optimises to O(1) 68 * if all priorities are identical. 69 */ 70 eventhandler_tag 71 eventhandler_register(struct eventhandler_list *list, char *name, 72 void *func, void *arg, int priority) 73 { 74 struct eventhandler_list *new_list; 75 struct eventhandler_entry_generic *eg; 76 struct eventhandler_entry *ep; 77 78 KASSERT(eventhandler_lists_initted, ("eventhandler registered too early")); 79 80 /* lock the eventhandler lists */ 81 mtx_lock(&eventhandler_mutex); 82 83 /* Do we need to find/create the (slow) list? */ 84 if (list == NULL) { 85 /* look for a matching, existing list */ 86 list = _eventhandler_find_list(name); 87 88 /* Do we need to create the list? */ 89 if (list == NULL) { 90 mtx_unlock(&eventhandler_mutex); 91 92 new_list = malloc(sizeof(struct eventhandler_list) + 93 strlen(name) + 1, M_EVENTHANDLER, M_WAITOK); 94 95 /* If someone else created it already, then use that one. */ 96 mtx_lock(&eventhandler_mutex); 97 list = _eventhandler_find_list(name); 98 if (list != NULL) { 99 free(new_list, M_EVENTHANDLER); 100 } else { 101 CTR2(KTR_EVH, "%s: creating list \"%s\"", __func__, name); 102 list = new_list; 103 list->el_flags = 0; 104 list->el_runcount = 0; 105 bzero(&list->el_lock, sizeof(list->el_lock)); 106 list->el_name = (char *)list + sizeof(struct eventhandler_list); 107 strcpy(list->el_name, name); 108 TAILQ_INSERT_HEAD(&eventhandler_lists, list, el_link); 109 } 110 } 111 } 112 if (!(list->el_flags & EHL_INITTED)) { 113 TAILQ_INIT(&list->el_entries); 114 mtx_init(&list->el_lock, name, "eventhandler list", MTX_DEF); 115 atomic_store_rel_int(&list->el_flags, EHL_INITTED); 116 } 117 mtx_unlock(&eventhandler_mutex); 118 119 /* allocate an entry for this handler, populate it */ 120 eg = malloc(sizeof(struct eventhandler_entry_generic), M_EVENTHANDLER, 121 M_WAITOK | M_ZERO); 122 eg->func = func; 123 eg->ee.ee_arg = arg; 124 eg->ee.ee_priority = priority; 125 KASSERT(priority != EHE_DEAD_PRIORITY, 126 ("%s: handler for %s registered with dead priority", __func__, name)); 127 128 /* sort it into the list */ 129 CTR4(KTR_EVH, "%s: adding item %p (function %p) to \"%s\"", __func__, eg, 130 func, name); 131 EHL_LOCK(list); 132 TAILQ_FOREACH(ep, &list->el_entries, ee_link) { 133 if (ep->ee_priority != EHE_DEAD_PRIORITY && 134 eg->ee.ee_priority < ep->ee_priority) { 135 TAILQ_INSERT_BEFORE(ep, &eg->ee, ee_link); 136 break; 137 } 138 } 139 if (ep == NULL) 140 TAILQ_INSERT_TAIL(&list->el_entries, &eg->ee, ee_link); 141 EHL_UNLOCK(list); 142 return(&eg->ee); 143 } 144 145 void 146 eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag) 147 { 148 struct eventhandler_entry *ep = tag; 149 150 EHL_LOCK_ASSERT(list, MA_OWNED); 151 if (ep != NULL) { 152 /* remove just this entry */ 153 if (list->el_runcount == 0) { 154 CTR3(KTR_EVH, "%s: removing item %p from \"%s\"", __func__, ep, 155 list->el_name); 156 TAILQ_REMOVE(&list->el_entries, ep, ee_link); 157 free(ep, M_EVENTHANDLER); 158 } else { 159 CTR3(KTR_EVH, "%s: marking item %p from \"%s\" as dead", __func__, 160 ep, list->el_name); 161 ep->ee_priority = EHE_DEAD_PRIORITY; 162 } 163 } else { 164 /* remove entire list */ 165 if (list->el_runcount == 0) { 166 CTR2(KTR_EVH, "%s: removing all items from \"%s\"", __func__, 167 list->el_name); 168 TAILQ_REMOVE(&list->el_entries, ep, ee_link); 169 while (!TAILQ_EMPTY(&list->el_entries)) { 170 ep = TAILQ_FIRST(&list->el_entries); 171 TAILQ_REMOVE(&list->el_entries, ep, ee_link); 172 free(ep, M_EVENTHANDLER); 173 } 174 } else { 175 CTR2(KTR_EVH, "%s: marking all items from \"%s\" as dead", 176 __func__, list->el_name); 177 TAILQ_FOREACH(ep, &list->el_entries, ee_link) 178 ep->ee_priority = EHE_DEAD_PRIORITY; 179 } 180 } 181 EHL_UNLOCK(list); 182 } 183 184 /* 185 * Internal version for use when eventhandler list is already locked. 186 */ 187 static struct eventhandler_list * 188 _eventhandler_find_list(char *name) 189 { 190 struct eventhandler_list *list; 191 192 mtx_assert(&eventhandler_mutex, MA_OWNED); 193 TAILQ_FOREACH(list, &eventhandler_lists, el_link) { 194 if (!strcmp(name, list->el_name)) 195 break; 196 } 197 return (list); 198 } 199 200 /* 201 * Lookup a "slow" list by name. Returns with the list locked. 202 */ 203 struct eventhandler_list * 204 eventhandler_find_list(char *name) 205 { 206 struct eventhandler_list *list; 207 208 if (!eventhandler_lists_initted) 209 return(NULL); 210 211 /* scan looking for the requested list */ 212 mtx_lock(&eventhandler_mutex); 213 list = _eventhandler_find_list(name); 214 if (list != NULL) 215 EHL_LOCK(list); 216 mtx_unlock(&eventhandler_mutex); 217 218 return(list); 219 } 220 221 /* 222 * Prune "dead" entries from an eventhandler list. 223 */ 224 void 225 eventhandler_prune_list(struct eventhandler_list *list) 226 { 227 struct eventhandler_entry *ep, *en; 228 229 CTR2(KTR_EVH, "%s: pruning list \"%s\"", __func__, list->el_name); 230 EHL_LOCK_ASSERT(list, MA_OWNED); 231 ep = TAILQ_FIRST(&list->el_entries); 232 while (ep != NULL) { 233 en = TAILQ_NEXT(ep, ee_link); 234 if (ep->ee_priority == EHE_DEAD_PRIORITY) { 235 TAILQ_REMOVE(&list->el_entries, ep, ee_link); 236 free(ep, M_EVENTHANDLER); 237 } 238 ep = en; 239 } 240 } 241