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 eventhandler_tag 72 eventhandler_register(struct eventhandler_list *list, const char *name, 73 void *func, void *arg, int priority) 74 { 75 struct eventhandler_list *new_list; 76 struct eventhandler_entry_generic *eg; 77 struct eventhandler_entry *ep; 78 79 KASSERT(eventhandler_lists_initted, ("eventhandler registered too early")); 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 /* allocate an entry for this handler, populate it */ 121 eg = malloc(sizeof(struct eventhandler_entry_generic), M_EVENTHANDLER, 122 M_WAITOK | M_ZERO); 123 eg->func = func; 124 eg->ee.ee_arg = arg; 125 eg->ee.ee_priority = priority; 126 KASSERT(priority != EHE_DEAD_PRIORITY, 127 ("%s: handler for %s registered with dead priority", __func__, name)); 128 129 /* sort it into the list */ 130 CTR4(KTR_EVH, "%s: adding item %p (function %p) to \"%s\"", __func__, eg, 131 func, name); 132 EHL_LOCK(list); 133 TAILQ_FOREACH(ep, &list->el_entries, ee_link) { 134 if (ep->ee_priority != EHE_DEAD_PRIORITY && 135 eg->ee.ee_priority < ep->ee_priority) { 136 TAILQ_INSERT_BEFORE(ep, &eg->ee, ee_link); 137 break; 138 } 139 } 140 if (ep == NULL) 141 TAILQ_INSERT_TAIL(&list->el_entries, &eg->ee, ee_link); 142 EHL_UNLOCK(list); 143 return(&eg->ee); 144 } 145 146 void 147 eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag) 148 { 149 struct eventhandler_entry *ep = tag; 150 151 EHL_LOCK_ASSERT(list, MA_OWNED); 152 if (ep != NULL) { 153 /* remove just this entry */ 154 if (list->el_runcount == 0) { 155 CTR3(KTR_EVH, "%s: removing item %p from \"%s\"", __func__, ep, 156 list->el_name); 157 TAILQ_REMOVE(&list->el_entries, ep, ee_link); 158 free(ep, M_EVENTHANDLER); 159 } else { 160 CTR3(KTR_EVH, "%s: marking item %p from \"%s\" as dead", __func__, 161 ep, list->el_name); 162 ep->ee_priority = EHE_DEAD_PRIORITY; 163 } 164 } else { 165 /* remove entire list */ 166 if (list->el_runcount == 0) { 167 CTR2(KTR_EVH, "%s: removing all items from \"%s\"", __func__, 168 list->el_name); 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(const 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(const 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