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 }
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