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
eventhandler_init(void * dummy __unused)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 *
eventhandler_find_or_create_list(const char * name)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
eventhandler_register_internal(struct eventhandler_list * list,const char * name,eventhandler_tag epn)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
eventhandler_register(struct eventhandler_list * list,const char * name,void * func,void * arg,int priority)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
vimage_eventhandler_register(struct eventhandler_list * list,const char * name,void * func,void * arg,int priority,vimage_iterator_func_t iterfunc)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
_eventhandler_deregister(struct eventhandler_list * list,eventhandler_tag tag,bool wait)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
eventhandler_deregister(struct eventhandler_list * list,eventhandler_tag tag)226 eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag)
227 {
228
229 _eventhandler_deregister(list, tag, true);
230 }
231
232 void
eventhandler_deregister_nowait(struct eventhandler_list * list,eventhandler_tag tag)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 *
_eventhandler_find_list(const char * name)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 *
eventhandler_find_list(const char * name)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
eventhandler_prune_list(struct eventhandler_list * list)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 *
eventhandler_create_list(const char * name)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