1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 1999 Michael Smith <[email protected]>
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/cdefs.h>
30 #include <sys/param.h>
31 #include <sys/kernel.h>
32 #include <sys/ktr.h>
33 #include <sys/lock.h>
34 #include <sys/malloc.h>
35 #include <sys/mutex.h>
36 #include <sys/proc.h>
37 #include <sys/systm.h>
38 #include <sys/eventhandler.h>
39
40 static MALLOC_DEFINE(M_EVENTHANDLER, "eventhandler", "Event handler records");
41
42 /* List of all eventhandler lists */
43 static TAILQ_HEAD(, eventhandler_list) eventhandler_lists;
44 static int eventhandler_lists_initted = 0;
45 static struct mtx eventhandler_mutex;
46
47 struct eventhandler_entry_generic
48 {
49 struct eventhandler_entry ee;
50 void (* func)(void);
51 };
52
53 static struct eventhandler_list *_eventhandler_find_list(const char *name);
54
55 /*
56 * Initialize the eventhandler mutex and list.
57 */
58 static void
eventhandler_init(void * dummy __unused)59 eventhandler_init(void *dummy __unused)
60 {
61 TAILQ_INIT(&eventhandler_lists);
62 mtx_init(&eventhandler_mutex, "eventhandler", NULL, MTX_DEF);
63 atomic_store_rel_int(&eventhandler_lists_initted, 1);
64 }
65 SYSINIT(eventhandlers, SI_SUB_EVENTHANDLER, SI_ORDER_FIRST, eventhandler_init,
66 NULL);
67
68 static struct eventhandler_list *
eventhandler_find_or_create_list(const char * name)69 eventhandler_find_or_create_list(const char *name)
70 {
71 struct eventhandler_list *list, *new_list;
72
73 /* look for a matching, existing list */
74 list = _eventhandler_find_list(name);
75
76 /* Do we need to create the list? */
77 if (list == NULL) {
78 mtx_unlock(&eventhandler_mutex);
79
80 new_list = malloc(sizeof(*new_list) + strlen(name) + 1,
81 M_EVENTHANDLER, M_WAITOK | M_ZERO);
82
83 /* If someone else created it already, then use that one. */
84 mtx_lock(&eventhandler_mutex);
85 list = _eventhandler_find_list(name);
86 if (list != NULL) {
87 free(new_list, M_EVENTHANDLER);
88 } else {
89 CTR2(KTR_EVH, "%s: creating list \"%s\"", __func__, name);
90 list = new_list;
91 TAILQ_INIT(&list->el_entries);
92 list->el_name = (char *)(list + 1);
93 strcpy(list->el_name, name);
94 mtx_init(&list->el_lock, list->el_name, "eventhandler list",
95 MTX_DEF);
96 TAILQ_INSERT_HEAD(&eventhandler_lists, list, el_link);
97 }
98 }
99 return (list);
100 }
101
102 /*
103 * Insertion is O(n) due to the priority scan, but optimises to O(1)
104 * if all priorities are identical.
105 */
106 static eventhandler_tag
eventhandler_register_internal(struct eventhandler_list * list,const char * name,eventhandler_tag epn)107 eventhandler_register_internal(struct eventhandler_list *list,
108 const char *name, eventhandler_tag epn)
109 {
110 struct eventhandler_entry *ep;
111
112 KASSERT(eventhandler_lists_initted, ("eventhandler registered too early"));
113 KASSERT(epn != NULL, ("%s: cannot register NULL event", __func__));
114
115 /* Do we need to find/create the list? */
116 if (list == NULL) {
117 mtx_lock(&eventhandler_mutex);
118 list = eventhandler_find_or_create_list(name);
119 mtx_unlock(&eventhandler_mutex);
120 }
121
122 KASSERT(epn->ee_priority != EHE_DEAD_PRIORITY,
123 ("%s: handler for %s registered with dead priority", __func__, name));
124
125 /* sort it into the list */
126 CTR4(KTR_EVH, "%s: adding item %p (function %p) to \"%s\"", __func__, epn,
127 ((struct eventhandler_entry_generic *)epn)->func, name);
128 EHL_LOCK(list);
129 TAILQ_FOREACH(ep, &list->el_entries, ee_link) {
130 if (ep->ee_priority != EHE_DEAD_PRIORITY &&
131 epn->ee_priority < ep->ee_priority) {
132 TAILQ_INSERT_BEFORE(ep, epn, ee_link);
133 break;
134 }
135 }
136 if (ep == NULL)
137 TAILQ_INSERT_TAIL(&list->el_entries, epn, ee_link);
138 EHL_UNLOCK(list);
139 return(epn);
140 }
141
142 eventhandler_tag
eventhandler_register(struct eventhandler_list * list,const char * name,void * func,void * arg,int priority)143 eventhandler_register(struct eventhandler_list *list, const char *name,
144 void *func, void *arg, int priority)
145 {
146 struct eventhandler_entry_generic *eg;
147
148 /* allocate an entry for this handler, populate it */
149 eg = malloc(sizeof(struct eventhandler_entry_generic), M_EVENTHANDLER,
150 M_WAITOK | M_ZERO);
151 eg->func = func;
152 eg->ee.ee_arg = arg;
153 eg->ee.ee_priority = priority;
154
155 return (eventhandler_register_internal(list, name, &eg->ee));
156 }
157
158 #ifdef VIMAGE
159 struct eventhandler_entry_generic_vimage
160 {
161 struct eventhandler_entry ee;
162 vimage_iterator_func_t func; /* Vimage iterator function. */
163 struct eventhandler_entry_vimage v_ee; /* Original func, arg. */
164 };
165
166 eventhandler_tag
vimage_eventhandler_register(struct eventhandler_list * list,const char * name,void * func,void * arg,int priority,vimage_iterator_func_t iterfunc)167 vimage_eventhandler_register(struct eventhandler_list *list, const char *name,
168 void *func, void *arg, int priority, vimage_iterator_func_t iterfunc)
169 {
170 struct eventhandler_entry_generic_vimage *eg;
171
172 /* allocate an entry for this handler, populate it */
173 eg = malloc(sizeof(struct eventhandler_entry_generic_vimage),
174 M_EVENTHANDLER, M_WAITOK | M_ZERO);
175 eg->func = iterfunc;
176 eg->v_ee.func = func;
177 eg->v_ee.ee_arg = arg;
178 eg->ee.ee_arg = &eg->v_ee;
179 eg->ee.ee_priority = priority;
180
181 return (eventhandler_register_internal(list, name, &eg->ee));
182 }
183 #endif
184
185 static void
_eventhandler_deregister(struct eventhandler_list * list,eventhandler_tag tag,bool wait)186 _eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag,
187 bool wait)
188 {
189 struct eventhandler_entry *ep = tag;
190
191 EHL_LOCK_ASSERT(list, MA_OWNED);
192 if (ep != NULL) {
193 /* remove just this entry */
194 if (list->el_runcount == 0) {
195 CTR3(KTR_EVH, "%s: removing item %p from \"%s\"", __func__, ep,
196 list->el_name);
197 TAILQ_REMOVE(&list->el_entries, ep, ee_link);
198 free(ep, M_EVENTHANDLER);
199 } else {
200 CTR3(KTR_EVH, "%s: marking item %p from \"%s\" as dead", __func__,
201 ep, list->el_name);
202 ep->ee_priority = EHE_DEAD_PRIORITY;
203 }
204 } else {
205 /* remove entire list */
206 if (list->el_runcount == 0) {
207 CTR2(KTR_EVH, "%s: removing all items from \"%s\"", __func__,
208 list->el_name);
209 while (!TAILQ_EMPTY(&list->el_entries)) {
210 ep = TAILQ_FIRST(&list->el_entries);
211 TAILQ_REMOVE(&list->el_entries, ep, ee_link);
212 free(ep, M_EVENTHANDLER);
213 }
214 } else {
215 CTR2(KTR_EVH, "%s: marking all items from \"%s\" as dead",
216 __func__, list->el_name);
217 TAILQ_FOREACH(ep, &list->el_entries, ee_link)
218 ep->ee_priority = EHE_DEAD_PRIORITY;
219 }
220 }
221 while (wait && list->el_runcount > 0)
222 mtx_sleep(list, &list->el_lock, 0, "evhrm", 0);
223 EHL_UNLOCK(list);
224 }
225
226 void
eventhandler_deregister(struct eventhandler_list * list,eventhandler_tag tag)227 eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag)
228 {
229
230 _eventhandler_deregister(list, tag, true);
231 }
232
233 void
eventhandler_deregister_nowait(struct eventhandler_list * list,eventhandler_tag tag)234 eventhandler_deregister_nowait(struct eventhandler_list *list,
235 eventhandler_tag tag)
236 {
237
238 _eventhandler_deregister(list, tag, false);
239 }
240
241 /*
242 * Internal version for use when eventhandler list is already locked.
243 */
244 static struct eventhandler_list *
_eventhandler_find_list(const char * name)245 _eventhandler_find_list(const char *name)
246 {
247 struct eventhandler_list *list;
248
249 mtx_assert(&eventhandler_mutex, MA_OWNED);
250 TAILQ_FOREACH(list, &eventhandler_lists, el_link) {
251 if (!strcmp(name, list->el_name))
252 break;
253 }
254 return (list);
255 }
256
257 /*
258 * Lookup a "slow" list by name. Returns with the list locked.
259 */
260 struct eventhandler_list *
eventhandler_find_list(const char * name)261 eventhandler_find_list(const char *name)
262 {
263 struct eventhandler_list *list;
264
265 if (!eventhandler_lists_initted)
266 return(NULL);
267
268 /* scan looking for the requested list */
269 mtx_lock(&eventhandler_mutex);
270 list = _eventhandler_find_list(name);
271 if (list != NULL)
272 EHL_LOCK(list);
273 mtx_unlock(&eventhandler_mutex);
274
275 return(list);
276 }
277
278 /*
279 * Prune "dead" entries from an eventhandler list.
280 */
281 void
eventhandler_prune_list(struct eventhandler_list * list)282 eventhandler_prune_list(struct eventhandler_list *list)
283 {
284 struct eventhandler_entry *ep, *en;
285 int pruned = 0;
286
287 CTR2(KTR_EVH, "%s: pruning list \"%s\"", __func__, list->el_name);
288 EHL_LOCK_ASSERT(list, MA_OWNED);
289 TAILQ_FOREACH_SAFE(ep, &list->el_entries, ee_link, en) {
290 if (ep->ee_priority == EHE_DEAD_PRIORITY) {
291 TAILQ_REMOVE(&list->el_entries, ep, ee_link);
292 free(ep, M_EVENTHANDLER);
293 pruned++;
294 }
295 }
296 if (pruned > 0)
297 wakeup(list);
298 }
299
300 /*
301 * Create (or get the existing) list so the pointer can be stored by
302 * EVENTHANDLER_LIST_DEFINE.
303 */
304 struct eventhandler_list *
eventhandler_create_list(const char * name)305 eventhandler_create_list(const char *name)
306 {
307 struct eventhandler_list *list;
308
309 KASSERT(eventhandler_lists_initted,
310 ("eventhandler list created too early"));
311
312 mtx_lock(&eventhandler_mutex);
313 list = eventhandler_find_or_create_list(name);
314 mtx_unlock(&eventhandler_mutex);
315
316 return (list);
317 }
318