1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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/cdefs.h>
30 __FBSDID("$FreeBSD: releng/12.0/sys/kern/subr_eventhandler.c 331227 2018-03-19 22:43:27Z mjoras $");
31
32 #include <sys/param.h>
33 #include <sys/kernel.h>
34 #include <sys/lock.h>
35 #include <sys/malloc.h>
36 #include <sys/mutex.h>
37 #include <sys/proc.h>
38 #include <sys/systm.h>
39 #include <sys/eventhandler.h>
40
41 static MALLOC_DEFINE(M_EVENTHANDLER, "eventhandler", "Event handler records");
42
43 /* List of all eventhandler lists */
44 static TAILQ_HEAD(, eventhandler_list) eventhandler_lists;
45 static int eventhandler_lists_initted = 0;
46 static struct mtx eventhandler_mutex;
47
48 struct eventhandler_entry_generic
49 {
50 struct eventhandler_entry ee;
51 void (* func)(void);
52 };
53
54 static struct eventhandler_list *_eventhandler_find_list(const char *name);
55
56 /*
57 * Initialize the eventhandler mutex and list.
58 */
59 static void
60 eventhandler_init(void *dummy __unused)
61 {
62 TAILQ_INIT(&eventhandler_lists);
63 mtx_init(&eventhandler_mutex, "eventhandler", NULL, MTX_DEF);
64 atomic_store_rel_int(&eventhandler_lists_initted, 1);
65 }
66 SYSINIT(eventhandlers, SI_SUB_EVENTHANDLER, SI_ORDER_FIRST, eventhandler_init,
67 NULL);
68
69 static struct eventhandler_list *
70 eventhandler_find_or_create_list(const char *name)
71 {
72 struct eventhandler_list *list, *new_list;
73
74 /* look for a matching, existing list */
75 list = _eventhandler_find_list(name);
76
77 /* Do we need to create the list? */
78 if (list == NULL) {
79 mtx_unlock(&eventhandler_mutex);
80
81 new_list = malloc(sizeof(*new_list) + strlen(name) + 1,
82 M_EVENTHANDLER, M_WAITOK | M_ZERO);
83
84 /* If someone else created it already, then use that one. */
85 mtx_lock(&eventhandler_mutex);
86 list = _eventhandler_find_list(name);
87 if (list != NULL) {
88 free(new_list, M_EVENTHANDLER);
89 } else {
90 CTR2(KTR_EVH, "%s: creating list \"%s\"", __func__, name);
91 list = new_list;
92 TAILQ_INIT(&list->el_entries);
93 list->el_name = (char *)(list + 1);
94 strcpy(list->el_name, name);
95 mtx_init(&list->el_lock, list->el_name, "eventhandler list",
96 MTX_DEF);
97 TAILQ_INSERT_HEAD(&eventhandler_lists, list, el_link);
98 }
99 }
100 return (list);
101 }
102
103 /*
104 * Insertion is O(n) due to the priority scan, but optimises to O(1)
105 * if all priorities are identical.
106 */
107 static eventhandler_tag
108 eventhandler_register_internal(struct eventhandler_list *list,
109 const char *name, eventhandler_tag epn)
110 {
111 struct eventhandler_entry *ep;
112
113 KASSERT(eventhandler_lists_initted, ("eventhandler registered too early"));
114 KASSERT(epn != NULL, ("%s: cannot register NULL event", __func__));
115
116 /* Do we need to find/create the list? */
117 if (list == NULL) {
118 mtx_lock(&eventhandler_mutex);
119 list = eventhandler_find_or_create_list(name);
120 mtx_unlock(&eventhandler_mutex);
121 }
122
123 KASSERT(epn->ee_priority != EHE_DEAD_PRIORITY,
124 ("%s: handler for %s registered with dead priority", __func__, name));
125
126 /* sort it into the list */
127 CTR4(KTR_EVH, "%s: adding item %p (function %p) to \"%s\"", __func__, epn,
128 ((struct eventhandler_entry_generic *)epn)->func, name);
129 EHL_LOCK(list);
130 TAILQ_FOREACH(ep, &list->el_entries, ee_link) {
131 if (ep->ee_priority != EHE_DEAD_PRIORITY &&
132 epn->ee_priority < ep->ee_priority) {
133 TAILQ_INSERT_BEFORE(ep, epn, ee_link);
134 break;
135 }
136 }
137 if (ep == NULL)
138 TAILQ_INSERT_TAIL(&list->el_entries, epn, ee_link);
139 EHL_UNLOCK(list);
140 return(epn);
141 }
142
143 eventhandler_tag
144 eventhandler_register(struct eventhandler_list *list, const char *name,
145 void *func, void *arg, int priority)
146 {
147 struct eventhandler_entry_generic *eg;
148
149 /* allocate an entry for this handler, populate it */
150 eg = malloc(sizeof(struct eventhandler_entry_generic), M_EVENTHANDLER,
151 M_WAITOK | M_ZERO);
152 eg->func = func;
153 eg->ee.ee_arg = arg;
154 eg->ee.ee_priority = priority;
155
156 return (eventhandler_register_internal(list, name, &eg->ee));
157 }
158
159 #ifdef VIMAGE
160 struct eventhandler_entry_generic_vimage
161 {
162 struct eventhandler_entry ee;
163 vimage_iterator_func_t func; /* Vimage iterator function. */
164 struct eventhandler_entry_vimage v_ee; /* Original func, arg. */
165 };
166
167 eventhandler_tag
168 vimage_eventhandler_register(struct eventhandler_list *list, const char *name,
169 void *func, void *arg, int priority, vimage_iterator_func_t iterfunc)
170 {
171 struct eventhandler_entry_generic_vimage *eg;
172
173 /* allocate an entry for this handler, populate it */
174 eg = malloc(sizeof(struct eventhandler_entry_generic_vimage),
175 M_EVENTHANDLER, M_WAITOK | M_ZERO);
176 eg->func = iterfunc;
177 eg->v_ee.func = func;
178 eg->v_ee.ee_arg = arg;
179 eg->ee.ee_arg = &eg->v_ee;
180 eg->ee.ee_priority = priority;
181
182 return (eventhandler_register_internal(list, name, &eg->ee));
183 }
184 #endif
185
186 static void
187 _eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag,
188 bool wait)
189 {
190 struct eventhandler_entry *ep = tag;
191
192 EHL_LOCK_ASSERT(list, MA_OWNED);
193 if (ep != NULL) {
194 /* remove just this entry */
195 if (list->el_runcount == 0) {
196 CTR3(KTR_EVH, "%s: removing item %p from \"%s\"", __func__, ep,
197 list->el_name);
198 TAILQ_REMOVE(&list->el_entries, ep, ee_link);
199 free(ep, M_EVENTHANDLER);
200 } else {
201 CTR3(KTR_EVH, "%s: marking item %p from \"%s\" as dead", __func__,
202 ep, list->el_name);
203 ep->ee_priority = EHE_DEAD_PRIORITY;
204 }
205 } else {
206 /* remove entire list */
207 if (list->el_runcount == 0) {
208 CTR2(KTR_EVH, "%s: removing all items from \"%s\"", __func__,
209 list->el_name);
210 while (!TAILQ_EMPTY(&list->el_entries)) {
211 ep = TAILQ_FIRST(&list->el_entries);
212 TAILQ_REMOVE(&list->el_entries, ep, ee_link);
213 free(ep, M_EVENTHANDLER);
214 }
215 } else {
216 CTR2(KTR_EVH, "%s: marking all items from \"%s\" as dead",
217 __func__, list->el_name);
218 TAILQ_FOREACH(ep, &list->el_entries, ee_link)
219 ep->ee_priority = EHE_DEAD_PRIORITY;
220 }
221 }
222 while (wait && list->el_runcount > 0)
223 mtx_sleep(list, &list->el_lock, 0, "evhrm", 0);
224 EHL_UNLOCK(list);
225 }
226
227 void
228 eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag)
229 {
230
231 _eventhandler_deregister(list, tag, true);
232 }
233
234 void
235 eventhandler_deregister_nowait(struct eventhandler_list *list,
236 eventhandler_tag tag)
237 {
238
239 _eventhandler_deregister(list, tag, false);
240 }
241
242 /*
243 * Internal version for use when eventhandler list is already locked.
244 */
245 static struct eventhandler_list *
246 _eventhandler_find_list(const char *name)
247 {
248 struct eventhandler_list *list;
249
250 mtx_assert(&eventhandler_mutex, MA_OWNED);
251 TAILQ_FOREACH(list, &eventhandler_lists, el_link) {
252 if (!strcmp(name, list->el_name))
253 break;
254 }
255 return (list);
256 }
257
258 /*
259 * Lookup a "slow" list by name. Returns with the list locked.
260 */
261 struct eventhandler_list *
262 eventhandler_find_list(const char *name)
263 {
264 struct eventhandler_list *list;
265
266 if (!eventhandler_lists_initted)
267 return(NULL);
268
269 /* scan looking for the requested list */
270 mtx_lock(&eventhandler_mutex);
271 list = _eventhandler_find_list(name);
272 if (list != NULL)
273 EHL_LOCK(list);
274 mtx_unlock(&eventhandler_mutex);
275
276 return(list);
277 }
278
279 /*
280 * Prune "dead" entries from an eventhandler list.
281 */
282 void
283 eventhandler_prune_list(struct eventhandler_list *list)
284 {
285 struct eventhandler_entry *ep, *en;
286 int pruned = 0;
287
288 CTR2(KTR_EVH, "%s: pruning list \"%s\"", __func__, list->el_name);
289 EHL_LOCK_ASSERT(list, MA_OWNED);
290 TAILQ_FOREACH_SAFE(ep, &list->el_entries, ee_link, en) {
291 if (ep->ee_priority == EHE_DEAD_PRIORITY) {
292 TAILQ_REMOVE(&list->el_entries, ep, ee_link);
293 free(ep, M_EVENTHANDLER);
294 pruned++;
295 }
296 }
297 if (pruned > 0)
298 wakeup(list);
299 }
300
301 /*
302 * Create (or get the existing) list so the pointer can be stored by
303 * EVENTHANDLER_LIST_DEFINE.
304 */
305 struct eventhandler_list *
306 eventhandler_create_list(const char *name)
307 {
308 struct eventhandler_list *list;
309
310 KASSERT(eventhandler_lists_initted,
311 ("eventhandler list created too early"));
312
313 mtx_lock(&eventhandler_mutex);
314 list = eventhandler_find_or_create_list(name);
315 mtx_unlock(&eventhandler_mutex);
316
317 return (list);
318 }
Cache object: b02b9acc6631f9f1de2d6f86cc7718c0
|