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 * $FreeBSD: releng/5.0/sys/kern/subr_eventhandler.c 100370 2002-07-19 17:44:44Z mux $
27 */
28
29 #include <sys/param.h>
30 #include <sys/kernel.h>
31 #include <sys/lock.h>
32 #include <sys/malloc.h>
33 #include <sys/mutex.h>
34 #include <sys/proc.h>
35 #include <sys/systm.h>
36 #include <sys/eventhandler.h>
37
38 static MALLOC_DEFINE(M_EVENTHANDLER, "eventhandler", "Event handler records");
39
40 /* List of 'slow' lists */
41 static TAILQ_HEAD(, eventhandler_list) eventhandler_lists;
42 static int eventhandler_lists_initted = 0;
43 static struct mtx eventhandler_mutex;
44
45 struct eventhandler_entry_generic
46 {
47 struct eventhandler_entry ee;
48 void (* func)(void);
49 };
50
51 /*
52 * Initialize the eventhandler mutex and list.
53 */
54 static void
55 eventhandler_init(void *dummy __unused)
56 {
57 TAILQ_INIT(&eventhandler_lists);
58 mtx_init(&eventhandler_mutex, "eventhandler", NULL, MTX_DEF | MTX_RECURSE);
59 eventhandler_lists_initted = 1;
60 }
61 SYSINIT(eventhandlers, SI_SUB_EVENTHANDLER, SI_ORDER_FIRST, eventhandler_init,
62 NULL)
63
64 /*
65 * Insertion is O(n) due to the priority scan, but optimises to O(1)
66 * if all priorities are identical.
67 */
68 eventhandler_tag
69 eventhandler_register(struct eventhandler_list *list, char *name,
70 void *func, void *arg, int priority)
71 {
72 struct eventhandler_entry_generic *eg;
73 struct eventhandler_entry *ep;
74
75 KASSERT(eventhandler_lists_initted, ("eventhandler registered too early"));
76
77 /* lock the eventhandler lists */
78 mtx_lock(&eventhandler_mutex);
79
80 /* Do we need to find/create the (slow) list? */
81 if (list == NULL) {
82 /* look for a matching, existing list */
83 list = eventhandler_find_list(name);
84
85 /* Do we need to create the list? */
86 if (list == NULL) {
87 if ((list = malloc(sizeof(struct eventhandler_list) + strlen(name)
88 + 1, M_EVENTHANDLER, M_NOWAIT)) == NULL) {
89 mtx_unlock(&eventhandler_mutex);
90 return(NULL);
91 }
92 list->el_flags = 0;
93 bzero(&list->el_lock, sizeof(list->el_lock));
94 list->el_name = (char *)list + sizeof(struct eventhandler_list);
95 strcpy(list->el_name, name);
96 TAILQ_INSERT_HEAD(&eventhandler_lists, list, el_link);
97 }
98 }
99 if (!(list->el_flags & EHE_INITTED)) {
100 TAILQ_INIT(&list->el_entries);
101 sx_init(&list->el_lock, name);
102 list->el_flags = EHE_INITTED;
103 }
104 mtx_unlock(&eventhandler_mutex);
105
106 /* allocate an entry for this handler, populate it */
107 if ((eg = malloc(sizeof(struct eventhandler_entry_generic),
108 M_EVENTHANDLER, M_NOWAIT)) == NULL) {
109 return(NULL);
110 }
111 eg->func = func;
112 eg->ee.ee_arg = arg;
113 eg->ee.ee_priority = priority;
114
115 /* sort it into the list */
116 EHE_LOCK(list);
117 for (ep = TAILQ_FIRST(&list->el_entries);
118 ep != NULL;
119 ep = TAILQ_NEXT(ep, ee_link)) {
120 if (eg->ee.ee_priority < ep->ee_priority) {
121 TAILQ_INSERT_BEFORE(ep, &eg->ee, ee_link);
122 break;
123 }
124 }
125 if (ep == NULL)
126 TAILQ_INSERT_TAIL(&list->el_entries, &eg->ee, ee_link);
127 EHE_UNLOCK(list);
128 return(&eg->ee);
129 }
130
131 void
132 eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag)
133 {
134 struct eventhandler_entry *ep = tag;
135
136 /* XXX insert diagnostic check here? */
137 EHE_LOCK(list);
138 if (ep != NULL) {
139 /* remove just this entry */
140 TAILQ_REMOVE(&list->el_entries, ep, ee_link);
141 free(ep, M_EVENTHANDLER);
142 } else {
143 /* remove entire list */
144 while (!TAILQ_EMPTY(&list->el_entries)) {
145 ep = TAILQ_FIRST(&list->el_entries);
146 TAILQ_REMOVE(&list->el_entries, ep, ee_link);
147 free(ep, M_EVENTHANDLER);
148 }
149 }
150 EHE_UNLOCK(list);
151 }
152
153 struct eventhandler_list *
154 eventhandler_find_list(char *name)
155 {
156 struct eventhandler_list *list;
157
158 if (!eventhandler_lists_initted)
159 return(NULL);
160
161 /* scan looking for the requested list */
162 mtx_lock(&eventhandler_mutex);
163 for (list = TAILQ_FIRST(&eventhandler_lists);
164 list != NULL;
165 list = TAILQ_NEXT(list, el_link)) {
166 if (!strcmp(name, list->el_name))
167 break;
168 }
169 mtx_unlock(&eventhandler_mutex);
170
171 return(list);
172 }
173
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