1 /*
2 * (MPSAFE)
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 * $FreeBSD: src/sys/kern/subr_eventhandler.c,v 1.3 1999/11/16 16:28:57 phk Exp $
29 */
30
31 #include <sys/param.h>
32 #include <sys/kernel.h>
33 #include <sys/malloc.h>
34 #include <sys/systm.h>
35 #include <sys/eventhandler.h>
36
37 MALLOC_DEFINE(M_EVENTHANDLER, "eventhandler", "Event handler records");
38
39 /* List of 'slow' lists */
40 static TAILQ_HEAD(, eventhandler_list) eventhandler_lists = TAILQ_HEAD_INITIALIZER(eventhandler_lists);
41 static struct lwkt_token evlist_token = LWKT_TOKEN_INITIALIZER(evlist_token);
42
43 struct eventhandler_entry_generic
44 {
45 struct eventhandler_entry ee;
46 void (* func)(void);
47 };
48
49 /*
50 * Insertion is O(n) due to the priority scan, but optimises to O(1)
51 * if all priorities are identical.
52 *
53 * MPSAFE
54 */
55 eventhandler_tag
eventhandler_register(struct eventhandler_list * list,const char * name,void * func,void * arg,int priority)56 eventhandler_register(struct eventhandler_list *list, const char *name,
57 void *func, void *arg, int priority)
58 {
59 struct eventhandler_entry_generic *eg;
60 struct eventhandler_entry *ep;
61
62 lwkt_gettoken(&evlist_token);
63
64 /*
65 * find/create the list as needed
66 */
67 while (list == NULL) {
68 list = eventhandler_find_list(name);
69 if (list)
70 break;
71 list = kmalloc(sizeof(struct eventhandler_list) + strlen(name) + 1,
72 M_EVENTHANDLER, M_INTWAIT);
73 if (eventhandler_find_list(name)) {
74 kfree(list, M_EVENTHANDLER);
75 list = NULL;
76 } else {
77 list->el_flags = 0;
78 list->el_name = (char *)list + sizeof(struct eventhandler_list);
79 strcpy(list->el_name, name);
80 TAILQ_INSERT_HEAD(&eventhandler_lists, list, el_link);
81 }
82 }
83
84 if (!(list->el_flags & EHE_INITTED)) {
85 TAILQ_INIT(&list->el_entries);
86 list->el_flags = EHE_INITTED;
87 }
88
89 /* allocate an entry for this handler, populate it */
90 eg = kmalloc(sizeof(struct eventhandler_entry_generic),
91 M_EVENTHANDLER, M_INTWAIT);
92 eg->func = func;
93 eg->ee.ee_arg = arg;
94 eg->ee.ee_priority = priority;
95
96 /* sort it into the list */
97 for (ep = TAILQ_FIRST(&list->el_entries);
98 ep != NULL;
99 ep = TAILQ_NEXT(ep, ee_link)) {
100 if (eg->ee.ee_priority < ep->ee_priority) {
101 TAILQ_INSERT_BEFORE(ep, &eg->ee, ee_link);
102 break;
103 }
104 }
105 if (ep == NULL)
106 TAILQ_INSERT_TAIL(&list->el_entries, &eg->ee, ee_link);
107 lwkt_reltoken(&evlist_token);
108
109 return(&eg->ee);
110 }
111
112 /*
113 * MPSAFE
114 */
115 void
eventhandler_deregister(struct eventhandler_list * list,eventhandler_tag tag)116 eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag)
117 {
118 struct eventhandler_entry *ep = tag;
119
120 lwkt_gettoken(&evlist_token);
121 /* XXX insert diagnostic check here? */
122
123 if (ep != NULL) {
124 /* remove just this entry */
125 TAILQ_REMOVE(&list->el_entries, ep, ee_link);
126 kfree(ep, M_EVENTHANDLER);
127 } else {
128 /* remove entire list */
129 while (!TAILQ_EMPTY(&list->el_entries)) {
130 ep = TAILQ_FIRST(&list->el_entries);
131 TAILQ_REMOVE(&list->el_entries, ep, ee_link);
132 kfree(ep, M_EVENTHANDLER);
133 }
134 }
135 lwkt_reltoken(&evlist_token);
136 }
137
138 /*
139 * Locate the requested list
140 */
141 struct eventhandler_list *
eventhandler_find_list(const char * name)142 eventhandler_find_list(const char *name)
143 {
144 struct eventhandler_list *list;
145
146 lwkt_gettoken(&evlist_token);
147 for (list = TAILQ_FIRST(&eventhandler_lists);
148 list != NULL;
149 list = TAILQ_NEXT(list, el_link)) {
150 if (!strcmp(name, list->el_name))
151 break;
152 }
153 lwkt_reltoken(&evlist_token);
154 return(list);
155 }
156