1 /* $NetBSD: subr_callback.c,v 1.4 2006/06/23 16:17:23 drochner Exp $ */
2
3 /*-
4 * Copyright (c)2006 YAMAMOTO Takashi,
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 __KERNEL_RCSID(0, "$NetBSD: subr_callback.c,v 1.4 2006/06/23 16:17:23 drochner Exp $");
31
32 #include <sys/param.h>
33 #include <sys/systm.h>
34 #include <sys/proc.h>
35 #include <sys/callback.h>
36
37 #define CH_WANT 1
38
39 void
40 callback_head_init(struct callback_head *ch)
41 {
42
43 memset(ch, 0, sizeof(struct callback_head));
44 simple_lock_init(&ch->ch_lock);
45 TAILQ_INIT(&ch->ch_q);
46 #if 0 /* already zero-initialized */
47 ch->ch_next = NULL;
48 ch->ch_nentries = 0;
49 ch->ch_running = 0;
50 ch->ch_flags = 0;
51 #endif
52 }
53
54 void
55 callback_register(struct callback_head *ch, struct callback_entry *ce,
56 void *obj, int (*fn)(struct callback_entry *, void *, void *))
57 {
58
59 ce->ce_func = fn;
60 ce->ce_obj = obj;
61 simple_lock(&ch->ch_lock);
62 TAILQ_INSERT_TAIL(&ch->ch_q, ce, ce_q);
63 ch->ch_nentries++;
64 simple_unlock(&ch->ch_lock);
65 }
66
67 void
68 callback_unregister(struct callback_head *ch, struct callback_entry *ce)
69 {
70
71 simple_lock(&ch->ch_lock);
72 while (ch->ch_running > 0) {
73 ch->ch_flags |= CH_WANT;
74 ltsleep(&ch->ch_running, PVM, "recunreg", 0, &ch->ch_lock);
75 }
76 if (__predict_false(ch->ch_next == ce)) {
77 ch->ch_next = TAILQ_NEXT(ce, ce_q);
78 }
79 TAILQ_REMOVE(&ch->ch_q, ce, ce_q);
80 ch->ch_nentries--;
81 simple_unlock(&ch->ch_lock);
82 }
83
84 static int
85 callback_runone(struct callback_head *ch, void *arg)
86 {
87 struct callback_entry *ce;
88 int result;
89
90 KASSERT(ch->ch_nentries > 0);
91 KASSERT(ch->ch_running > 0);
92
93 ce = ch->ch_next;
94 if (ce == NULL) {
95 ce = TAILQ_FIRST(&ch->ch_q);
96 }
97 KASSERT(ce != NULL);
98 result = (*ce->ce_func)(ce, ce->ce_obj, arg);
99 ch->ch_next = TAILQ_NEXT(ce, ce_q);
100 return result;
101 }
102
103 static void
104 callback_run_enter(struct callback_head *ch)
105 {
106
107 simple_lock(&ch->ch_lock);
108 ch->ch_running++;
109 simple_unlock(&ch->ch_lock);
110 }
111
112 static void
113 callback_run_leave(struct callback_head *ch)
114 {
115
116 simple_lock(&ch->ch_lock);
117 KASSERT(ch->ch_running > 0);
118 ch->ch_running--;
119 if (ch->ch_running == 0 && (ch->ch_flags & CH_WANT) != 0) {
120 ch->ch_flags &= ~CH_WANT;
121 wakeup(&ch->ch_running);
122 }
123 simple_unlock(&ch->ch_lock);
124 }
125
126 int
127 callback_run_roundrobin(struct callback_head *ch, void *arg)
128 {
129 int i;
130 int n;
131 int result = 0;
132
133 callback_run_enter(ch);
134 n = ch->ch_nentries;
135 for (i = 0; i < n; i++) {
136 result = callback_runone(ch, arg);
137 if (result != CALLBACK_CHAIN_CONTINUE) {
138 break;
139 }
140 }
141 callback_run_leave(ch);
142
143 return result;
144 }
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