1/*	$NetBSD: subr_callback.c,v 1.6 2007/12/05 07:06:54 ad 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 1.6 2007/12/05 07:06:54 ad Exp $");
31
32#include <sys/param.h>
33#include <sys/systm.h>
34#include <sys/proc.h>
35#include <sys/callback.h>
36
37void
38callback_head_init(struct callback_head *ch, int ipl)
39{
40
41	memset(ch, 0, sizeof(struct callback_head));
42	mutex_init(&ch->ch_lock, MUTEX_DEFAULT, ipl);
43	cv_init(&ch->ch_cv, "callback");
44	TAILQ_INIT(&ch->ch_q);
45#if 0 /* already zero-initialized */
46	ch->ch_next = NULL;
47	ch->ch_nentries = 0;
48	ch->ch_running = 0;
49	ch->ch_flags = 0;
50#endif
51}
52
53void
54callback_head_destroy(struct callback_head *ch)
55{
56
57	mutex_destroy(&ch->ch_lock);
58	cv_destroy(&ch->ch_cv);
59}
60
61void
62callback_register(struct callback_head *ch, struct callback_entry *ce,
63    void *obj, int (*fn)(struct callback_entry *, void *, void *))
64{
65
66	KASSERT(fn != NULL);
67	ce->ce_func = fn;
68	ce->ce_obj = obj;
69	mutex_enter(&ch->ch_lock);
70	TAILQ_INSERT_TAIL(&ch->ch_q, ce, ce_q);
71	ch->ch_nentries++;
72	mutex_exit(&ch->ch_lock);
73}
74
75void
76callback_unregister(struct callback_head *ch, struct callback_entry *ce)
77{
78
79	mutex_enter(&ch->ch_lock);
80	while (ch->ch_running > 0)
81		cv_wait(&ch->ch_cv, &ch->ch_lock);
82	if (__predict_false(ch->ch_next == ce)) {
83		ch->ch_next = TAILQ_NEXT(ce, ce_q);
84	}
85	TAILQ_REMOVE(&ch->ch_q, ce, ce_q);
86	ch->ch_nentries--;
87	mutex_exit(&ch->ch_lock);
88}
89
90static int
91callback_runone(struct callback_head *ch, void *arg)
92{
93	struct callback_entry *ce;
94	int result;
95
96	KASSERT(ch->ch_nentries > 0);
97	KASSERT(ch->ch_running > 0);
98
99	ce = ch->ch_next;
100	if (ce == NULL) {
101		ce = TAILQ_FIRST(&ch->ch_q);
102	}
103	KASSERT(ce != NULL);
104	KASSERT(ce->ce_func != NULL);
105	result = (*ce->ce_func)(ce, ce->ce_obj, arg);
106	ch->ch_next = TAILQ_NEXT(ce, ce_q);
107	return result;
108}
109
110static void
111callback_run_enter(struct callback_head *ch)
112{
113
114	mutex_enter(&ch->ch_lock);
115	ch->ch_running++;
116	mutex_exit(&ch->ch_lock);
117}
118
119static void
120callback_run_leave(struct callback_head *ch)
121{
122
123	mutex_enter(&ch->ch_lock);
124	KASSERT(ch->ch_running > 0);
125	ch->ch_running--;
126	if (ch->ch_running == 0)
127		cv_broadcast(&ch->ch_cv);
128	mutex_exit(&ch->ch_lock);
129}
130
131int
132callback_run_roundrobin(struct callback_head *ch, void *arg)
133{
134	int i;
135	int n;
136	int result = 0;
137
138	callback_run_enter(ch);
139	n = ch->ch_nentries;
140	for (i = 0; i < n; i++) {
141		result = callback_runone(ch, arg);
142		if (result != CALLBACK_CHAIN_CONTINUE) {
143			break;
144		}
145	}
146	callback_run_leave(ch);
147
148	return result;
149}
150