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 37 void 38 callback_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 53 void 54 callback_head_destroy(struct callback_head *ch) 55 { 56 57 mutex_destroy(&ch->ch_lock); 58 cv_destroy(&ch->ch_cv); 59 } 60 61 void 62 callback_register(struct callback_head *ch, struct callback_entry *ce, 63 void *obj, int (*fn)(struct callback_entry *, void *, void *)) 64 { 65 66 ce->ce_func = fn; 67 ce->ce_obj = obj; 68 mutex_enter(&ch->ch_lock); 69 TAILQ_INSERT_TAIL(&ch->ch_q, ce, ce_q); 70 ch->ch_nentries++; 71 mutex_exit(&ch->ch_lock); 72 } 73 74 void 75 callback_unregister(struct callback_head *ch, struct callback_entry *ce) 76 { 77 78 mutex_enter(&ch->ch_lock); 79 while (ch->ch_running > 0) 80 cv_wait(&ch->ch_cv, &ch->ch_lock); 81 if (__predict_false(ch->ch_next == ce)) { 82 ch->ch_next = TAILQ_NEXT(ce, ce_q); 83 } 84 TAILQ_REMOVE(&ch->ch_q, ce, ce_q); 85 ch->ch_nentries--; 86 mutex_exit(&ch->ch_lock); 87 } 88 89 static int 90 callback_runone(struct callback_head *ch, void *arg) 91 { 92 struct callback_entry *ce; 93 int result; 94 95 KASSERT(ch->ch_nentries > 0); 96 KASSERT(ch->ch_running > 0); 97 98 ce = ch->ch_next; 99 if (ce == NULL) { 100 ce = TAILQ_FIRST(&ch->ch_q); 101 } 102 KASSERT(ce != NULL); 103 result = (*ce->ce_func)(ce, ce->ce_obj, arg); 104 ch->ch_next = TAILQ_NEXT(ce, ce_q); 105 return result; 106 } 107 108 static void 109 callback_run_enter(struct callback_head *ch) 110 { 111 112 mutex_enter(&ch->ch_lock); 113 ch->ch_running++; 114 mutex_exit(&ch->ch_lock); 115 } 116 117 static void 118 callback_run_leave(struct callback_head *ch) 119 { 120 121 mutex_enter(&ch->ch_lock); 122 KASSERT(ch->ch_running > 0); 123 ch->ch_running--; 124 if (ch->ch_running == 0) 125 cv_broadcast(&ch->ch_cv); 126 mutex_exit(&ch->ch_lock); 127 } 128 129 int 130 callback_run_roundrobin(struct callback_head *ch, void *arg) 131 { 132 int i; 133 int n; 134 int result = 0; 135 136 callback_run_enter(ch); 137 n = ch->ch_nentries; 138 for (i = 0; i < n; i++) { 139 result = callback_runone(ch, arg); 140 if (result != CALLBACK_CHAIN_CONTINUE) { 141 break; 142 } 143 } 144 callback_run_leave(ch); 145 146 return result; 147 } 148