1 /* $NetBSD: subr_callback.c,v 1.7 2009/11/24 20:11:50 rmind 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 1.7 2009/11/24 20:11:50 rmind 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 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 75 void 76 callback_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 90 static int 91 callback_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 } 109 110 static void 111 callback_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 } 118 119 static void 120 callback_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 } 130 131 int 132 callback_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