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subr_callback.c revision 1.5.16.1 
      1 /*	$NetBSD: subr_callback.c,v 1.5.16.1 2007/12/08 17:57:45 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 1.5.16.1 2007/12/08 17:57:45 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