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subr_callback.c revision 1.2 
      1 /*	$NetBSD: subr_callback.c,v 1.2 2006/05/27 07:42:42 yamt 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 1.2 2006/05/27 07:42:42 yamt 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 	simple_lock_init(&ch->ch_lock);
     44 	TAILQ_INIT(&ch->ch_q);
     45 	ch->ch_next = NULL;
     46 	ch->ch_nentries = 0;
     47 	ch->ch_running = 0;
     48 	ch->ch_flags = 0;
     49 }
     50 
     51 void
     52 callback_register(struct callback_head *ch, struct callback_entry *ce,
     53     void *obj, int (*fn)(struct callback_entry *, void *, void *))
     54 {
     55 
     56 	ce->ce_func = fn;
     57 	ce->ce_obj = obj;
     58 	simple_lock(&ch->ch_lock);
     59 	TAILQ_INSERT_TAIL(&ch->ch_q, ce, ce_q);
     60 	ch->ch_nentries++;
     61 	simple_unlock(&ch->ch_lock);
     62 }
     63 
     64 void
     65 callback_unregister(struct callback_head *ch, struct callback_entry *ce)
     66 {
     67 
     68 	simple_lock(&ch->ch_lock);
     69 	while (ch->ch_running > 0) {
     70 		ch->ch_flags |= CH_WANT;
     71 		ltsleep(&ch->ch_running, PVM, "recunreg", 0, &ch->ch_lock);
     72 	}
     73 	if (__predict_false(ch->ch_next == ce)) {
     74 		ch->ch_next = TAILQ_NEXT(ce, ce_q);
     75 	}
     76 	TAILQ_REMOVE(&ch->ch_q, ce, ce_q);
     77 	ch->ch_nentries--;
     78 	simple_unlock(&ch->ch_lock);
     79 }
     80 
     81 static int
     82 callback_runone(struct callback_head *ch, void *arg)
     83 {
     84 	struct callback_entry *ce;
     85 	int result;
     86 
     87 	KASSERT(ch->ch_nentries > 0);
     88 	KASSERT(ch->ch_running > 0);
     89 
     90 	ce = ch->ch_next;
     91 	if (ce == NULL) {
     92 		ce = TAILQ_FIRST(&ch->ch_q);
     93 	}
     94 	KASSERT(ce != NULL);
     95 	result = (*ce->ce_func)(ce, ce->ce_obj, arg);
     96 	ch->ch_next = TAILQ_NEXT(ce, ce_q);
     97 	return result;
     98 }
     99 
    100 static void
    101 callback_run_enter(struct callback_head *ch)
    102 {
    103 
    104 	simple_lock(&ch->ch_lock);
    105 	ch->ch_running++;
    106 	simple_unlock(&ch->ch_lock);
    107 }
    108 
    109 static void
    110 callback_run_leave(struct callback_head *ch)
    111 {
    112 
    113 	simple_lock(&ch->ch_lock);
    114 	KASSERT(ch->ch_running > 0);
    115 	ch->ch_running--;
    116 	if (ch->ch_running == 0 && (ch->ch_flags & CH_WANT) != 0) {
    117 		ch->ch_flags &= ~CH_WANT;
    118 		wakeup(&ch->ch_running);
    119 	}
    120 	simple_unlock(&ch->ch_lock);
    121 }
    122 
    123 int
    124 callback_run_roundrobin(struct callback_head *ch, void *arg)
    125 {
    126 	int i;
    127 	int n;
    128 	int result = 0;
    129 
    130 	callback_run_enter(ch);
    131 	n = ch->ch_nentries;
    132 	for (i = 0; i < n; i++) {
    133 		result = callback_runone(ch, arg);
    134 		if (result != CALLBACK_CHAIN_CONTINUE) {
    135 			break;
    136 		}
    137 	}
    138 	callback_run_leave(ch);
    139 
    140 	return result;
    141 }
    142