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subr_callback.c revision 1.3 
      1 /*	$NetBSD: subr_callback.c,v 1.3 2006/06/21 17:16:00 drochner 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 1.3 2006/06/21 17:16:00 drochner 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 	memset(ch, 0, sizeof(struct callback_head));
     44 	simple_lock_init(&ch->ch_lock);
     45 	TAILQ_INIT(&ch->ch_q);
     46 }
     47 
     48 void
     49 callback_register(struct callback_head *ch, struct callback_entry *ce,
     50     void *obj, int (*fn)(struct callback_entry *, void *, void *))
     51 {
     52 
     53 	ce->ce_func = fn;
     54 	ce->ce_obj = obj;
     55 	simple_lock(&ch->ch_lock);
     56 	TAILQ_INSERT_TAIL(&ch->ch_q, ce, ce_q);
     57 	ch->ch_nentries++;
     58 	simple_unlock(&ch->ch_lock);
     59 }
     60 
     61 void
     62 callback_unregister(struct callback_head *ch, struct callback_entry *ce)
     63 {
     64 
     65 	simple_lock(&ch->ch_lock);
     66 	while (ch->ch_running > 0) {
     67 		ch->ch_flags |= CH_WANT;
     68 		ltsleep(&ch->ch_running, PVM, "recunreg", 0, &ch->ch_lock);
     69 	}
     70 	if (__predict_false(ch->ch_next == ce)) {
     71 		ch->ch_next = TAILQ_NEXT(ce, ce_q);
     72 	}
     73 	TAILQ_REMOVE(&ch->ch_q, ce, ce_q);
     74 	ch->ch_nentries--;
     75 	simple_unlock(&ch->ch_lock);
     76 }
     77 
     78 static int
     79 callback_runone(struct callback_head *ch, void *arg)
     80 {
     81 	struct callback_entry *ce;
     82 	int result;
     83 
     84 	KASSERT(ch->ch_nentries > 0);
     85 	KASSERT(ch->ch_running > 0);
     86 
     87 	ce = ch->ch_next;
     88 	if (ce == NULL) {
     89 		ce = TAILQ_FIRST(&ch->ch_q);
     90 	}
     91 	KASSERT(ce != NULL);
     92 	result = (*ce->ce_func)(ce, ce->ce_obj, arg);
     93 	ch->ch_next = TAILQ_NEXT(ce, ce_q);
     94 	return result;
     95 }
     96 
     97 static void
     98 callback_run_enter(struct callback_head *ch)
     99 {
    100 
    101 	simple_lock(&ch->ch_lock);
    102 	ch->ch_running++;
    103 	simple_unlock(&ch->ch_lock);
    104 }
    105 
    106 static void
    107 callback_run_leave(struct callback_head *ch)
    108 {
    109 
    110 	simple_lock(&ch->ch_lock);
    111 	KASSERT(ch->ch_running > 0);
    112 	ch->ch_running--;
    113 	if (ch->ch_running == 0 && (ch->ch_flags & CH_WANT) != 0) {
    114 		ch->ch_flags &= ~CH_WANT;
    115 		wakeup(&ch->ch_running);
    116 	}
    117 	simple_unlock(&ch->ch_lock);
    118 }
    119 
    120 int
    121 callback_run_roundrobin(struct callback_head *ch, void *arg)
    122 {
    123 	int i;
    124 	int n;
    125 	int result = 0;
    126 
    127 	callback_run_enter(ch);
    128 	n = ch->ch_nentries;
    129 	for (i = 0; i < n; i++) {
    130 		result = callback_runone(ch, arg);
    131 		if (result != CALLBACK_CHAIN_CONTINUE) {
    132 			break;
    133 		}
    134 	}
    135 	callback_run_leave(ch);
    136 
    137 	return result;
    138 }
    139