subr_callback.c

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    1 /*      $NetBSD: subr_callback.c,v 1.4 2006/06/23 16:17:23 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 1.4 2006/06/23 16:17:23 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 #if 0 /* already zero-initialized */
   47         ch->ch_next = NULL;
   48         ch->ch_nentries = 0;
   49         ch->ch_running = 0;
   50         ch->ch_flags = 0;
   51 #endif
   52 }
   53 
   54 void
   55 callback_register(struct callback_head *ch, struct callback_entry *ce,
   56     void *obj, int (*fn)(struct callback_entry *, void *, void *))
   57 {
   58 
   59         ce->ce_func = fn;
   60         ce->ce_obj = obj;
   61         simple_lock(&ch->ch_lock);
   62         TAILQ_INSERT_TAIL(&ch->ch_q, ce, ce_q);
   63         ch->ch_nentries++;
   64         simple_unlock(&ch->ch_lock);
   65 }
   66 
   67 void
   68 callback_unregister(struct callback_head *ch, struct callback_entry *ce)
   69 {
   70 
   71         simple_lock(&ch->ch_lock);
   72         while (ch->ch_running > 0) {
   73                 ch->ch_flags |= CH_WANT;
   74                 ltsleep(&ch->ch_running, PVM, "recunreg", 0, &ch->ch_lock);
   75         }
   76         if (__predict_false(ch->ch_next == ce)) {
   77                 ch->ch_next = TAILQ_NEXT(ce, ce_q);
   78         }
   79         TAILQ_REMOVE(&ch->ch_q, ce, ce_q);
   80         ch->ch_nentries--;
   81         simple_unlock(&ch->ch_lock);
   82 }
   83 
   84 static int
   85 callback_runone(struct callback_head *ch, void *arg)
   86 {
   87         struct callback_entry *ce;
   88         int result;
   89 
   90         KASSERT(ch->ch_nentries > 0);
   91         KASSERT(ch->ch_running > 0);
   92 
   93         ce = ch->ch_next;
   94         if (ce == NULL) {
   95                 ce = TAILQ_FIRST(&ch->ch_q);
   96         }
   97         KASSERT(ce != NULL);
   98         result = (*ce->ce_func)(ce, ce->ce_obj, arg);
   99         ch->ch_next = TAILQ_NEXT(ce, ce_q);
  100         return result;
  101 }
  102 
  103 static void
  104 callback_run_enter(struct callback_head *ch)
  105 {
  106 
  107         simple_lock(&ch->ch_lock);
  108         ch->ch_running++;
  109         simple_unlock(&ch->ch_lock);
  110 }
  111 
  112 static void
  113 callback_run_leave(struct callback_head *ch)
  114 {
  115 
  116         simple_lock(&ch->ch_lock);
  117         KASSERT(ch->ch_running > 0);
  118         ch->ch_running--;
  119         if (ch->ch_running == 0 && (ch->ch_flags & CH_WANT) != 0) {
  120                 ch->ch_flags &= ~CH_WANT;
  121                 wakeup(&ch->ch_running);
  122         }
  123         simple_unlock(&ch->ch_lock);
  124 }
  125 
  126 int
  127 callback_run_roundrobin(struct callback_head *ch, void *arg)
  128 {
  129         int i;
  130         int n;
  131         int result = 0;
  132 
  133         callback_run_enter(ch);
  134         n = ch->ch_nentries;
  135         for (i = 0; i < n; i++) {
  136                 result = callback_runone(ch, arg);
  137                 if (result != CALLBACK_CHAIN_CONTINUE) {
  138                         break;
  139                 }
  140         }
  141         callback_run_leave(ch);
  142 
  143         return result;
  144 }

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FreeBSD/Linux Kernel Cross Reference sys/kern/subr_callback.c

FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_callback.c