subr_callback.c

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    1 /*      $NetBSD: subr_callback.c,v 1.6 2007/12/05 07:06:54 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 1.6 2007/12/05 07:06:54 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 }

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

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