sys/kern/subr_callback.c

   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         KASSERT(fn != NULL);
  67         ce->ce_func = fn;
  68         ce->ce_obj = obj;
  69         mutex_enter(&ch->ch_lock);
  70         TAILQ_INSERT_TAIL(&ch->ch_q, ce, ce_q);
  71         ch->ch_nentries++;
  72         mutex_exit(&ch->ch_lock);
  73 }
  74
  75 void
  76 callback_unregister(struct callback_head *ch, struct callback_entry *ce)
  77 {
  78
  79         mutex_enter(&ch->ch_lock);
  80         while (ch->ch_running > 0)
  81                 cv_wait(&ch->ch_cv, &ch->ch_lock);
  82         if (__predict_false(ch->ch_next == ce)) {
  83                 ch->ch_next = TAILQ_NEXT(ce, ce_q);
  84         }
  85         TAILQ_REMOVE(&ch->ch_q, ce, ce_q);
  86         ch->ch_nentries--;
  87         mutex_exit(&ch->ch_lock);
  88 }
  89
  90 static int
  91 callback_runone(struct callback_head *ch, void *arg)
  92 {
  93         struct callback_entry *ce;
  94         int result;
  95
  96         KASSERT(ch->ch_nentries > 0);
  97         KASSERT(ch->ch_running > 0);
  98
  99         ce = ch->ch_next;
 100         if (ce == NULL) {
 101                 ce = TAILQ_FIRST(&ch->ch_q);
 102         }
 103         KASSERT(ce != NULL);
 104         KASSERT(ce->ce_func != NULL);
 105         result = (*ce->ce_func)(ce, ce->ce_obj, arg);
 106         ch->ch_next = TAILQ_NEXT(ce, ce_q);
 107         return result;
 108 }
 109
 110 static void
 111 callback_run_enter(struct callback_head *ch)
 112 {
 113
 114         mutex_enter(&ch->ch_lock);
 115         ch->ch_running++;
 116         mutex_exit(&ch->ch_lock);
 117 }
 118
 119 static void
 120 callback_run_leave(struct callback_head *ch)
 121 {
 122
 123         mutex_enter(&ch->ch_lock);
 124         KASSERT(ch->ch_running > 0);
 125         ch->ch_running--;
 126         if (ch->ch_running == 0)
 127                 cv_broadcast(&ch->ch_cv);
 128         mutex_exit(&ch->ch_lock);
 129 }
 130
 131 int
 132 callback_run_roundrobin(struct callback_head *ch, void *arg)
 133 {
 134         int i;
 135         int n;
 136         int result = 0;
 137
 138         callback_run_enter(ch);
 139         n = ch->ch_nentries;
 140         for (i = 0; i < n; i++) {
 141                 result = callback_runone(ch, arg);
 142                 if (result != CALLBACK_CHAIN_CONTINUE) {
 143                         break;
 144                 }
 145         }
 146         callback_run_leave(ch);
 147
 148         return result;
 149 }