sys/kern/subr_eventhandler.c

   1 /*
   2  * (MPSAFE)
   3  *
   4  * Copyright (c) 1999 Michael Smith <msmith@freebsd.org>
   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  * $FreeBSD: src/sys/kern/subr_eventhandler.c,v 1.3 1999/11/16 16:28:57 phk Exp $
  29  */
  30
  31 #include <sys/param.h>
  32 #include <sys/kernel.h>
  33 #include <sys/malloc.h>
  34 #include <sys/systm.h>
  35 #include <sys/eventhandler.h>
  36
  37 MALLOC_DEFINE(M_EVENTHANDLER, "eventhandler", "Event handler records");
  38
  39 /* List of 'slow' lists */
  40 static TAILQ_HEAD(, eventhandler_list)  eventhandler_lists = TAILQ_HEAD_INITIALIZER(eventhandler_lists);
  41 static struct lwkt_token evlist_token = LWKT_TOKEN_INITIALIZER(evlist_token);
  42
  43 struct eventhandler_entry_generic
  44 {
  45     struct eventhandler_entry   ee;
  46     void                        (* func)(void);
  47 };
  48
  49 /*
  50  * Insertion is O(n) due to the priority scan, but optimises to O(1)
  51  * if all priorities are identical.
  52  *
  53  * MPSAFE
  54  */
  55 eventhandler_tag
  56 eventhandler_register(struct eventhandler_list *list, const char *name,
  57                       void *func, void *arg, int priority)
  58 {
  59     struct eventhandler_entry_generic   *eg;
  60     struct eventhandler_entry           *ep;
  61
  62     lwkt_gettoken(&evlist_token);
  63
  64     /*
  65      * find/create the list as needed
  66      */
  67     while (list == NULL) {
  68         list = eventhandler_find_list(name);
  69         if (list)
  70                 break;
  71         list = kmalloc(sizeof(struct eventhandler_list) + strlen(name) + 1,
  72                        M_EVENTHANDLER, M_INTWAIT);
  73         if (eventhandler_find_list(name)) {
  74             kfree(list, M_EVENTHANDLER);
  75             list = NULL;
  76         } else {
  77             list->el_flags = 0;
  78             list->el_name = (char *)list + sizeof(struct eventhandler_list);
  79             strcpy(list->el_name, name);
  80             TAILQ_INSERT_HEAD(&eventhandler_lists, list, el_link);
  81         }
  82     }
  83
  84     if (!(list->el_flags & EHE_INITTED)) {
  85         TAILQ_INIT(&list->el_entries);
  86         list->el_flags = EHE_INITTED;
  87     }
  88
  89     /* allocate an entry for this handler, populate it */
  90     eg = kmalloc(sizeof(struct eventhandler_entry_generic),
  91                 M_EVENTHANDLER, M_INTWAIT);
  92     eg->func = func;
  93     eg->ee.ee_arg = arg;
  94     eg->ee.ee_priority = priority;
  95
  96     /* sort it into the list */
  97     for (ep = TAILQ_FIRST(&list->el_entries);
  98          ep != NULL;
  99          ep = TAILQ_NEXT(ep, ee_link)) {
 100         if (eg->ee.ee_priority < ep->ee_priority) {
 101             TAILQ_INSERT_BEFORE(ep, &eg->ee, ee_link);
 102             break;
 103         }
 104     }
 105     if (ep == NULL)
 106         TAILQ_INSERT_TAIL(&list->el_entries, &eg->ee, ee_link);
 107     lwkt_reltoken(&evlist_token);
 108
 109     return(&eg->ee);
 110 }
 111
 112 /*
 113  * MPSAFE
 114  */
 115 void
 116 eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag)
 117 {
 118     struct eventhandler_entry   *ep = tag;
 119
 120     lwkt_gettoken(&evlist_token);
 121     /* XXX insert diagnostic check here? */
 122
 123     if (ep != NULL) {
 124         /* remove just this entry */
 125         TAILQ_REMOVE(&list->el_entries, ep, ee_link);
 126         kfree(ep, M_EVENTHANDLER);
 127     } else {
 128         /* remove entire list */
 129         while (!TAILQ_EMPTY(&list->el_entries)) {
 130             ep = TAILQ_FIRST(&list->el_entries);
 131             TAILQ_REMOVE(&list->el_entries, ep, ee_link);
 132             kfree(ep, M_EVENTHANDLER);
 133         }
 134     }
 135     lwkt_reltoken(&evlist_token);
 136 }
 137
 138 /*
 139  * Locate the requested list
 140  */
 141 struct eventhandler_list *
 142 eventhandler_find_list(const char *name)
 143 {
 144     struct eventhandler_list    *list;
 145
 146     lwkt_gettoken(&evlist_token);
 147     for (list = TAILQ_FIRST(&eventhandler_lists);
 148          list != NULL;
 149          list = TAILQ_NEXT(list, el_link)) {
 150         if (!strcmp(name, list->el_name))
 151             break;
 152     }
 153     lwkt_reltoken(&evlist_token);
 154     return(list);
 155 }