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  * $DragonFly: src/sys/kern/subr_eventhandler.c,v 1.5 2006/09/05 03:48:12 dillon Exp $
  30  */
  31
  32 #include <sys/param.h>
  33 #include <sys/kernel.h>
  34 #include <sys/malloc.h>
  35 #include <sys/systm.h>
  36 #include <sys/eventhandler.h>
  37
  38 #include <sys/mplock2.h>
  39
  40 MALLOC_DEFINE(M_EVENTHANDLER, "eventhandler", "Event handler records");
  41
  42 /* List of 'slow' lists */
  43 static TAILQ_HEAD(, eventhandler_list)  eventhandler_lists = TAILQ_HEAD_INITIALIZER(eventhandler_lists);
  44 static struct lwkt_token evlist_token = LWKT_TOKEN_INITIALIZER(evlist_token);
  45
  46 struct eventhandler_entry_generic
  47 {
  48     struct eventhandler_entry   ee;
  49     void                        (* func)(void);
  50 };
  51
  52 /*
  53  * Insertion is O(n) due to the priority scan, but optimises to O(1)
  54  * if all priorities are identical.
  55  *
  56  * MPSAFE
  57  */
  58 eventhandler_tag
  59 eventhandler_register(struct eventhandler_list *list, char *name,
  60                       void *func, void *arg, int priority)
  61 {
  62     struct eventhandler_entry_generic   *eg;
  63     struct eventhandler_entry           *ep;
  64
  65     lwkt_gettoken(&evlist_token);
  66
  67     /*
  68      * find/create the list as needed
  69      */
  70     while (list == NULL) {
  71         list = eventhandler_find_list(name);
  72         if (list)
  73                 break;
  74         list = kmalloc(sizeof(struct eventhandler_list) + strlen(name) + 1,
  75                        M_EVENTHANDLER, M_INTWAIT);
  76         if (eventhandler_find_list(name)) {
  77             kfree(list, M_EVENTHANDLER);
  78             list = NULL;
  79         } else {
  80             list->el_flags = 0;
  81             list->el_name = (char *)list + sizeof(struct eventhandler_list);
  82             strcpy(list->el_name, name);
  83             TAILQ_INSERT_HEAD(&eventhandler_lists, list, el_link);
  84         }
  85     }
  86
  87     if (!(list->el_flags & EHE_INITTED)) {
  88         TAILQ_INIT(&list->el_entries);
  89         list->el_flags = EHE_INITTED;
  90     }
  91
  92     /* allocate an entry for this handler, populate it */
  93     eg = kmalloc(sizeof(struct eventhandler_entry_generic),
  94                 M_EVENTHANDLER, M_INTWAIT);
  95     eg->func = func;
  96     eg->ee.ee_arg = arg;
  97     eg->ee.ee_priority = priority;
  98
  99     /* sort it into the list */
 100     for (ep = TAILQ_FIRST(&list->el_entries);
 101          ep != NULL;
 102          ep = TAILQ_NEXT(ep, ee_link)) {
 103         if (eg->ee.ee_priority < ep->ee_priority) {
 104             TAILQ_INSERT_BEFORE(ep, &eg->ee, ee_link);
 105             break;
 106         }
 107     }
 108     if (ep == NULL)
 109         TAILQ_INSERT_TAIL(&list->el_entries, &eg->ee, ee_link);
 110     lwkt_reltoken(&evlist_token);
 111
 112     return(&eg->ee);
 113 }
 114
 115 /*
 116  * MPSAFE
 117  */
 118 void
 119 eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag)
 120 {
 121     struct eventhandler_entry   *ep = tag;
 122
 123     lwkt_gettoken(&evlist_token);
 124     /* XXX insert diagnostic check here? */
 125
 126     if (ep != NULL) {
 127         /* remove just this entry */
 128         TAILQ_REMOVE(&list->el_entries, ep, ee_link);
 129         kfree(ep, M_EVENTHANDLER);
 130     } else {
 131         /* remove entire list */
 132         while (!TAILQ_EMPTY(&list->el_entries)) {
 133             ep = TAILQ_FIRST(&list->el_entries);
 134             TAILQ_REMOVE(&list->el_entries, ep, ee_link);
 135             kfree(ep, M_EVENTHANDLER);
 136         }
 137     }
 138     lwkt_reltoken(&evlist_token);
 139 }
 140
 141 /*
 142  * Locate the requested list
 143  */
 144 struct eventhandler_list *
 145 eventhandler_find_list(char *name)
 146 {
 147     struct eventhandler_list    *list;
 148
 149     lwkt_gettoken(&evlist_token);
 150     for (list = TAILQ_FIRST(&eventhandler_lists);
 151          list != NULL;
 152          list = TAILQ_NEXT(list, el_link)) {
 153         if (!strcmp(name, list->el_name))
 154             break;
 155     }
 156     lwkt_reltoken(&evlist_token);
 157     return(list);
 158 }