sys/kern/subr_eventhandler.c

   1 /*-
   2  * Copyright (c) 1999 Michael Smith <msmith@freebsd.org>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  *
  26  * $FreeBSD: src/sys/kern/subr_eventhandler.c,v 1.3 1999/11/16 16:28:57 phk Exp $
  27  * $DragonFly: src/sys/kern/subr_eventhandler.c,v 1.3 2004/08/06 22:32:07 dillon Exp $
  28  */
  29
  30 #include <sys/param.h>
  31 #include <sys/kernel.h>
  32 #include <sys/malloc.h>
  33 #include <sys/systm.h>
  34 #include <sys/eventhandler.h>
  35
  36 MALLOC_DEFINE(M_EVENTHANDLER, "eventhandler", "Event handler records");
  37
  38 /* List of 'slow' lists */
  39 static TAILQ_HEAD(, eventhandler_list)  eventhandler_lists;
  40 static int                              eventhandler_lists_initted = 0;
  41
  42 struct eventhandler_entry_generic
  43 {
  44     struct eventhandler_entry   ee;
  45     void                        (* func)(void);
  46 };
  47
  48 /*
  49  * Insertion is O(n) due to the priority scan, but optimises to O(1)
  50  * if all priorities are identical.
  51  */
  52 eventhandler_tag
  53 eventhandler_register(struct eventhandler_list *list, char *name,
  54                       void *func, void *arg, int priority)
  55 {
  56     struct eventhandler_entry_generic   *eg;
  57     struct eventhandler_entry           *ep;
  58
  59     /* avoid the need for a SYSINIT just to init the list */
  60     if (!eventhandler_lists_initted) {
  61         TAILQ_INIT(&eventhandler_lists);
  62         eventhandler_lists_initted = 1;
  63     }
  64
  65     /* Do we need to find/create the (slow) list? */
  66     if (list == NULL) {
  67         /* look for a matching, existing list */
  68         list = eventhandler_find_list(name);
  69
  70         /* Do we need to create the list? */
  71         if (list == NULL) {
  72             list = malloc(sizeof(struct eventhandler_list) + strlen(name) + 1,
  73                            M_EVENTHANDLER, M_INTWAIT);
  74             list->el_flags = 0;
  75             list->el_name = (char *)list + sizeof(struct eventhandler_list);
  76             strcpy(list->el_name, name);
  77             TAILQ_INSERT_HEAD(&eventhandler_lists, list, el_link);
  78         }
  79     }
  80     if (!(list->el_flags & EHE_INITTED)) {
  81         TAILQ_INIT(&list->el_entries);
  82         list->el_flags = EHE_INITTED;
  83     }
  84
  85     /* allocate an entry for this handler, populate it */
  86     eg = malloc(sizeof(struct eventhandler_entry_generic),
  87                 M_EVENTHANDLER, M_INTWAIT);
  88     eg->func = func;
  89     eg->ee.ee_arg = arg;
  90     eg->ee.ee_priority = priority;
  91
  92     /* sort it into the list */
  93     for (ep = TAILQ_FIRST(&list->el_entries);
  94          ep != NULL;
  95          ep = TAILQ_NEXT(ep, ee_link)) {
  96         if (eg->ee.ee_priority < ep->ee_priority) {
  97             TAILQ_INSERT_BEFORE(ep, &eg->ee, ee_link);
  98             break;
  99         }
 100     }
 101     if (ep == NULL)
 102         TAILQ_INSERT_TAIL(&list->el_entries, &eg->ee, ee_link);
 103     return(&eg->ee);
 104 }
 105
 106 void
 107 eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag)
 108 {
 109     struct eventhandler_entry   *ep = tag;
 110
 111     /* XXX insert diagnostic check here? */
 112     if (ep != NULL) {
 113         /* remove just this entry */
 114         TAILQ_REMOVE(&list->el_entries, ep, ee_link);
 115         free(ep, M_EVENTHANDLER);
 116     } else {
 117         /* remove entire list */
 118         while (!TAILQ_EMPTY(&list->el_entries)) {
 119             ep = TAILQ_FIRST(&list->el_entries);
 120             TAILQ_REMOVE(&list->el_entries, ep, ee_link);
 121             free(ep, M_EVENTHANDLER);
 122         }
 123     }
 124 }
 125
 126 struct eventhandler_list *
 127 eventhandler_find_list(char *name)
 128 {
 129     struct eventhandler_list    *list;
 130
 131     /* scan looking for the requested list */
 132     for (list = TAILQ_FIRST(&eventhandler_lists);
 133          list != NULL;
 134          list = TAILQ_NEXT(list, el_link)) {
 135         if (!strcmp(name, list->el_name))
 136             break;
 137     }
 138     return(list);
 139 }