FreeBSD-5.3/sys/kern/subr_eventhandler.c
/*-
* Copyright (c) 1999 Michael Smith <msmith@freebsd.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: src/sys/kern/subr_eventhandler.c,v 1.21 2003/06/11 00:56:57 obrien Exp $");
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/systm.h>
#include <sys/eventhandler.h>
static MALLOC_DEFINE(M_EVENTHANDLER, "eventhandler", "Event handler records");
/* List of 'slow' lists */
static TAILQ_HEAD(, eventhandler_list) eventhandler_lists;
static int eventhandler_lists_initted = 0;
static struct mtx eventhandler_mutex;
struct eventhandler_entry_generic
{
struct eventhandler_entry ee;
void (* func)(void);
};
static struct eventhandler_list *_eventhandler_find_list(char *name);
/*
* Initialize the eventhandler mutex and list.
*/
static void
eventhandler_init(void *dummy __unused)
{
TAILQ_INIT(&eventhandler_lists);
mtx_init(&eventhandler_mutex, "eventhandler", NULL, MTX_DEF);
atomic_store_rel_int(&eventhandler_lists_initted, 1);
}
SYSINIT(eventhandlers, SI_SUB_EVENTHANDLER, SI_ORDER_FIRST, eventhandler_init,
NULL)
/*
* Insertion is O(n) due to the priority scan, but optimises to O(1)
* if all priorities are identical.
*/
eventhandler_tag
eventhandler_register(struct eventhandler_list *list, char *name,
void *func, void *arg, int priority)
{
struct eventhandler_list *new_list;
struct eventhandler_entry_generic *eg;
struct eventhandler_entry *ep;
KASSERT(eventhandler_lists_initted, ("eventhandler registered too early"));
/* lock the eventhandler lists */
mtx_lock(&eventhandler_mutex);
/* Do we need to find/create the (slow) list? */
if (list == NULL) {
/* look for a matching, existing list */
list = _eventhandler_find_list(name);
/* Do we need to create the list? */
if (list == NULL) {
mtx_unlock(&eventhandler_mutex);
new_list = malloc(sizeof(struct eventhandler_list) +
strlen(name) + 1, M_EVENTHANDLER, M_WAITOK);
/* If someone else created it already, then use that one. */
mtx_lock(&eventhandler_mutex);
list = _eventhandler_find_list(name);
if (list != NULL) {
free(new_list, M_EVENTHANDLER);
} else {
CTR2(KTR_EVH, "%s: creating list \"%s\"", __func__, name);
list = new_list;
list->el_flags = 0;
list->el_runcount = 0;
bzero(&list->el_lock, sizeof(list->el_lock));
list->el_name = (char *)list + sizeof(struct eventhandler_list);
strcpy(list->el_name, name);
TAILQ_INSERT_HEAD(&eventhandler_lists, list, el_link);
}
}
}
if (!(list->el_flags & EHL_INITTED)) {
TAILQ_INIT(&list->el_entries);
mtx_init(&list->el_lock, name, "eventhandler list", MTX_DEF);
atomic_store_rel_int(&list->el_flags, EHL_INITTED);
}
mtx_unlock(&eventhandler_mutex);
/* allocate an entry for this handler, populate it */
eg = malloc(sizeof(struct eventhandler_entry_generic), M_EVENTHANDLER,
M_WAITOK | M_ZERO);
eg->func = func;
eg->ee.ee_arg = arg;
eg->ee.ee_priority = priority;
KASSERT(priority != EHE_DEAD_PRIORITY,
("%s: handler for %s registered with dead priority", __func__, name));
/* sort it into the list */
CTR4(KTR_EVH, "%s: adding item %p (function %p) to \"%s\"", __func__, eg,
func, name);
EHL_LOCK(list);
TAILQ_FOREACH(ep, &list->el_entries, ee_link) {
if (ep->ee_priority != EHE_DEAD_PRIORITY &&
eg->ee.ee_priority < ep->ee_priority) {
TAILQ_INSERT_BEFORE(ep, &eg->ee, ee_link);
break;
}
}
if (ep == NULL)
TAILQ_INSERT_TAIL(&list->el_entries, &eg->ee, ee_link);
EHL_UNLOCK(list);
return(&eg->ee);
}
void
eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag)
{
struct eventhandler_entry *ep = tag;
EHL_LOCK_ASSERT(list, MA_OWNED);
if (ep != NULL) {
/* remove just this entry */
if (list->el_runcount == 0) {
CTR3(KTR_EVH, "%s: removing item %p from \"%s\"", __func__, ep,
list->el_name);
TAILQ_REMOVE(&list->el_entries, ep, ee_link);
free(ep, M_EVENTHANDLER);
} else {
CTR3(KTR_EVH, "%s: marking item %p from \"%s\" as dead", __func__,
ep, list->el_name);
ep->ee_priority = EHE_DEAD_PRIORITY;
}
} else {
/* remove entire list */
if (list->el_runcount == 0) {
CTR2(KTR_EVH, "%s: removing all items from \"%s\"", __func__,
list->el_name);
TAILQ_REMOVE(&list->el_entries, ep, ee_link);
while (!TAILQ_EMPTY(&list->el_entries)) {
ep = TAILQ_FIRST(&list->el_entries);
TAILQ_REMOVE(&list->el_entries, ep, ee_link);
free(ep, M_EVENTHANDLER);
}
} else {
CTR2(KTR_EVH, "%s: marking all items from \"%s\" as dead",
__func__, list->el_name);
TAILQ_FOREACH(ep, &list->el_entries, ee_link)
ep->ee_priority = EHE_DEAD_PRIORITY;
}
}
EHL_UNLOCK(list);
}
/*
* Internal version for use when eventhandler list is already locked.
*/
static struct eventhandler_list *
_eventhandler_find_list(char *name)
{
struct eventhandler_list *list;
mtx_assert(&eventhandler_mutex, MA_OWNED);
TAILQ_FOREACH(list, &eventhandler_lists, el_link) {
if (!strcmp(name, list->el_name))
break;
}
return (list);
}
/*
* Lookup a "slow" list by name. Returns with the list locked.
*/
struct eventhandler_list *
eventhandler_find_list(char *name)
{
struct eventhandler_list *list;
if (!eventhandler_lists_initted)
return(NULL);
/* scan looking for the requested list */
mtx_lock(&eventhandler_mutex);
list = _eventhandler_find_list(name);
if (list != NULL)
EHL_LOCK(list);
mtx_unlock(&eventhandler_mutex);
return(list);
}
/*
* Prune "dead" entries from an eventhandler list.
*/
void
eventhandler_prune_list(struct eventhandler_list *list)
{
struct eventhandler_entry *ep, *en;
CTR2(KTR_EVH, "%s: pruning list \"%s\"", __func__, list->el_name);
EHL_LOCK_ASSERT(list, MA_OWNED);
ep = TAILQ_FIRST(&list->el_entries);
while (ep != NULL) {
en = TAILQ_NEXT(ep, ee_link);
if (ep->ee_priority == EHE_DEAD_PRIORITY) {
TAILQ_REMOVE(&list->el_entries, ep, ee_link);
free(ep, M_EVENTHANDLER);
}
ep = en;
}
}