From a4bf8740bb46d337eb18ae335c2f3b023098c63d Mon Sep 17 00:00:00 2001
From: msmith <msmith@FreeBSD.org>
Date: Fri, 22 Sep 2000 03:17:35 +0000
Subject: Make the EVENTHANDLER mechanism MP-safe. Events can now be invoked
without holding the Giant lock.
---
sys/kern/subr_eventhandler.c | 24 +++++++++++++++++++++---
1 file changed, 21 insertions(+), 3 deletions(-)
(limited to 'sys/kern/subr_eventhandler.c')
diff --git a/sys/kern/subr_eventhandler.c b/sys/kern/subr_eventhandler.c
index c23441d..1b9b739 100644
--- a/sys/kern/subr_eventhandler.c
+++ b/sys/kern/subr_eventhandler.c
@@ -58,9 +58,13 @@ eventhandler_register(struct eventhandler_list *list, char *name,
/* avoid the need for a SYSINIT just to init the list */
if (!eventhandler_lists_initted) {
TAILQ_INIT(&eventhandler_lists);
+ mtx_init(&eventhandler_mutex, "eventhandler", MTX_DEF);
eventhandler_lists_initted = 1;
}
+ /* lock the eventhandler lists */
+ mtx_enter(&eventhandler_mutex, MTX_DEF);
+
/* Do we need to find/create the (slow) list? */
if (list == NULL) {
/* look for a matching, existing list */
@@ -69,8 +73,10 @@ eventhandler_register(struct eventhandler_list *list, char *name,
/* Do we need to create the list? */
if (list == NULL) {
if ((list = malloc(sizeof(struct eventhandler_list) + strlen(name) + 1,
- M_EVENTHANDLER, M_NOWAIT)) == NULL)
+ M_EVENTHANDLER, M_NOWAIT)) == NULL) {
+ mtx_exit(&eventhandler_mutex, MTX_DEF);
return(NULL);
+ }
list->el_flags = 0;
list->el_name = (char *)list + sizeof(struct eventhandler_list);
strcpy(list->el_name, name);
@@ -79,18 +85,22 @@ eventhandler_register(struct eventhandler_list *list, char *name,
}
if (!(list->el_flags & EHE_INITTED)) {
TAILQ_INIT(&list->el_entries);
+ mtx_init(&list->el_mutex, name, MTX_DEF);
list->el_flags = EHE_INITTED;
}
/* allocate an entry for this handler, populate it */
if ((eg = malloc(sizeof(struct eventhandler_entry_generic),
- M_EVENTHANDLER, M_NOWAIT)) == NULL)
+ M_EVENTHANDLER, M_NOWAIT)) == NULL) {
+ mtx_exit(&eventhandler_mutex, MTX_DEF);
return(NULL);
+ }
eg->func = func;
eg->ee.ee_arg = arg;
eg->ee.ee_priority = priority;
/* sort it into the list */
+ mtx_enter(&list->el_mutex, MTX_DEF);
for (ep = TAILQ_FIRST(&list->el_entries);
ep != NULL;
ep = TAILQ_NEXT(ep, ee_link)) {
@@ -101,6 +111,8 @@ eventhandler_register(struct eventhandler_list *list, char *name,
}
if (ep == NULL)
TAILQ_INSERT_TAIL(&list->el_entries, &eg->ee, ee_link);
+ mtx_exit(&list->el_mutex, MTX_DEF);
+ mtx_exit(&eventhandler_mutex, MTX_DEF);
return(&eg->ee);
}
@@ -110,6 +122,7 @@ eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag)
struct eventhandler_entry *ep = tag;
/* XXX insert diagnostic check here? */
+ mtx_enter(&list->el_mutex, MTX_DEF);
if (ep != NULL) {
/* remove just this entry */
TAILQ_REMOVE(&list->el_entries, ep, ee_link);
@@ -122,19 +135,24 @@ eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag)
free(ep, M_EVENTHANDLER);
}
}
+ mtx_exit(&list->el_mutex, MTX_DEF);
}
struct eventhandler_list *
eventhandler_find_list(char *name)
{
struct eventhandler_list *list;
-
+
/* scan looking for the requested list */
+ mtx_enter(&eventhandler_mutex, MTX_DEF);
for (list = TAILQ_FIRST(&eventhandler_lists);
list != NULL;
list = TAILQ_NEXT(list, el_link)) {
if (!strcmp(name, list->el_name))
break;
}
+ mtx_exit(&eventhandler_mutex, MTX_DEF);
+
return(list);
}
+
--
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