1 files changed, 108 insertions, 41 deletions

diff --git a/sys/kern/subr_eventhandler.c b/sys/kern/subr_eventhandler.c
index 27f21f0..a56f1e4 100644
--- a/sys/kern/subr_eventhandler.c
+++ b/sys/kern/subr_eventhandler.c
@@ -48,6 +48,8 @@ struct eventhandler_entry_generic
     void			(* func)(void);
 };
 
+static struct eventhandler_list *_eventhandler_find_list(char *name);
+
 /*
  * Initialize the eventhandler mutex and list.
  */
@@ -55,8 +57,8 @@ static void
 eventhandler_init(void *dummy __unused)
 {
     TAILQ_INIT(&eventhandler_lists);
-    mtx_init(&eventhandler_mutex, "eventhandler", NULL, MTX_DEF | MTX_RECURSE);
-    eventhandler_lists_initted = 1;
+    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)
@@ -69,6 +71,7 @@ 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;
     
@@ -80,51 +83,62 @@ eventhandler_register(struct eventhandler_list *list, char *name,
     /* Do we need to find/create the (slow) list? */
     if (list == NULL) {
 	/* look for a matching, existing list */
-	list = eventhandler_find_list(name);
+	list = _eventhandler_find_list(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) {
-		mtx_unlock(&eventhandler_mutex);
-		return(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);
 	    }
-	    list->el_flags = 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 & EHE_INITTED)) {
+    if (!(list->el_flags & EHL_INITTED)) {
 	TAILQ_INIT(&list->el_entries);
-	sx_init(&list->el_lock, name);
-	list->el_flags = EHE_INITTED;
+	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 */
-    if ((eg = malloc(sizeof(struct eventhandler_entry_generic), 
-		     M_EVENTHANDLER, M_NOWAIT)) == NULL) {
-	return(NULL);
-    }
+    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 */
-    EHE_LOCK(list);
-    for (ep = TAILQ_FIRST(&list->el_entries);
-	 ep != NULL; 
-	 ep = TAILQ_NEXT(ep, ee_link)) {
-	if (eg->ee.ee_priority < ep->ee_priority) {
+    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);
-    EHE_UNLOCK(list);
+    EHL_UNLOCK(list);
     return(&eg->ee);
 }
 
@@ -133,23 +147,59 @@ eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag)
 {
     struct eventhandler_entry	*ep = tag;
 
-    /* XXX insert diagnostic check here? */
-    EHE_LOCK(list);
+    EHL_LOCK_ASSERT(list, MA_OWNED);
     if (ep != NULL) {
 	/* remove just this entry */
-	TAILQ_REMOVE(&list->el_entries, ep, ee_link);
-	free(ep, M_EVENTHANDLER);
+	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 */
-	while (!TAILQ_EMPTY(&list->el_entries)) {
-	    ep = TAILQ_FIRST(&list->el_entries);
+	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);
-	    free(ep, M_EVENTHANDLER);
+	    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;
 	}
     }
-    EHE_UNLOCK(list);
+    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)
 {
@@ -160,14 +210,31 @@ eventhandler_find_list(char *name)
     
     /* scan looking for the requested list */
     mtx_lock(&eventhandler_mutex);
-    for (list = TAILQ_FIRST(&eventhandler_lists); 
-	 list != NULL; 
-	 list = TAILQ_NEXT(list, el_link)) {
-	if (!strcmp(name, list->el_name))
-	    break;
-    }
+    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;
+    }
+}