- Convert the per-eventhandler list mutex to a lockmgr lock so that it can

  be safely held across an eventhandler function call.
- Fix an instance of the head of an eventhandler list being read without
  the lock being held.
- Break down and use a SYSINIT at the new SI_SUB_EVENTHANDLER to initialize
  the eventhandler global mutex and the eventhandler list of lists rather
  than using a non-MP safe initialization during the first call to
  eventhandler_register().
- Add in a KASSERT() to eventhandler_register() to ensure that we don't try
  to register an eventhandler before things have been initialized.

3 files changed, 29 insertions, 21 deletions

diff --git a/sys/kern/subr_eventhandler.c b/sys/kern/subr_eventhandler.c
index 417d73e..ca35a05 100644
--- a/sys/kern/subr_eventhandler.c
+++ b/sys/kern/subr_eventhandler.c
@@ -29,6 +29,7 @@
 #include <sys/param.h>
 #include <sys/kernel.h>
 #include <sys/malloc.h>
+#include <sys/mutex.h>
 #include <sys/systm.h>
 #include <sys/eventhandler.h>
 
@@ -45,6 +46,19 @@ struct eventhandler_entry_generic
     void			(* func)(void);
 };
 
+/*
+ * Initialize the eventhandler mutex and list.
+ */
+static void
+eventhandler_init(void *dummy __unused)
+{
+    TAILQ_INIT(&eventhandler_lists);
+    mtx_init(&eventhandler_mutex, "eventhandler", MTX_DEF);
+    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.
@@ -56,12 +70,7 @@ eventhandler_register(struct eventhandler_list *list, char *name,
     struct eventhandler_entry_generic	*eg;
     struct eventhandler_entry		*ep;
     
-    /* 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;
-    }
+    KASSERT(eventhandler_lists_initted, ("eventhandler registered too early"));
 
     /* lock the eventhandler lists */
     mtx_enter(&eventhandler_mutex, MTX_DEF);
@@ -86,7 +95,7 @@ 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);
+	lockinit(&list->el_lock, PZERO, name, 0, 0);
 	list->el_flags = EHE_INITTED;
     }
     
@@ -101,7 +110,7 @@ eventhandler_register(struct eventhandler_list *list, char *name,
     eg->ee.ee_priority = priority;
     
     /* sort it into the list */
-    mtx_enter(&list->el_mutex, MTX_DEF);
+    lockmgr(&list->el_lock, LK_EXCLUSIVE, NULL, CURPROC);
     for (ep = TAILQ_FIRST(&list->el_entries);
 	 ep != NULL; 
 	 ep = TAILQ_NEXT(ep, ee_link)) {
@@ -112,7 +121,7 @@ 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);
+    lockmgr(&list->el_lock, LK_RELEASE, NULL, CURPROC);
     mtx_exit(&eventhandler_mutex, MTX_DEF);
     return(&eg->ee);
 }
@@ -123,7 +132,7 @@ 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);
+    lockmgr(&list->el_lock, LK_EXCLUSIVE, NULL, CURPROC);
     if (ep != NULL) {
 	/* remove just this entry */
 	TAILQ_REMOVE(&list->el_entries, ep, ee_link);
@@ -136,7 +145,7 @@ eventhandler_deregister(struct eventhandler_list *list, eventhandler_tag tag)
 	    free(ep, M_EVENTHANDLER);
 	}
     }
-    mtx_exit(&list->el_mutex, MTX_DEF);
+    lockmgr(&list->el_lock, LK_RELEASE, NULL, CURPROC);
 }
 
 struct eventhandler_list *
diff --git a/sys/sys/eventhandler.h b/sys/sys/eventhandler.h
index 4a1e01a..1c011e2 100644
--- a/sys/sys/eventhandler.h
+++ b/sys/sys/eventhandler.h
@@ -30,7 +30,7 @@
 #define SYS_EVENTHANDLER_H
 
 #include <sys/queue.h>
-#include <sys/mutex.h>
+#include <sys/lock.h>
 
 struct eventhandler_entry 
 {
@@ -44,7 +44,7 @@ struct eventhandler_list
     char				*el_name;
     int					el_flags;
 #define EHE_INITTED	(1<<0)
-    struct mtx				el_mutex;
+    struct lock				el_lock;
     TAILQ_ENTRY(eventhandler_list)	el_link;
     TAILQ_HEAD(,eventhandler_entry)	el_entries;
 };
@@ -77,18 +77,18 @@ struct __hack
 #define EVENTHANDLER_FAST_INVOKE(name, args...)					\
 do {										\
     struct eventhandler_list *_el = &Xeventhandler_list_ ## name ;		\
-    struct eventhandler_entry *_ep = TAILQ_FIRST(&(_el->el_entries));		\
-    struct eventhandler_entry *_en;						\
+    struct eventhandler_entry *_ep, *_en;					\
 										\
     if (_el->el_flags & EHE_INITTED) {						\
+	lockmgr(&_el->el_lock, LK_EXCLUSIVE, NULL, CURPROC);			\
+	_ep = TAILQ_FIRST(&(_el->el_entries));					\
 	while (_ep != NULL) {							\
-	    mtx_enter(&_el->el_mutex, MTX_DEF);					\
 	    _en = TAILQ_NEXT(_ep, ee_link);					\
-	    mtx_exit(&_el->el_mutex, MTX_DEF);					\
 	    ((struct eventhandler_entry_ ## name *)_ep)->eh_func(_ep->ee_arg , 	\
 								 ## args); 	\
 	    _ep = _en;								\
 	}									\
+	lockmgr(&_el->el_lock, LK_RELEASE, NULL, CURPROC);			\
     }										\
 } while (0)
 
@@ -120,17 +120,15 @@ do {										\
 										\
     if (((_el = eventhandler_find_list(#name)) != NULL) && 			\
 	(_el->el_flags & EHE_INITTED)) {					\
-	mtx_enter(&_el->el_mutex, MTX_DEF);					\
+	lockmgr(&_el->el_lock, LK_EXCLUSIVE, NULL, CURPROC);			\
 	_ep = TAILQ_FIRST(&(_el->el_entries));					\
-	mtx_exit(&_el->el_mutex, MTX_DEF);					\
 	while (_ep != NULL) {							\
-	    mtx_enter(&_el->el_mutex, MTX_DEF);					\
 	    _en = TAILQ_NEXT(_ep, ee_link);					\
-	    mtx_exit(&_el->el_mutex, MTX_DEF);					\
 	    ((struct eventhandler_entry_ ## name *)_ep)->eh_func(_ep->ee_arg , 	\
 								 ## args); 	\
 	    _ep = _en;								\
 	}									\
+	lockmgr(&_el->el_lock, LK_RELEASE, NULL, CURPROC);			\
     }										\
 } while (0)
 
diff --git a/sys/sys/kernel.h b/sys/sys/kernel.h
index 7d1f57c..7474b42 100644
--- a/sys/sys/kernel.h
+++ b/sys/sys/kernel.h
@@ -114,6 +114,7 @@ enum sysinit_sub_id {
 	SI_SUB_KMEM		= 0x1800000,	/* kernel memory*/
 	SI_SUB_KVM_RSRC		= 0x1A00000,	/* kvm operational limits*/
 	SI_SUB_LOCK		= 0x1B00000,	/* lockmgr locks */
+	SI_SUB_EVENTHANDLER	= 0x1C00000,	/* eventhandler init */
 	SI_SUB_CPU		= 0x2000000,	/* CPU resource(s)*/
 	SI_SUB_KLD		= 0x2100000,	/* KLD and module setup */
 	SI_SUB_INTRINSIC	= 0x2200000,	/* proc 0*/