--- kern_timeout.c.orig	Sun Jun 11 13:18:07 2006
+++ kern_timeout.c	Sun Jun 11 13:31:04 2006
@@ -45,6 +45,7 @@
 #include <sys/ktr.h>
 #include <sys/lock.h>
 #include <sys/mutex.h>
+#include <sys/sdt.h>
 #include <sys/proc.h>
 #include <sys/sysctl.h>

@@ -268,7 +269,9 @@
 				binuptime(&bt1);
 #endif
 				THREAD_NO_SLEEPING();
+				SDT_PROBE(kernel, callout, entry, c, 0, 0, 0, 0);
 				c_func(c_arg);
+				SDT_PROBE(kernel, callout, return, c, 0, 0, 0, 0);
 				THREAD_SLEEPING_OK();
 #ifdef DIAGNOSTIC
 				binuptime(&bt2);