Index: sys/kern/kern_sx.c
===================================================================
RCS file: /private/FreeBSD/src/sys/kern/kern_sx.c,v
retrieving revision 1.21
diff -u -p -r1.21 kern_sx.c
--- sys/kern/kern_sx.c	28 Jan 2004 20:39:57 -0000	1.21
+++ sys/kern/kern_sx.c	3 Feb 2004 18:12:41 -0000
@@ -344,6 +344,17 @@ _sx_assert(struct sx *sx, int what, cons
 			    sx->sx_object.lo_name, file, line);
 		mtx_unlock(sx->sx_lock);
 		break;
+	case SX_UNLOCKED:
+#ifdef WITNESS
+		witness_assert(&sx->sx_object, what, file, line);
+#else
+		mtx_lock(sx->sx_lock);
+		if (sx->sx_cnt != 0 && sx->sx_xholder == curthread)
+			printf("Lock %s locked @ %s:%d\n",
+			    sx->sx_object.lo_name, file, line);
+		mtx_unlock(sx->sx_lock);
+#endif
+		break;
 	default:
 		panic("Unknown sx lock assertion: %d @ %s:%d", what, file,
 		    line);
Index: sys/sys/sx.h
===================================================================
RCS file: /private/FreeBSD/src/sys/sys/sx.h,v
retrieving revision 1.17
diff -u -p -r1.17 sx.h
--- sys/sys/sx.h	2 Apr 2002 18:18:56 -0000	1.17
+++ sys/sys/sx.h	3 Feb 2004 18:05:08 -0000
@@ -85,6 +85,7 @@ struct sx_args {
 #define	sx_downgrade(sx)	_sx_downgrade((sx), LOCK_FILE, LOCK_LINE)
 
 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT)
+#define	SX_UNLOCKED		LA_UNLOCKED
 #define	SX_LOCKED		LA_LOCKED
 #define	SX_SLOCKED		LA_SLOCKED
 #define	SX_XLOCKED		LA_XLOCKED
Index: share/man/man9/sx.9
===================================================================
RCS file: /private/FreeBSD/src/share/man/man9/sx.9,v
retrieving revision 1.25
diff -u -p -r1.25 sx.9
--- share/man/man9/sx.9	1 Jan 2004 05:16:35 -0000	1.25
+++ share/man/man9/sx.9	3 Feb 2004 18:15:10 -0000
@@ -136,7 +136,7 @@ for the assertions specified in
 .Ar what
 and panics if they are not met.
 The following assertions are supported:
-.Bl -tag -width ".Dv SX_XLOCKED"
+.Bl -tag -width ".Dv SX_UNLOCKED"
 .It Dv SX_LOCKED
 Assert that the current thread has either a shared or an exclusive lock on the
 .Vt sx
@@ -148,6 +148,11 @@ lock pointed to by
 the first argument.
 .It Dv SX_XLOCKED
 Assert that the current thread has an exclusive lock on the
+.Vt sx
+lock pointed to
+by the first argument.
+.It Dv SX_UNLOCKED
+Assert that the current thread has no lock on the
 .Vt sx
 lock pointed to
 by the first argument.