Index: if.c
===================================================================
RCS file: /cvs/src/sys/net/if.c,v
retrieving revision 1.473
diff -u -p -r1.473 if.c
--- if.c	4 Jan 2017 03:56:15 -0000	1.473
+++ if.c	10 Jan 2017 00:26:47 -0000
@@ -1806,9 +1806,16 @@ ifioctl(struct socket *so, u_long cmd, c
 		ifp->if_flags = (ifp->if_flags & IFF_CANTCHANGE) |
 			(ifr->ifr_flags & ~IFF_CANTCHANGE);
 
+		/*
+		 * XXX: If if_ioctl is not set, or it is but returns ENOTTY
+		 * because SIOCSIFFLAGS isn't handled by the driver,
+		 * IFF_RUNNING will not end up set.
+		 */
 		if (ifp->if_ioctl != NULL) {
 			error = (*ifp->if_ioctl)(ifp, cmd, data);
-			if (error != 0) {
+			if (error == ENOTTY)
+				error = 0;
+			else if (error != 0) {
 				ifp->if_flags = oif_flags;
 				break;
 			}