Index: if.c
===================================================================
RCS file: /cvs/src/sys/net/if.c,v
retrieving revision 1.552
diff -u -p -r1.552 if.c
--- if.c	17 May 2018 11:04:14 -0000	1.552
+++ if.c	29 May 2018 23:46:40 -0000
@@ -2112,13 +2112,12 @@ ifioctl(struct socket *so, u_long cmd, c
 	case SIOCSIFLLPRIO:
 		if ((error = suser(p)))
 			break;
-		if (ifr->ifr_llprio > UCHAR_MAX) {
+		if (ifr->ifr_llprio < IFQ_MINPRIO ||
+		    ifr->ifr_llprio > IFQ_MAXPRIO) {
 			error = EINVAL;
 			break;
 		}
-		NET_LOCK();
 		ifp->if_llprio = ifr->ifr_llprio;
-		NET_UNLOCK();
 		break;
 
 	case SIOCSETKALIVE:
Index: if.h
===================================================================
RCS file: /cvs/src/sys/net/if.h,v
retrieving revision 1.193
diff -u -p -r1.193 if.h
--- if.h	25 Apr 2018 16:05:58 -0000	1.193
+++ if.h	29 May 2018 23:46:40 -0000
@@ -126,6 +126,7 @@ struct	if_data {
 };
 
 #define IFQ_NQUEUES	8
+#define IFQ_MINPRIO	0
 #define IFQ_MAXPRIO	IFQ_NQUEUES - 1
 #define IFQ_DEFPRIO	3