Make it possible to set a larger MTU by attempting to set MTUs on all

trunk ports first.  If that succeeds, and we're inside our own bounds,
so be it.

Still not ideal -- adding a port after changing an MTU doesn't change
port's MTU, but a step in the right direction.

PR:		kern/95417
Submitted by:	Vladimir Ivanov <wawa AT yandex-team DOT ru>
MFC after:	3 days

I've slightly edited a patch to make the conditional logic positive
and remove (what I think was) a redundant ng_fec_init() call.

1 files changed, 19 insertions, 1 deletions

diff --git a/sys/netgraph/ng_fec.c b/sys/netgraph/ng_fec.c
index 972a00a..e47abab 100644
--- a/sys/netgraph/ng_fec.c
+++ b/sys/netgraph/ng_fec.c
@@ -694,10 +694,28 @@ ng_fec_ioctl(struct ifnet *ifp, u_long command, caddr_t data)
 	/* These two are mostly handled at a higher layer */
 	case SIOCSIFADDR:
 	case SIOCGIFADDR:
-	case SIOCSIFMTU:
 		error = ether_ioctl(ifp, command, data);
 		break;
 
+	case SIOCSIFMTU:
+		if (ifr->ifr_mtu >= NG_FEC_MTU_MIN &&
+		    ifr->ifr_mtu <= NG_FEC_MTU_MAX) {
+			struct ng_fec_portlist *p;
+			struct ifnet *bifp;
+
+			TAILQ_FOREACH(p, &b->ng_fec_ports, fec_list) {
+				bifp = p->fec_if;
+				error = (*bifp->if_ioctl)(bifp, SIOCSIFMTU,
+				    data);
+				if (error != 0)
+					break;
+			}
+			if (error == 0)
+				ifp->if_mtu = ifr->ifr_mtu;
+		} else
+			error = EINVAL;
+		break;
+
 	/* Set flags */
 	case SIOCSIFFLAGS:
 		/*