Should vlan_input() ever be called with ifp pointing to a non-Ethernet

interface, do not just assign -1 to tag because it breaks the logic of
the code to follow.  The better way is to handle this case as an unsupported
protocol and return unless INVARIANTS is in effect and we can panic.
Panic is good there because the scenario can happen only because of a
coding error elsewhere.

We also should show the interface name in the panic message for easier
debugging of the problem, should it ever emerge.

Submitted by:	qingli (initially)

1 files changed, 5 insertions, 4 deletions

diff --git a/sys/net/if_vlan.c b/sys/net/if_vlan.c
index 34ef7ee..9883066 100644
--- a/sys/net/if_vlan.c
+++ b/sys/net/if_vlan.c
@@ -926,12 +926,13 @@ vlan_input(struct ifnet *ifp, struct mbuf *m)
 			evl->evl_encap_proto = evl->evl_proto;
 			break;
 		default:
-			tag = (uint16_t) -1;
 #ifdef INVARIANTS
-			panic("%s: unsupported if_type (%u)",
-			      __func__, ifp->if_type);
+			panic("%s: %s has unsupported if_type %u",
+			      __func__, ifp->if_xname, ifp->if_type);
 #endif
-			break;
+			m_freem(m);
+			ifp->if_noproto++;
+			return;
 		}
 	}