From 663f556b03a86b66ce6a9af1edf229ef74775676 Mon Sep 17 00:00:00 2001
From: Kristof Provost <kp@FreeBSD.org>
Date: Tue, 19 Jul 2022 00:23:50 +0200
Subject: [PATCH] if_vlan: allow vlan and vlanproto to be changed

It's currently not possible to change the vlan ID or vlan protocol (i.e.
802.1q vs. 802.1ad) without de-configuring the interface (i.e. ifconfig
vlanX -vlandev).
Add a specific flow for this, allowing both the protocol and id (but not
parent interface) to be changed without going through the '-vlandev'
step.

Reviewed by:	glebius
Sponsored by:	Rubicon Communications, LLC ("Netgate")
Differential Revision:	https://reviews.freebsd.org/D35846
---
 sys/net/if_vlan.c | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/sys/net/if_vlan.c b/sys/net/if_vlan.c
index f8af0fd3d915..03a06f09c541 100644
--- a/sys/net/if_vlan.c
+++ b/sys/net/if_vlan.c
@@ -1538,8 +1538,24 @@ vlan_config(struct ifvlan *ifv, struct ifnet *p, uint16_t vid,
 	 */
 	if (vid == 0 || vid == 0xFFF || (vid & ~EVL_VLID_MASK))
 		return (EINVAL);
-	if (ifv->ifv_trunk)
-		return (EBUSY);
+	if (ifv->ifv_trunk) {
+		trunk = ifv->ifv_trunk;
+		if (trunk->parent != p)
+			return (EBUSY);
+
+		VLAN_XLOCK();
+
+		ifv->ifv_proto = proto;
+
+		if (ifv->ifv_vid != vid) {
+			/* Re-hash */
+			vlan_remhash(trunk, ifv);
+			ifv->ifv_vid = vid;
+			error = vlan_inshash(trunk, ifv);
+		}
+		/* Will unlock */
+		goto done;
+	}
 
 	VLAN_XLOCK();
 	if (p->if_vlantrunk == NULL) {