From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Hemminger <shemminger@vyatta.com>
Subject: [PATCH] vlan: propogate MTU changes
Date: Mon, 6 Oct 2008 17:30:24 +0200
Message-ID: <20081006173024.2741cc01@speedy>
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Cc: netdev@vger.kernel.org
To: Patrick McHardy <kaber@trash.net>,
	"David S. Miller" <davem@davemloft.net>
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Propogate MTU changes of underlying device to all related VLAN
devices.
see: https://bugzilla.vyatta.com/show_bug.cgi?id=3742

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
---
There might be some discussion about whether to preserve MTU changes
on the vlan device if done after startup, but this seems like the best,
most direct fix.

--- a/net/8021q/vlan.c	2008-10-06 17:03:58.000000000 +0200
+++ b/net/8021q/vlan.c	2008-10-06 17:08:33.000000000 +0200
@@ -477,6 +477,17 @@ static int vlan_device_event(struct noti
 
 		break;
 
+	case NETDEV_CHANGEMTU:
+		/* Propogate MTU of underlying device */
+		for (i = 0; i < VLAN_GROUP_ARRAY_LEN; i++) {
+			vlandev = vlan_group_get_device(grp, i);
+			if (!vlandev)
+				continue;
+
+			vlandev->mtu = dev->mtu;
+		}
+		break;
+
 	case NETDEV_DOWN:
 		/* Put all VLANs for this dev in the down state too.  */
 		for (i = 0; i < VLAN_GROUP_ARRAY_LEN; i++) {