From 8a706a29fc9feeed5fb10e87d7b2a8f8ce6e21a4 Mon Sep 17 00:00:00 2001
From: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Date: Mon, 22 Dec 2014 19:04:14 +0900
Subject: [PATCH] net: Fix stacked vlan offload features computation

commit 796f2da81bead71ffc91ef70912cd8d1827bf756 upstream.

When vlan tags are stacked, it is very likely that the outer tag is stored
in skb->vlan_tci and skb->protocol shows the inner tag's vlan_proto.
Currently netif_skb_features() first looks at skb->protocol even if there
is the outer tag in vlan_tci, thus it incorrectly retrieves the protocol
encapsulated by the inner vlan instead of the inner vlan protocol.
This allows GSO packets to be passed to HW and they end up being
corrupted.

Fixes: 58e998c6d239 ("offloading: Force software GSO for multiple vlan tags.")
Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.2:
 - We don't support 802.1ad tag offload
 - Keep passing protocol to harmonize_features()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
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