From mboxrd@z Thu Jan 1 00:00:00 1970 From: Patrick McHardy Subject: Re: [PATCH v2 net] vlan: Mask off vlan acceleration features on vlan device. Date: Thu, 27 Mar 2014 08:14:26 +0000 Message-ID: <20140327081425.GA2479@macbook.localnet> References: <1395865521-2318-1-git-send-email-vyasevic@redhat.com> <1395865711-3347-1-git-send-email-vyasevic@redhat.com> <20140326.171038.2150319831233512825.davem@davemloft.net> <20140326211504.GA21393@macbook.localnet> <53337678.9050208@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: David Miller , netdev@vger.kernel.org To: Vlad Yasevich Return-path: Received: from stinky.trash.net ([213.144.137.162]:42178 "EHLO stinky.trash.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753781AbaC0IOb (ORCPT ); Thu, 27 Mar 2014 04:14:31 -0400 Content-Disposition: inline In-Reply-To: <53337678.9050208@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, Mar 26, 2014 at 08:53:12PM -0400, Vlad Yasevich wrote: > On 03/26/2014 05:15 PM, Patrick McHardy wrote: > > On Wed, Mar 26, 2014 at 05:10:38PM -0400, David Miller wrote: > >> From: Vlad Yasevich > >> Date: Wed, 26 Mar 2014 16:28:31 -0400 > >> > >>> Some drivers incorrectly assign vlan acceleration features to > >>> vlan_features thus causing issues for Q-in-Q vlan configurations. > >>> Prevent this once and for all by masking off acceleration features > >>> for vlan devices until such time as we support stacked acceleration. > >>> > >>> Signed-off-by: Vlad Yasevich > >> > >> So what if we do have chips that can offload Q-in-Q? Will we use > >> a new flag? > > > > For 802.1ad that was the intention, using the NETIF_F_HW_VLAN_STAG_* flags. > > > > But we can't really do that as we don't carry multiple vlan_tci in the > skb. If the card advertises VLAN_STAG_*, then we'll offload that, but > CTAG will have to be computed by software. More infrastructure is > needed to support nested vlan offloads. True, we'd need more room in the skb to store both tags for Q-in-Q.