From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <4B0BB2A7.5040707@trash.net>
Date: Tue, 24 Nov 2009 11:17:11 +0100
From: Patrick McHardy <kaber@trash.net>
MIME-Version: 1.0
References: <1259024166-28158-1-git-send-email-arnd@arndb.de>
	<1259024166-28158-2-git-send-email-arnd@arndb.de>
	<4B0BAC97.6010000@trash.net> <200911241002.20904.arnd@arndb.de>
In-Reply-To: <200911241002.20904.arnd@arndb.de>
Content-Type: text/plain; charset=ISO-8859-15
Content-Transfer-Encoding: 7bit
Subject: Re: [Bridge] [PATCH 1/4] veth: move loopback logic to common
	location
List-Id: Linux Ethernet Bridging <bridge.lists.linux-foundation.org>
List-Unsubscribe: <https://lists.linux-foundation.org/mailman/listinfo/bridge>, 
	<mailto:bridge-request@lists.linux-foundation.org?subject=unsubscribe>
List-Archive: <http://lists.linux-foundation.org/pipermail/bridge>
List-Post: <mailto:bridge@lists.linux-foundation.org>
List-Help: <mailto:bridge-request@lists.linux-foundation.org?subject=help>
List-Subscribe: <https://lists.linux-foundation.org/mailman/listinfo/bridge>, 
	<mailto:bridge-request@lists.linux-foundation.org?subject=subscribe>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Herbert Xu <herbert@gondor.apana.org.au>, Eric Dumazet <eric.dumazet@gmail.com>, Anna Fischer <anna.fischer@hp.com>, netdev@vger.kernel.org, bridge@lists.linux-foundation.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Mark Smith <lk-netdev@lk-netdev.nosense.org>, Gerhard Stenzel <gerhard.stenzel@de.ibm.com>, "Eric W. Biederman" <ebiederm@xmission.com>, Jens Osterkamp <jens@linux.vnet.ibm.com>, Patrick Mullaney <pmullaney@novell.com>, Stephen Hemminger <shemminger@vyatta.com>, Edge Virtual Bridging <evb@yahoogroups.com>, David Miller <davem@davemloft.net>

Arnd Bergmann wrote:
> On Tuesday 24 November 2009 09:51:19 Patrick McHardy wrote:
>>> +     skb_dst_drop(skb);
>>> +     skb->tstamp.tv64 = 0;
>>> +     skb->pkt_type = PACKET_HOST;
>>> +     skb->protocol = eth_type_trans(skb, dev);
>>> +     skb->mark = 0;
>> skb->mark clearing should stay private to veth since its usually
>> supposed to stay intact. The only exception is packets crossing
>> namespaces, where they should appear like a freshly received skbs.
> 
> But isn't that what we want in macvlan as well when we're
> forwarding from one downstream interface to another?

In the TX direction you can use the mark for TC classification
on the underlying device.

> I did all my testing with macvlan interfaces in separate namespaces
> communicating with each other, so I'd assume that we should always
> clear skb->mark and skb->dst in this function.

Good point, in that case we probably should clear it as well. But
in the non-namespace case the TC classification currently works and
this is consistent with any other virtual device driver, so it
should continue to work.