From mboxrd@z Thu Jan  1 00:00:00 1970
From: =?ISO-8859-1?Q?Nicolas_de_Peslo=FCan?=
	<nicolas.2p.debian@gmail.com>
Subject: Re: [patch net-next-2.6] net: vlan: make non-hw-accel rx path similar
 to hw-accel
Date: Sun, 03 Apr 2011 11:27:29 +0200
Message-ID: <4D983D81.2020500@gmail.com>
References: <1301739966-7604-1-git-send-email-jpirko@redhat.com> <20110402085524.6692131a@nehalam> <20110402182711.GA11885@psychotron.redhat.com>
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Cc: Stephen Hemminger <shemminger@linux-foundation.org>,
	netdev@vger.kernel.org, davem@davemloft.net, kaber@trash.net,
	fubar@us.ibm.com, eric.dumazet@gmail.com, andy@greyhouse.net,
	xiaosuo@gmail.com, jesse@nicira.com
To: Jiri Pirko <jpirko@redhat.com>
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Le 02/04/2011 20:27, Jiri Pirko a =E9crit :
> Sat, Apr 02, 2011 at 05:55:24PM CEST, shemminger@linux-foundation.org=
 wrote:
>> On Sat,  2 Apr 2011 12:26:06 +0200
>> Jiri Pirko<jpirko@redhat.com>  wrote:
<snip>
>>> +	rawp =3D skb->data;
>>> +	if (*(unsigned short *) rawp =3D=3D 0xFFFF)
>>> +		/*
>>> +		 * This is a magic hack to spot IPX packets. Older Novell
>>> +		 * breaks the protocol design and runs IPX over 802.3 without
>>> +		 * an 802.2 LLC layer. We look for FFFF which isn't a used
>>> +		 * 802.2 SSAP/DSAP. This won't work for fault tolerant netware
>>> +		 * but does for the rest.
>>> +		 */
>>> +		skb->protocol =3D htons(ETH_P_802_3);
>>> +	else
>>> +		/*
>>> +		 * Real 802.2 LLC
>>> +		 */
>>> +		skb->protocol =3D htons(ETH_P_802_2);
>>> +}
>>
>> What about doublely tagged packets?
>
> No problem. Once they are untagged and reinjected they are untagged
> again and reinjected again:
>
> ->  __netif_reveive_skb
> vlan_untag
> vlan_do_receive
> ->  __netif_receive_skb
> vlan_untag
> vlan_do_receive

Hi Jiri,

Instead of untagging and reinjecting, wouldn't it be possible to remove=
 all 802.1Q headers in a loop=20
and directly deliver the untagged skb? Are there any hw-accel implement=
ations that remove several=20
level of tagging?

	Nicolas.