From mboxrd@z Thu Jan  1 00:00:00 1970
From: Vlad Yasevich <vyasevic@redhat.com>
Subject: Re: [PATCH v2 net] net: Always untag vlan-tagged traffic on input.
Date: Mon, 29 Sep 2014 09:54:58 -0400
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References: <1407523333-31455-1-git-send-email-vyasevic@redhat.com> <54295449.7030203@6wind.com> <20140929130543.GB1839@nanopsycho.orion> <542962CF.6000602@6wind.com>
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Cc: netdev@vger.kernel.org, Patrick McHardy <kaber@trash.net>,
	Nithin Nayak Sujir <nsujir@broadcom.com>,
	Michael Chan <mchan@broadcom.com>
To: nicolas.dichtel@6wind.com, Jiri Pirko <jiri@resnulli.us>
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On 09/29/2014 09:46 AM, Nicolas Dichtel wrote:
> Le 29/09/2014 15:05, Jiri Pirko a =E9crit :
>> Mon, Sep 29, 2014 at 02:44:57PM CEST, nicolas.dichtel@6wind.com wrot=
e:
>>> Le 08/08/2014 20:42, Vladislav Yasevich a =E9crit :
>>> [snip]
>>>>
>>>> The patch attempt to fix this another way.  It moves the vlan head=
er
>>>> stipping code out of the vlan module and always builds it into the
>>>> kernel network core.  This way, even if vlan is not supported on
>>>> a virtualizatoin host, the virtual machines running on top of such
>>>> host will still work with VLANs enabled.
>>> After this patch (0d5501c1c828 ("net: Always untag vlan-tagged traf=
fic on
>>> input.")), tcpdump will not be able to display the VLAN header on i=
nput path.
>>> Is this really intended?
>>
>> I assume you are talking about the case when CONFIG_VLAN_8021Q is "n=
"
>> right? Because if it is "m" of "y" I see no change in the code.
> Right.
>=20
>>
>> In case of CONFIG_VLAN_8021Q is "n" the only change is that for
>> non-accelerated path, skb->vlan_tci is set and vlan header is stripp=
ed.
>> This makes the path same to accelerated path.
>>
>> tcpdump should be able to cope with skb->vlan_tci
> My fault, I've tested with a quite old tcpdump version, with a recent=
 one it
> works perfectly!

Thanks.   BTW,  did that old tcpdump version work correctly when CONFIG=
_VLAN_8021Q
was y or m?  My guess is that it would not.

-vlad

>=20
>=20
> Thank you,
> Nicolas