netdev - RE: [Intel-wired-lan] [RFC PATCH net] e1000e: keep vlan interfaces functional after rxvlan off

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Message-ID: <36CDDD56DDB4D44E911123902EFC26B05B53DC0B@HASMSX110.ger.corp.intel.com>
Date:	Wed, 1 Jun 2016 08:56:34 +0000
From:	"Ruinskiy, Dima" <dima.ruinskiy@...el.com>
To:	"Brown, Aaron F" <aaron.f.brown@...el.com>,
	"Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>,
	Jarod Wilson <jarod@...hat.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Avargil, Raanan" <raanan.avargil@...el.com>
CC:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"intel-wired-lan@...ts.osuosl.org" <intel-wired-lan@...ts.osuosl.org>
Subject: RE: [Intel-wired-lan] [RFC PATCH net] e1000e: keep vlan interfaces
 functional after rxvlan off

>-----Original Message-----
>From: Intel-wired-lan [mailto:intel-wired-lan-bounces@...ts.osuosl.org] On
>Behalf Of Brown, Aaron F
>Sent: Friday, 27 May, 2016 04:31
>To: Kirsher, Jeffrey T; Jarod Wilson; linux-kernel@...r.kernel.org; Avargil,
>Raanan
>Cc: netdev@...r.kernel.org; intel-wired-lan@...ts.osuosl.org
>Subject: Re: [Intel-wired-lan] [RFC PATCH net] e1000e: keep vlan interfaces
>functional after rxvlan off
>
>> From: Intel-wired-lan
>> [mailto:intel-wired-lan-bounces@...ts.osuosl.org] On Behalf Of Jeff
>> Kirsher
>> Sent: Wednesday, May 18, 2016 2:40 PM
>> To: Jarod Wilson <jarod@...hat.com>; linux-kernel@...r.kernel.org;
>> Avargil, Raanan <raanan.avargil@...el.com>
>> Cc: netdev@...r.kernel.org; intel-wired-lan@...ts.osuosl.org
>> Subject: Re: [Intel-wired-lan] [RFC PATCH net] e1000e: keep vlan
>> interfaces functional after rxvlan off
>>
>> On Tue, 2016-05-17 at 15:03 -0400, Jarod Wilson wrote:
>> > I've got a bug report about an e1000e interface, where a vlan
>> > interface is set up on top of it:
>> >
>> > $ ip link add link ens1f0 name ens1f0.99 type vlan id 99 $ ip link
>> > set ens1f0 up $ ip link set ens1f0.99 up $ ip addr add 192.168.99.92
>> > dev ens1f0.99
>> >
>> > At this point, I can ping another host on vlan 99, ip 192.168.99.91.
>> > However, if I do the following:
>> >
>> > $ ethtool -K ens1f0 rxvlan off
>> >
>> > Then no traffic passes on ens1f0.99. It comes back if I toggle
>> > rxvlan on again. I'm not sure if this is actually intended behavior,
>> > or if there's a lack of software vlan stripping fallback, or what,
>> > but things continue to work if I simply don't call
>> > e1000e_vlan_strip_disable() if there are active vlans (plagiarizing
>> > a function from the e1000 driver here) on the interface.
>> >
>> > Also slipped a related-ish fix to the kerneldoc text for
>> > e1000e_vlan_strip_disable here...
>> >
>> > CC: Jeff Kirsher <jeffrey.t.kirsher@...el.com>
>> > CC: intel-wired-lan@...ts.osuosl.org
>> > CC: netdev@...r.kernel.org
>> > Signed-off-by: Jarod Wilson <jarod@...hat.com>
>> > ---
>> >  drivers/net/ethernet/intel/e1000e/netdev.c | 15 +++++++++++++--
>> >  1 file changed, 13 insertions(+), 2 deletions(-)
>>
>> Raanan, please review this patch.  Even though it is an RFC I will be
>> adding it to my queue for testing.
>> http://patchwork.ozlabs.org/patch/623238/
>
>Yup, without this patch disabling rxvlan offload does indeed break vlan
>connectivity and with the patch I can disable and re-enable rxvlan offloads as
>much as I care to.  It also makes it through my regression tests without
>problems.

Well, what the patch essentially does is block disabling RX VLAN stripping
if any VLANs are active, so there is nothing surprising there. You are
essentially running with VLAN offloads enabled all the time. :)

>
>Tested-by: Aaron Brown <aaron.f.brown@...el.com>
>
>This is from functional - does it work - testing perspective so review is
>probably still in order.

I am not sure if this behavior is by design or not, and whether un-stripped
VLAN traffic is being blocked by the HW, the driver or the stack.

I have two questions:
1) Does the unpatched behavior change if promiscuous RX is set in the HW?
2) Is the behavior different in other devices (igb, ixgbe)?
Do they allow VLAN traffic to pass even if VLAN offloads are disabled?

I believe that the e1000e behavior should be consistent with other devices,
whatever that behavior is.
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