Patchwork [net] veth: Fix vlan_features so as to be able to use stacked vlan interfaces

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Submitter Toshiaki Makita
Date Feb. 18, 2014, 12:20 p.m.
Message ID <1392726009-8083-1-git-send-email-makita.toshiaki@lab.ntt.co.jp>
Download mbox | patch
Permalink /patch/321427/
State Accepted
Delegated to: David Miller
Headers show

Comments

Toshiaki Makita - Feb. 18, 2014, 12:20 p.m.
Even if we create a stacked vlan interface such as veth0.10.20, it sends
single tagged frames (tagged with only vid 10).
Because vlan_features of a veth interface has the
NETIF_F_HW_VLAN_[CTAG/STAG]_TX bits, veth0.10 also has that feature, so
dev_hard_start_xmit(veth0.10) doesn't call __vlan_put_tag() and
vlan_dev_hard_start_xmit(veth0.10) overwrites vlan_tci.
This prevents us from using a combination of 802.1ad and 802.1Q
in containers, etc.

Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
---
 drivers/net/veth.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
Flavio Leitner - Feb. 19, 2014, 4:13 a.m.
On Tue, Feb 18, 2014 at 09:20:08PM +0900, Toshiaki Makita wrote:
> Even if we create a stacked vlan interface such as veth0.10.20, it sends
> single tagged frames (tagged with only vid 10).
> Because vlan_features of a veth interface has the
> NETIF_F_HW_VLAN_[CTAG/STAG]_TX bits, veth0.10 also has that feature, so
> dev_hard_start_xmit(veth0.10) doesn't call __vlan_put_tag() and
> vlan_dev_hard_start_xmit(veth0.10) overwrites vlan_tci.
> This prevents us from using a combination of 802.1ad and 802.1Q
> in containers, etc.
> 
> Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
> ---
>  drivers/net/veth.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/veth.c b/drivers/net/veth.c
> index 2ec2041..5b37437 100644
> --- a/drivers/net/veth.c
> +++ b/drivers/net/veth.c
> @@ -285,7 +285,8 @@ static void veth_setup(struct net_device *dev)
>  	dev->ethtool_ops = &veth_ethtool_ops;
>  	dev->features |= NETIF_F_LLTX;
>  	dev->features |= VETH_FEATURES;
> -	dev->vlan_features = dev->features;
> +	dev->vlan_features = dev->features &
> +			     ~(NETIF_F_HW_VLAN_CTAG_TX | NETIF_F_HW_VLAN_STAG_TX);
>  	dev->destructor = veth_dev_free;
>  
>  	dev->hw_features = VETH_FEATURES;
> -- 
> 1.8.1.2
> 

Why that isn't a problem with another software device?
Although this patch might fix the issue, it seems to me that
the middle devices shouldn't use the same feature flags.
I mean, vlan.20 should add the header, then vlan.10 should
offload the tag to veth.  Otherwise, for any vlan on top of
veth there will be an unneeded memmove().

fbl
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Toshiaki Makita - Feb. 19, 2014, 5:22 a.m.
(2014/02/19 13:13), Flavio Leitner wrote:
> On Tue, Feb 18, 2014 at 09:20:08PM +0900, Toshiaki Makita wrote:
>> Even if we create a stacked vlan interface such as veth0.10.20, it sends
>> single tagged frames (tagged with only vid 10).
>> Because vlan_features of a veth interface has the
>> NETIF_F_HW_VLAN_[CTAG/STAG]_TX bits, veth0.10 also has that feature, so
>> dev_hard_start_xmit(veth0.10) doesn't call __vlan_put_tag() and
>> vlan_dev_hard_start_xmit(veth0.10) overwrites vlan_tci.
>> This prevents us from using a combination of 802.1ad and 802.1Q
>> in containers, etc.
>>
>> Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
>> ---
>>  drivers/net/veth.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/veth.c b/drivers/net/veth.c
>> index 2ec2041..5b37437 100644
>> --- a/drivers/net/veth.c
>> +++ b/drivers/net/veth.c
>> @@ -285,7 +285,8 @@ static void veth_setup(struct net_device *dev)
>>  	dev->ethtool_ops = &veth_ethtool_ops;
>>  	dev->features |= NETIF_F_LLTX;
>>  	dev->features |= VETH_FEATURES;
>> -	dev->vlan_features = dev->features;
>> +	dev->vlan_features = dev->features &
>> +			     ~(NETIF_F_HW_VLAN_CTAG_TX | NETIF_F_HW_VLAN_STAG_TX);
>>  	dev->destructor = veth_dev_free;
>>  
>>  	dev->hw_features = VETH_FEATURES;
>> -- 
>> 1.8.1.2
>>
> 
> Why that isn't a problem with another software device?
> Although this patch might fix the issue, it seems to me that
> the middle devices shouldn't use the same feature flags.
> I mean, vlan.20 should add the header, then vlan.10 should
> offload the tag to veth.  Otherwise, for any vlan on top of
> veth there will be an unneeded memmove().

In this case with this patch, vlan_dev_hard_start_xmit(veth0.10.20) set
vlan_tci, dev_hard_start_xmit(veth0.10) put it into skb->data, and
vlan_dev_hard_start_xmit(veth0.10) set vlan_tci again.
dev_hard_start_xmit(veth0) doesn't put it into skb->data because veth0
has NETIF_F_HW_VLAN_*TAG_TX feature.

Similarly, in not stacked vlan case, for example if veth0.10 has no vlan
intarface on it, vlan_dev_hard_start_xmit(veth0.10) set vlan_tci and
dev_hard_start_xmit(veth0) doesn't put it into skb->data.
There will be no unnecessary memmove().

Although I haven't looked over all, other drivers don't seem to have
NETIF_F_HW_VLAN_*TAG_TX in vlan_features (at least, bridge, vxlan,
e1000e, and bnx2x don't).

Thanks,
Toshiaki Makita
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Flavio Leitner - Feb. 20, 2014, 1:02 a.m.
On Wed, Feb 19, 2014 at 02:22:06PM +0900, Toshiaki Makita wrote:
> (2014/02/19 13:13), Flavio Leitner wrote:
> > On Tue, Feb 18, 2014 at 09:20:08PM +0900, Toshiaki Makita wrote:
> >> Even if we create a stacked vlan interface such as veth0.10.20, it sends
> >> single tagged frames (tagged with only vid 10).
> >> Because vlan_features of a veth interface has the
> >> NETIF_F_HW_VLAN_[CTAG/STAG]_TX bits, veth0.10 also has that feature, so
> >> dev_hard_start_xmit(veth0.10) doesn't call __vlan_put_tag() and
> >> vlan_dev_hard_start_xmit(veth0.10) overwrites vlan_tci.
> >> This prevents us from using a combination of 802.1ad and 802.1Q
> >> in containers, etc.
> >>
> >> Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
> >> ---
> >>  drivers/net/veth.c | 3 ++-
> >>  1 file changed, 2 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/net/veth.c b/drivers/net/veth.c
> >> index 2ec2041..5b37437 100644
> >> --- a/drivers/net/veth.c
> >> +++ b/drivers/net/veth.c
> >> @@ -285,7 +285,8 @@ static void veth_setup(struct net_device *dev)
> >>  	dev->ethtool_ops = &veth_ethtool_ops;
> >>  	dev->features |= NETIF_F_LLTX;
> >>  	dev->features |= VETH_FEATURES;
> >> -	dev->vlan_features = dev->features;
> >> +	dev->vlan_features = dev->features &
> >> +			     ~(NETIF_F_HW_VLAN_CTAG_TX | NETIF_F_HW_VLAN_STAG_TX);
> >>  	dev->destructor = veth_dev_free;
> >>  
> >>  	dev->hw_features = VETH_FEATURES;
> >> -- 
> >> 1.8.1.2
> >>
> > 
> > Why that isn't a problem with another software device?
> > Although this patch might fix the issue, it seems to me that
> > the middle devices shouldn't use the same feature flags.
> > I mean, vlan.20 should add the header, then vlan.10 should
> > offload the tag to veth.  Otherwise, for any vlan on top of
> > veth there will be an unneeded memmove().
> 
> In this case with this patch, vlan_dev_hard_start_xmit(veth0.10.20) set
> vlan_tci, dev_hard_start_xmit(veth0.10) put it into skb->data, and
> vlan_dev_hard_start_xmit(veth0.10) set vlan_tci again.
> dev_hard_start_xmit(veth0) doesn't put it into skb->data because veth0
> has NETIF_F_HW_VLAN_*TAG_TX feature.
> 
> Similarly, in not stacked vlan case, for example if veth0.10 has no vlan
> intarface on it, vlan_dev_hard_start_xmit(veth0.10) set vlan_tci and
> dev_hard_start_xmit(veth0) doesn't put it into skb->data.
> There will be no unnecessary memmove().
> 
> Although I haven't looked over all, other drivers don't seem to have
> NETIF_F_HW_VLAN_*TAG_TX in vlan_features (at least, bridge, vxlan,
> e1000e, and bnx2x don't).
> 
> Thanks,
> Toshiaki Makita
> 

Alright, the code looks good and I didn't notice anything
different on my testing env.

Acked-by: Flavio Leitner <fbl@redhat.com>

Thanks!
fbl
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David Miller - Feb. 20, 2014, 7:16 a.m.
From: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Date: Tue, 18 Feb 2014 21:20:08 +0900

> Even if we create a stacked vlan interface such as veth0.10.20, it sends
> single tagged frames (tagged with only vid 10).
> Because vlan_features of a veth interface has the
> NETIF_F_HW_VLAN_[CTAG/STAG]_TX bits, veth0.10 also has that feature, so
> dev_hard_start_xmit(veth0.10) doesn't call __vlan_put_tag() and
> vlan_dev_hard_start_xmit(veth0.10) overwrites vlan_tci.
> This prevents us from using a combination of 802.1ad and 802.1Q
> in containers, etc.
> 
> Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>

Applied and queued up for -stable.
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Patch

diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index 2ec2041..5b37437 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -285,7 +285,8 @@  static void veth_setup(struct net_device *dev)
 	dev->ethtool_ops = &veth_ethtool_ops;
 	dev->features |= NETIF_F_LLTX;
 	dev->features |= VETH_FEATURES;
-	dev->vlan_features = dev->features;
+	dev->vlan_features = dev->features &
+			     ~(NETIF_F_HW_VLAN_CTAG_TX | NETIF_F_HW_VLAN_STAG_TX);
 	dev->destructor = veth_dev_free;
 
 	dev->hw_features = VETH_FEATURES;