macvlan: fix gso_max_size setting

macvlan: fix gso_max_size setting

[Patrick McHardy]

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Fix macvlan gso_max_size setting. Based on net-next-2.6.git.


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commit 198a1fd488e7ebec080d1d2da7947cb9e1aacebf
Author: Patrick McHardy <kaber@trash.net>
Date:   Mon Nov 23 11:28:22 2009 +0100

    macvlan: fix gso_max_size setting
    
    gso_max_size must be set based on the value of the underlying device to
    support devices not using the full 64k.
    
    Signed-off-by: Patrick McHardy <kaber@trash.net>

diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index ae2b5c7..7b0ef0c 100644
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -376,6 +376,7 @@ static int macvlan_init(struct net_device *dev)
 	dev->state		= (dev->state & ~MACVLAN_STATE_MASK) |
 				  (lowerdev->state & MACVLAN_STATE_MASK);
 	dev->features 		= lowerdev->features & MACVLAN_FEATURES;
+	dev->gso_max_size	= lowerdev->gso_max_size;
 	dev->iflink		= lowerdev->ifindex;
 	dev->hard_header_len	= lowerdev->hard_header_len;
 
@@ -652,6 +653,7 @@ static int macvlan_device_event(struct notifier_block *unused,
 	case NETDEV_FEAT_CHANGE:
 		list_for_each_entry(vlan, &port->vlans, list) {
 			vlan->dev->features = dev->features & MACVLAN_FEATURES;
+			vlan->dev->gso_max_size = dev->gso_max_size;
 			netdev_features_change(vlan->dev);
 		}
 		break;

Re: macvlan: fix gso_max_size setting

[David Miller]

From: Patrick McHardy <kaber@trash.net>
Date: Mon, 23 Nov 2009 11:33:06 +0100

> Fix macvlan gso_max_size setting. Based on net-next-2.6.git.

Pretty serious defect, maybe net-2.6 material?

If someone hits this, it's going to trigger something awful.

Re: macvlan: fix gso_max_size setting

[Patrick McHardy]

David Miller wrote:
> From: Patrick McHardy <kaber@trash.net>
> Date: Mon, 23 Nov 2009 11:33:06 +0100
>
>   
>> Fix macvlan gso_max_size setting. Based on net-next-2.6.git.
>
> Pretty serious defect, maybe net-2.6 material?

Sure, please take it in net-2.6.
>
> If someone hits this, it's going to trigger something awful.

Don't drivers simply drop the packet? Otherwise I think you
should be able to trigger the same problem using the TC mirred
action.

Re: macvlan: fix gso_max_size setting

[David Miller]

From: Patrick McHardy <kaber@trash.net>
Date: Mon, 23 Nov 2009 23:11:07 +0100

> David Miller wrote:
>> From: Patrick McHardy <kaber@trash.net>
>> Date: Mon, 23 Nov 2009 11:33:06 +0100
>>
>>   
>>> Fix macvlan gso_max_size setting. Based on net-next-2.6.git.
>>
>> Pretty serious defect, maybe net-2.6 material?
> 
> Sure, please take it in net-2.6.

Done, thanks.

>>
>> If someone hits this, it's going to trigger something awful.
> 
> Don't drivers simply drop the packet? Otherwise I think you
> should be able to trigger the same problem using the TC mirred
> action.

I see nothing in the IXGBE driver's transmit code paths which guard
against this.

Re: macvlan: fix gso_max_size setting

[Patrick McHardy]

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David Miller wrote:
> From: Patrick McHardy <kaber@trash.net>
> Date: Mon, 23 Nov 2009 23:11:07 +0100
>
>   
>> David Miller wrote:
>>     
>>> From: Patrick McHardy <kaber@trash.net>
>>> Date: Mon, 23 Nov 2009 11:33:06 +0100
>>>
>>>   
>>>       
>>>> Fix macvlan gso_max_size setting. Based on net-next-2.6.git.
>>>>         
>>> Pretty serious defect, maybe net-2.6 material?
>>>       
>> Sure, please take it in net-2.6.
>>     
>
> Done, thanks.
>
>   
>>> If someone hits this, it's going to trigger something awful.
>>>       
>> Don't drivers simply drop the packet? Otherwise I think you
>> should be able to trigger the same problem using the TC mirred
>> action.
>>     
>
> I see nothing in the IXGBE driver's transmit code paths which guard
> against this.
>   


Perhaps we should simply fall back to software in that case.
Compile tested only.



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net: fall back to software segmentation if skb length exceeds dev->gso_max_size

Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index ffc3106..edd1e2b 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1943,7 +1943,8 @@ static inline int netif_needs_gso(struct net_device *dev, struct sk_buff *skb)
 {
 	return skb_is_gso(skb) &&
 	       (!skb_gso_ok(skb, dev->features) ||
-		unlikely(skb->ip_summed != CHECKSUM_PARTIAL));
+		unlikely(skb->ip_summed != CHECKSUM_PARTIAL) ||
+		unlikely(skb->len > dev->gso_max_size));
 }
 
 static inline void netif_set_gso_max_size(struct net_device *dev,

Re: macvlan: fix gso_max_size setting

[Herbert Xu]

On Mon, Nov 23, 2009 at 11:33:05PM +0100, Patrick McHardy wrote:
> 
> Perhaps we should simply fall back to software in that case.
> Compile tested only.

Sure.

Since ixgbe appears to be the only driver in our entire tree
that has this limitation, I think it might make more sense to
move this special-case check into it and get it to do software
GSO just like tg3 does for a few other cases that the hardware
can't handle.

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
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Re: macvlan: fix gso_max_size setting

[Patrick McHardy]

Herbert Xu wrote:
> On Mon, Nov 23, 2009 at 11:33:05PM +0100, Patrick McHardy wrote:
>> Perhaps we should simply fall back to software in that case.
>> Compile tested only.
> 
> Sure.
> 
> Since ixgbe appears to be the only driver in our entire tree
> that has this limitation, I think it might make more sense to
> move this special-case check into it and get it to do software
> GSO just like tg3 does for a few other cases that the hardware
> can't handle.

Sure, that would also be fine. I'll leave that for the Intel
guys however :)