[PATCH] Clear IFF_XMIT_DST_RELEASE for teql interfaces

[PATCH] Clear IFF_XMIT_DST_RELEASE for teql interfaces

[Tom Hughes]

The sch_teql module, which can be used to load balance over a set of
underlying interfaces, stopped working after 2.6.30 and has been
broken in all kernels since then for any underlying interface which
requires the addition of link level headers.

The problem is that the transmit routine relies on being able to
access the destination address in the skb in order to do address
resolution once it has decided which underlying interface it is going
to transmit through.

In 2.6.31 the IFF_XMIT_DST_RELEASE flag was introduced, and set by
default for all interfaces, which causes the destination address to be
released before the transmit routine for the interface is called.

The solution is to clear that flag for teql interfaces.

Signed-off-by: Tom Hughes <tom@compton.nu>
---
 net/sched/sch_teql.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/net/sched/sch_teql.c b/net/sched/sch_teql.c
index 3415b6c..807643b 100644
--- a/net/sched/sch_teql.c
+++ b/net/sched/sch_teql.c
@@ -449,6 +449,7 @@ static __init void teql_master_setup(struct net_device *dev)
 	dev->tx_queue_len	= 100;
 	dev->flags		= IFF_NOARP;
 	dev->hard_header_len	= LL_MAX_HEADER;
+	dev->priv_flags		&= ~IFF_XMIT_DST_RELEASE;
 }
 
 static LIST_HEAD(master_dev_list);
-- 
1.7.0.1

Re: [PATCH] Clear IFF_XMIT_DST_RELEASE for teql interfaces

[jamal]

On Wed, 2010-06-16 at 09:24 +0100, Tom Hughes wrote:
> The sch_teql module, which can be used to load balance over a set of
> underlying interfaces, stopped working after 2.6.30 and has been
> broken in all kernels since then for any underlying interface which
> requires the addition of link level headers.
> 
> The problem is that the transmit routine relies on being able to
> access the destination address in the skb in order to do address
> resolution once it has decided which underlying interface it is going
> to transmit through.
> 
> In 2.6.31 the IFF_XMIT_DST_RELEASE flag was introduced, and set by
> default for all interfaces, which causes the destination address to be
> released before the transmit routine for the interface is called.
> 
> The solution is to clear that flag for teql interfaces.
> 
> Signed-off-by: Tom Hughes <tom@compton.nu>

Sounds reasonable. Lets CC Eric and get his ACK.

cheers,
jamal

Re: [PATCH] Clear IFF_XMIT_DST_RELEASE for teql interfaces

[Eric Dumazet]

Le mercredi 16 juin 2010 à 09:25 -0400, jamal a écrit :
> On Wed, 2010-06-16 at 09:24 +0100, Tom Hughes wrote:
> > The sch_teql module, which can be used to load balance over a set of
> > underlying interfaces, stopped working after 2.6.30 and has been
> > broken in all kernels since then for any underlying interface which
> > requires the addition of link level headers.
> > 
> > The problem is that the transmit routine relies on being able to
> > access the destination address in the skb in order to do address
> > resolution once it has decided which underlying interface it is going
> > to transmit through.
> > 
> > In 2.6.31 the IFF_XMIT_DST_RELEASE flag was introduced, and set by
> > default for all interfaces, which causes the destination address to be
> > released before the transmit routine for the interface is called.
> > 
> > The solution is to clear that flag for teql interfaces.
> > 
> > Signed-off-by: Tom Hughes <tom@compton.nu>
> 
> Sounds reasonable. Lets CC Eric and get his ACK.
> 
> cheers,
> jamal
> 

Sure, I already Acked in on a previous message 5 days ago (although not
a formal patch, Stephen forwarded a bugzilla entry)

http://permalink.gmane.org/gmane.linux.network/163688

Please David, could you add bugzilla entry in commit ?

https://bugzilla.kernel.org/show_bug.cgi?id=16183

Acked-by: Eric Dumazet <eric.dumazet@gmail.com>

Thanks !

Re: [PATCH] Clear IFF_XMIT_DST_RELEASE for teql interfaces

[David Miller]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Wed, 16 Jun 2010 16:14:20 +0200

> Please David, could you add bugzilla entry in commit ?
> 
> https://bugzilla.kernel.org/show_bug.cgi?id=16183
> 
> Acked-by: Eric Dumazet <eric.dumazet@gmail.com>

Done and applied, thanks everyone.