[PATCH] netdev: don't always reset iflink when registering

[PATCH] netdev: don't always reset iflink when registering

[Tom Goff]

Bound tunnel devices set their iflink to the ifindex of the underlying
network interface when created.  It shouldn't be reset by the
registration process.

Signed-off-by: Tom Goff <thomas.goff@boeing.com>
---
 net/core/dev.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 59d4394..c00d625 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5067,7 +5067,8 @@ int register_netdevice(struct net_device *dev)
 	netdev_set_addr_lockdep_class(dev);
 	netdev_init_queue_locks(dev);
 
-	dev->iflink = -1;
+	if (dev->iflink <= 0)
+		dev->iflink = -1;
 
 	/* Init, if this function is available */
 	if (dev->netdev_ops->ndo_init) {
-- 
1.6.3.3

Re: [PATCH] netdev: don't always reset iflink when registering

[Patrick McHardy]

Tom Goff wrote:
> Bound tunnel devices set their iflink to the ifindex of the underlying
> network interface when created.  It shouldn't be reset by the
> registration process.
>   

Which ones exactly? Usually they do this in ->setup() or later on.

RE: [PATCH] netdev: don't always reset iflink when registering

[Goff, Thomas]

From: Patrick McHardy <mailto:kaber@trash.net>
Sent: Monday, March 22, 2010 10:43 AM
> 
> Tom Goff wrote:
> > Bound tunnel devices set their iflink to the ifindex of the 
> underlying
> > network interface when created.  It shouldn't be reset by the
> > registration process.
> >   
> 
> Which ones exactly? Usually they do this in ->setup() or later on.

I observed the issue with a bound gre tunnel where:

	ipgre_newlink()
		...
		ipgre_tunnel_bind_dev()	/* set dev->iflink */
		...
		register_netdevice()	/* reset dev->iflink */

There's a similar pattern in ipv6/sit.c:

	ipip6_tunnel_locate()
		...
		ipip6_tunnel_init()
			...
			ipip6_tunnel_bind_dev()	/* set dev->iflink */
		...
		register_netdevice()		/* reset dev->iflink */

So maybe it makes more sense to change these if that's more consistent
with other cases.

Thanks for looking at this and the tc stuff.

  Tom

Re: [PATCH] netdev: don't always reset iflink when registering

[David Miller]

From: "Goff, Thomas" <Thomas.Goff@boeing.com>
Date: Mon, 22 Mar 2010 12:06:46 -0700

> So maybe it makes more sense to change these if that's more consistent
> with other cases.

Yes, it does.  The canonical place to set ->iflink by hand
is the ->ndo_init() method of the device.