[ewg] Re: [PATCH] IB/ipoib: set child MTU as the parent's

[Eli Cohen]

On Tue, Apr 29, 2008 at 9:18 PM, Roland Dreier <rdreier at cisco.com> wrote:
>
> This changelog is a little too short for me to understand what this is
> fixing.  It seems that child devices are left with a bogus MTU until
> they complete their multicast join, is that it?

The situation is even worse since even when multicast join completes,
the device's MTU
will not be updated since the following statment

                dev->mtu = min(priv->mcast_mtu, priv->admin_mtu);

 at ipoib_mcast_join_task() yields zero since admin mtu is zero.

>
> Do child devices also need to copy over the checksum offload/LSO stuff
> from the parent?
>

I think they do but it would require using two fields for flags at the
private data. priv->flags would
save flags that relate to the state of the net device, and say,
priv->cap_flags, to save stuff like LRO,
checksum or any other stuff related to capabilities. What do you think?