Re: kern/53562: bridge(4) breaks segmentation / TX checksum offloading

[Christoph Badura <bad%bsd.de@localhost>]

On Wed, Sep 05, 2018 at 09:04:16PM +0900, Rin Okuyama wrote:
> With both patches, TX works fine through an interface added to bridge,
> even if TSO is enabled. However, RX from an host which shares the
> interface via bridge does not work for larger packets (because of TSO?).
> RX of smaller packets and TX work for that host.

I would not expect any TSO flags to be set on a packet that is received
from another host.  The packet should have been segmented on other host
already.

> I'm not sure if my setup should work in principle...

Maybe you could describe your setup in more detail.  Looking at the PR I
don't understand what exactly your setup is.

It might be worth going over the original PR kern/27007 again.  Also note
the second part of PR kern/21831 by yamt@.

Note that in kern/27007 the damage was actually done only when ipf was
enabled on the bridge interface.  It might well be that my change was
not correct because it was to broad.  Maybe ipf has changed since, so that
packets do not get corrupted anymore in this case, too.

Looking back at the code I think the comment could have been worded
better.  If you move it out of bridge_enqueue() it would be nice if the
comment could be expanded.  Like, what exactly the circumstances are that
the flags have been set and why they need clearing.

Maybe we need ATF tests.  That certainly would be nice.  Also we now have
more test cases to consider: npf and pf active on the bridge.

--chris