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

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

The following reply was made to PR kern/53562; it has been noted by GNATS.

From: Christoph Badura <bad%bsd.de@localhost>
To: Rin Okuyama <rokuyama%rk.phys.keio.ac.jp@localhost>
Cc: Ryota Ozaki <ozaki-r%netbsd.org@localhost>, Masanobu SAITOH <msaitoh%execsw.org@localhost>,
	"gnats-bugs%NetBSD.org@localhost" <gnats-bugs%netbsd.org@localhost>,
	kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost,
	netbsd-bugs%netbsd.org@localhost
Subject: Re: kern/53562: bridge(4) breaks segmentation / TX checksum
 offloading
Date: Wed, 5 Sep 2018 23:51:37 +0200

 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