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Re: [rfc 0/3] IPVS: checksum updates

To: Julius Volz <juliusv@xxxxxxxxxx>
Subject: Re: [rfc 0/3] IPVS: checksum updates
Cc: lvs-devel@xxxxxxxxxxxxxxx, netdev@xxxxxxxxxxxxxxx, Siim Põder <siim@xxxxxxxxxxxxxxx>, Julian Anastasov <ja@xxxxxx>, Malcolm Turnbull <malcolm@xxxxxxxxxxxxxxxx>, Vince Busam <vbusam@xxxxxxxxxx>, Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
From: Simon Horman <horms@xxxxxxxxxxxx>
Date: Mon, 8 Sep 2008 21:57:35 +1000
On Mon, Sep 08, 2008 at 01:42:59PM +0200, Julius Volz wrote:
> On Mon, Sep 08, 2008 at 08:41:22PM +1000, Simon Horman wrote:
> > On Mon, Sep 08, 2008 at 12:03:04PM +0200, Julius Volz wrote:
> > > On Mon, Sep 8, 2008 at 4:04 AM, Simon Horman wrote:
> > > > Hi,
> > > >
> > > > The impetus for this series of patches is Julian Anastasov noting
> > > > that "load balance IPv4 connections from a local process" checks
> > > > for 0 TCP checksums. Herbert Xu confirmed that this is not legal,
> > > > even on loopback traffic, but that rather partial checksums are
> > > > possible.
> > > >
> > > > The first patch in this series is a proposed solution to handle
> > > > partial checksums for both TCP and UDP.
> > > >
> > > > The other two patches clean things up a bit.
> > > >
> > > > I have not tested this code beyond compilation yet.
> > > 
> > > After some first tests, remote connections are still working, but not
> > > local ones from the director. The TCP handshake works and the
> > > connection is established, but all following packets arriving at the
> > > real server have an incorrect TCP checksum.
> > > 
> > > Btw., this happens both with and without this last series of patches,
> > > so I can't get the local client feature working at all. Looking at it
> > > further...
> > 
> > Ok, is this for both IPv4 & IPv6? Does it still occur with just the first
> > patch in this series applied?
> 
> It's for both, although I only tested IPv4 at first. Here is a complete
> test matrix of what works when:
> 
> CR = connection refused
> T = connection timeout
> C = connection established, but not working afterwards
> OK = working
> 
>                       remote client | local client
> COMMIT                        v4      v6    | v4      v6
> ======================================|=================
> CSUM 3/3              OK      T     | C       T
> CSUM 2/3              OK      T     | C       T
> CSUM 1/3              OK      T     | OK      T
> W/O CSUM              OK      T     | C       T
> ...                                 |
> f2428ed5              OK      T     | CR      CR
> 4856c84c              OK      CR    | CR      CR
> f94fd041 (my last one)        OK      OK    | CR      CR
> 
> So the last time that IPv6 was working _at all_ was at my last commit of
> the big v6 series...

Ok, I'm really sorry about that :-(

Do you want me to revert f2428ed5 & 4856c84c until this has been tracked down?

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