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

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Date:	Mon, 8 Sep 2008 22:04:15 +1000
From:	Simon Horman <horms@...ge.net.au>
To:	Julius Volz <juliusv@...gle.com>
Cc:	lvs-devel@...r.kernel.org, netdev@...r.kernel.org,
	Siim Põder <siim@...rad-teel.net>,
	Julian Anastasov <ja@....bg>,
	Malcolm Turnbull <malcolm@...dbalancer.org>,
	Vince Busam <vbusam@...gle.com>,
	Herbert Xu <herbert@...dor.apana.org.au>
Subject: Re: [rfc 0/3] IPVS: checksum updates

On Mon, Sep 08, 2008 at 09:57:35PM +1000, Simon Horman wrote:
> 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?
> 

Hi,

Does 4856c84c + the following change (which you pointed out over the
weekend) work for remote IPv6 ?

diff --git a/net/ipv4/ipvs/ip_vs_core.c b/net/ipv4/ipvs/ip_vs_core.c
index 26e3d99..c413444 100644
--- a/net/ipv4/ipvs/ip_vs_core.c
+++ b/net/ipv4/ipvs/ip_vs_core.c
@@ -1282,7 +1282,7 @@ ip_vs_in(unsigned int hooknum, struct sk_buff *skb,
 	 *	Don't handle local packets on IPv6 for now
 	 */
 	if (unlikely(skb->pkt_type != PACKET_HOST ||
-		     (af == AF_INET6 || (skb->dev->flags & IFF_LOOPBACK ||
+		     (af == AF_INET6 && (skb->dev->flags & IFF_LOOPBACK ||
 					 skb->sk)))) {
 		IP_VS_DBG_BUF(12, "packet type=%d proto=%d daddr=%s ignored\n",
 			      skb->pkt_type,
--
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