Re: [PATCH] IPVS: Add handling of incoming ICMPV6_PKT_TOOBIG messages

To: Julius Volz <julius.volz@xxxxxxxxx>
Subject: Re: [PATCH] IPVS: Add handling of incoming ICMPV6_PKT_TOOBIG messages
Cc: lvs-devel@xxxxxxxxxxxxxxx, netdev@xxxxxxxxxxxxxxx, robert.gallagher@xxxxxxxxx
From: Simon Horman <horms@xxxxxxxxxxxx>
Date: Fri, 10 Jul 2009 19:56:44 +1000
On Thu, Jul 02, 2009 at 04:43:39PM +0200, Julius Volz wrote:
> Hi Simon,
> On Sun, Jun 28, 2009 at 5:43 PM, Simon Horman<horms@xxxxxxxxxxxx> wrote:
> > On Wed, Jun 24, 2009 at 03:22:32PM +0200, Julius Volz wrote:
> >> Add handling of incoming ICMPv6 Packet Too Big messages. This message
> >> is received when a realserver sends a packet >PMTU to the client. The
> >> hop on this path with insufficient MTU will generate an ICMPv6 Packet
> >> Too Big message back to the VIP. The LVS server receives this message,
> >> but the call to the function handling this has been missing. Thus, IPVS
> >> fails to forward the message to the real server, which then does not
> >> adjust the path MTU. This patch adds the missing call to
> >> ip_vs_in_icmp_v6() in ip_vs_in() to handle this situation.
> >>
> >> Thanks to Rob Gallagher from HEAnet for reporting this issue and for
> >> testing this patch in production (with direct routing mode).
> >>
> >> Signed-off-by: Julius Volz <julius.volz@xxxxxxxxx>
> >> Tested-by: Rob Gallagher <robert.gallagher@xxxxxxxxx>
> >
> > Hi Julius, Hi Rob,
> >
> > this seems reasonable to me, although it seems that the following
> > code is common. I wonder if its repetition could be removed.
> >
> >                        if (related)
> >                                return verdict;
> >                        ip_vs_fill_iphdr(af, skb_network_header(skb), &iph);
> I agree, though I see no "nice" way to remove this duplication
> considering the ifs and #ifdefs around this. You could move the
> related and verdict variables to the top of the function and then
> recheck afterwards whether one of these ICMP-handling branches was
> entered and put the common code in there. But this seems more
> cumbersome to me than repeating the code. Maybe you see a nicer way?
> Btw., exactly this structure already exists in ip_vs_out(), which is
> why I adopted it like this for ip_vs_in().

Hi Julius,

sorry for the delay in responding, I've been off-line / recovering from
being off-line.

I couldn't see an obvious way either, though I was hoping that
you might :-) As you can't I'm happy to go with what you originally

Acked-by: Simon Horman <horms@xxxxxxxxxxxx>
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