netdev - Re: [PATCHv4 net-next] VXLAN: fix nonfunctional neigh

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Message-ID: <CAJZOPZ+b=VbRkczaTwysT_DW0y_YX-0rt17T4iqs5JoJGx2KCg@mail.gmail.com>
Date:	Tue, 18 Mar 2014 22:13:08 +0200
From:	Or Gerlitz <or.gerlitz@...il.com>
To:	Stephen Hemminger <stephen@...workplumber.org>,
	David L Stevens <dlstevens@...ibm.com>
Cc:	David Miller <davem@...emloft.net>,
	Stephen Hemminger <shemminger@...tta.com>,
	Cong Wang <amwang@...hat.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCHv4 net-next] VXLAN: fix nonfunctional neigh_reduce

On Tue, Mar 18, 2014, Stephen Hemminger <stephen@...workplumber.org> wrote:
> On Tue, 18 Mar 2014 15:31:21 -0400
> David L Stevens <dlstevens@...ibm.com> wrote:
>
>>
>>       The VXLAN neigh_reduce() code is completely non-functional since
>> check-in. Specific errors:
>>
>> 1) The original code drops all packets with a multicast destination address,
>>       even though neighbor solicitations are sent to the solicited-node
>>       address, a multicast address. The code after this check was never run.
>> 2) The neighbor table lookup used the IPv6 header destination, which is the
>>       solicited node address, rather than the target address from the
>>       neighbor solicitation. So neighbor lookups would always fail if it
>>       got this far. Also for L3MISSes.
>> 3) The code calls ndisc_send_na(), which does a send on the tunnel device.
>>       The context for neigh_reduce() is the transmit path, vxlan_xmit(),
>>       where the host or a bridge-attached neighbor is trying to transmit
>>       a neighbor solicitation. To respond to it, the tunnel endpoint needs
>>       to do a *receive* of the appropriate neighbor advertisement. Doing a
>>       send, would only try to send the advertisement, encapsulated, to the
>>       remote destinations in the fdb -- hosts that definitely did not do the
>>       corresponding solicitation.
>> 4) The code uses the tunnel endpoint IPv6 forwarding flag to determine the
>>       isrouter flag in the advertisement. This has nothing to do with whether
>>       or not the target is a router, and generally won't be set since the
>>       tunnel endpoint is bridging, not routing, traffic.
>>
>>       The patch below creates a proxy neighbor advertisement to respond to
>> neighbor solicitions as intended, providing proper IPv6 support for neighbor
>> reduction.
>>
>> Changes since v3:
>>       - code cleanup suggested by Brian Haley
>> Changes since v2:
>>       - code cleanup suggested by Stephen Hemminger and Daniel Baluta
>> Changes since v1:
>>       - reworked code to be structurally similar to arp_reduce()

David, if you generate the patch with git format-patch it will also
produce a ---- line below the signature, I don't think we need to
carry the revision history for the future generations, so you just put
it there and when the maintainer picks the patch git am strips these
lines

> Minor checkpatch nits.
>
> WARNING: 'Signed-off-by:' is the preferred signature form
> #94:
> Signed-Off-By: David L Stevens <dlstevens@...ibm.com>
>
> ERROR: trailing whitespace
> #182: FILE: drivers/net/vxlan.c:1417:
> +^I^I&pip6->daddr, sizeof(*na)+olen, IPPROTO_ICMPV6, $
>
> total: 1 errors, 3 warnings, 157 lines checked

I would highly recommend to use the --strict flag so if you have also
CHECK: comments they can (need) be addressed as well.
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