From: roopa <roopa@cumulusnetworks•com>
To: nicolas.dichtel@6wind•com
Cc: davem@davemloft•net, mkubecek@suse•cz, Mazziesaccount@gmail•com,
hannes@stressinduktion•org, kuznet@ms2•inr.ac.ru,
jmorris@namei•org, yoshfuji@linux-ipv6•org,
netdev@vger•kernel.org
Subject: Re: [PATCH net v3] ipv6: fix multipath route replace error recovery
Date: Tue, 08 Sep 2015 06:53:09 -0700 [thread overview]
Message-ID: <55EEE845.60501@cumulusnetworks.com> (raw)
In-Reply-To: <55EEB086.7000100@6wind.com>
On 9/8/15, 2:55 AM, Nicolas Dichtel wrote:
> Le 08/09/2015 02:42, roopa a écrit :
>> On 9/6/15, 1:46 PM, Roopa Prabhu wrote:
>>> From: Roopa Prabhu <roopa@cumulusnetworks•com>
>>>
>>> Problem:
>>> The ecmp route replace support for ipv6 in the kernel, deletes the
>>> existing ecmp route too early, ie when it installs the first nexthop.
>>> If there is an error in installing the subsequent nexthops, its too
>>> late
>>> to recover the already deleted existing route
>>>
>>> This patch fixes the problem with the following:
>>> a) Changes the existing multipath route add code to a two stage
>>> process:
>>> build rt6_infos + insert them
>>> ip6_route_add rt6_info creation code is moved into
>>> ip6_route_info_create.
>>> b) This ensures that all errors are caught during building rt6_infos
>>> and we fail early
>>>
>> The other way I have been thinking of solving the problem is to mark
>> the sibling
>> routes being replaced with some state
>> ...so they can be restored on error. Still figuring out a way to do
>> this in a
>> clean and non-intrusive way.
> If I'm not wrong, the only error which may result to an inconsistent
> list of
> nexthops is ENOMEM (after your patch). I'm not sure it's worth to add
> too much
> complexity to the code to handle this error.
yes, agreed. And that's the reason i went down the path presented in
the patch in context.
I was just reflecting back on the other possible implementations. thanks
for the review.
>
>> Or maybe just save the sibling routes (rt6_infos) being replaced in
>> a list and
>> re-insert them on error.
> Yes, but we can also fail to re-insert the route.
ack.
posting v4 soon.
prev parent reply other threads:[~2015-09-08 13:53 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-06 20:46 [PATCH net v3] ipv6: fix multipath route replace error recovery Roopa Prabhu
2015-09-07 12:37 ` Nicolas Dichtel
2015-09-08 0:14 ` roopa
2015-09-08 0:42 ` roopa
2015-09-08 9:55 ` Nicolas Dichtel
2015-09-08 13:53 ` roopa [this message]
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