Hi Andrew,

They’re the first UT I’ve seen that screen scrape show output. I wasn’t sure 
this was acceptable practice. But if I had a better alternative I’d have 
suggested it already…

/neale

From: Andrew 👽 Yourtchenko <[email protected]>
Date: Wednesday 6 May 2020 at 15:45
To: Nick Zavaritsky <[email protected]>
Cc: "[email protected]" <[email protected]>, "Neale Ranns (nranns)" 
<[email protected]>
Subject: Re: [vpp-dev] DPO leak in various tunnel types (gtpu, geneve, vxlan, 
...)

Nick,

Fixes are always good, and especially with the UTs, so thanks a lot !

I took a glance at the UTs...

one question and the bigger remark:

1) The UT stuff looks fairly straightforward except the tests are IPv4-only - 
is it enough test only one address family ? If yes - a comment inside the UT 
would be cool..

2) the deletion of ipv6 parameter in vpp_papi_provider.py seems like some stray 
unrelated change which sneaked in ? (That’s actually what made me to -1).

That’s the only two things I could see, the UTs seem fairly straightforward.

--a


On 6 May 2020, at 13:55, Nick Zavaritsky <[email protected]> wrote:
Dear VPP hackers,

May I kindly ask to do a code review of the proposed fix?

Thanks,
N



On 21. Apr 2020, at 15:15, Neale Ranns (nranns) 
<[email protected]<mailto:[email protected]>> wrote:

Hi Nick,

A +1 from me for the VPP change, thank you.
I’m all for UT too, but I’ll let some others review the UT first before I merge.

/neale

From: <[email protected]<mailto:[email protected]>> on behalf of Nick 
Zavaritsky <[email protected]<mailto:[email protected]>>
Date: Tuesday 21 April 2020 at 14:57
To: "[email protected]<mailto:[email protected]>" 
<[email protected]<mailto:[email protected]>>
Subject: [vpp-dev] DPO leak in various tunnel types (gtpu, geneve, vxlan, ...)

Dear VPP hackers,

We are spawning and destroying GTPU tunnels at a high rate. Only 10K tunnels 
ever exist simultaneously in our test.

With default settings, we observe out of memory error in load_balance_create 
after approximately .5M tunnel create commands. Apparently, load balancers are 
leaking.

As far as my understanding goes, a load_balancer is first created in 
fib_entry_track, to get notifications about the route changes. This is only 
created once for a unique DIP and the refcount is correctly decremented once 
the last subscription ceases.

The refcount is also bumped in gtpu_tunnel_restack_dpo, when next_dpo is 
updated. Since the later is never reset, the refcount never drops to zero.

This is straightforward to exercise in CLI: create and immediately destroy 
several GTPU tunnels. Compare `show dpo memory` output before and after.

It looks like other tunnel types, namely geneve, vxlan, vxlan-gpe and vxlan-gbp 
are also susceptible.

My take was to add a call to dpo_reset in add_del_tunnel delete path. Please 
take a look at the patch: https://gerrit.fd.io/r/c/vpp/+/26617

Note: was unable to make a test case for vxlan and vxlan-gbp since they don't 
point next_dpo at a load balancer but rather at a dpo picked up from a bucket 
in the load balancer.

Best,
N


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