Just to finalise this thread:

+ my earlier test must have been incorrectly specifying the packet, and 
I decided to specify the packet as a hex string instead, using a packet 
captured from our LAN
+ running my test on the Sep/2014 snapshot revealed the issue
+ running my test on the Apr/2015 snapshot showed the flow deletion 
worked, ie no issue

Seems as if I should do an upgrade!

Tony

On 30/04/15 02:26, Ben Pfaff wrote:
> I'm glad to hear that you're tracking down the problem.  Good luck.
>
> On Wed, Apr 29, 2015 at 06:05:48AM +0000, Tony van der Peet wrote:
>> OK, downloaded OVS from top of master, and wrote a unit test that
>> hopefully would have reproduced the problem (I guess I should run that
>> test on the version we are actually using). Anyway, the test passed.
>> Looking more closely at the code, I can see that in flow_put and
>> flow_del in dpif-netdev.c, the way the hashes are calculated seems to
>> have changed. I suspect that this is why the code no longer exhibits
>> this behaviour.
>>
>> So, for now I don't think I want any help on this issue. I'll keep
>> working on this as a background activity, but will probably do an update
>> from the upstream repo sometime soon and see if the problem goes away
>> after that.
>>
>> Thanks for the earlier response.
>>
>> Tony
>>
>> On 25/04/15 07:14, Tony van der Peet wrote:
>>> Just to get dates in order:
>>>
>>> Jun/2014 - deliveries to master branch that introduce IGMP fields to flow 
>>> structure
>>> Sep/2014 - we update from tip of master
>>> Apr/2014 - I notice this potential issue
>>>
>>> I am running a simple ryu application (using code from 
>>> https://github.com/samrussell/nss) and connecting my desktop PC to our main 
>>> LAN. Flows with multicast addresses appear to come and go, but I suspect 
>>> it's IGMPv3 Membership Reports (type 0x22) that are causing flows to be 
>>> created that then persist.
>>>
>>> In this application at least, matching is done purely on source and 
>>> destination MAC, so the existence of these flows is probably not that much 
>>> of a problem since the flows will cover many other packets that aren't 
>>> Membership reports. It's not really that surprising that this might not be 
>>> noticed since the switch is behaving perfectly normally and acceptably.
>>>
>>> To your point of reproducing on unmodified OpenVSwitch, yes, I will do 
>>> that, and report further. Time zones and public holidays mean that it won't 
>>> be until next week.
>>>
>>> Tony
>>> ________________________________________
>>> From: Ben Pfaff <[email protected]>
>>> Sent: Friday, 24 April 2015 11:08 a.m.
>>> To: Tony van der Peet
>>> Cc: [email protected]
>>> Subject: Re: [ovs-discuss] IGMP fields added to the flow structure causes 
>>> problem?
>>>
>>> On Thu, Apr 23, 2015 at 12:03:08AM +0000, Tony van der Peet wrote:
>>>> I have been investigating some anomalous behaviour in a switch
>>>> (developed by us, based on OpenVSwitch code). It appears that flows
>>>> added as a result of receiving IGMP packets are never deleted. Here's
>>>> one of the flows (this is a switch running a simple MAC learning
>>>> application, so you don't see the upper level fields).
>>>>
>>>> recirc_id(0),in_port(2),eth(src=38:60:77:8b:d9:0a,dst=01:00:5e:00:00:16),eth_type(0x0800),ipv4(frag=no),
>>>>  packets:26, bytes:2236, used:9.600s, actions:1,6,5,4,3
>>>>
>>>> Here's a log message I'm seeing:
>>>>
>>>> 2015 Apr 23 12:33:23 awplus ovs-vswitchd: 
>>>> 02570|dpif(revalidator4)|WARN|system@ovs-system: failed to flow_del (No 
>>>> such file or directory)
>>>>    
>>>> skb_priority(0),skb_mark(0),recirc_id(0),dp_hash(0),in_port(2),eth(src=38:60:77:8b:d9:0a,dst=01:00:5e:00:00:16),eth_type(0x0800),ipv4(src=10.33.22.24,dst=224.0.0.22,proto=2,tos=0xc0,ttl=1,frag=no)
>>> Thanks for the report.  I'm a little surprised to hear about this, since
>>> that code is somewhat old (I think you said September 2014) and I don't
>>> remember getting similar reports before.  Can you explain how to
>>> reproduce the problem (with unmodified OVS)?
>>>
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