netdev - Re: [PATCH v2 net] neighbor: Call __ipv4_neigh_lookup_noref in neigh

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Date:   Sun, 5 May 2019 11:43:39 -0600
From:   David Ahern <dsahern@...il.com>
To:     David Miller <davem@...emloft.net>, dsahern@...nel.org
Cc:     netdev@...r.kernel.org, alan.maguire@...cle.com,
        jwestfall@...realistic.net
Subject: Re: [PATCH v2 net] neighbor: Call __ipv4_neigh_lookup_noref in
 neigh_xmit

On 5/5/19 11:42 AM, David Miller wrote:
> From: David Ahern <dsahern@...nel.org>
> Date: Fri,  3 May 2019 08:55:01 -0700
> 
>> From: David Ahern <dsahern@...il.com>
>>
>> Commit cd9ff4de0107 changed the key for IFF_POINTOPOINT devices to
>> INADDR_ANY, but neigh_xmit which is used for MPLS encapsulations was not
>> updated to use the altered key. The result is that every packet Tx does
>> a lookup on the gateway address which does not find an entry, a new one
>> is created only to find the existing one in the table right before the
>> insert since arp_constructor was updated to reset the primary key. This
>> is seen in the allocs and destroys counters:
>>     ip -s -4 ntable show | head -10 | grep alloc
>>
>> which increase for each packet showing the unnecessary overhread.
>>
>> Fix by having neigh_xmit use __ipv4_neigh_lookup_noref for NEIGH_ARP_TABLE.
>> Define __ipv4_neigh_lookup_noref in case CONFIG_INET is not set.
>>
>> v2
>> - define __ipv4_neigh_lookup_noref in case CONFIG_INET is not set as
>>   reported by kbuild test robot
>>
>> Fixes: cd9ff4de0107 ("ipv4: Make neigh lookup keys for loopback/point-to-point devices be INADDR_ANY")
>> Reported-by: Alan Maguire <alan.maguire@...cle.com>
>> Signed-off-by: David Ahern <dsahern@...il.com>
>>
>> Signed-off-by: David Ahern <dsahern@...il.com>
> 
> Double signoff and this patch doesn't apply to the net tree.
> 

oops on the double signoff; you actually took v1 so I need to send a delta.