Subject: Re: [PATCH net-next] rtnl: don't account unused struct ifla_port_vsi in rtnl_port_size

From: Daniel Borkmann <[email-masked]>
Date: Fri, 17 Feb 2017 21:40:41 +0100

On 02/17/2017 08:57 PM, David Miller wrote:
> From: Daniel Borkmann <[email-masked]>
> Date: Fri, 17 Feb 2017 01:56:11 +0100
>
>> When allocating rtnl dump messages, struct ifla_port_vsi is never dumped,
>> so we can save header plus payload in rtnl_port_size(). Infact, attribute
>> IFLA_PORT_VSI_TYPE and struct ifla_port_vsi are not used anywhere in
>> the kernel. We only need to keep the nla policy should applications in
>> user space be filling this out. Same NLA_BINARY issue exists as was fixed
>> in 364d5716a7ad ("rtnetlink: ifla_vf_policy: fix misuses of NLA_BINARY")
>> and others, but then again IFLA_PORT_VSI_TYPE is not used anywhere, so
>> just add a comment that it's unused.
>>
>> Signed-off-by: Daniel Borkmann <[email-masked]>
>> ---
>>   ( Found while reviewing NLA_BINARY longer time ago. )
>
> Applied, but whether or not this is emitted it controlled by how a driver
> implements ->ndo_get_vf_port().
>
> Therefore, in the future some driver could fill this in.

Agree, in that case, it can be undone; when I checked, this part
was added 7 years ago via 57b610805ce9 ("net: Add netlink support
for virtual port management (was iovnl)") and never had a single
user since then.