Re: [rdma-next 07/22] RDMA/core: Remove unimplemented node_types and node transport

Dennis Dalessandro
2017-08-11T18:13:01Z

On 8/11/2017 12:46 PM, Hal Rosenstock wrote:
> On 8/11/2017 6:49 AM, Leon Romanovsky wrote:
>> From: Leon Romanovsky <leonro-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
>>
>> There is no need to carry code, which is not implemented in any
>> underlying hardware. This patch removes unimplemented node_types and
>> their respective node transport layers.
>
> We have supported IB switches and routers since day 1 of OpenIB and
> linux-rdma. Although not the original intent, there are still no in-tree
> consumers, but there are several out of tree ones. Every time this issue
> has come up in the past, it has been decided to continue to support
> them. Effectively, IB routers and switches are grandfathered.

I swear I remember having this exact conversation but can't find it in
my mail. Figures. Well regardless...

> Rather than doing this, perhaps a better approach would be to supply
> some skeleton drivers for IB switch and router.

If someone were to volunteer to do that I could see leaving the
functionality, no not functionality, the non-functioning code, leaving
that in on a _temporary_ basis. In reality though it's been years that
this has been sitting there.

I can see the grandfather clause applying to stuff in the kernel tree,
or even publicly available implementations at a stretch (even then still
probably not). If there any any out of tree switch/router drivers, what
is the likelihood that they support the latest and greatest kernel out
of the box anyway? Is this really going to be a huge problem for them? I
doubt it.

On the flip side, is this code that's been there for forever and a day
really that big of a problem? No not really. It would be good to clean
it up if no one has that big of a problem and I'm not going to argue
very strongly on one side or the other.

-Denny