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Date: Tue, 30 May 2023 15:14:01 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Cc: Kuniyuki Iwashima <kuniyu@amazon.com>, davem@davemloft.net,
 dsahern@kernel.org, edumazet@google.com, kuni1840@gmail.com,
 netdev@vger.kernel.org, pabeni@redhat.com
Subject: Re: [PATCH v1 net-next 00/14] udp: Farewell to UDP-Lite.
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On Tue, 30 May 2023 16:16:20 -0400 Willem de Bruijn wrote:
> Is it a significant burden to keep the protocol, in case anyone is
> willing to maintain it?
> 
> If consensus is that it is time to remove, a warning may not be
> sufficient for people to notice.
> 
> Perhaps break it, but in a way that can be undone trivially,
> preferably even without recompiling the kernel. Say, returning
> EOPNOTSUPP on socket creation, unless a sysctl has some magic
> non-deprecated value. But maybe I'm overthinking it. There must be
> prior art for this?

It may be the most intertwined feature we attempted to remove.
UFO was smaller, right?

Did deprecation warnings ever work? 

How about we try to push a WARN_ONCE() on socket creation to net and
stable? With a message along the lines of "UDP lite is assumed to have
no users, and is been deleted, please contact netdev@.."

Then delete the whole thing in net-next? Hopefully pushing to stable
would expedite user reports? We'll find out if Greg throws rotten fruit
at us or not..