[PATCH v1 net-next 2/4] net: Retire DCCP.

[Casey Schaufler]

On 4/7/2025 10:22 PM, Christian Göttsche wrote:
> Apr 8, 2025 03:35:15 Paul Moore <paul at paul-moore.com>:
>
>> On Mon, Apr 7, 2025 at 7:19 PM Kuniyuki Iwashima <kuniyu at amazon.com> wrote:
>>> DCCP was orphaned in 2021 by commit 054c4610bd05 ("MAINTAINERS: dccp:
>>> move Gerrit Renker to CREDITS"), which noted that the last maintainer
>>> had been inactive for five years.
>>>
>>> In recent years, it has become a playground for syzbot, and most changes
>>> to DCCP have been odd bug fixes triggered by syzbot.  Apart from that,
>>> the only changes have been driven by treewide or networking API updates
>>> or adjustments related to TCP.
>>>
>>> Thus, in 2023, we announced we would remove DCCP in 2025 via commit
>>> b144fcaf46d4 ("dccp: Print deprecation notice.").
>>>
>>> Since then, only one individual has contacted the netdev mailing list. [0]
>>>
>>> There is ongoing research for Multipath DCCP.  The repository is hosted
>>> on GitHub [1], and development is not taking place through the upstream
>>> community.  While the repository is published under the GPLv2 license,
>>> the scheduling part remains proprietary, with a LICENSE file [2] stating:
>>>
>>>   "This is not Open Source software."
>>>
>>> The researcher mentioned a plan to address the licensing issue, upstream
>>> the patches, and step up as a maintainer, but there has been no further
>>> communication since then.
>>>
>>> Maintaining DCCP for a decade without any real users has become a burden.
>>>
>>> Therefore, it's time to remove it.
>>>
>>> Removing DCCP will also provide significant benefits to TCP.  It allows
>>> us to freely reorganize the layout of struct inet_connection_sock, which
>>> is currently shared with DCCP, and optimize it to reduce the number of
>>> cachelines accessed in the TCP fast path.
>>>
>>> Note that we leave uAPI headers alone for userspace programs.
>>>
>>> Link: https://lore.kernel.org/netdev/20230710182253.81446-1-kuniyu@amazon.com/T/#u #[0]
>>> Link: https://github.com/telekom/mp-dccp #[1]
>>> Link: https://github.com/telekom/mp-dccp/blob/mpdccp_v03_k5.10/net/dccp/non_gpl_scheduler/LICENSE #[2]
>>> Signed-off-by: Kuniyuki Iwashima <kuniyu at amazon.com>
>> Adding the LSM and SELinux lists for obvious reasons, as well as Casey
>> directly since he maintains Smack and I don't see him on the To/CC
>> line.

It's annoying that I found out about this indirectly. No biscuit.

Nonetheless, for the Smack bits:

Acked-by: Casey Schaufler <casey at schaufler-ca.com>