Re: Patch "mptcp: strict local address ID selection" has been added to the 5.17-stable tree

[Mat Martineau <mathew.j.martineau@linux.intel.com>]

On Mon, 23 May 2022, Matthieu Baerts wrote:

> On 23/05/2022 17:33, Matthieu Baerts wrote:
>> Hi Mat, Paolo,
>>
>> (- stable list and netdev maintainers, + mptcp list)
>>
>> On 23/05/2022 05:06, Sasha Levin wrote:
>>> This is a note to let you know that I've just added the patch titled
>>>
>>>     mptcp: strict local address ID selection
>>>
>>> to the 5.17-stable tree which can be found at:
>>>     http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
>>>
>>> The filename of the patch is:
>>>      mptcp-strict-local-address-id-selection.patch
>>> and it can be found in the queue-5.17 subdirectory.
>>>
>>> If you, or anyone else, feels it should not be added to the stable tree,
>>> please let <stable@vger.kernel.org> know about it.
>>
>>
>> Do we want the patch below to be backported to stable?
>>
>> It think it is slightly changing the behaviour and we might not want it
>> there, no?
>
> (...)
>
>>> diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
>>> index aec767ee047a..e4413b3e50c2 100644
>>> --- a/net/mptcp/protocol.h
>>> +++ b/net/mptcp/protocol.h
>>> @@ -442,7 +442,8 @@ struct mptcp_subflow_context {
>>>  		rx_eof : 1,
>>>  		can_ack : 1,        /* only after processing the remote a key */
>>>  		disposable : 1,	    /* ctx can be free at ulp release time */
>>> -		stale : 1;	    /* unable to snd/rcv data, do not use for xmit */
>>> +		stale : 1,	    /* unable to snd/rcv data, do not use for xmit */
>>> +		local_id_valid : 1; /* local_id is correctly initialized */
>
> I guess the reason this patch has been added to the stable queue is
> because this patch adds 'local_id_valid' element here in
> 'mptcp_subflow_context' structure.
>
> If you look at "mptcp: Do TCP fallback on early DSS checksum failure"
> patch, Mat added 'valid_csum_seen' just after 'local_id_valid'.
>
> If we don't want  "mptcp: strict local address ID selection" to be
> backported, we can probably easily resolve the conflict and send a new
> version adding 'valid_csum_seen' just after 'stale'.
>

Like Paolo, I don't have a strong preference - but since the dependency is 
only because of diff context (not because of any actual functionality) the 
choice seems less clear!

I'm not aware of any negative impacts from "mptcp: strict local address ID 
selection", so I lean in Paolo's direction to let -stable cherry-pick the 
"extra" commit to make the stable process easier.

I'll try running the self tests on 5.15 and 5.17 -stable with these 
commits and see if there is any problem there.

--
Mat Martineau
Intel