Re: [PATCH net-next 04/11] mptcp: introduce add_addr_v6_port_drop_ts sysctl knob

[Matthieu Baerts]

Hi Eric,

On 01/06/2026 15:44, Eric Dumazet wrote:
> On Sun, May 31, 2026 at 10:24 PM Matthieu Baerts (NGI0)
> <matttbe@xxxxxxxxxx> wrote:
>>
>> This sysctl is going to be used in the next commits to drop TCP
>> timestamps option, to be able to send an ADD_ADDR with a v6 IP address
>> and a port number. It is enabled by default.
>>
>> This knob is explicitly disabled in the MPTCP Join selftest, with the
>> "signal addr list progresses after tx drop" subtest, to continue
>> verifying the previous behaviour where the ADD_ADDR is not sent due to a
>> lack of space.
>>
>> While at it, move syn_retrans_before_tcp_fallback down from struct
>> mptcp_pernet, to avoid creating another 3 bytes hole.
>>
>> Reviewed-by: Mat Martineau <martineau@xxxxxxxxxx>
>> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@xxxxxxxxxx>
> 
> ...
> 
>>  };
>> @@ -94,6 +95,11 @@ const char *mptcp_get_scheduler(const struct net *net)
>>         return mptcp_get_pernet(net)->scheduler;
>>  }
>>
>> +unsigned int mptcp_add_addr_v6_port_drop_ts(const struct net *net)
>> +{
>> +       return mptcp_get_pernet(net)->add_addr_v6_port_drop_ts;
>> +}
> 
> Please use READ_ONCE() over sysctls.
> This will avoid future patches from KCSAN bots.

Good point, I will do that.

I see READ_ONCE() should be used over all other MPTCP sysctls. I can
send fixes to net for those.

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.