Hi Eric,

On 01/06/2026 15:44, Eric Dumazet wrote:

On Sun, May 31, 2026 at 10:24 PM Matthieu Baerts (NGI0)
[off-list ref] wrote:

quoted

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@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>

...

quoted

 };

@@ -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.