mptcp: fix msk->timer_ival reset

In this kernel version, icsk->icsk_rto_min is not initialised, because this version doesn't contain commit ea4eb2adb0d3 ("mptcp: honour configured min/max RTO in retransmit paths").

Reset it to TCP_RTO_MIN, which is how msk->timer_ival is also reset in __mptcp_init_sock() in this version.

---
 net/mptcp/protocol.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index e9967d55b8ac..d0e3e17c698e 100644
@@ -3312,7 +3312,7 @@ static int mptcp_disconnect(struct sock *sk, int flags)
 	/* The later subflow close can not kick again the tout timer,
 	 * as the msk is already in closed status.
 	 */
-	msk->timer_ival = icsk->icsk_rto_min;
+	msk->timer_ival = TCP_RTO_MIN;
 	sk_stop_timer_sync(sk, &sk->mptcp_retransmit_timer);
 	icsk->icsk_mtup.probe_timestamp = 0;
 	sk_stop_timer_sync(sk, &icsk->mptcp_tout_timer);

2.55.0

Hi Matthieu,

Thank you for your modifications, that's great!

Our CI did some validations and here is its report:

- KVM Validation: normal (except selftest_mptcp_join): Unstable: 1 failed test(s): selftest_simult_flows ⚠️
- KVM Validation: normal (only selftest_mptcp_join): Success! ✅
- KVM Validation: debug (except selftest_mptcp_join): Success! ✅
- KVM Validation: debug (only selftest_mptcp_join): Success! ✅
- KVM Validation: btf-normal (only bpftest_all): Success! ✅
- KVM Validation: btf-debug (only bpftest_all): Success! ✅
- Perf: Success! ✅
- Task: https://github.com/multipath-tcp/mptcp_net-next/actions/runs/37354848622

Initiator: Patchew Applier
Commits: https://github.com/multipath-tcp/mptcp_net-next/commits/5e6b2c55e0be
Patchwork: https://patchwork.kernel.org/project/mptcp/list/?series=1179808

If there are some issues, you can reproduce them using the same environment as the one used by the CI thanks to a docker image, e.g.:

    $ cd [kernel source code]
    $ docker run -v "${PWD}:${PWD}:rw" -w "${PWD}" --privileged --rm -it \
        --pull always mptcp/mptcp-upstream-virtme-docker:latest \
        auto-normal

For more details:

https://github.com/multipath-tcp/mptcp-upstream-virtme-docker

Please note that despite all the efforts that have been already done to have a stable tests suite when executed on a public CI like here, it is possible some reported issues are not due to your modifications. Still, do not hesitate to help us improve that ;-)

Cheers,
MPTCP GH Action bot
Bot operated by Matthieu Baerts (NGI0 Core)

Queued for 6.18, thanks.

Thanks,
Sasha