Tries to follow the subflow most recently used from transmit.

Signed-off-by: Florian Westphal <fw(a)strlen.de>
---
 net/mptcp/sockopt.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c
index c1ffc3603b4f..27ea5b1ea57e 100644
--- a/net/mptcp/sockopt.c
+++ b/net/mptcp/sockopt.c
@@ -657,6 +657,28 @@ static int mptcp_getsockopt_first_sf_only(struct mptcp_sock *msk, int level, int
 	return ret;
 }
 
+static int mptcp_getsockopt_tcp_info(struct mptcp_sock *msk, char __user *optval, int __user *optlen)
+{
+	struct mptcp_subflow_context *subflow;
+	struct sock *sk = (struct sock *)msk;
+	struct sock *ssk = NULL;
+	int ret = -EOPNOTSUPP;
+
+	lock_sock(sk);
+	mptcp_for_each_subflow(msk, subflow) {
+		ssk = mptcp_subflow_tcp_sock(subflow);
+
+		if (ssk == msk->last_snd)
+			break;
+	}
+
+	if (ssk)
+		ret = tcp_getsockopt(ssk, SOL_TCP, TCP_INFO, optval, optlen);
+
+	release_sock(sk);
+	return ret;
+}
+
 static int mptcp_getsockopt_sol_tcp(struct mptcp_sock *msk, int optname,
 				    char __user *optval, int __user *optlen)
 {
@@ -665,6 +687,8 @@ static int mptcp_getsockopt_sol_tcp(struct mptcp_sock *msk, int optname,
 	case TCP_CONGESTION:
 		return mptcp_getsockopt_first_sf_only(msk, SOL_TCP, optname,
 						      optval, optlen);
+	case TCP_INFO:
+		return mptcp_getsockopt_tcp_info(msk, optval, optlen);
 	}
 	return -EOPNOTSUPP;
 }
-- 
2.26.2