Similar to PRIORITY/KEEPALIVE: needs to be mirrored to all subflows.

Signed-off-by: Florian Westphal <fw(a)strlen.de>
---
 net/mptcp/sockopt.c | 48 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c
index 9a87c50e21a4..a78e51ead3ae 100644
--- a/net/mptcp/sockopt.c
+++ b/net/mptcp/sockopt.c
@@ -136,6 +136,45 @@ static int mptcp_setsockopt_sol_socket_int(struct mptcp_sock *msk, int optname,
 	return -ENOPROTOOPT;
 }
 
+static int mptcp_setsockopt_sol_socket_linger(struct mptcp_sock *msk, sockptr_t optval,
+					      unsigned int optlen)
+{
+	struct mptcp_subflow_context *subflow;
+	struct sock *sk = (struct sock *)msk;
+	struct linger ling;
+	sockptr_t kopt;
+	int ret;
+
+	if (optlen < sizeof(ling))
+		return -EINVAL;
+
+	if (copy_from_sockptr(&ling, optval, sizeof(ling)))
+		return -EFAULT;
+
+	kopt = KERNEL_SOCKPTR(&ling);
+	ret = sock_setsockopt(sk->sk_socket, SOL_SOCKET, SO_LINGER, kopt, sizeof(ling));
+	if (ret)
+		return ret;
+
+	lock_sock(sk);
+	mptcp_for_each_subflow(msk, subflow) {
+		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
+		bool slow = lock_sock_fast(ssk);
+
+		if (!ling.l_onoff)
+			sock_reset_flag(ssk, SOCK_LINGER);
+		else {
+			ssk->sk_lingertime = sk->sk_lingertime;
+			sock_set_flag(ssk, SOCK_LINGER);
+		}
+
+		unlock_sock_fast(ssk, slow);
+	}
+
+	release_sock(sk);
+	return 0;
+}
+
 static int mptcp_setsockopt_sol_socket(struct mptcp_sock *msk, int optname,
 				       sockptr_t optval, unsigned int optlen)
 {
@@ -175,6 +214,8 @@ static int mptcp_setsockopt_sol_socket(struct mptcp_sock *msk, int optname,
 	case SO_RCVBUF:
 	case SO_RCVBUFFORCE:
 		return mptcp_setsockopt_sol_socket_int(msk, optname, optval, optlen);
+	case SO_LINGER:
+		return mptcp_setsockopt_sol_socket_linger(msk, optval, optlen);
 	}
 
 	return sock_setsockopt(sk->sk_socket, SOL_SOCKET, optname, optval, optlen);
@@ -492,6 +533,13 @@ static void sync_socket_options(struct mptcp_sock *msk, struct sock *ssk)
 
 	WRITE_ONCE(ssk->sk_sndbuf, sk->sk_sndbuf);
 	WRITE_ONCE(ssk->sk_rcvbuf, sk->sk_rcvbuf);
+
+	if (sock_flag(sk, SOCK_LINGER)) {
+		ssk->sk_lingertime = sk->sk_lingertime;
+		sock_set_flag(ssk, SOCK_LINGER);
+	} else {
+		sock_reset_flag(ssk, SOCK_LINGER);
+	}
 	unlock_sock_fast(ssk, slow);
 }
 
-- 
2.26.2