netdev - [PATCH net-next 3/4] mptcp: handle defer connect in mptcp

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Date:   Mon, 26 Sep 2022 16:27:38 -0700
From:   Mat Martineau <mathew.j.martineau@...ux.intel.com>
To:     netdev@...r.kernel.org
Cc:     Dmytro Shytyi <dmytro@...tyi.net>, davem@...emloft.net,
        kuba@...nel.org, pabeni@...hat.com, edumazet@...gle.com,
        benjamin.hesmans@...sares.net, matthieu.baerts@...sares.net,
        mptcp@...ts.linux.dev,
        Mat Martineau <mathew.j.martineau@...ux.intel.com>
Subject: [PATCH net-next 3/4] mptcp: handle defer connect in mptcp_sendmsg

From: Dmytro Shytyi <dmytro@...tyi.net>

When TCP_FASTOPEN_CONNECT has been set on the socket before a connect,
the defer flag is set and must be handled when sendmsg is called.

This is similar to what is done in tcp_sendmsg_locked().

Acked-by: Paolo Abeni <pabeni@...hat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@...sares.net>
Co-developed-by: Benjamin Hesmans <benjamin.hesmans@...sares.net>
Signed-off-by: Benjamin Hesmans <benjamin.hesmans@...sares.net>
Signed-off-by: Dmytro Shytyi <dmytro@...tyi.net>
Signed-off-by: Mat Martineau <mathew.j.martineau@...ux.intel.com>
---
 net/mptcp/protocol.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 866dfad3cde6..fc753896caa0 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1677,6 +1677,7 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 {
 	struct mptcp_sock *msk = mptcp_sk(sk);
 	struct page_frag *pfrag;
+	struct socket *ssock;
 	size_t copied = 0;
 	int ret = 0;
 	long timeo;
@@ -1690,6 +1691,27 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 
 	lock_sock(sk);
 
+	ssock = __mptcp_nmpc_socket(msk);
+	if (unlikely(ssock && inet_sk(ssock->sk)->defer_connect)) {
+		struct sock *ssk = ssock->sk;
+		int copied_syn = 0;
+
+		lock_sock(ssk);
+
+		ret = tcp_sendmsg_fastopen(ssk, msg, &copied_syn, len, NULL);
+		copied += copied_syn;
+		if (ret == -EINPROGRESS && copied_syn > 0) {
+			/* reflect the new state on the MPTCP socket */
+			inet_sk_state_store(sk, inet_sk_state_load(ssk));
+			release_sock(ssk);
+			goto out;
+		} else if (ret) {
+			release_sock(ssk);
+			goto out;
+		}
+		release_sock(ssk);
+	}
+
 	timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
 
 	if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) {
-- 
2.37.3