tcp: export tcp_sendmsg_fastopen

It will be used to support TCP FastOpen with MPTCP in the following
commit.
Acked-by: NPaolo Abeni <pabeni@redhat.com>
Reviewed-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Co-developed-by: NDmytro Shytyi <dmytro@shytyi.net>
Signed-off-by: NDmytro Shytyi <dmytro@shytyi.net>
Signed-off-by: NBenjamin Hesmans <benjamin.hesmans@tessares.net>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

include/net/tcp.h

@@ -327,6 +327,8 @@ void tcp_remove_empty_skb(struct sock *sk);
 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
 int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
 int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size);
+int tcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg, int *copied,
+			 size_t size, struct ubuf_info *uarg);
 int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size,
 		 int flags);
 int tcp_sendpage_locked(struct sock *sk, struct page *page, int offset,

net/ipv4/tcp.c

@@ -1162,9 +1162,8 @@ void tcp_free_fastopen_req(struct tcp_sock *tp)
 	}
 }
 
-static int tcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg,
-				int *copied, size_t size,
-				struct ubuf_info *uarg)
+int tcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg, int *copied,
+			 size_t size, struct ubuf_info *uarg)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	struct inet_sock *inet = inet_sk(sk);