From: Geliang Tang <tanggeliang@kylinos.cn>

Extract the TCP_ULP setsockopt operation into a tcp_sock_set_ulp() helper
so that it can also be used in MPTCP.

Co-developed-by: Gang Yan <yangang@kylinos.cn>
Signed-off-by: Gang Yan <yangang@kylinos.cn>
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 include/linux/tcp.h |  1 +
 net/ipv4/tcp.c      | 42 ++++++++++++++++++++++++------------------
 2 files changed, 25 insertions(+), 18 deletions(-)

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 6f0becc26402..46b83895908c 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -645,6 +645,7 @@ int tcp_sock_set_syncnt(struct sock *sk, int val);
 int tcp_sock_set_user_timeout(struct sock *sk, int val);
 int tcp_sock_set_maxseg(struct sock *sk, int val);
 int tcp_sock_get_ulp(struct sock *sk, sockptr_t optval, sockptr_t optlen);
+int tcp_sock_set_ulp(struct sock *sk, sockptr_t optval, unsigned int optlen);
 
 static inline bool dst_tcp_usec_ts(const struct dst_entry *dst)
 {
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 1ba5794574c7..1ad7e5ed6f25 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3809,6 +3809,28 @@ int tcp_sock_set_maxseg(struct sock *sk, int val)
 	return 0;
 }
 
+int tcp_sock_set_ulp(struct sock *sk, sockptr_t optval, unsigned int optlen)
+{
+	char name[TCP_ULP_NAME_MAX];
+	int err = 0;
+	size_t len;
+	int val;
+
+	if (optlen < 1)
+		return -EINVAL;
+
+	len = min_t(long, TCP_ULP_NAME_MAX - 1, optlen);
+	val = strncpy_from_sockptr(name, optval, len);
+	if (val < 0)
+		return -EFAULT;
+	name[val] = 0;
+
+	sockopt_lock_sock(sk);
+	err = tcp_set_ulp(sk, name);
+	sockopt_release_sock(sk);
+	return err;
+}
+
 /*
  *	Socket option code for TCP.
  */
@@ -3842,24 +3864,8 @@ int do_tcp_setsockopt(struct sock *sk, int level, int optname,
 		sockopt_release_sock(sk);
 		return err;
 	}
-	case TCP_ULP: {
-		char name[TCP_ULP_NAME_MAX];
-
-		if (optlen < 1)
-			return -EINVAL;
-
-		val = strncpy_from_sockptr(name, optval,
-					min_t(long, TCP_ULP_NAME_MAX - 1,
-					      optlen));
-		if (val < 0)
-			return -EFAULT;
-		name[val] = 0;
-
-		sockopt_lock_sock(sk);
-		err = tcp_set_ulp(sk, name);
-		sockopt_release_sock(sk);
-		return err;
-	}
+	case TCP_ULP:
+		return tcp_sock_set_ulp(sk, optval, optlen);
 	case TCP_FASTOPEN_KEY: {
 		__u8 key[TCP_FASTOPEN_KEY_BUF_LENGTH];
 		__u8 *backup_key = NULL;
-- 
2.51.0