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From:   Matthieu Baerts <matthieu.baerts@tessares.net>
Date:   Fri, 11 Aug 2023 17:57:19 +0200
Subject: [PATCH net-next 06/14] net: factor out __inet_listen_sk() helper
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Message-Id: <20230811-upstream-net-next-20230811-mptcp-get-rid-of-msk-subflow-v1-6-36183269ade8@tessares.net>
References: <20230811-upstream-net-next-20230811-mptcp-get-rid-of-msk-subflow-v1-0-36183269ade8@tessares.net>
In-Reply-To: <20230811-upstream-net-next-20230811-mptcp-get-rid-of-msk-subflow-v1-0-36183269ade8@tessares.net>
To:     mptcp@lists.linux.dev, Mat Martineau <martineau@kernel.org>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        David Ahern <dsahern@kernel.org>
Cc:     netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        Matthieu Baerts <matthieu.baerts@tessares.net>
Precedence: bulk

From: Paolo Abeni <pabeni@redhat.com>

The mptcp protocol maintains an additional socket just to easily
invoke a few stream operations on the first subflow. One of them
is inet_listen().

Factor out an helper operating directly on the (locked) struct sock,
to allow get rid of the above dependency in the next patch without
duplicating the existing code.

No functional changes intended.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
---
 include/net/inet_common.h |  1 +
 net/ipv4/af_inet.c        | 38 ++++++++++++++++++++++----------------
 2 files changed, 23 insertions(+), 16 deletions(-)

diff --git a/include/net/inet_common.h b/include/net/inet_common.h
index 8e97de700991..f50a644d87a9 100644
--- a/include/net/inet_common.h
+++ b/include/net/inet_common.h
@@ -40,6 +40,7 @@ int inet_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
 		 int flags);
 int inet_shutdown(struct socket *sock, int how);
 int inet_listen(struct socket *sock, int backlog);
+int __inet_listen_sk(struct sock *sk, int backlog);
 void inet_sock_destruct(struct sock *sk);
 int inet_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len);
 int inet_bind_sk(struct sock *sk, struct sockaddr *uaddr, int addr_len);
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 2fd23437c1d2..c59da65f19d2 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -187,24 +187,13 @@ static int inet_autobind(struct sock *sk)
 	return 0;
 }
 
-/*
- *	Move a socket into listening state.
- */
-int inet_listen(struct socket *sock, int backlog)
+int __inet_listen_sk(struct sock *sk, int backlog)
 {
-	struct sock *sk = sock->sk;
-	unsigned char old_state;
+	unsigned char old_state = sk->sk_state;
 	int err, tcp_fastopen;
 
-	lock_sock(sk);
-
-	err = -EINVAL;
-	if (sock->state != SS_UNCONNECTED || sock->type != SOCK_STREAM)
-		goto out;
-
-	old_state = sk->sk_state;
 	if (!((1 << old_state) & (TCPF_CLOSE | TCPF_LISTEN)))
-		goto out;
+		return -EINVAL;
 
 	WRITE_ONCE(sk->sk_max_ack_backlog, backlog);
 	/* Really, if the socket is already in listen state
@@ -227,10 +216,27 @@ int inet_listen(struct socket *sock, int backlog)
 
 		err = inet_csk_listen_start(sk);
 		if (err)
-			goto out;
+			return err;
+
 		tcp_call_bpf(sk, BPF_SOCK_OPS_TCP_LISTEN_CB, 0, NULL);
 	}
-	err = 0;
+	return 0;
+}
+
+/*
+ *	Move a socket into listening state.
+ */
+int inet_listen(struct socket *sock, int backlog)
+{
+	struct sock *sk = sock->sk;
+	int err = -EINVAL;
+
+	lock_sock(sk);
+
+	if (sock->state != SS_UNCONNECTED || sock->type != SOCK_STREAM)
+		goto out;
+
+	err = __inet_listen_sk(sk, backlog);
 
 out:
 	release_sock(sk);

-- 
2.40.1