netdev - [PATCH net-next 06/12] mptcp: Add mptcp_close

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Date:   Tue, 28 Jul 2020 15:12:04 -0700
From:   Mat Martineau <mathew.j.martineau@...ux.intel.com>
To:     netdev@...r.kernel.org
Cc:     Mat Martineau <mathew.j.martineau@...ux.intel.com>,
        mptcp@...ts.01.org, matthieu.baerts@...sares.net, pabeni@...hat.com
Subject: [PATCH net-next 06/12] mptcp: Add mptcp_close_state() helper

This will be used to transition to the appropriate state on close and
determine if a DATA_FIN needs to be sent for that state transition.

Signed-off-by: Mat Martineau <mathew.j.martineau@...ux.intel.com>
---
 net/mptcp/protocol.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index e1c71bfd61a3..51370b69e30b 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1498,6 +1498,33 @@ static void mptcp_subflow_shutdown(struct sock *ssk, int how)
 	release_sock(ssk);
 }
 
+static const unsigned char new_state[16] = {
+	/* current state:     new state:      action:	*/
+	[0 /* (Invalid) */] = TCP_CLOSE,
+	[TCP_ESTABLISHED]   = TCP_FIN_WAIT1 | TCP_ACTION_FIN,
+	[TCP_SYN_SENT]      = TCP_CLOSE,
+	[TCP_SYN_RECV]      = TCP_FIN_WAIT1 | TCP_ACTION_FIN,
+	[TCP_FIN_WAIT1]     = TCP_FIN_WAIT1,
+	[TCP_FIN_WAIT2]     = TCP_FIN_WAIT2,
+	[TCP_TIME_WAIT]     = TCP_CLOSE,	/* should not happen ! */
+	[TCP_CLOSE]         = TCP_CLOSE,
+	[TCP_CLOSE_WAIT]    = TCP_LAST_ACK  | TCP_ACTION_FIN,
+	[TCP_LAST_ACK]      = TCP_LAST_ACK,
+	[TCP_LISTEN]        = TCP_CLOSE,
+	[TCP_CLOSING]       = TCP_CLOSING,
+	[TCP_NEW_SYN_RECV]  = TCP_CLOSE,	/* should not happen ! */
+};
+
+static int mptcp_close_state(struct sock *sk)
+{
+	int next = (int)new_state[sk->sk_state];
+	int ns = next & TCP_STATE_MASK;
+
+	inet_sk_state_store(sk, ns);
+
+	return next & TCP_ACTION_FIN;
+}
+
 static void mptcp_close(struct sock *sk, long timeout)
 {
 	struct mptcp_subflow_context *subflow, *tmp;
-- 
2.28.0