inet: add TCP_NEW_SYN_RECV state

TCP_SYN_RECV state is currently used by fast open sockets.

Initial TCP requests (the pseudo sockets created when a SYN is received)
are not yet associated to a state. They are attached to their parent,
and the parent is in TCP_LISTEN state.

This commit adds TCP_NEW_SYN_RECV state, so that we can convert
TCP stack to a different schem gradually.

This state is not exported to user space.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/tcp_states.h

@@ -25,6 +25,7 @@ enum {
 	TCP_LAST_ACK,
 	TCP_LISTEN,
 	TCP_CLOSING,	/* Now a valid state */
+	TCP_NEW_SYN_RECV,
 
 	TCP_MAX_STATES	/* Leave at the end! */
 };
@@ -44,7 +45,8 @@ enum {
 	TCPF_CLOSE_WAIT	 = (1 << 8),
 	TCPF_LAST_ACK	 = (1 << 9),
 	TCPF_LISTEN	 = (1 << 10),
-	TCPF_CLOSING	 = (1 << 11) 
+	TCPF_CLOSING	 = (1 << 11),
+	TCPF_NEW_SYN_RECV = (1 << 12),
 };
 
 #endif	/* _LINUX_TCP_STATES_H */