mptcp: remove unneeded check on first subflow

Currently we explicitly check for the first subflow being
NULL in a couple of places, even if we don't need any
special actions in such scenario.

Just drop the unneeded checks, to avoid confusion.
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/mptcp/options.c

@@ -952,7 +952,7 @@ bool mptcp_update_rcv_data_fin(struct mptcp_sock *msk, u64 data_fin_seq, bool us
 	 * should match. If they mismatch, the peer is misbehaving and
 	 * we will prefer the most recent information.
 	 */
-	if (READ_ONCE(msk->rcv_data_fin) || !READ_ONCE(msk->first))
+	if (READ_ONCE(msk->rcv_data_fin))
 		return false;
 
 	WRITE_ONCE(msk->rcv_data_fin_seq,

net/mptcp/protocol.c

@@ -493,7 +493,7 @@ static bool mptcp_check_data_fin(struct sock *sk)
 	u64 rcv_data_fin_seq;
 	bool ret = false;
 
-	if (__mptcp_check_fallback(msk) || !msk->first)
+	if (__mptcp_check_fallback(msk))
 		return ret;
 
 	/* Need to ack a DATA_FIN received from a peer while this side