mptcp: clean-up MPJ option writing

Check for all MPJ variant at once, this reduces the number
of conditionals traversed on average and will simplify the
next patch.

No functional change intended.
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

@@ -1385,7 +1385,8 @@ void mptcp_write_options(__be32 *ptr, const struct tcp_sock *tp,
 
 		/* MPC is additionally mutually exclusive with MP_PRIO */
 		goto mp_capable_done;
-	} else if (OPTION_MPTCP_MPJ_SYN & opts->suboptions) {
+	} else if (OPTIONS_MPTCP_MPJ & opts->suboptions) {
+		if (OPTION_MPTCP_MPJ_SYN & opts->suboptions) {
 			*ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
 					      TCPOLEN_MPTCP_MPJ_SYN,
 					      opts->backup, opts->join_id);
@@ -1401,11 +1402,12 @@ void mptcp_write_options(__be32 *ptr, const struct tcp_sock *tp,
 			ptr += 2;
 			put_unaligned_be32(opts->nonce, ptr);
 			ptr += 1;
-	} else if (OPTION_MPTCP_MPJ_ACK & opts->suboptions) {
+		} else {
 			*ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
 					      TCPOLEN_MPTCP_MPJ_ACK, 0, 0);
 			memcpy(ptr, opts->hmac, MPTCPOPT_HMAC_LEN);
 			ptr += 5;
+		}
 	} else if (OPTION_MPTCP_ADD_ADDR & opts->suboptions) {
 		u8 len = TCPOLEN_MPTCP_ADD_ADDR_BASE;
 		u8 echo = MPTCP_ADDR_ECHO;