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.

Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

net/mptcp/options.c

@@ -1381,27 +1381,29 @@ 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) {
- *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
- TCPOLEN_MPTCP_MPJ_SYN,
- opts->backup, opts->join_id);
- put_unaligned_be32(opts->token, ptr);
- ptr += 1;
- put_unaligned_be32(opts->nonce, ptr);
- ptr += 1;
- } else if (OPTION_MPTCP_MPJ_SYNACK & opts->suboptions) {
- *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
- TCPOLEN_MPTCP_MPJ_SYNACK,
- opts->backup, opts->join_id);
- put_unaligned_be64(opts->thmac, ptr);
- ptr += 2;
- put_unaligned_be32(opts->nonce, ptr);
- ptr += 1;
- } else if (OPTION_MPTCP_MPJ_ACK & opts->suboptions) {
- *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
- TCPOLEN_MPTCP_MPJ_ACK, 0, 0);
- memcpy(ptr, opts->hmac, MPTCPOPT_HMAC_LEN);
- ptr += 5;
+ } 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);
+ put_unaligned_be32(opts->token, ptr);
+ ptr += 1;
+ put_unaligned_be32(opts->nonce, ptr);
+ ptr += 1;
+ } else if (OPTION_MPTCP_MPJ_SYNACK & opts->suboptions) {
+ *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
+ TCPOLEN_MPTCP_MPJ_SYNACK,
+ opts->backup, opts->join_id);
+ put_unaligned_be64(opts->thmac, ptr);
+ ptr += 2;
+ put_unaligned_be32(opts->nonce, ptr);
+ ptr += 1;
+ } 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;