sctp: move transport pathmtu calc away of sctp_assoc_add_peer

There was only one case that sctp_assoc_add_peer couldn't handle, which
is when SPP_PMTUD_DISABLE is set and pathmtu not initialized.
So add this situation to sctp_transport_route and reuse what was
already in there.
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sctp/associola.c

@@ -652,15 +652,8 @@ struct sctp_transport *sctp_assoc_add_peer(struct sctp_association *asoc,
 	 */
 	peer->param_flags = asoc->param_flags;
 
-	sctp_transport_route(peer, NULL, sp);
-
 	/* Initialize the pmtu of the transport. */
-	if (peer->param_flags & SPP_PMTUD_DISABLE) {
-		if (asoc->pathmtu)
-			peer->pathmtu = asoc->pathmtu;
-		else
-			peer->pathmtu = SCTP_DEFAULT_MAXSEGMENT;
-	}
+	sctp_transport_route(peer, NULL, sp);
 
 	/* If this is the first transport addr on this association,
 	 * initialize the association PMTU to the peer's PMTU.

net/sctp/transport.c

@@ -310,8 +310,12 @@ void sctp_transport_route(struct sctp_transport *transport,
 			     (transport == asoc->peer.active_path)))
 			opt->pf->to_sk_saddr(&transport->saddr,
 					     asoc->base.sk);
-	} else
+	} else if ((transport->param_flags & SPP_PMTUD_DISABLE) &&
+		   asoc && asoc->pathmtu) {
+		transport->pathmtu = asoc->pathmtu;
+	} else {
 		transport->pathmtu = SCTP_DEFAULT_MAXSEGMENT;
+	}
 }
 
 /* Hold a reference to a transport.  */