sctp: Correclty set changeover_active for SFR-CACC

Right now, any time we set a primary transport we set
the changeover_active flag.  As a result, we invoke SFR-CACC
even when there has been no changeover events.

Only set changeover_active, when there is a true changeover
event, i.e. we had a primary path and we are changing to
another transport.
Signed-off-by: NVlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/sctp/associola.c

@@ -474,6 +474,15 @@ static void sctp_association_destroy(struct sctp_association *asoc)
 void sctp_assoc_set_primary(struct sctp_association *asoc,
 			    struct sctp_transport *transport)
 {
+	int changeover = 0;
+
+	/* it's a changeover only if we already have a primary path
+	 * that we are changing
+	 */
+	if (asoc->peer.primary_path != NULL &&
+	    asoc->peer.primary_path != transport)
+		changeover = 1 ;
+
 	asoc->peer.primary_path = transport;
 
 	/* Set a default msg_name for events. */
@@ -499,12 +508,12 @@ void sctp_assoc_set_primary(struct sctp_association *asoc,
 	 * double switch to the same destination address.
 	 */
 	if (transport->cacc.changeover_active)
-		transport->cacc.cycling_changeover = 1;
+		transport->cacc.cycling_changeover = changeover;
 
 	/* 2) The sender MUST set CHANGEOVER_ACTIVE to indicate that
 	 * a changeover has occurred.
 	 */
-	transport->cacc.changeover_active = 1;
+	transport->cacc.changeover_active = changeover;
 
 	/* 3) The sender MUST store the next TSN to be sent in
 	 * next_tsn_at_change.