net: sctp: Don't transition to PF state when transport has exhausted 'Path.Max.Retrans'.

Don't transition to the PF state on every strike after 'Path.Max.Retrans'.
Per draft-ietf-tsvwg-sctp-failover-03 Section 5.1.6:

   Additional (PMR - PFMR) consecutive timeouts on a PF destination
   confirm the path failure, upon which the destination transitions to the
   Inactive state.  As described in [RFC4960], the sender (i) SHOULD notify
   ULP about this state transition, and (ii) transmit heartbeats to the
   Inactive destination at a lower frequency as described in Section 8.3 of
   [RFC4960].

This also prevents sending SCTP_ADDR_UNREACHABLE to the user as the state
bounces between SCTP_INACTIVE and SCTP_PF for each subsequent strike.
Signed-off-by: Karl Heiss <kheiss@gmail.com>
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sctp/sm_sideeffect.c

@@ -496,11 +496,10 @@ static void sctp_do_8_2_transport_strike(sctp_cmd_seq_t *commands,
 
 	/* If the transport error count is greater than the pf_retrans
 	 * threshold, and less than pathmaxrtx, and if the current state
-	 * is not SCTP_UNCONFIRMED, then mark this transport as Partially
-	 * Failed, see SCTP Quick Failover Draft, section 5.1
+	 * is SCTP_ACTIVE, then mark this transport as Partially Failed,
+	 * see SCTP Quick Failover Draft, section 5.1
 	 */
-	if ((transport->state != SCTP_PF) &&
-	   (transport->state != SCTP_UNCONFIRMED) &&
+	if ((transport->state == SCTP_ACTIVE) &&
 	   (asoc->pf_retrans < transport->pathmaxrxt) &&
 	   (transport->error_count > asoc->pf_retrans)) {