Merge branch 'for-4.16/nfit' into libnvdimm-for-nextlibnvdimm-for-4.16

1 files changed, 16 insertions, 12 deletions

diff --git a/net/sctp/input.c b/net/sctp/input.c
index 621b5ca3fd1c..141c9c466ec1 100644
--- a/net/sctp/input.c
+++ b/net/sctp/input.c
@@ -399,20 +399,24 @@ void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc,
 		return;
 	}
 
-	if (t->param_flags & SPP_PMTUD_ENABLE) {
-		/* Update transports view of the MTU */
-		sctp_transport_update_pmtu(t, pmtu);
-
-		/* Update association pmtu. */
-		sctp_assoc_sync_pmtu(asoc);
-	}
+	if (!(t->param_flags & SPP_PMTUD_ENABLE))
+		/* We can't allow retransmitting in such case, as the
+		 * retransmission would be sized just as before, and thus we
+		 * would get another icmp, and retransmit again.
+		 */
+		return;
 
-	/* Retransmit with the new pmtu setting.
-	 * Normally, if PMTU discovery is disabled, an ICMP Fragmentation
-	 * Needed will never be sent, but if a message was sent before
-	 * PMTU discovery was disabled that was larger than the PMTU, it
-	 * would not be fragmented, so it must be re-transmitted fragmented.
+	/* Update transports view of the MTU. Return if no update was needed.
+	 * If an update wasn't needed/possible, it also doesn't make sense to
+	 * try to retransmit now.
 	 */
+	if (!sctp_transport_update_pmtu(t, pmtu))
+		return;
+
+	/* Update association pmtu. */
+	sctp_assoc_sync_pmtu(asoc);
+
+	/* Retransmit with the new pmtu setting. */
 	sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD);
 }