Merge tag 'trace-v4.15-rc4-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rosted...

[mirror_ubuntu-bionic-kernel.git] / net / sctp / input.c

diff --git a/net/sctp/input.c b/net/sctp/input.c
index 621b5ca3fd1c17c3d7ef7bb1c7677ab98cebbe77..141c9c466ec172ff67930cf38eb02a49e01a12ab 100644 (file)
--- 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);
 }