>> Transport pathmtu can not be updated, when PMTUD is disabled >> and pathmtu is condigured as fixed. Unconditional update t->pathmtu >> will result in overwriting parameter configured by user >> and lack of GSO usage. >Seems right, the update of dst's mtu from elsewhere shouldn't >affect SCTP either if SPP_PMTUD_DISABLE flag is set. I agree. >Can you please try to fix it with this? > >diff --git a/net/sctp/output.c b/net/sctp/output.c >index a6aa17d..9f53323 100644 >--- a/net/sctp/output.c >+++ b/net/sctp/output.c >@@ -103,8 +103,8 @@ void sctp_packet_config(struct sctp_packet >*packet, __u32 vtag, > sctp_transport_route(tp, NULL, sp); > if (asoc->param_flags & SPP_PMTUD_ENABLE) > sctp_assoc_sync_pmtu(asoc); >- } else if (!sctp_transport_pmtu_check(tp)) { >- if (asoc->param_flags & SPP_PMTUD_ENABLE) >+ } else if (asoc->param_flags & SPP_PMTUD_ENABLE) { >+ if (!sctp_transport_pmtu_check(tp)) > sctp_assoc_sync_pmtu(asoc); > } This proposal is better. I've tested above. Result is OK. Tested-by: Jacek Szafraniec <jacek.szafraniec@xxxxxxxxx> Thanks!