From mboxrd@z Thu Jan 1 00:00:00 1970 From: Guillaume Autran Subject: Re: Possible BUG in IPv4 TCP window handling, all recent 2.4.x/2.6.x kernels Date: Fri, 02 Sep 2005 12:18:52 -0400 Message-ID: <43187B6C.7020203@mrv.com> References: <20050901.154300.118239765.davem@davemloft.net> <2d02c76a84655d212634a91002b3eccd@psc.edu> <43184D79.6040009@mrv.com> <20050902135256.GC12617@yakov.inr.ac.ru> <43185E81.2070300@mrv.com> <20050902154424.GA15060@yakov.inr.ac.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: To: linux-net@vger.kernel.org, netdev@vger.kernel.org In-Reply-To: <20050902154424.GA15060@yakov.inr.ac.ru> Sender: linux-net-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Hi Alexey, Do you think this will also fix Ion's issue with small window size never going back up ? Thanks Guillaume. Alexey Kuznetsov wrote: >Hello! > > > >>Here are the dumps... >> >> > >I see. It has nothing to do with clamping. Indeed this is a very old bug. >Frankly speaking I even was aware about this at some moment >(so that if the sender was Linux it would not happen. It was fixed there. :-)) > >With such small window sender is forced to send a tiny segment >via SWS override timer and receiver is confused in believing this >is sender's mss, so the result is broken SWS avoidance. > >I think you can cure it deleting the following lines: > > /* If PSH is not set, packet should be > * full sized, provided peer TCP is not badly broken. > * This observation (if it is correct 8)) allows > * to handle super-low mtu links fairly. > */ > (len >= TCP_MIN_MSS + sizeof(struct tcphdr) && > !(tcp_flag_word(skb->h.th)&TCP_REMNANT))) { > > >in tcp_input.c:tcp_measure_rcv_mss() at receiver side. > > >Alexey > > > -- ======================================= Guillaume Autran Senior Software Engineer MRV Communications, Inc. Tel: (978) 952-4932 office E-mail: gautran@mrv.com =======================================