From owner-svn-src-stable@FreeBSD.ORG Thu Feb 21 21:48:39 2013 Return-Path: Delivered-To: svn-src-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by hub.freebsd.org (Postfix) with ESMTP id 1A123E59; Thu, 21 Feb 2013 21:48:39 +0000 (UTC) (envelope-from markj@FreeBSD.org) Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:1900:2254:2068::e6a:0]) by mx1.freebsd.org (Postfix) with ESMTP id E8101E59; Thu, 21 Feb 2013 21:48:38 +0000 (UTC) Received: from svn.freebsd.org ([127.0.1.70]) by svn.freebsd.org (8.14.5/8.14.5) with ESMTP id r1LLmc0f084901; Thu, 21 Feb 2013 21:48:38 GMT (envelope-from markj@svn.freebsd.org) Received: (from markj@localhost) by svn.freebsd.org (8.14.5/8.14.5/Submit) id r1LLmcoX084900; Thu, 21 Feb 2013 21:48:38 GMT (envelope-from markj@svn.freebsd.org) Message-Id: <201302212148.r1LLmcoX084900@svn.freebsd.org> From: Mark Johnston Date: Thu, 21 Feb 2013 21:48:38 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-6@freebsd.org Subject: svn commit: r247136 - stable/6/sys/netinet X-SVN-Group: stable-6 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-stable@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: SVN commit messages for all the -stable branches of the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 21 Feb 2013 21:48:39 -0000 Author: markj Date: Thu Feb 21 21:48:38 2013 New Revision: 247136 URL: http://svnweb.freebsd.org/changeset/base/247136 Log: MFC r239672 (by rrs): This small change takes care of a race condition that can occur when both sides close at the same time. If that occurs, without this fix the connection enters FIN1 on both sides and they will forever send FIN|ACK at each other until the connection times out. This is because we stopped processing the FIN|ACK and thus did not advance the sequence and so never ACK'd each others FIN. This fix adjusts it so we *do* process the FIN properly and the race goes away ;-) Approved by: emaste (co-mentor) Modified: stable/6/sys/netinet/tcp_input.c Directory Properties: stable/6/sys/ (props changed) Modified: stable/6/sys/netinet/tcp_input.c ============================================================================== --- stable/6/sys/netinet/tcp_input.c Thu Feb 21 21:47:35 2013 (r247135) +++ stable/6/sys/netinet/tcp_input.c Thu Feb 21 21:48:38 2013 (r247136) @@ -1908,6 +1908,16 @@ trimthenstep6: } } else tp->snd_cwnd += tp->t_maxseg; + if ((thflags & TH_FIN) && + (TCPS_HAVERCVDFIN(tp->t_state) == 0)) { + /* + * If its a fin we need to process + * it to avoid a race where both + * sides enter FIN-WAIT and send FIN|ACK + * at the same time. + */ + break; + } (void) tcp_output(tp); goto drop; } else if (tp->t_dupacks == tcprexmtthresh) { @@ -1951,6 +1961,16 @@ trimthenstep6: } tp->snd_nxt = th->th_ack; tp->snd_cwnd = tp->t_maxseg; + if ((thflags & TH_FIN) && + (TCPS_HAVERCVDFIN(tp->t_state) == 0)) { + /* + * If its a fin we need to process + * it to avoid a race where both + * sides enter FIN-WAIT and send FIN|ACK + * at the same time. + */ + break; + } (void) tcp_output(tp); KASSERT(tp->snd_limited <= 2, ("tp->snd_limited too big")); @@ -1974,6 +1994,16 @@ trimthenstep6: (tp->snd_nxt - tp->snd_una) + (tp->t_dupacks - tp->snd_limited) * tp->t_maxseg; + if ((thflags & TH_FIN) && + (TCPS_HAVERCVDFIN(tp->t_state) == 0)) { + /* + * If its a fin we need to process + * it to avoid a race where both + * sides enter FIN-WAIT and send FIN|ACK + * at the same time. + */ + break; + } (void) tcp_output(tp); sent = tp->snd_max - oldsndmax; if (sent > tp->t_maxseg) {