From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261703AbULBRzm (ORCPT ); Thu, 2 Dec 2004 12:55:42 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261686AbULBRzl (ORCPT ); Thu, 2 Dec 2004 12:55:41 -0500 Received: from users.ccur.com ([208.248.32.211]:27424 "EHLO gamx.iccur.com") by vger.kernel.org with ESMTP id S261703AbULBRye (ORCPT ); Thu, 2 Dec 2004 12:54:34 -0500 Date: Thu, 2 Dec 2004 12:54:18 -0500 From: Joe Korty To: Roland McGrath Cc: Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: waitid breaks telnet Message-ID: <20041202175418.GA9716@tsunami.ccur.com> Reply-To: joe.korty@ccur.com References: <20041201232204.GA29829@tsunami.ccur.com> <200412012358.iB1Nwk3C002166@magilla.sf.frob.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200412012358.iB1Nwk3C002166@magilla.sf.frob.com> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 01, 2004 at 03:58:46PM -0800, Roland McGrath wrote: > Since I can only manage so far to see this once in a blue moon, and you can > produce it frequently, it would be helpful if you can diagnose the problem > some. That is, figure out exactly what wrong results from a wait* call is > at fault. Hi Roland, I've been playing with this most of the morning, finally got strace attached to the telnet daemon, but it did me no good .. everything works when straced. My technique was to replace /usr/sbin/in.telnetd with a script that invokes the original binary under strace: # cd /usr/sbin # mv in.telnetd in.telnet.d.orig # cat <in.telnetd /usr/bin/strace -ff -o /tmp/telnet.log.$$ /usr/sbin/in.telnetd.orig "$@" EOF # chmod 755 in.telnetd Earlier this morning I systematically repeated my earlier, haphazard experiments. I built three kernels from two sources: the first source was the pure 2.6.7-rc1-bk7 tree, the second the same tree with the suspect waitid patch applied. From these I built various kernels with and without SMP and PREEMPT and ran at least seven 'telnet' tests on each. The results: kernel smp preempt | 1 2 3 4 5 6 7 8 9 ====================================================== bk7 Y Y | g g g g g g g bk7+waitid Y Y | F F F F F F F bk7+waitid N N | F g F F g g g F g