From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263226AbVGOH3F (ORCPT ); Fri, 15 Jul 2005 03:29:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263232AbVGOH3F (ORCPT ); Fri, 15 Jul 2005 03:29:05 -0400 Received: from caramon.arm.linux.org.uk ([212.18.232.186]:9740 "EHLO caramon.arm.linux.org.uk") by vger.kernel.org with ESMTP id S263226AbVGOH3D (ORCPT ); Fri, 15 Jul 2005 03:29:03 -0400 Date: Fri, 15 Jul 2005 08:28:59 +0100 From: Russell King To: karl malbrain Cc: "Linux-Kernel@Vger. Kernel. Org" Subject: Re: 2.6.9: serial_core: uart_open Message-ID: <20050715082859.B23102@flint.arm.linux.org.uk> Mail-Followup-To: karl malbrain , "Linux-Kernel@Vger. Kernel. Org" References: <20050714195717.B10410@flint.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: ; from karl@petzent.com on Thu, Jul 14, 2005 at 03:35:07PM -0700 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 14, 2005 at 03:35:07PM -0700, karl malbrain wrote: > AT LAST I HAVE SOME DATA!!! > > The problem is that ALL SYSTEM CALLS to open "/dev/tty" are blocking!! even > with O_NDELAY set and even from completely disjoint sessions. I discovered > this via issuing "strace sh". That's why the new xterm windows froze. > > The original process doing the open("/dev/ttyS1", O_RDWR) is listed in the > ps aux listing as status S+. Ok, 'S' means it's sleeping. Can you enable Magic SYSRQ, and ensure that you have a large kernel log buffer (the LOG_BUF_SHIFT configuration symbol). Ensure that /proc/sys/kernel/sysrq is 1, and re-run your test such that you have something else waiting (eg, the strace sh). Then hit Alt-SysRQ-T. You can then read the kernel messages with dmesg - you may need the -s argument to capture the entire kernel buffer. This will tell us where all processes are sleeping. -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 Serial core