From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932101AbWAUK14 (ORCPT ); Sat, 21 Jan 2006 05:27:56 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932104AbWAUK14 (ORCPT ); Sat, 21 Jan 2006 05:27:56 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:51095 "EHLO mx3.mail.elte.hu") by vger.kernel.org with ESMTP id S932101AbWAUK1z (ORCPT ); Sat, 21 Jan 2006 05:27:55 -0500 Date: Sat, 21 Jan 2006 11:28:08 +0100 From: Ingo Molnar To: Steven Rostedt Cc: john stultz , Thomas Gleixner , LKML Subject: Re: [PATCH RT] don't let printk unconditionally turn on interrupts Message-ID: <20060121102808.GB991@elte.hu> References: <1137811001.6762.179.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1137811001.6762.179.camel@localhost.localdomain> User-Agent: Mutt/1.4.2.1i X-ELTE-SpamScore: 0.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=0.0 required=5.9 tests=AWL autolearn=no SpamAssassin version=3.0.3 0.0 AWL AWL: From: address is in the auto white-list X-ELTE-VirusStatus: clean Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Steven Rostedt wrote: > Ingo, > > My first try at booting -rt8 on my machine crashed immediately. No > nmi, no nothing. Just a lockup at the registration of the ACPI_PM > timer. This would happen every time, and after struggling for a while, > I finally found out why! > > The printk in timeofday_periodic_hook that is called holding the > write_lock of system_time_lock (a raw_seq_lock) was causing lots of > havoc. The printk would turn on interrupts, and then I would get a > deadlock when the interrupt would do a read on system_time_lock. argh. This piece of code has caused so many problems already. Some people want console drivers to be preemptible, but i guess being able to boot trumps things ;) could you check out the variant in 2.6.15-rt11 - i tweaked it slightly over yours, hopefully making the behavior more consistent. Ingo