Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755427AbXEDTCi (ORCPT ); Fri, 4 May 2007 15:02:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030840AbXEDTCi (ORCPT ); Fri, 4 May 2007 15:02:38 -0400 Received: from caffeine.uwaterloo.ca ([129.97.134.17]:46102 "EHLO caffeine.csclub.uwaterloo.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755364AbXEDTCh (ORCPT ); Fri, 4 May 2007 15:02:37 -0400 Date: Fri, 4 May 2007 15:02:36 -0400 To: Don Fry Cc: Frederik Deweerdt , linux-kernel@vger.kernel.org, netdev@vger.kernel.org Subject: Re: Strange soft lockup detected message (looks like spin_lock bug in pcnet32) Message-ID: <20070504190236.GE8753@csclub.uwaterloo.ca> References: <20070503203143.GA8753@csclub.uwaterloo.ca> <20070504141024.GB8753@csclub.uwaterloo.ca> <20070504143326.GD24769@slug> <20070504151934.GA8754@csclub.uwaterloo.ca> <20070504153438.GE24769@slug> <20070504154009.GE8751@csclub.uwaterloo.ca> <20070504174456.GC8753@csclub.uwaterloo.ca> <20070504175017.GD8753@csclub.uwaterloo.ca> <20070504182433.GA11595@verizon.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070504182433.GA11595@verizon.net> User-Agent: Mutt/1.5.13 (2006-08-11) From: lsorense@csclub.uwaterloo.ca (Lennart Sorensen) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1428 Lines: 36 On Fri, May 04, 2007 at 11:24:33AM -0700, Don Fry wrote: > All instances of obtaining the lock in pcnet32 are done as > spin_lock_irqsave except the interrupt handler itself. The interrupt mask > needs to be saved everywhere else, but the interrupt handler is known not > to need to save the flags. > > If the lock is held and the same CPU tries to get the lock again, it will > wait a very long time ;-(. I believe the locking is fine for a > non-preemptable kernel, but I have little experience with a preemptable > kernel. > > When does a preemptable kernel allow interrupts to occur? I have no idea actually. > Is there a bug in this particular architectures locking code? On i386? I hope not. > From looking at preempt-locking.txt the driver has (1) no per-cpu data, > (2) 'CPU state protection' should be fine, > (3) the 'lock is acquired and released by the same task'. > I don't see a problem unless I am misunderstanding something. Well I don't know, but something is going wrong and causing the soft lock up. I must admit I am surprised if an interrupt can occour while handling an interrupt, but then again maybe that is supposed to be allowed. -- Len Sorensen - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/