Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755172AbYGCT5N (ORCPT ); Thu, 3 Jul 2008 15:57:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753647AbYGCT46 (ORCPT ); Thu, 3 Jul 2008 15:56:58 -0400 Received: from www.tglx.de ([62.245.132.106]:52071 "EHLO www.tglx.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753405AbYGCT45 (ORCPT ); Thu, 3 Jul 2008 15:56:57 -0400 Date: Thu, 3 Jul 2008 21:55:38 +0200 From: "Hans J. Koch" To: Paul Mundt Cc: "Hans J. Koch" , Uwe Kleine-K??nig , Magnus Damm , "linux-kernel@vger.kernel.org" , "gregkh@suse.de" , "akpm@linux-foundation.org" , "tglx@linutronix.de" Subject: Re: [PATCH] uio: User IRQ Mode Message-ID: <20080703195538.GC3197@local> References: <20080702105951.22648.2197.sendpatchset@rx1.opensource.se> <20080702125400.GC3199@local> <20080703071019.GC12214@digi.com> <20080703124505.GB3197@local> <20080703132316.GA1040@linux-sh.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080703132316.GA1040@linux-sh.org> User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1618 Lines: 39 On Thu, Jul 03, 2008 at 10:23:16PM +0900, Paul Mundt wrote: > On Thu, Jul 03, 2008 at 02:45:05PM +0200, Hans J. Koch wrote: > > On Thu, Jul 03, 2008 at 09:10:19AM +0200, Uwe Kleine-K??nig wrote: > > > Moreover this might prevent some bugs. (And obviously this > > > function has the potential to have a buggy implementation as > > > the comment by Alan Cox shows.) > > > > For me, this shows two things: > > > > - I never ever had to use disable_irq_nosync() in any UIO driver yet, > > otherwise I would have noticed. > > > > - Magnus turned in a patch that he never tested. > > > Note that the deadlock in question is in relation to SMP, it's true that > the patch was never tested in an SMP environment and only on UP, but it > certainly was tested. Ok, so I take back that accusation ;-) Nonetheless, the patch changes a UIO core file, and everything in there should work in all situations on all architectures unless there is a _very_ good reason to do something different. This not only applies to SMP issues but also to the limitation to non-shared interrupts. > The vast majority of driver writers don't have a > need to use disable_irq_nosync(), so whether you've had to use it or not > is largely irrelevant to the conversation at hand ;-) Sure ;-) I merely wanted to point out that this is an unusual way to handle an interrupt. Thanks, Hans -- 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/