Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S270922AbUJUUIv (ORCPT ); Thu, 21 Oct 2004 16:08:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S270928AbUJUUEP (ORCPT ); Thu, 21 Oct 2004 16:04:15 -0400 Received: from smtp.Lynuxworks.com ([207.21.185.24]:45074 "EHLO smtp.lynuxworks.com") by vger.kernel.org with ESMTP id S270843AbUJUT7p (ORCPT ); Thu, 21 Oct 2004 15:59:45 -0400 Date: Thu, 21 Oct 2004 12:58:42 -0700 To: Jens Axboe Cc: Thomas Gleixner , Rui Nuno Capela , Ingo Molnar , LKML , Lee Revell , mark_h_johnson@raytheon.com, "K.R. Foley" , Bill Huey , Adam Heath , Florian Schmidt , Michal Schmidt , Fernando Pablo Lopez-Lezcano Subject: Re: [patch] Real-Time Preemption, -RT-2.6.9-rc4-mm1-U8 Message-ID: <20041021195842.GA23864@nietzsche.lynx.com> References: <20041016153344.GA16766@elte.hu> <20041018145008.GA25707@elte.hu> <20041019124605.GA28896@elte.hu> <20041019180059.GA23113@elte.hu> <20041020094508.GA29080@elte.hu> <30690.195.245.190.93.1098349976.squirrel@195.245.190.93> <1098350190.26758.24.camel@thomas> <20041021095344.GA10531@suse.de> <1098352441.26758.30.camel@thomas> <20041021101103.GC10531@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20041021101103.GC10531@suse.de> User-Agent: Mutt/1.5.6+20040907i From: Bill Huey (hui) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 938 Lines: 20 On Thu, Oct 21, 2004 at 12:11:03PM +0200, Jens Axboe wrote: > I didn't look at the USB code, I'm just saying that it's perfectly valid > use of a semaphore the pattern you describe (process A holding it, > process B releasing it). A lot of things are perfectly "valid" in the Linux kernel regarding stuff like that are a bit irregular. But the preemption work about to stress these things in ways that was never designed to which is why these patches are needed. Having a clear use of various locking conventions is key to getting this system to behave in a predictable manner. Quite simply, Linux was never targetted to do this and the sloppiness is showing so it's got to be removed. bill - 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/