Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932223AbWC1Vfr (ORCPT ); Tue, 28 Mar 2006 16:35:47 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932227AbWC1Vfr (ORCPT ); Tue, 28 Mar 2006 16:35:47 -0500 Received: from www.osadl.org ([213.239.205.134]:22435 "EHLO mail.tglx.de") by vger.kernel.org with ESMTP id S932223AbWC1Vfq (ORCPT ); Tue, 28 Mar 2006 16:35:46 -0500 Subject: Re: PI patch against 2.6.16-rt9 From: Thomas Gleixner Reply-To: tglx@linutronix.de To: Esben Nielsen Cc: Ingo Molnar , linux-kernel@vger.kernel.org In-Reply-To: References: Content-Type: text/plain Date: Tue, 28 Mar 2006 23:36:42 +0200 Message-Id: <1143581802.5344.229.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.6.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1191 Lines: 34 On Tue, 2006-03-28 at 22:17 +0100, Esben Nielsen wrote: > I think we talk about the situation No, we talk about existing lock chains L(0) --> L(n). > B locks 1 C locks 2 D locks 3 > B locks 2, boosts C and block > A locks 2 > A is boost B > A drop it's spinlocks and is preempted > C unlocks 2 and auto unboosts > B is running > B locks 3, boosts C and blocks > A gets a CPU again > A boosts B > A boosts D > > Is there anything wrong with that? > And in the case where A==D there indeed is a deadlock which will be > detected. If you get to L(x) the underlying dependencies might have changed already as well as the dependencies x ... n. We might get false positives in the deadlock detection that way, as a deadlock is an "atomic" state. tglx - 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/