Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757271AbXLBUIa (ORCPT ); Sun, 2 Dec 2007 15:08:30 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752179AbXLBUIU (ORCPT ); Sun, 2 Dec 2007 15:08:20 -0500 Received: from netrider.rowland.org ([192.131.102.5]:3380 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1756909AbXLBUIT (ORCPT ); Sun, 2 Dec 2007 15:08:19 -0500 Date: Sun, 2 Dec 2007 15:08:18 -0500 (EST) From: Alan Stern X-X-Sender: stern@netrider.rowland.org To: Arjan van de Ven cc: Ingo Molnar , Linux-pm mailing list , Kernel development list Subject: Re: Need lockdep help In-Reply-To: <20071202120411.2aac7720@laptopd505.fenrus.org> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 861 Lines: 21 On Sun, 2 Dec 2007, Arjan van de Ven wrote: > > This creates a lockdep violation; each rwsem in turn is locked while > > the other is being held. However the only way this could lead to > > deadlock would be if there was already a bug in the system Power > > Management code (overlapping notifications). > > or.. modifications to the notifier chain while all this is happening > (remember: rwsems are fair, once a writer shows up, all readers wait) But modifications to the notifier chain don't invoke the callout routines. Hence they won't try to lock the new rwsem and won't lead to deadlock. Alan Stern -- 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/