From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Chinner Subject: Re: [BUG on PREEMPT_RT, 2.6.23.1-rt5] in rt-mutex code and signals Date: Mon, 19 Nov 2007 09:26:20 +1100 Message-ID: <20071118222620.GN66820511@sgi.com> References: <3efb10970711170344n670d8b69w6679d494922c5bb@mail.gmail.com> <1195316550.25393.21.camel@imap.mvista.com> <3efb10970711170909n3acca605j70525e36faf8da7f@mail.gmail.com> <1195320569.25393.38.camel@imap.mvista.com> <20071117174608.GA30641@elte.hu> <1195322141.25393.41.camel@imap.mvista.com> <20071117180430.GA10768@elte.hu> <1195323177.25393.56.camel@imap.mvista.com> <1195389230.6747.5.camel@twins> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Daniel Walker , Ingo Molnar , Remy Bohmer , Steven Rostedt , Thomas Gleixner , RT , linux-kernel , Dave Chinner To: Peter Zijlstra Return-path: Received: from relay1.sgi.com ([192.48.171.29]:33132 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752527AbXKRW0t (ORCPT ); Sun, 18 Nov 2007 17:26:49 -0500 Content-Disposition: inline In-Reply-To: <1195389230.6747.5.camel@twins> Sender: linux-rt-users-owner@vger.kernel.org List-Id: linux-rt-users.vger.kernel.org On Sun, Nov 18, 2007 at 01:33:50PM +0100, Peter Zijlstra wrote: > > On Sat, 2007-11-17 at 10:12 -0800, Daniel Walker wrote: > > > What specifically is wrong with dev->sem ? > > Nothing really, other than that they use semaphores to avoid lockdep :-/ > > I think I know how to annotate this, after Alan Stern explained all the > use cases, but I haven't come around to implementing it. Hope to do that > soonish. > > Another real semaphore user is XFS, they really use the down/up > asymmetry that semaphores allow, last time I spoke with Dave Chinner he > didn't know a way around this. Hasn't changed recently. We could convert some to completions, but others are much more difficult. Cheers, Dave. -- Dave Chinner Principal Engineer SGI Australian Software Group