From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [BUG on PREEMPT_RT, 2.6.23.1-rt5] in rt-mutex code and signals Date: Sun, 18 Nov 2007 13:33:50 +0100 Message-ID: <1195389230.6747.5.camel@twins> References: <3efb10970711160751l279fe99dl9f3a130a4373a449@mail.gmail.com> <3efb10970711161502m6216bf5rc19a34184b4f3a2b@mail.gmail.com> <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> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Ingo Molnar , Remy Bohmer , Steven Rostedt , Thomas Gleixner , RT , linux-kernel , Dave Chinner To: Daniel Walker Return-path: Received: from pentafluge.infradead.org ([213.146.154.40]:50196 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751505AbXKRMfI (ORCPT ); Sun, 18 Nov 2007 07:35:08 -0500 In-Reply-To: <1195323177.25393.56.camel@imap.mvista.com> Sender: linux-rt-users-owner@vger.kernel.org List-Id: linux-rt-users.vger.kernel.org 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.