Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262473AbTEVDxK (ORCPT ); Wed, 21 May 2003 23:53:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262482AbTEVDxK (ORCPT ); Wed, 21 May 2003 23:53:10 -0400 Received: from dyn-ctb-210-9-245-156.webone.com.au ([210.9.245.156]:60933 "EHLO chimp.local.net") by vger.kernel.org with ESMTP id S262473AbTEVDxJ (ORCPT ); Wed, 21 May 2003 23:53:09 -0400 Message-ID: <3ECC4C3A.9000903@cyberone.com.au> Date: Thu, 22 May 2003 14:04:10 +1000 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.3) Gecko/20030327 Debian/1.3-4 X-Accept-Language: en MIME-Version: 1.0 To: Robert White CC: Rik van Riel , David Woodhouse , ptb@it.uc3m.es, William Lee Irwin III , "Martin J. Bligh" , linux-kernel@vger.kernel.org Subject: Re: recursive spinlocks. Shoot. References: In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1270 Lines: 37 Robert White wrote: >>From: Rik van Riel [mailto:riel@surriel.com]On Behalf Of Rik van Riel >> > >>So call_EE_ messes with the data structure which call_ER_ >>has locked, unexpectedly because the recursive locking >>doesn't show up as an error. >> > >Yes and no. It all hinges on that nonsensical use of "unexpectedly". > >(I'll be using fully abstract examples from here on out to prevent the >function call police from busting me again on a technicality... 8-) > Oh come on! Now I won't get into this argument, but you can't win by saying "if this were implemented in such a way that recursive locking is required, then recursive locking is required here"!! Look: I could easily reimplement your snark so it doesn't have to call the last "whangle" - now see how it can be done completely lockless with a memory barrier between a and b? Locking is an implementation issue, and as such I think you'll have to come up with a real problem or some real code. You must have some target problem in mind? Best regards, Nick - 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/