From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S268117AbUH1Vqo (ORCPT ); Sat, 28 Aug 2004 17:46:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S268052AbUH1Vpy (ORCPT ); Sat, 28 Aug 2004 17:45:54 -0400 Received: from waste.org ([209.173.204.2]:43406 "EHLO waste.org") by vger.kernel.org with ESMTP id S268113AbUH1VoK (ORCPT ); Sat, 28 Aug 2004 17:44:10 -0400 Date: Sat, 28 Aug 2004 16:43:57 -0500 From: Matt Mackall To: Andrew Morton Cc: Adrian Bunk , mrmacman_g4@mac.com, linux-kernel@vger.kernel.org Subject: Re: [2.6 patch][1/3] ipc/ BUG -> BUG_ON conversions Message-ID: <20040828214357.GN5414@waste.org> References: <20040828151137.GA12772@fs.tum.de> <20040828151544.GB12772@fs.tum.de> <098EB4E1-F90C-11D8-A7C9-000393ACC76E@mac.com> <20040828162633.GG12772@fs.tum.de> <20040828125816.206ef7fa.akpm@osdl.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20040828125816.206ef7fa.akpm@osdl.org> User-Agent: Mutt/1.3.28i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Aug 28, 2004 at 12:58:16PM -0700, Andrew Morton wrote: > Adrian Bunk wrote: > > > > > Anything you put in BUG_ON() must *NOT* have side effects. > > >... > > > > I'd have said exactly the same some time ago, but I was convinced by > > Arjan that if done correctly, a BUG_ON() with side effects is possible > > with no extra cost even if you want to make BUG configurably do nothing. > > Nevertheless, I think I'd prefer that we not move code which has > side-effects into BUG_ONs. For some reason it seems neater that way. > > Plus one would like to be able to do > > BUG_ON(strlen(str) > 22); > > and have strlen() not be evaluated if BUG_ON is disabled. Well, strlen doesn't actually have a side effect, so it could be marked pure and then be optimized away. I'll push configurable BUG_ON support from -tiny to you shortly so this will stop being theoretical. -- Mathematics is the supreme nostalgia of our time.