Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753538Ab2KLPZF (ORCPT ); Mon, 12 Nov 2012 10:25:05 -0500 Received: from caramon.arm.linux.org.uk ([78.32.30.218]:40952 "EHLO caramon.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752979Ab2KLPZE (ORCPT ); Mon, 12 Nov 2012 10:25:04 -0500 Date: Mon, 12 Nov 2012 15:23:49 +0000 From: Russell King - ARM Linux To: Maarten Lankhorst Cc: Sasha Levin , linux-kernel@vger.kernel.org, Kukjin Kim , linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org Subject: Re: [PATCH] ARM: EXYNOS: use BUG_ON where possible Message-ID: <20121112152349.GH28327@n2100.arm.linux.org.uk> References: <1352406191-14303-1-git-send-email-sasha.levin@oracle.com> <1352406191-14303-5-git-send-email-sasha.levin@oracle.com> <50A111DD.6080504@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <50A111DD.6080504@gmail.com> User-Agent: Mutt/1.5.19 (2009-01-05) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1573 Lines: 36 On Mon, Nov 12, 2012 at 04:12:29PM +0100, Maarten Lankhorst wrote: > Op 08-11-12 21:23, Sasha Levin schreef: > > @@ -465,10 +465,8 @@ static void __init combiner_cascade_irq(unsigned int combiner_nr, unsigned int i > > else > > max_nr = EXYNOS4_MAX_COMBINER_NR; > > > > - if (combiner_nr >= max_nr) > > - BUG(); > > - if (irq_set_handler_data(irq, &combiner_data[combiner_nr]) != 0) > > - BUG(); > > + BUG_ON(combiner_nr >= max_nr); > > + BUG_ON(irq_set_handler_data(irq, &combiner_data[combiner_nr]) != 0); > > Is it really a good idea to put functions that perform work in a BUG_ON? > I don't know, but for some reason it just feels wrong. I'd expect code to > compile fine if BUG_ON was a noop, so doing verification calls only, not > actual work.. Well, it is currently defined as: include/asm-generic/bug.h:#define BUG_ON(condition) do { if (unlikely(condition)) BUG(); } while(0) include/asm-generic/bug.h:#define BUG_ON(condition) do { if (condition) ; } while(0) but as these can be overridden, I don't think relying on those implementations is a good idea; to do so would be fragile. Eg, what if the BUG_ON() implementation becomes just: #define BUG_ON(x) then the function call itself vanishes. So, only put the actual bug test inside a BUG_ON(), not the functional part which must always be executed. -- 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/