Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756464AbdCUKPu (ORCPT ); Tue, 21 Mar 2017 06:15:50 -0400 Received: from mail.fireflyinternet.com ([109.228.58.192]:50323 "EHLO fireflyinternet.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751792AbdCUKPs (ORCPT ); Tue, 21 Mar 2017 06:15:48 -0400 X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.65.138; Date: Tue, 21 Mar 2017 09:56:52 +0000 From: Chris Wilson To: Arnd Bergmann Cc: Daniel Vetter , Jani Nikula , David Airlie , Tvrtko Ursulin , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/3] drm/i915: split out check for noncontiguous pfn range Message-ID: <20170321095652.GB11338@nuc-i3427.alporthouse.com> Mail-Followup-To: Chris Wilson , Arnd Bergmann , Daniel Vetter , Jani Nikula , David Airlie , Tvrtko Ursulin , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org References: <20170320094335.1266306-1-arnd@arndb.de> <20170320094335.1266306-2-arnd@arndb.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170320094335.1266306-2-arnd@arndb.de> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 873 Lines: 20 On Mon, Mar 20, 2017 at 10:40:28AM +0100, Arnd Bergmann wrote: > We get a warning with gcc-7 about a pointless comparison when > using a linear memmap: > > drivers/gpu/drm/i915/selftests/scatterlist.c: In function 'alloc_table': > drivers/gpu/drm/i915/selftests/scatterlist.c:219:66: error: self-comparison always evaluates to false [-Werror=tautological-compare] > > Splitting out the comparison into a separate function avoids the warning > and makes it slightly more obvious what happens. I worried whether gcc will simply get smarter and apply its warning more consistently, but I agree the helper is good documentation. > Fixes: 935a2f776aa5 ("drm/i915: Add some selftests for sg_table manipulation") > Signed-off-by: Arnd Bergmann Reviewed-by: Chris Wilson -Chris -- Chris Wilson, Intel Open Source Technology Centre