From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bernd Petrovitsch Subject: Re: [PATCH] trivial: disable sparse' warning for "potentially expensive pointer subtraction". Date: Thu, 23 Sep 2010 14:41:43 +0200 Message-ID: <1285245703.32001.19.camel@thorin> References: <1282321333.25235.0.camel@thorin> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: Received: from esgaroth.petrovitsch.at ([78.47.184.11]:4185 "EHLO esgaroth.petrovitsch.priv.at" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753529Ab0IWMmL (ORCPT ); Thu, 23 Sep 2010 08:42:11 -0400 In-Reply-To: Sender: linux-sparse-owner@vger.kernel.org List-Id: linux-sparse@vger.kernel.org To: Jiri Kosina Cc: linux-kbuild@vger.kernel.org, Namhyung Kim , Andi Kleen , Arnd Bergmann , linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, dhowells@redhat.com, MXns RullgXrd , linux-sparse@vger.kernel.org Also Cc:ed linux-sparse@vger.kernel.org On Don, 2010-09-23 at 13:23 +0200, Jiri Kosina wrote: > On Fri, 20 Aug 2010, Bernd Petrovitsch wrote: > > > Rationale: With a somewhat current gcc (or a somewhat sane peephole > > optimizer), the (expensive) "div" is converted to a "shift" or > > "mul" with the inverse. > > This warning is disabled per default in sparse but the "-Wall" in > > the kernels CFLAGS enables it. > > > > Signed-off-by: Bernd Petrovitsch > > --- > > This patch is trivial and affects only calls to sparse (read: make C=1) and > > removes false warnings. So it should be considered for inclusion immediately. > > > > Sorry for the long Cc: - I included everyone in the thread and added > > linux-kbuild@ (as it IMHO belongs there) and trivial@ (because of the > > complexity of the patch). > > > > Makefile | 2 +- > > 1 files changed, 1 insertions(+), 1 deletions(-) > > > > diff --git a/Makefile b/Makefile > > index f3bdff8..851c0fa 100644 > > --- a/Makefile > > +++ b/Makefile > > @@ -330,7 +330,7 @@ PERL = perl > > CHECK = sparse > > > > CHECKFLAGS := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__ \ > > - -Wbitwise -Wno-return-void $(CF) > > + -Wbitwise -Wno-return-void -Wno-ptr-subtraction-blows $(CF) > > CFLAGS_MODULE = > > AFLAGS_MODULE = > > LDFLAGS_MODULE = > > What is the status of this patch? I don't see it Nacked, but it's not in > linux-next either. More details: The head (as in git://git.kernel.org/pub/scm/devel/sparse/chrisl/sparse.git) has "-Wall" renamed to "-Wsparse-all". So the above patch is pretty pointless. But sparse-0.4.2 - the latest release according to https://sparse.wiki.kernel.org/index.php/Main_Page - hasn't that renamed. Bernd -- mobile: +43 664 4416156 http://www.sysprog.at/ Linux Software Development, Consulting and Services