From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755330Ab3APR5E (ORCPT ); Wed, 16 Jan 2013 12:57:04 -0500 Received: from co9ehsobe005.messaging.microsoft.com ([207.46.163.28]:38921 "EHLO co9outboundpool.messaging.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752756Ab3APR5C (ORCPT ); Wed, 16 Jan 2013 12:57:02 -0500 X-Forefront-Antispam-Report: CIP:132.245.1.197;KIP:(null);UIP:(null);IPV:NLI;H:BLUPRD0712HT002.namprd07.prod.outlook.com;RD:none;EFVD:NLI X-SpamScore: -4 X-BigFish: PS-4(zzbb2dI98dI9371I1432Izz1ee6h1de0h1202h1e76h1d1ah1d2ahzz8275dhz2dh2a8h668h839h947hd25he5bhf0ah1288h12a5h12a9h12bdh137ah13b6h1441h14ddh1504h1537h153bh162dh1631h1758h1765h1155h) Message-ID: <50F6E9B3.5010202@caviumnetworks.com> Date: Wed, 16 Jan 2013 09:56:03 -0800 From: David Daney User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Ralf Baechle CC: Cong Ding , Jim Quinlan , , Subject: Re: [PATCH] mpis: cavium-octeon/executive/cvmx-l2c.c: fix uninitialized variable References: <1358200025-15994-1-git-send-email-dinggnu@gmail.com> <20130116105757.GB26569@linux-mips.org> In-Reply-To: <20130116105757.GB26569@linux-mips.org> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [64.2.3.195] X-OriginatorOrg: caviumnetworks.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/16/2013 02:57 AM, Ralf Baechle wrote: > On Mon, Jan 14, 2013 at 10:47:03PM +0100, Cong Ding wrote: > >> the variable dummy is used without initialization. > > Interesting - I wonder how you found this one. My compiler (gcc 4.7) > doesn't warn about this one. > I get no warnings either. So I wonder what the point of churning up the code is. David Daney > Nor does gcc notice that the whole summing up business is wasted efford. > > So here's my counter proposal. It works because ptr is a volatile pointer > so the compiler will always dereference it even if the returned value is > not being used. The resulting code is a bit smaller. > > Ralf > > Signed-off-by: Ralf Baechle > > arch/mips/cavium-octeon/executive/cvmx-l2c.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/mips/cavium-octeon/executive/cvmx-l2c.c b/arch/mips/cavium-octeon/executive/cvmx-l2c.c > index 9f883bf..ec3e059 100644 > --- a/arch/mips/cavium-octeon/executive/cvmx-l2c.c > +++ b/arch/mips/cavium-octeon/executive/cvmx-l2c.c > @@ -286,7 +286,7 @@ uint64_t cvmx_l2c_read_perf(uint32_t counter) > static void fault_in(uint64_t addr, int len) > { > volatile char *ptr; > - volatile char dummy; > + > /* > * Adjust addr and length so we get all cache lines even for > * small ranges spanning two cache lines. > @@ -300,7 +300,7 @@ static void fault_in(uint64_t addr, int len) > */ > CVMX_DCACHE_INVALIDATE; > while (len > 0) { > - dummy += *ptr; > + *ptr; > len -= CVMX_CACHE_LINE_SIZE; > ptr += CVMX_CACHE_LINE_SIZE; > } > > >