From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752140Ab3LJCOX (ORCPT ); Mon, 9 Dec 2013 21:14:23 -0500 Received: from mail-pb0-f48.google.com ([209.85.160.48]:49731 "EHLO mail-pb0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751396Ab3LJCOS (ORCPT ); Mon, 9 Dec 2013 21:14:18 -0500 Message-ID: <52A67973.20904@gmail.com> Date: Tue, 10 Dec 2013 10:16:19 +0800 From: Chen Gang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130110 Thunderbird/17.0.2 MIME-Version: 1.0 To: Seth Jennings CC: Seth Jennings , linux-mm@kvack.org, "linux-kernel@vger.kernel.org" , James Hogan Subject: Re: [PATCH] mm/zswap.c: add BUG() for default case in zswap_writeback_entry() References: <52A53024.9090701@gmail.com> <20131209153626.GA3752@cerebellum.variantweb.net> In-Reply-To: <20131209153626.GA3752@cerebellum.variantweb.net> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/09/2013 11:36 PM, Seth Jennings wrote: > On Mon, Dec 09, 2013 at 10:51:16AM +0800, Chen Gang wrote: >> Recommend to add default case to avoid compiler's warning, although at >> present, the original implementation is still correct. >> >> The related warning (with allmodconfig for metag): >> >> CC mm/zswap.o >> mm/zswap.c: In function 'zswap_writeback_entry': >> mm/zswap.c:537: warning: 'ret' may be used uninitialized in this function >> >> >> Signed-off-by: Chen Gang >> --- >> mm/zswap.c | 2 ++ >> 1 files changed, 2 insertions(+), 0 deletions(-) >> >> diff --git a/mm/zswap.c b/mm/zswap.c >> index 5a63f78..bfd1807 100644 >> --- a/mm/zswap.c >> +++ b/mm/zswap.c >> @@ -585,6 +585,8 @@ static int zswap_writeback_entry(struct zbud_pool *pool, unsigned long handle) >> >> /* page is up to date */ >> SetPageUptodate(page); >> + default: >> + BUG(); > > Typically, the way you want to address this is initialize ret to 0 > at declaration time if not every control path will set that value. > At least, your suggestion sounds reasonable. But I am also aware that normally need content 'default' for 'switch', so I choose this fix way. And sorry, current patch is incorrect (need 'break' before 'default'), so if no additional suggestions or discussions or completions, I will/should send patch v2 for it. Thanks. -- Chen Gang Open, share, and attitude like air, water and life which God blessed