From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yh0-f53.google.com (mail-yh0-f53.google.com [209.85.213.53]) by kanga.kvack.org (Postfix) with ESMTP id 2DC1A6B0044 for ; Mon, 9 Dec 2013 21:14:20 -0500 (EST) Received: by mail-yh0-f53.google.com with SMTP id b20so3405402yha.40 for ; Mon, 09 Dec 2013 18:14:20 -0800 (PST) Received: from mail-pb0-x230.google.com (mail-pb0-x230.google.com [2607:f8b0:400e:c01::230]) by mx.google.com with ESMTPS id v65si11949612yhp.158.2013.12.09.18.14.18 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 09 Dec 2013 18:14:19 -0800 (PST) Received: by mail-pb0-f48.google.com with SMTP id md12so6609358pbc.35 for ; Mon, 09 Dec 2013 18:14:18 -0800 (PST) Message-ID: <52A67973.20904@gmail.com> Date: Tue, 10 Dec 2013 10:16:19 +0800 From: Chen Gang MIME-Version: 1.0 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: owner-linux-mm@kvack.org List-ID: To: Seth Jennings Cc: Seth Jennings , linux-mm@kvack.org, "linux-kernel@vger.kernel.org" , James Hogan 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org