From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B3755C433E3 for ; Mon, 15 Jun 2020 08:26:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9A9912068E for ; Mon, 15 Jun 2020 08:26:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728946AbgFOI0z (ORCPT ); Mon, 15 Jun 2020 04:26:55 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:5828 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728852AbgFOI0y (ORCPT ); Mon, 15 Jun 2020 04:26:54 -0400 Received: from DGGEMS401-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id EF3B0151BA05F3817A22; Mon, 15 Jun 2020 16:26:35 +0800 (CST) Received: from [10.134.22.195] (10.134.22.195) by smtp.huawei.com (10.3.19.201) with Microsoft SMTP Server (TLS) id 14.3.487.0; Mon, 15 Jun 2020 16:26:25 +0800 Subject: Re: [f2fs-dev] [PATCH] f2fs: Eliminate usage of uninitialized_var() macro To: Jason Yan , , , , CC: Kees Cook , References: <20200615040212.3681503-1-yanaijie@huawei.com> From: Chao Yu Message-ID: Date: Mon, 15 Jun 2020 16:26:25 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20200615040212.3681503-1-yanaijie@huawei.com> Content-Type: text/plain; charset="windows-1252" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.134.22.195] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020/6/15 12:02, Jason Yan wrote: > This is an effort to eliminate the uninitialized_var() macro[1]. > > The use of this macro is the wrong solution because it forces off ANY > analysis by the compiler for a given variable. It even masks "unused > variable" warnings. > > Quoted from Linus[2]: > > "It's a horrible thing to use, in that it adds extra cruft to the > source code, and then shuts up a compiler warning (even the _reliable_ > warnings from gcc)." > > The gcc option "-Wmaybe-uninitialized" has been disabled and this change > will not produce any warnnings even with "make W=1". > > [1] https://github.com/KSPP/linux/issues/81 > [2] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/ > > Cc: Kees Cook > Signed-off-by: Jason Yan > --- > fs/f2fs/data.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c > index 326c63879ddc..e6ec61274d76 100644 > --- a/fs/f2fs/data.c > +++ b/fs/f2fs/data.c > @@ -2856,7 +2856,7 @@ static int f2fs_write_cache_pages(struct address_space *mapping, > }; > #endif > int nr_pages; > - pgoff_t uninitialized_var(writeback_index); > + pgoff_t writeback_index; I suggest to delete this variable directly, as we did for mm in commit 28659cc8cc87 (mm/page-writeback.c: remove unused variable). Thanks, > pgoff_t index; > pgoff_t end; /* Inclusive */ > pgoff_t done_index; >