From patchwork Mon Jun 15 03:58:43 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jason Yan X-Patchwork-Id: 11603749 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 52CA16A2 for ; Mon, 15 Jun 2020 03:58:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3BA302078A for ; Mon, 15 Jun 2020 03:58:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728092AbgFOD6C (ORCPT ); Sun, 14 Jun 2020 23:58:02 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:5826 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727971AbgFOD6C (ORCPT ); Sun, 14 Jun 2020 23:58:02 -0400 Received: from DGGEMS407-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id CC6FE1D69C05C425FA7A; Mon, 15 Jun 2020 11:57:59 +0800 (CST) Received: from huawei.com (10.175.127.227) by DGGEMS407-HUB.china.huawei.com (10.3.19.207) with Microsoft SMTP Server id 14.3.487.0; Mon, 15 Jun 2020 11:57:49 +0800 From: Jason Yan To: , , , , CC: Jason Yan , Kees Cook , "Ming Lei" Subject: [PATCH] block: Eliminate usage of uninitialized_var() macro Date: Mon, 15 Jun 2020 11:58:43 +0800 Message-ID: <20200615035843.3334350-1-yanaijie@huawei.com> X-Mailer: git-send-email 2.25.4 MIME-Version: 1.0 X-Originating-IP: [10.175.127.227] X-CFilter-Loop: Reflected Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org 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 Cc: Ming Lei Signed-off-by: Jason Yan --- block/blk-merge.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/blk-merge.c b/block/blk-merge.c index f0b0bae075a0..006402edef6b 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -473,7 +473,7 @@ static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio, struct scatterlist *sglist, struct scatterlist **sg) { - struct bio_vec uninitialized_var(bvec), bvprv = { NULL }; + struct bio_vec bvec, bvprv = { NULL }; struct bvec_iter iter; int nsegs = 0; bool new_bio = false;