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: 11603751 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 6EB6892A for ; Mon, 15 Jun 2020 03:58:21 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 6DC312078A for ; Mon, 15 Jun 2020 03:58:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6DC312078A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-18961-patchwork-kernel-hardening=patchwork.kernel.org@lists.openwall.com Received: (qmail 3423 invoked by uid 550); 15 Jun 2020 03:58:17 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 3400 invoked from network); 15 Jun 2020 03:58:16 -0000 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 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;