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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 799E8C43382 for ; Wed, 26 Sep 2018 14:42:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3E22F2086E for ; Wed, 26 Sep 2018 14:42:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3E22F2086E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728107AbeIZUzq (ORCPT ); Wed, 26 Sep 2018 16:55:46 -0400 Received: from szxga07-in.huawei.com ([45.249.212.35]:53333 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727048AbeIZUzq (ORCPT ); Wed, 26 Sep 2018 16:55:46 -0400 Received: from DGGEMS409-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 64A0D77B56CA4; Wed, 26 Sep 2018 22:42:25 +0800 (CST) Received: from [127.0.0.1] (10.177.29.68) by DGGEMS409-HUB.china.huawei.com (10.3.19.209) with Microsoft SMTP Server id 14.3.399.0; Wed, 26 Sep 2018 22:42:24 +0800 Message-ID: <5BAB9ACF.6040102@huawei.com> Date: Wed, 26 Sep 2018 22:42:23 +0800 From: zhong jiang User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:12.0) Gecko/20120428 Thunderbird/12.0.1 MIME-Version: 1.0 To: =?ISO-8859-1?Q?Michal_Such=E1nek?= CC: , , , , Subject: Re: [PATCH] powerpc: Move a dereference below a NULL test References: <1537962368-14019-1-git-send-email-zhongjiang@huawei.com> <20180926162232.250c0090@naga> In-Reply-To: <20180926162232.250c0090@naga> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 8bit X-Originating-IP: [10.177.29.68] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018/9/26 22:22, Michal Suchánek wrote: > On Wed, 26 Sep 2018 19:46:08 +0800 > zhong jiang wrote: > >> It is safe to move dereference below a NULL test. >> >> Signed-off-by: zhong jiang >> --- >> arch/powerpc/kernel/cacheinfo.c | 5 ++--- >> 1 file changed, 2 insertions(+), 3 deletions(-) >> >> diff --git a/arch/powerpc/kernel/cacheinfo.c >> b/arch/powerpc/kernel/cacheinfo.c index a8f20e5..7f19714 100644 >> --- a/arch/powerpc/kernel/cacheinfo.c >> +++ b/arch/powerpc/kernel/cacheinfo.c >> @@ -401,14 +401,13 @@ static struct cache >> *cache_lookup_or_instantiate(struct device_node *node, struct cache >> *cache; >> cache = cache_lookup_by_node(node); >> + if (!cache) >> + cache = cache_do_one_devnode(node, level); >> >> WARN_ONCE(cache && cache->level != level, > This has also null test so cache should be dereferenced only when > non-null here. :-[ , you're right. I forget WARN_ONCE. please ignore the patch. Sincerely, zhong jiang > Thanks > > Michal > > . >