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=-6.6 required=3.0 tests=FROM_EXCESS_BASE64, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED 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 E4EE0C43382 for ; Wed, 26 Sep 2018 14:22:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A652620676 for ; Wed, 26 Sep 2018 14:22:39 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A652620676 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de 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 S1727722AbeIZUfs (ORCPT ); Wed, 26 Sep 2018 16:35:48 -0400 Received: from mx2.suse.de ([195.135.220.15]:52532 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726768AbeIZUfs (ORCPT ); Wed, 26 Sep 2018 16:35:48 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id A60E1ACE1; Wed, 26 Sep 2018 14:22:35 +0000 (UTC) Date: Wed, 26 Sep 2018 16:22:32 +0200 From: Michal =?UTF-8?B?U3VjaMOhbmVr?= To: zhong jiang Cc: , , , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] powerpc: Move a dereference below a NULL test Message-ID: <20180926162232.250c0090@naga> In-Reply-To: <1537962368-14019-1-git-send-email-zhongjiang@huawei.com> References: <1537962368-14019-1-git-send-email-zhongjiang@huawei.com> X-Mailer: Claws Mail 3.17.1 (GTK+ 2.24.32; x86_64-suse-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Thanks Michal