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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 D56FBC43382 for ; Tue, 25 Sep 2018 11:20:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8B25820671 for ; Tue, 25 Sep 2018 11:20:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8B25820671 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.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 S1728951AbeIYR11 (ORCPT ); Tue, 25 Sep 2018 13:27:27 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39382 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727606AbeIYR11 (ORCPT ); Tue, 25 Sep 2018 13:27:27 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 2C07A31500B4; Tue, 25 Sep 2018 11:20:23 +0000 (UTC) Received: from localhost (ovpn-8-17.pek2.redhat.com [10.72.8.17]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 55AEB5C5E1; Tue, 25 Sep 2018 11:20:19 +0000 (UTC) Date: Tue, 25 Sep 2018 19:20:16 +0800 From: Baoquan He To: Bjorn Helgaas Cc: Lianbo Jiang , Vivek Goyal , linux-kernel@vger.kernel.org, kexec@lists.infradead.org, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, akpm@linux-foundation.org, dan.j.williams@intel.com, thomas.lendacky@amd.com, baiyaowei@cmss.chinamobile.com, tiwai@suse.de, bp@suse.de, brijesh.singh@amd.com, dyoung@redhat.com Subject: Re: [PATCH 3/3] resource: Fix find_next_iomem_res() iteration issue Message-ID: <20180925112016.GZ2555@MiWiFi-R3L-srv> References: <153782698067.130337.12079523922130875402.stgit@bhelgaas-glaptop.roam.corp.google.com> <153782730364.130337.17794279728329113665.stgit@bhelgaas-glaptop.roam.corp.google.com> <20180925085846.GY2555@MiWiFi-R3L-srv> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180925085846.GY2555@MiWiFi-R3L-srv> User-Agent: Mutt/1.9.1 (2017-09-22) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.41]); Tue, 25 Sep 2018 11:20:23 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/25/18 at 04:58pm, Baoquan He wrote: > Hi Bjorn, > > On 09/24/18 at 05:15pm, Bjorn Helgaas wrote: > > @@ -359,32 +362,31 @@ static int find_next_iomem_res(struct resource *res, unsigned long desc, > > read_unlock(&resource_lock); > > if (!p) > > return -1; > > + > > /* copy data */ > > - if (res->start < p->start) > > - res->start = p->start; > > - if (res->end > p->end) > > - res->end = p->end; > > + res->start = max(start, p->start); > > + res->end = min(end, p->end); > > res->flags = p->flags; > > I think this fix is good. However, is it OK to keep res->flags always, > never touch it in find_next_iomem_res()? We just iterate and update > region, its start and end. So just removing that "res->flags = p->flags;" > line might involve much less code changes. Rethink about it, I was wrong. Please ignore my comment.