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=-14.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 3E1CBC433E1 for ; Thu, 25 Mar 2021 16:01:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1C79061A27 for ; Thu, 25 Mar 2021 16:01:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229771AbhCYQA5 (ORCPT ); Thu, 25 Mar 2021 12:00:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43018 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229734AbhCYQAN (ORCPT ); Thu, 25 Mar 2021 12:00:13 -0400 Received: from mail-pg1-x52b.google.com (mail-pg1-x52b.google.com [IPv6:2607:f8b0:4864:20::52b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0227EC06174A; Thu, 25 Mar 2021 09:00:13 -0700 (PDT) Received: by mail-pg1-x52b.google.com with SMTP id i22so2236424pgl.4; Thu, 25 Mar 2021 09:00:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=ZcvhcVz5SG2l7TXInHqovR8N9PaEaZR96rNMcB7kOXk=; b=pp1Kf4zTb2NfmDO8cXK0HieHJTNPmvsxJ6ggSSvRUo9kraDTjTaT9V5A4XaGwVEuV9 PhA5Shv1c+CmSsjqRDA9L687Mj/lU1h5fph7uhcSRgz6YwrNlPE4/PUfGQ5OwfQLkO1G L41/AWv57WPnUwkoBUzl9dsA6ZsRy7pPyq/3nzEDf8uHIRU9gQcZo1HdOf1Ov4+oLBJv Vj8lOS3yOkKTpxAXlj4ohj/4Wm7Z4entt6uwTGdDs3PZI5PjMSNfoPiEQYzO8Xko8Dgk 9tV9P5p8Z+XumFarrbu3KrZ++oScPcn8U/Spbn/XFxYefGC7qAop0NrqqmR4CEyIgcyJ bV7w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=ZcvhcVz5SG2l7TXInHqovR8N9PaEaZR96rNMcB7kOXk=; b=m3+GLYRD4fCl3lxMdWwi2rhu5jwIyZDGHR+/+rEo5kTXAfDqY/qoCR3VR0p8IqoUsX 6HfBDl3ZpM9BPCOZadv82H9I/IB2zYfRWne1fc3JgE/badM8WJNcRos5n6egYLl/9GE2 6bgAzUC7DufnobjfsFSZJlKeP3HZ5zXoygO4w0Fgi6R/ZFGFys1/jo/xgk55k5DozZc9 2xO7IREgU86TZ3O+n3IKL9TwRwheVyN+Sp1zrMGpQLdaIhodDrzRTlQA+wa/Rl2y8Hn7 zbu6UAKuiIxlY00DRoqBOA0tBO8Rrz3BfmRqDuzYU92c+uHRjjxt15Sk8UF45A51te8c bZcQ== X-Gm-Message-State: AOAM531cD+3j3w3jfuF17Rp1rmP5K73nrpzeOalaCXq0USde/fmj8oXB p1FJP/8Z5ERCmxotX8l9dyw= X-Google-Smtp-Source: ABdhPJxCNSdkDyjilxVM+ECwNojpw9K4zwtShTSL38PVGXdGCOLaxgmGKsFkiVZMv1u4RLNOqLm0dQ== X-Received: by 2002:a62:2a8b:0:b029:21c:3016:3a9f with SMTP id q133-20020a622a8b0000b029021c30163a9fmr8954623pfq.38.1616688012560; Thu, 25 Mar 2021 09:00:12 -0700 (PDT) Received: from mail.google.com ([141.164.41.4]) by smtp.gmail.com with ESMTPSA id b19sm6359351pfo.7.2021.03.25.09.00.10 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Thu, 25 Mar 2021 09:00:12 -0700 (PDT) Date: Thu, 25 Mar 2021 16:00:07 +0000 From: Changbin Du To: Rob Herring Cc: Changbin Du , Frank Rowand , devicetree@vger.kernel.org, "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] of/fdt: Check dtb pointer first in unflatten_device_tree Message-ID: <20210325155954.iun4hdcegi4b3qm2@mail.google.com> References: <20210324150425.20688-1-changbin.du@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20180716-508-7c9a6d Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 24, 2021 at 10:52:30AM -0600, Rob Herring wrote: > On Wed, Mar 24, 2021 at 9:04 AM Changbin Du wrote: > > > > The setup_arch() would invoke unflatten_device_tree() even no > > valid fdt found. So we'd better check it first and return early. > > > > Signed-off-by: Changbin Du > > --- > > drivers/of/fdt.c | 5 +++++ > > 1 file changed, 5 insertions(+) > > > > diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c > > index dcc1dd96911a..05d439d63bc5 100644 > > --- a/drivers/of/fdt.c > > +++ b/drivers/of/fdt.c > > @@ -1225,6 +1225,11 @@ bool __init early_init_dt_scan(void *params) > > */ > > void __init unflatten_device_tree(void) > > { > > + if (!initial_boot_params) { > > + pr_warn("No valid device tree found, continuing without\n"); > > How are you going to see this message if you have no DT? > This aligns to what unflatten_and_copy_device_tree() does. > > + return; > > And the arch is supposed to just continue on oblivious that it has no DT? > As checking the arch code(arm, riscv), I suppose so. > > + } > > + > > __unflatten_device_tree(initial_boot_params, NULL, &of_root, > > early_init_dt_alloc_memory_arch, false); > > Soon as you get here with a NULL initial_boot_params, you'll get a > backtrace and halt. > No, we have returned before. > > > > -- > > 2.30.2 > > -- Cheers, Changbin Du