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=-5.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 20D9EC4727E for ; Mon, 5 Oct 2020 10:37:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BC26620795 for ; Mon, 5 Oct 2020 10:37:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="fHgpEcUk" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725946AbgJEKg6 (ORCPT ); Mon, 5 Oct 2020 06:36:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59840 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725936AbgJEKg6 (ORCPT ); Mon, 5 Oct 2020 06:36:58 -0400 Received: from mail-lf1-x141.google.com (mail-lf1-x141.google.com [IPv6:2a00:1450:4864:20::141]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 254A7C0613CE; Mon, 5 Oct 2020 03:36:58 -0700 (PDT) Received: by mail-lf1-x141.google.com with SMTP id b12so10212470lfp.9; Mon, 05 Oct 2020 03:36:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=kXGxjrOECHo9Yx49QGExKC9VMrc3WpIW0kWli+WP6Wc=; b=fHgpEcUk5a1h/ZYcayz+n0HgwtBBcLPVDH60MdlYmQ6q1uhKixndlzQykidqHB5mtc t7XUXd/3M0YfRU8TRKSXnGeHzqymcHGdb1kkyPyhdnpxwVjek93PKmlERJT4spxrSsML e+biqMhblP2vDC8cAxpMc8nsz/z6v3bi/eewYMM0Bc9Ny6ftNgynxoM/naeY49qKQVz1 Ktlp94D90cRnpS1+z4iSVuSzTxrglQg71Jp4A2mFLyYW2yW7RPnvt9B1pXqGm/eRAGfD FhPkYwF9oFyvg4CFrmcpjP+1PK+iQI5FUhTSr7Jy25Czo1auDwZR79F2nQqqL8ZHr1wV jHwg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=kXGxjrOECHo9Yx49QGExKC9VMrc3WpIW0kWli+WP6Wc=; b=bRxfZ3FYMyPF1P+c2K1O0WjjrPwBt2V0T6khUj3u5jHLLXBCKq6EfdIbdqGGUbfuas gFrn1d3gtYGcJFRKSLrfAD70hxIxhl2gpn7qlsAEDM/k7fRzsWzrCQtgnDBzCH+ZIns2 kAJ5i5rBquzpEVv7wCHpZHVavrgliHvX3LT9pK2J+4k+4m0FrvaQXbjaB4HRw4vgBsGb sYSgg2fcg72wde12PGuE9q3zPnzrs3iUZekkhHxE3xZwj+63qosOFS6XMI/D2kR8fRWy vGb0mgtU1i1na7plz+RQHjUzLHIBRUBd/nCBHXOPqyQRFESz2yM26PNRgUtBILQwusGR mTzg== X-Gm-Message-State: AOAM531J+MtmjqdPjAtJirg5txRLVgb8VTvUZPz6aauRecUBkmIcSVfZ UbQAB3rI/jSKj0xCVNmXdPUBmmwCxRk= X-Google-Smtp-Source: ABdhPJyJ9IH5yjJ1w3bo8h3abEOag+7Bnq7V9LkS3PO1PNhlyJ50gniAAz1mop6Ok01XMQ2/IMImiw== X-Received: by 2002:a19:7e0d:: with SMTP id z13mr5049605lfc.455.1601894216462; Mon, 05 Oct 2020 03:36:56 -0700 (PDT) Received: from [192.168.2.145] ([109.252.91.252]) by smtp.googlemail.com with ESMTPSA id i18sm2561967lfo.243.2020.10.05.03.36.55 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 05 Oct 2020 03:36:55 -0700 (PDT) Subject: Re: [PATCH v4 2/3] iommu/tegra-smmu: Rework tegra_smmu_probe_device() To: Thierry Reding Cc: Nicolin Chen , joro@8bytes.org, vdumpa@nvidia.com, jonathanh@nvidia.com, linux-tegra@vger.kernel.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org References: <20201002060807.32138-1-nicoleotsuka@gmail.com> <20201002060807.32138-3-nicoleotsuka@gmail.com> <0c66bab9-0132-d3fb-ea4e-de1278cf2b04@gmail.com> <20201005095351.GI425362@ulmo> From: Dmitry Osipenko Message-ID: Date: Mon, 5 Oct 2020 13:36:55 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20201005095351.GI425362@ulmo> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-tegra@vger.kernel.org 05.10.2020 12:53, Thierry Reding пишет: > On Fri, Oct 02, 2020 at 05:50:08PM +0300, Dmitry Osipenko wrote: >> 02.10.2020 17:22, Dmitry Osipenko пишет: >>>> static int tegra_smmu_of_xlate(struct device *dev, >>>> struct of_phandle_args *args) >>>> { >>>> + struct platform_device *iommu_pdev = of_find_device_by_node(args->np); >>>> + struct tegra_mc *mc = platform_get_drvdata(iommu_pdev); >>>> u32 id = args->args[0]; >>>> >>>> + of_node_put(args->np); >>>> + >>>> + if (!mc || !mc->smmu) >>>> + return -EPROBE_DEFER; >>> platform_get_drvdata(NULL) will crash. >>> >> >> Actually, platform_get_drvdata(NULL) can't happen. I overlooked this. > > How so? It's technically possible for the iommus property to reference a > device tree node for which no platform device will ever be created, in > which case of_find_device_by_node() will return NULL. That's very > unlikely and perhaps worth just crashing on to make sure it gets fixed > immediately. The tegra_smmu_ops are registered from the SMMU driver itself and MC driver sets platform data before SMMU is initialized, hence device is guaranteed to exist and mc can't be NULL.