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,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 80D8DC4363A for ; Mon, 5 Oct 2020 09:53:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 477D620776 for ; Mon, 5 Oct 2020 09:53:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="WCC2gEff" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725930AbgJEJxz (ORCPT ); Mon, 5 Oct 2020 05:53:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53186 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725919AbgJEJxz (ORCPT ); Mon, 5 Oct 2020 05:53:55 -0400 Received: from mail-ej1-x644.google.com (mail-ej1-x644.google.com [IPv6:2a00:1450:4864:20::644]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 40761C0613CE; Mon, 5 Oct 2020 02:53:55 -0700 (PDT) Received: by mail-ej1-x644.google.com with SMTP id u21so11016048eja.2; Mon, 05 Oct 2020 02:53:55 -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=tSNvIJ6n/8PydPpekJ3sBZyLSmyQXmedjUmwZXMurMo=; b=WCC2gEffyxEhzVrQNJMtnmNTSoUUlpfjFkvf9eRqLzEJ9LA0ehw10XSgqvJx76A3ip kUazxGYkWWM0N7bRnnWYWQlXKslfVFRf4wvmPEK2JSFJIEfYoHnv9wlqtT/5h8h1KDEj qkxF1atxUk2xVIUzKvp0v+ORc4LYFEihJ+chWpuQtb3nFFQYZ8Lv1REbPLvp8jPlSM/o JjTJyceLbPgYy3s3ae88L6ngca5cL88GCs6eBAVJ8+DatuXO6dQYoZkO8ksmKthOuA8k d+wBWlESELfkIhwLFeIJYwRskd3V37LRuVyNmc5+OwBWpFN3r+vcYjH2eiMyniU4/PuM hLcQ== 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=tSNvIJ6n/8PydPpekJ3sBZyLSmyQXmedjUmwZXMurMo=; b=ZJJacbcgznomMW0MRFdGKqv/HaDjTK4z7pFLMg0Os5YYZUS7/STY4X2Ap/ePUzV8ba NVDF8iNUeMWM2ld5865HYRHCzJMh9xLZgfPIiN+IkDVjAP1Vq+JwGL+n7cQwvzKq8pNk 3hWZPleCWIFjhky6ych7PQCIm2GV2ab4mY7a+FFFyruz1//Ungwjc9r0eikUUCPbRu3W YS8NSTJH4YSEpWE6a/d25YW6dHMKWGxPauSSDUBw+lkjwLINYGYkABA0gdyVRKB5c00/ +8y1r2Z7cHrR8OnEigNT5F6pbu89l0Pjre0lCOlbCqIxw0nC45Ju7GE9lSGxXQoFsY6L btBA== X-Gm-Message-State: AOAM533sZnM2Y94oFScv5GLalLbNZyrkflMeBOU9b5PgY/u2nmd760Cm 2+arAxBR9/PpBxEoMd+mg/mUcxIBYnE= X-Google-Smtp-Source: ABdhPJxgzAOZ4Qeah+nCeFuiSWn88H4ILEdKN/5a6C7QNL1MKO0q6rEqKvyjihuNnGDqmUMjqS+F8g== X-Received: by 2002:a17:907:7215:: with SMTP id dr21mr14431042ejc.239.1601891633938; Mon, 05 Oct 2020 02:53:53 -0700 (PDT) Received: from localhost ([217.111.27.204]) by smtp.gmail.com with ESMTPSA id x2sm8286307edr.65.2020.10.05.02.53.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 05 Oct 2020 02:53:52 -0700 (PDT) Date: Mon, 5 Oct 2020 11:53:51 +0200 From: Thierry Reding To: Dmitry Osipenko 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 Subject: Re: [PATCH v4 2/3] iommu/tegra-smmu: Rework tegra_smmu_probe_device() Message-ID: <20201005095351.GI425362@ulmo> References: <20201002060807.32138-1-nicoleotsuka@gmail.com> <20201002060807.32138-3-nicoleotsuka@gmail.com> <0c66bab9-0132-d3fb-ea4e-de1278cf2b04@gmail.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="FUFe+yI/t+r3nyH4" Content-Disposition: inline In-Reply-To: <0c66bab9-0132-d3fb-ea4e-de1278cf2b04@gmail.com> User-Agent: Mutt/1.14.7 (2020-08-29) Precedence: bulk List-ID: X-Mailing-List: linux-tegra@vger.kernel.org --FUFe+yI/t+r3nyH4 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Oct 02, 2020 at 05:50:08PM +0300, Dmitry Osipenko wrote: > 02.10.2020 17:22, Dmitry Osipenko =D0=BF=D0=B8=D1=88=D0=B5=D1=82: > >> static int tegra_smmu_of_xlate(struct device *dev, > >> struct of_phandle_args *args) > >> { > >> + struct platform_device *iommu_pdev =3D of_find_device_by_node(args->= np); > >> + struct tegra_mc *mc =3D platform_get_drvdata(iommu_pdev); > >> u32 id =3D args->args[0]; > >> =20 > >> + of_node_put(args->np); > >> + > >> + if (!mc || !mc->smmu) > >> + return -EPROBE_DEFER; > > platform_get_drvdata(NULL) will crash. > >=20 >=20 > 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. 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