From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: [PATCH 1/2] iommu/tegra: Add support for struct iommu_device Date: Wed, 30 Aug 2017 14:09:03 +0200 Message-ID: <20170830120902.kqtxh2ls4ob7xpwy@8bytes.org> References: <1502317752-8792-1-git-send-email-joro@8bytes.org> <1502317752-8792-2-git-send-email-joro@8bytes.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Jon Hunter Cc: Hiroshi Doyu , Thierry Reding , Robin Murphy , iommu@lists.linux-foundation.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org, Joerg Roedel List-Id: linux-tegra@vger.kernel.org Hi Jon, On Wed, Aug 30, 2017 at 12:04:38PM +0100, Jon Hunter wrote: > With next-20170829 I am seeing several Tegra boards crashing [0][1] on > boot in tegra_smmu_probe() and the bisect is point to this commit. Looks > like there maybe a sequence problem between calls to bus_set_iommu() and > iommu_device_add_sysfs() which results in a NULL pointer dereference. Thanks for the report. Can you please test whether the patch below fixes the problem? Thanks, Joerg diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c index 2802e12e6a54..48ffbe95a663 100644 --- a/drivers/iommu/tegra-smmu.c +++ b/drivers/iommu/tegra-smmu.c @@ -949,10 +949,6 @@ struct tegra_smmu *tegra_smmu_probe(struct device *dev, tegra_smmu_ahb_enable(); - err = bus_set_iommu(&platform_bus_type, &tegra_smmu_ops); - if (err < 0) - return ERR_PTR(err); - err = iommu_device_sysfs_add(&smmu->iommu, dev, NULL, dev_name(dev)); if (err) return ERR_PTR(err); @@ -965,6 +961,10 @@ struct tegra_smmu *tegra_smmu_probe(struct device *dev, return ERR_PTR(err); } + err = bus_set_iommu(&platform_bus_type, &tegra_smmu_ops); + if (err < 0) + return ERR_PTR(err); + if (IS_ENABLED(CONFIG_DEBUG_FS)) tegra_smmu_debugfs_init(smmu);