Commit cf910f61 authored Nov 25, 2020 by Nicolin Chen Committed by Will Deacon Nov 25, 2020

iommu/tegra-smmu: Unwrap tegra_smmu_group_get



The tegra_smmu_group_get was added to group devices in different
SWGROUPs and it'd return a NULL group pointer upon a mismatch at
tegra_smmu_find_group(), so for most of clients/devices, it very
likely would mismatch and need a fallback generic_device_group().

But now tegra_smmu_group_get handles devices in same SWGROUP too,
which means that it would allocate a group for every new SWGROUP
or would directly return an existing one upon matching a SWGROUP,
i.e. any device will go through this function.

So possibility of having a NULL group pointer in device_group()
is upon failure of either devm_kzalloc() or iommu_group_alloc().
In either case, calling generic_device_group() no longer makes a
sense. Especially for devm_kzalloc() failing case, it'd cause a
problem if it fails at devm_kzalloc() yet succeeds at a fallback
generic_device_group(), because it does not create a group->list
for other devices to match.

This patch simply unwraps the function to clean it up.

Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
Tested-by: Dmitry Osipenko <digetx@gmail.com>
Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Link: https://lore.kernel.org/r/20201125101013.14953-2-nicoleotsuka@gmail.com


Signed-off-by: Will Deacon <will@kernel.org>

parent f8394f23

drivers/iommu/tegra-smmu.c

+4 −15

Original line number	Diff line number	Diff line
		@@ -903,10 +903,12 @@ static void tegra_smmu_group_release(void *iommu_data)
		mutex_unlock(&smmu->lock);
		}

		static struct iommu_group tegra_smmu_group_get(struct tegra_smmu smmu,
		unsigned int swgroup)
		static struct iommu_group tegra_smmu_device_group(struct device dev)
		{
		struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
		struct tegra_smmu *smmu = dev_iommu_priv_get(dev);
		const struct tegra_smmu_group_soc *soc;
		unsigned int swgroup = fwspec->ids[0];
		struct tegra_smmu_group *group;
		struct iommu_group *grp;

		@@ -950,19 +952,6 @@ static struct iommu_group tegra_smmu_group_get(struct tegra_smmu smmu,
		return group->group;
		}

		static struct iommu_group tegra_smmu_device_group(struct device dev)
		{
		struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
		struct tegra_smmu *smmu = dev_iommu_priv_get(dev);
		struct iommu_group *group;

		group = tegra_smmu_group_get(smmu, fwspec->ids[0]);
		if (!group)
		group = generic_device_group(dev);

		return group;
		}

		static int tegra_smmu_of_xlate(struct device *dev,
		struct of_phandle_args *args)
		{

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