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[v2,1/2] iommu/tegra-smmu: Unwrap tegra_smmu_group_get

Message ID 20200928235901.28337-2-nicoleotsuka@gmail.com
State New
Headers show
Series iommu/tegra-smmu: Two followup changes | expand

Commit Message

Nicolin Chen Sept. 28, 2020, 11:59 p.m. UTC
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>

 * Changed type of swgroup to "unsigned int", following Thierry's

 drivers/iommu/tegra-smmu.c | 19 ++++---------------
 1 file changed, 4 insertions(+), 15 deletions(-)
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diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
index 0becdbfea306..ec4c9dafff95 100644
--- a/drivers/iommu/tegra-smmu.c
+++ b/drivers/iommu/tegra-smmu.c
@@ -903,10 +903,12 @@  static void tegra_smmu_group_release(void *iommu_data)
-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)