Commit 5b30fbfa authored by Thierry Reding's avatar Thierry Reding Committed by Joerg Roedel
Browse files

iommu/tegra-smmu: Balance IOMMU group reference count 



For groups that are shared between multiple devices, care must be taken
to acquire a reference for each device, otherwise the IOMMU core ends up
dropping the last reference too early, which will cause the group to be
released while consumers may still be thinking that they're holding a
reference to it.

Signed-off-by: default avatarThierry Reding <treding@nvidia.com>
Link: https://lore.kernel.org/r/20200806155404.3936074-3-thierry.reding@gmail.com


Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent 00295702

drivers/iommu/tegra-smmu.c

+3 −1
Original line number Diff line number Diff line
@@ -818,6 +818,7 @@ static struct iommu_group *tegra_smmu_group_get(struct tegra_smmu *smmu, 
{

	const struct tegra_smmu_group_soc *soc;

	struct tegra_smmu_group *group;

	struct iommu_group *grp;



	soc = tegra_smmu_find_group(smmu, swgroup);

	if (!soc)
@@ -827,8 +828,9 @@ static struct iommu_group *tegra_smmu_group_get(struct tegra_smmu *smmu, 


	list_for_each_entry(group, &smmu->groups, list)

		if (group->soc == soc) {

			grp = iommu_group_ref_get(group->group);

			mutex_unlock(&smmu->lock);

			return group->group;

			return grp;

		}



	group = devm_kzalloc(smmu->dev, sizeof(*group), GFP_KERNEL);