From 5b30fbfa2aa5c068444d576b1c87b2bd1bddf0ba Mon Sep 17 00:00:00 2001 From: Thierry Reding Date: Thu, 6 Aug 2020 17:54:03 +0200 Subject: [PATCH] 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: Thierry Reding Link: https://lore.kernel.org/r/20200806155404.3936074-3-thierry.reding@gmail.com Signed-off-by: Joerg Roedel --- drivers/iommu/tegra-smmu.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c index 1ffdafe8..c439c09 100644 --- a/drivers/iommu/tegra-smmu.c +++ b/drivers/iommu/tegra-smmu.c @@ -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); -- 2.7.4