iommu/arm-smmu: Fix arm_smmu_device refcount leak when arm_smmu_rpm_get fails

arm_smmu_rpm_get() invokes pm_runtime_get_sync(), which increases the
refcount of the "smmu" even though the return value is less than 0.

The reference counting issue happens in some error handling paths of
arm_smmu_rpm_get() in its caller functions. When arm_smmu_rpm_get()
fails, the caller functions forget to decrease the refcount of "smmu"
increased by arm_smmu_rpm_get(), causing a refcount leak.

Fix this issue by calling pm_runtime_resume_and_get() instead of
pm_runtime_get_sync() in arm_smmu_rpm_get(), which can keep the refcount
balanced in case of failure.

Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Link: https://lore.kernel.org/r/1623293672-17954-1-git-send-email-xiyuyang19@fudan.edu.cn
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
index 88a3023..5de5cf5 100644 (file)
--- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
@@ -74,7 +74,7 @@ static bool using_legacy_binding, using_generic_binding;
 static inline int arm_smmu_rpm_get(struct arm_smmu_device *smmu)
 {
        if (pm_runtime_enabled(smmu->dev))
-               return pm_runtime_get_sync(smmu->dev);
+               return pm_runtime_resume_and_get(smmu->dev);
 
        return 0;
 }