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    Subject[PATCH AUTOSEL 5.4 36/63] iommu/arm-smmu: Fix arm_smmu_device refcount leak when arm_smmu_rpm_get fails
    Date
    From: Xiyu Yang <xiyuyang19@fudan.edu.cn>

    [ Upstream commit 1adf30f198c26539a62d761e45af72cde570413d ]

    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>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/iommu/arm-smmu.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
    index 7c503a6bc585..abf4cf285548 100644
    --- a/drivers/iommu/arm-smmu.c
    +++ b/drivers/iommu/arm-smmu.c
    @@ -114,7 +114,7 @@ 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;
    }
    --
    2.30.2
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