commit ed1ac3c977 upstream.
Commit 0b4eeee287 ("iommu/arm-smmu-qcom: Register the TBU driver in
qcom_smmu_impl_init") intended to also probe the TBU driver when
CONFIG_ARM_SMMU_QCOM_DEBUG is disabled, but also moved the corresponding
platform_driver_register() call into qcom_smmu_impl_init() which is
called from arm_smmu_device_probe().
However, it neither makes sense to register drivers from probe()
callbacks of other drivers, nor does the driver core allow registering
drivers with a device lock already being held.
The latter was revealed by commit dc23806a7c ("driver core: enforce
device_lock for driver_match_device()") leading to a deadlock condition
described in [1].
Additionally, it was noted by Robin that the current approach is
potentially racy with async probe [2].
Hence, fix this by registering the qcom_smmu_tbu_driver from
module_init(). Unfortunately, due to the vendoring of the driver, this
requires an indirection through arm-smmu-impl.c.
Reported-by: Mark Brown <broonie@kernel.org>
Closes: https://lore.kernel.org/lkml/7ae38e31-ef31-43ad-9106-7c76ea0e8596@sirena.org.uk/
Link: https://lore.kernel.org/lkml/DFU7CEPUSG9A.1KKGVW4HIPMSH@kernel.org/ [1]
Link: https://lore.kernel.org/lkml/0c0d3707-9ea5-44f9-88a1-a65c62e3df8d@arm.com/ [2]
Fixes: dc23806a7c ("driver core: enforce device_lock for driver_match_device()")
Fixes: 0b4eeee287 ("iommu/arm-smmu-qcom: Register the TBU driver in qcom_smmu_impl_init")
Acked-by: Robin Murphy <robin.murphy@arm.com>
Tested-by: Bjorn Andersson <andersson@kernel.org>
Reviewed-by: Bjorn Andersson <andersson@kernel.org>
Acked-by: Konrad Dybcio <konradybcio@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Tested-by: Ioana Ciornei <ioana.ciornei@nxp.com> #LX2160ARDB
Tested-by: Wang Jiayue <akaieurus@gmail.com>
Reviewed-by: Wang Jiayue <akaieurus@gmail.com>
Tested-by: Mark Brown <broonie@kernel.org>
Acked-by: Joerg Roedel <joerg.roedel@amd.com>
Link: https://patch.msgid.link/20260121141215.29658-1-dakr@kernel.org
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
bb99c46423