From ed1ac3c977dd6b119405fa36dd41f7151bd5b4de Mon Sep 17 00:00:00 2001 From: Danilo Krummrich Date: Wed, 21 Jan 2026 15:12:01 +0100 Subject: [PATCH] iommu/arm-smmu-qcom: do not register driver in probe() Commit 0b4eeee2876f ("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 dc23806a7c47 ("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 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: dc23806a7c47 ("driver core: enforce device_lock for driver_match_device()") Fixes: 0b4eeee2876f ("iommu/arm-smmu-qcom: Register the TBU driver in qcom_smmu_impl_init") Acked-by: Robin Murphy Tested-by: Bjorn Andersson Reviewed-by: Bjorn Andersson Acked-by: Konrad Dybcio Reviewed-by: Greg Kroah-Hartman Tested-by: Ioana Ciornei #LX2160ARDB Tested-by: Wang Jiayue Reviewed-by: Wang Jiayue Tested-by: Mark Brown Acked-by: Joerg Roedel Link: https://patch.msgid.link/20260121141215.29658-1-dakr@kernel.org Signed-off-by: Danilo Krummrich --- drivers/iommu/arm/arm-smmu/arm-smmu-impl.c | 14 +++++++++++++ drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 14 +++++++++---- drivers/iommu/arm/arm-smmu/arm-smmu.c | 24 +++++++++++++++++++++- drivers/iommu/arm/arm-smmu/arm-smmu.h | 5 +++++ 4 files changed, 52 insertions(+), 5 deletions(-) diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c b/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c index db9b9a8e139c8..4565a58bb213f 100644 --- a/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c @@ -228,3 +228,17 @@ struct arm_smmu_device *arm_smmu_impl_init(struct arm_smmu_device *smmu) return smmu; } + +int __init arm_smmu_impl_module_init(void) +{ + if (IS_ENABLED(CONFIG_ARM_SMMU_QCOM)) + return qcom_smmu_module_init(); + + return 0; +} + +void __exit arm_smmu_impl_module_exit(void) +{ + if (IS_ENABLED(CONFIG_ARM_SMMU_QCOM)) + qcom_smmu_module_exit(); +} diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c index 573085349df34..22906d2c9a2db 100644 --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c @@ -774,10 +774,6 @@ struct arm_smmu_device *qcom_smmu_impl_init(struct arm_smmu_device *smmu) { const struct device_node *np = smmu->dev->of_node; const struct of_device_id *match; - static u8 tbu_registered; - - if (!tbu_registered++) - platform_driver_register(&qcom_smmu_tbu_driver); #ifdef CONFIG_ACPI if (np == NULL) { @@ -802,3 +798,13 @@ struct arm_smmu_device *qcom_smmu_impl_init(struct arm_smmu_device *smmu) return smmu; } + +int __init qcom_smmu_module_init(void) +{ + return platform_driver_register(&qcom_smmu_tbu_driver); +} + +void __exit qcom_smmu_module_exit(void) +{ + platform_driver_unregister(&qcom_smmu_tbu_driver); +} diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c index 5e690cf85ec96..1e218fbea35a0 100644 --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c @@ -2365,7 +2365,29 @@ static struct platform_driver arm_smmu_driver = { .remove = arm_smmu_device_remove, .shutdown = arm_smmu_device_shutdown, }; -module_platform_driver(arm_smmu_driver); + +static int __init arm_smmu_init(void) +{ + int ret; + + ret = platform_driver_register(&arm_smmu_driver); + if (ret) + return ret; + + ret = arm_smmu_impl_module_init(); + if (ret) + platform_driver_unregister(&arm_smmu_driver); + + return ret; +} +module_init(arm_smmu_init); + +static void __exit arm_smmu_exit(void) +{ + arm_smmu_impl_module_exit(); + platform_driver_unregister(&arm_smmu_driver); +} +module_exit(arm_smmu_exit); MODULE_DESCRIPTION("IOMMU API for ARM architected SMMU implementations"); MODULE_AUTHOR("Will Deacon "); diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.h b/drivers/iommu/arm/arm-smmu/arm-smmu.h index 2dbf3243b5ad2..26d2e33cd328b 100644 --- a/drivers/iommu/arm/arm-smmu/arm-smmu.h +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.h @@ -540,6 +540,11 @@ struct arm_smmu_device *arm_smmu_impl_init(struct arm_smmu_device *smmu); struct arm_smmu_device *nvidia_smmu_impl_init(struct arm_smmu_device *smmu); struct arm_smmu_device *qcom_smmu_impl_init(struct arm_smmu_device *smmu); +int __init arm_smmu_impl_module_init(void); +void __exit arm_smmu_impl_module_exit(void); +int __init qcom_smmu_module_init(void); +void __exit qcom_smmu_module_exit(void); + void arm_smmu_write_context_bank(struct arm_smmu_device *smmu, int idx); int arm_mmu500_reset(struct arm_smmu_device *smmu); -- 2.47.3