Commit ed1ac3c9 authored by Danilo Krummrich's avatar Danilo Krummrich
Browse files

iommu/arm-smmu-qcom: do not register driver in probe() 



Commit 0b4eeee2 ("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 dc23806a ("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: default avatarMark 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: dc23806a ("driver core: enforce device_lock for driver_match_device()")
Fixes: 0b4eeee2 ("iommu/arm-smmu-qcom: Register the TBU driver in qcom_smmu_impl_init")
Acked-by: default avatarRobin Murphy <robin.murphy@arm.com>
Tested-by: default avatarBjorn Andersson <andersson@kernel.org>
Reviewed-by: default avatarBjorn Andersson <andersson@kernel.org>
Acked-by: default avatarKonrad Dybcio <konradybcio@kernel.org>
Reviewed-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Tested-by: Ioana Ciornei <ioana.ciornei@nxp.com> #LX2160ARDB
Tested-by: default avatarWang Jiayue <akaieurus@gmail.com>
Reviewed-by: default avatarWang Jiayue <akaieurus@gmail.com>
Tested-by: default avatarMark Brown <broonie@kernel.org>
Acked-by: default avatarJoerg Roedel <joerg.roedel@amd.com>
Link: https://patch.msgid.link/20260121141215.29658-1-dakr@kernel.org


Signed-off-by: default avatarDanilo Krummrich <dakr@kernel.org>
parent dc23806a

drivers/iommu/arm/arm-smmu/arm-smmu-impl.c

+14 −0
Original line number Diff line number Diff line
@@ -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();

}

drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c

+10 −4
Original line number Diff line number Diff line
@@ -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);

}

drivers/iommu/arm/arm-smmu/arm-smmu.c

+23 −1
Original line number Diff line number Diff line
@@ -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 <will@kernel.org>");

drivers/iommu/arm/arm-smmu/arm-smmu.h

+5 −0
Original line number Diff line number Diff line
@@ -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);