Re: [PATCH v3 01/13] iommu/arm-smmu-v3: Add arm_smmu_attach_release()

[sashiko-bot@kernel.org]

> The IOPF teardown is done in arm_smmu_remove_master_domain() when releasing
> the master_domain on detach, under the global arm_smmu_asid_lock mutex. But
> the teardown must drain any in-flight IOPF (for the old domain), before the
> master_domain is freed via iopf_queue_flush_dev() calling flush_workqueue()
> that can block on user-faulting page-fault handlers. Doing so while holding
> the arm_smmu_asid_lock would stall any unrelated attachment in the system.
> 
> Split the teardown out of arm_smmu_remove_master_domain(), to a new helper
> arm_smmu_attach_release() that runs after arm_smmu_asid_lock is released.
> 
> Since no other device would use the old master_domain that is being freed,
> it's safe to move out of arm_smmu_asid_lock (still under the protection of
> iommu_group->mutex).
> 
> Note: this is a pure refactor; no functional change.
> 
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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