[PATCH v14 07/10] iommu/arm-smmu-v3: Maintain a SID->device structure

[niliqiang]

> It is expected that a single SMMU instance is highly likely to have more 
> than one device behind it, and therefore more than one StreamID to keep 
> track of.

Thanks for your explanation. I now understand the role of the `mutex_lock` statement.
However, I have a new question that I hope you can help me with: I noticed that the
function `arm_smmu_insert_master`, which includes the `mutex_lock` statement, was
introduced in Linux version 5.13. For kernel code before version 5.13, how do we
ensure that there's no resource contention when multiple devices are loaded
behind a single SMMU instance?

Currently, we're indeed encountering resource contention issues when loading
multiple device drivers on the 5.10 kernel. Do you have any suggestions on
how to resolve this issue?

Thanks.