Re: [PATCH 0/6] firmware: qcom: scm: Fixes for concurrency

[Dmitry Baryshkov <dmitry.baryshkov@linaro.org>]

On Tue, Nov 19, 2024 at 07:33:16PM +0100, Krzysztof Kozlowski wrote:
> SCM driver looks messy in terms of handling concurrency of probe.  The
> driver exports interface which is guarded by global '__scm' variable
> but:
> 1. Lacks proper read barrier (commit adding write barriers mixed up
>    READ_ONCE with a read barrier).
> 2. Lacks barriers or checks for '__scm' in multiple places.
> 3. Lacks probe error cleanup.
> 
> I fixed here few visible things, but this was not tested extensively.  I
> tried only SM8450.
> 
> ARM32 and SC8280xp/X1E platforms would be useful for testing as well.

ARM32 devices are present in the lab.

> 
> All the issues here are non-urgent, IOW, they were here for some time
> (v6.10-rc1 and earlier).
> 
> Best regards,
> Krzysztof
> 
> ---
> Krzysztof Kozlowski (6):
>       firmware: qcom: scm: Fix missing read barrier in qcom_scm_is_available()
>       firmware: qcom: scm: Fix missing read barrier in qcom_scm_get_tzmem_pool()
>       firmware: qcom: scm: Handle various probe ordering for qcom_scm_assign_mem()
>       [RFC/RFT] firmware: qcom: scm: Cleanup global '__scm' on probe failures
>       firmware: qcom: scm: smc: Handle missing SCM device
>       firmware: qcom: scm: smc: Narrow 'mempool' variable scope
> 
>  drivers/firmware/qcom/qcom_scm-smc.c |  6 +++-
>  drivers/firmware/qcom/qcom_scm.c     | 55 +++++++++++++++++++++++++-----------
>  2 files changed, 44 insertions(+), 17 deletions(-)
> ---
> base-commit: 414c97c966b69e4a6ea7b32970fa166b2f9b9ef0
> change-id: 20241119-qcom-scm-missing-barriers-and-all-sort-of-srap-a25d59074882
> 
> Best regards,
> -- 
> Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> 

-- 
With best wishes
Dmitry