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SubjectRe: [PATCH v7 1/6] soc: qcom: pdr: protect locator_addr with the main mutex
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On 4/24/2024 2:27 AM, Dmitry Baryshkov wrote:
> If the service locator server is restarted fast enough, the PDR can
> rewrite locator_addr fields concurrently. Protect them by placing
> modification of those fields under the main pdr->lock.
>
> Fixes: fbe639b44a82 ("soc: qcom: Introduce Protection Domain Restart helpers")
> Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8550-QRD
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> ---
> drivers/soc/qcom/pdr_interface.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/soc/qcom/pdr_interface.c b/drivers/soc/qcom/pdr_interface.c
> index a1b6a4081dea..19cfe4b41235 100644
> --- a/drivers/soc/qcom/pdr_interface.c
> +++ b/drivers/soc/qcom/pdr_interface.c
> @@ -76,12 +76,12 @@ static int pdr_locator_new_server(struct qmi_handle *qmi,
> locator_hdl);
> struct pdr_service *pds;
>
> + mutex_lock(&pdr->lock);
> /* Create a local client port for QMI communication */
> pdr->locator_addr.sq_family = AF_QIPCRTR;
> pdr->locator_addr.sq_node = svc->node;
> pdr->locator_addr.sq_port = svc->port;
>
> - mutex_lock(&pdr->lock);
> pdr->locator_init_complete = true;
> mutex_unlock(&pdr->lock);
>
> @@ -104,10 +104,10 @@ static void pdr_locator_del_server(struct qmi_handle *qmi,
>
> mutex_lock(&pdr->lock);
> pdr->locator_init_complete = false;
> - mutex_unlock(&pdr->lock);
>
> pdr->locator_addr.sq_node = 0;
> pdr->locator_addr.sq_port = 0;
> + mutex_unlock(&pdr->lock);
> }
>
> static const struct qmi_ops pdr_locator_ops = {
>

These two functions are provided as qmi_ops handlers in pdr_locator_ops.
Aren't they serialized in the qmi handle's workqueue since it as an
ordered_workqueue? Even in a fast pdr scenario I don't think we would
see a race condition between these two functions.

The other access these two functions do race against is in the
pdr_notifier_work. I think you would need to protect locator_addr in
pdr_get_domain_list since the qmi_send_request there uses
'pdr->locator_addr'.

Thanks!
Chris

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