On Thu, 25 Apr 2024 at 22:30, Chris Lew <quic_clew@xxxxxxxxxxx> wrote:
>
>
> 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@xxxxxxxxxx> # on SM8550-QRD
> > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> > ---
> > 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, I missed it initially. I think I'd keep the rest of the
changes and expand the lock to cover pdr_get_domain_list().
>
> Thanks!
> Chris
--
With best wishes
Dmitry
