On Thu, Feb 06, 2025 at 04:13:25PM -0600, Bjorn Andersson wrote:
> On Wed, Jan 29, 2025 at 09:25:44PM +0530, Mukesh Ojha wrote:
> > When some client process A call pdr_add_lookup() to add the look up for
> > the service and does schedule locator work, later a process B got a new
> > server packet indicating locator is up and call pdr_locator_new_server()
> > which eventually sets pdr->locator_init_complete to true which process A
> > sees and takes list lock and queries domain list but it will timeout due
> > to deadlock as the response will queued to the same qmi->wq and it is
> > ordered workqueue and process B is not able to complete new server
> > request work due to deadlock on list lock.
> >
> > Process A Process B
> >
> > process_scheduled_works()
> > pdr_add_lookup() qmi_data_ready_work()
> > process_scheduled_works() pdr_locator_new_server()
> > pdr->locator_init_complete=true;
> > pdr_locator_work()
> > mutex_lock(&pdr->list_lock);
> >
> > pdr_locate_service() mutex_lock(&pdr->list_lock);
> >
> > pdr_get_domain_list()
> > pr_err("PDR: %s get domain list
> > txn wait failed: %d\n",
> > req->service_name,
> > ret);
> >
> > Fix it by removing the unnecessary list iteration as the list iteration
> > is already being done inside locator work, so avoid it here and just
> > call schedule_work() here.
> >
>
> I came to the same patch while looking into the issue related to
> in-kernel pd-mapper reported here:
> https://lore.kernel.org/lkml/Zqet8iInnDhnxkT9@xxxxxxxxxxxxxxxxxxxx/
>
> So:
> Reviewed-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxxxxxxxx>
> Tested-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxxxxxxxx>
Thanks.,
>
> > Fixes: fbe639b44a82 ("soc: qcom: Introduce Protection Domain Restart helpers")
> > CC: stable@xxxxxxxxxxxxxxx
> > Signed-off-by: Saranya R <quic_sarar@xxxxxxxxxxx>
>
> Can we please use full names?
I have informed her about this and she wants the same name to be mentioned here as well.
>
> > Signed-off-by: Mukesh Ojha <mukesh.ojha@xxxxxxxxxxxxxxxx>
>
> Unfortunately I can't merge this; Saranya's S-o-b comes first which
> implies that she authored the patch, but you're listed as author.
I will correct it.
-Mukesh
>
> Regards,
> Bjorn
>
> > ---
> > Changes in v2:
> > - Added Fixes tag,
> >
> > drivers/soc/qcom/pdr_interface.c | 8 +-------
> > 1 file changed, 1 insertion(+), 7 deletions(-)
> >
> > diff --git a/drivers/soc/qcom/pdr_interface.c b/drivers/soc/qcom/pdr_interface.c
> > index 328b6153b2be..71be378d2e43 100644
> > --- a/drivers/soc/qcom/pdr_interface.c
> > +++ b/drivers/soc/qcom/pdr_interface.c
> > @@ -75,7 +75,6 @@ static int pdr_locator_new_server(struct qmi_handle *qmi,
> > {
> > struct pdr_handle *pdr = container_of(qmi, struct pdr_handle,
> > locator_hdl);
> > - struct pdr_service *pds;
> >
> > mutex_lock(&pdr->lock);
> > /* Create a local client port for QMI communication */
> > @@ -87,12 +86,7 @@ static int pdr_locator_new_server(struct qmi_handle *qmi,
> > mutex_unlock(&pdr->lock);
> >
> > /* Service pending lookup requests */
> > - mutex_lock(&pdr->list_lock);
> > - list_for_each_entry(pds, &pdr->lookups, node) {
> > - if (pds->need_locator_lookup)
> > - schedule_work(&pdr->locator_work);
> > - }
> > - mutex_unlock(&pdr->list_lock);
> > + schedule_work(&pdr->locator_work);
> >
> > return 0;
> > }
> > --
> > 2.34.1
> >
