On Thu, Dec 12, 2024 at 12:06:12PM +0200, Jani Nikula wrote:
> On Thu, 12 Dec 2024, Imre Deak <imre.deak@xxxxxxxxx> wrote:
> > The connectors enumerated by the GETRESOURCES ioctl may not be fully
> > initialized yet wrt. to the state set up during connector registration
> > (for instance the connector's debugfs/sysfs interfaces may not exist
> > yet). This can happen in two ways:
> >
> > 1. Connectors initialized and added to the
> > drm_mode_config::connector_list during driver loading will be visible
> > to the GETRESOURCES ioctl caller once the driver is registered via
> > drm_dev_register()->drm_minor_register(DRM_MINOR_PRIMARY) and before
> > the connectors are registered via drm_dev_register()->
> > drm_modeset_register_all().
> >
> > 2. Dynamic connectors (MST) - after being initialized - may be added to
> > the connector_list after the driver is loaded and registered and before
> > the connector's userspace interfaces (debugfs, sysfs etc.) are added
> > in drm_connector_dynamic_register().
> >
> > A solution for 1. would be to register the driver only after the
> > connectors are registered, for 2. to add the connector to connector_list
> > only after the userspace interfaces are registered.
> >
> > The fix would require a bigger change, not the topic of this patchset,
> > so adding only a FIXME comment here.
>
> References to "this patchset" become meaningless after this has been
> committed.
I wondered if the Link: added when the patch is committed provides the
context, but I suppose the link can get stale. I can reword the above to:
"The fix requires a bigger change, for now adding a FIXME: comment for
it."
> Reviewed-by: Jani Nikula <jani.nikula@xxxxxxxxx>
>
> >
> > Suggested-by: Simona Vetter <simona.vetter@xxxxxxxx>
> > Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx>
> > ---
> > drivers/gpu/drm/drm_mode_config.c | 9 +++++++++
> > 1 file changed, 9 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
> > index 37d2e0a4ef4be..8642a2fb25a90 100644
> > --- a/drivers/gpu/drm/drm_mode_config.c
> > +++ b/drivers/gpu/drm/drm_mode_config.c
> > @@ -150,6 +150,15 @@ int drm_mode_getresources(struct drm_device *dev, void *data,
> > drm_connector_list_iter_begin(dev, &conn_iter);
> > count = 0;
> > connector_id = u64_to_user_ptr(card_res->connector_id_ptr);
> > + /*
> > + * FIXME: the connectors on the list may not be fully initialized yet,
> > + * if the ioctl is called before the connectors are registered. (See
> > + * drm_dev_register()->drm_modeset_register_all() for static and
> > + * drm_connector_dynamic_register() for dynamic connectors.)
> > + * The driver should only get registered after static connectors are
> > + * fully initialized and dynamic connectors should be added to the
> > + * connector list only after fully initializing them.
> > + */
> > drm_for_each_connector_iter(connector, &conn_iter) {
> > /* only expose writeback connectors if userspace understands them */
> > if (!file_priv->writeback_connectors &&
>
> --
> Jani Nikula, Intel
