On Thu, Oct 04, 2018 at 08:29:50PM -0400, Lyude Paul wrote: > With the exception of modesets which would switch the DPMS state of a > connector from on to off, we want to make sure that we disallow all > modesets which would result in enabling a new monitor or a new mode > configuration on a monitor if the connector for the display in question > is no longer registered. This allows us to stop userspace from trying to > enable new displays on connectors for an MST topology that were just > removed from the system, without preventing userspace from disabling > DPMS on those connectors. > > Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx> > Cc: stable@xxxxxxxxxxxxxxx Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx> > --- > drivers/gpu/drm/drm_atomic_helper.c | 21 ++++++++++++++++++++- > 1 file changed, 20 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c > index 80be74df7ba6..ce2decfc6826 100644 > --- a/drivers/gpu/drm/drm_atomic_helper.c > +++ b/drivers/gpu/drm/drm_atomic_helper.c > @@ -307,6 +307,26 @@ update_connector_routing(struct drm_atomic_state *state, > return 0; > } > > + crtc_state = drm_atomic_get_new_crtc_state(state, > + new_connector_state->crtc); > + /* > + * For compatibility with legacy users, we want to make sure that > + * we allow DPMS On->Off modesets on unregistered connectors. Modesets > + * which would result in anything else must be considered invalid, to > + * avoid turning on new displays on dead connectors. > + * > + * Since the connector can be unregistered at any point during an > + * atomic check or commit, this is racy. But that's OK: all we care > + * about is ensuring that userspace can't do anything but shut off the > + * display on a connector that was destroyed after it's been notified, > + * not before. > + */ > + if (!READ_ONCE(connector->registered) && crtc_state->active) { > + DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] is not registered\n", > + connector->base.id, connector->name); > + return -EINVAL; > + } > + > funcs = connector->helper_private; > > if (funcs->atomic_best_encoder) > @@ -351,7 +371,6 @@ update_connector_routing(struct drm_atomic_state *state, > > set_best_encoder(state, new_connector_state, new_encoder); > > - crtc_state = drm_atomic_get_new_crtc_state(state, new_connector_state->crtc); > crtc_state->connectors_changed = true; > > DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] using [ENCODER:%d:%s] on [CRTC:%d:%s]\n", > -- > 2.17.1 > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch