drm/connector: Add FIXME for GETRESOURCES ioctl wrt. uninited connectors

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 requires a bigger change, for now adding a FIXME: comment for
it.

v2: Remove references to the patchset from the commit log. (Jani)

Suggested-by: Simona Vetter <simona.vetter@ffwll.ch>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Wayne Lin <Wayne.Lin@amd.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241211230328.4012496-3-imre.deak@intel.com

diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
index 37d2e0a..8642a2f 100644 (file)
--- 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 &&