drm/connector: notify userspace on hotplug after register complete

drm connector notifies userspace on hotplug event prematurely before
late_register and mode_object register completes. This leads to a race
between userspace and kernel on updating the IDR list. So, move the
notification to end of connector register.

Signed-off-by: Jeykumar Sankaran <jsanka@codeaurora.org>
Signed-off-by: Steve Cohen <cohens@codeaurora.org>
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/1591155451-10393-1-git-send-email-jsanka@codeaurora.org

drivers/gpu/drm/drm_connector.c

@@ -27,6 +27,7 @@
 #include <drm/drm_print.h>
 #include <drm/drm_drv.h>
 #include <drm/drm_file.h>
+#include <drm/drm_sysfs.h>
 
 #include <linux/uaccess.h>
 
@@ -523,6 +524,10 @@ int drm_connector_register(struct drm_connector *connector)
 	drm_mode_object_register(connector->dev, &connector->base);
 
 	connector->registration_state = DRM_CONNECTOR_REGISTERED;
+
+	/* Let userspace know we have a new connector */
+	drm_sysfs_hotplug_event(connector->dev);
+
 	goto unlock;
 
 err_debugfs:

drivers/gpu/drm/drm_sysfs.c

@@ -291,9 +291,6 @@ int drm_sysfs_connector_add(struct drm_connector *connector)
 		return PTR_ERR(connector->kdev);
 	}
 
-	/* Let userspace know we have a new connector */
-	drm_sysfs_hotplug_event(dev);
-
 	if (connector->ddc)
 		return sysfs_create_link(&connector->kdev->kobj,
 				 &connector->ddc->dev.kobj, "ddc");