[PATCH v2 03/21] drm: Make drm_connector_register() safe against multiple calls

[Chris Wilson]

Protect against drivers that may try to register the connector more
than once, or who try to unregister it multiple times.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: dri-devel at lists.freedesktop.org
---
 drivers/gpu/drm/drm_crtc.c | 9 +++++++++
 include/drm/drm_crtc.h     | 1 +
 2 files changed, 10 insertions(+)

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 81641544ac3e..8b9ee921a9e1 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -1030,6 +1030,9 @@ int drm_connector_register(struct drm_connector *connector)
 {
 	int ret;
 
+	if (connector->registered)
+		return 0;
+
 	ret = drm_sysfs_connector_add(connector);
 	if (ret)
 		return ret;
@@ -1047,6 +1050,7 @@ int drm_connector_register(struct drm_connector *connector)
 
 	drm_mode_object_register(connector->dev, &connector->base);
 
+	connector->registered = true;
 	return 0;
 
 err_debugfs:
@@ -1065,11 +1069,16 @@ EXPORT_SYMBOL(drm_connector_register);
  */
 void drm_connector_unregister(struct drm_connector *connector)
 {
+	if (!connector->registered)
+		return;
+
 	if (connector->funcs->early_unregister)
 		connector->funcs->early_unregister(connector);
 
 	drm_sysfs_connector_remove(connector);
 	drm_debugfs_connector_remove(connector);
+
+	connector->registered = false;
 }
 EXPORT_SYMBOL(drm_connector_unregister);
 
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 77b775cff4e7..35e47eea5ee1 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -1212,6 +1212,7 @@ struct drm_connector {
 	bool interlace_allowed;
 	bool doublescan_allowed;
 	bool stereo_allowed;
+	bool registered;
 	struct list_head modes; /* list of modes on this connector */
 
 	enum drm_connector_status status;
-- 
2.8.1