Re: [PATCH 4.19 11/57] drm/atomic_helper: Stop modesets on unregistered connectors harder

Hi!

From: Lyude Paul lyude@redhat.com

commit de9f8eea5a44b0b756d3d6345af7f8e630a3c8c0 upstream.

So this says protected by mutex:

/**

• * @registered: Is this connector exposed (registered) with userspace?
  

• * @registration_state: Is this connector initializing, exposed
  

• * (registered) with userspace, or unregistered?
  

• *
  

  • Protected by @mutex.
  */

• bool registered;

• enum drm_connector_registration_state registration_state;

/** * @modes: @@ -1165,6 +1214,24 @@ static inline void drm_connector_unrefer drm_connector_put(connector); } +/**

• • drm_connector_is_unregistered - has the connector been unregistered from
• • userspace?
• • @connector: DRM connector
• • Checks whether or not @connector has been unregistered from userspace.
• • Returns:
• • True if the connector was unregistered, false if the connector is
• • registered or has not yet been registered with userspace.
• */

+static inline bool +drm_connector_is_unregistered(struct drm_connector *connector) +{

• return READ_ONCE(connector->registration_state) ==

• DRM_CONNECTOR_UNREGISTERED;
  

+}

But this uses READ_ONCE() for protection, and corresponding WRITE_ONCE() is nowhere to be seen. Should this take the mutex, too?

Best regards, Pavel