drm: prevent double-(un)registration for connectors
If we're unlucky then the registration from a hotplugged connector
might race with the final registration step on driver load. And since
MST topology discover is asynchronous that's even somewhat likely.
v2: Also update the kerneldoc for @registered!
v3: Review from Chris:
- Improve kerneldoc for late_register/early_unregister callbacks.
- Use mutex_destroy.
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Reported-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161218133545.2106-1-daniel.vetter@ffwll.ch
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index 0e41a2e..e4f23cc 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -381,6 +381,8 @@ struct drm_connector_funcs {
* core drm connector interfaces. Everything added from this callback
* should be unregistered in the early_unregister callback.
*
+ * This is called while holding drm_connector->mutex.
+ *
* Returns:
*
* 0 on success, or a negative error code on failure.
@@ -395,6 +397,8 @@ struct drm_connector_funcs {
* late_register(). It is called from drm_connector_unregister(),
* early in the driver unload sequence to disable userspace access
* before data structures are torndown.
+ *
+ * This is called while holding drm_connector->mutex.
*/
void (*early_unregister)(struct drm_connector *connector);
@@ -559,7 +563,6 @@ struct drm_cmdline_mode {
* @interlace_allowed: can this connector handle interlaced modes?
* @doublescan_allowed: can this connector handle doublescan?
* @stereo_allowed: can this connector handle stereo modes?
- * @registered: is this connector exposed (registered) with userspace?
* @modes: modes available on this connector (from fill_modes() + user)
* @status: one of the drm_connector_status enums (connected, not, or unknown)
* @probed_modes: list of modes derived directly from the display
@@ -608,6 +611,13 @@ struct drm_connector {
char *name;
/**
+ * @mutex: Lock for general connector state, but currently only protects
+ * @registered. Most of the connector state is still protected by the
+ * mutex in &drm_mode_config.
+ */
+ struct mutex mutex;
+
+ /**
* @index: Compacted connector index, which matches the position inside
* the mode_config.list for drivers not supporting hot-add/removing. Can
* be used as an array index. It is invariant over the lifetime of the
@@ -620,6 +630,10 @@ struct drm_connector {
bool interlace_allowed;
bool doublescan_allowed;
bool stereo_allowed;
+ /**
+ * @registered: Is this connector exposed (registered) with userspace?
+ * Protected by @mutex.
+ */
bool registered;
struct list_head modes; /* list of modes on this connector */
