drm: Don't race connector registration

I was under the misconception that the sysfs dev stuff can be fully
set up, and then registered all in one step with device_add. That's
true for properties and property groups, but not for parents and child
devices. Those must be fully registered before you can register a
child.

Add a bit of tracking to make sure that asynchronous mst connector
hotplugging gets this right. For consistency we rely upon the implicit
barriers of the connector->mutex, which is taken anyway, to ensure
that at least either the connector or device registration call will
work out.

Mildly tested since I can't reliably reproduce this on my mst box
here.

Reported-by: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1484237756-2720-1-git-send-email-daniel.vetter@ffwll.ch

diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index 8be60a4576b3f2c9099a175d6bfe08dd3aa8b0c7..7a7019ac93884eeeba046ad62b3c81037796beb7 100644 (file)
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -379,6 +379,9 @@ int drm_connector_register(struct drm_connector *connector)
 {
        int ret = 0;
 
+       if (!connector->dev->registered)
+               return 0;
+
        mutex_lock(&connector->mutex);
        if (connector->registered)
                goto unlock;

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index a525751b4559e9f3cc99850d5aac6e5c3eb6f16c..6594b4088f11bc8e5aa6a6c308ba3fdf633921a3 100644 (file)
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -745,6 +745,8 @@ int drm_dev_register(struct drm_device *dev, unsigned long flags)
        if (ret)
                goto err_minors;
 
+       dev->registered = true;
+
        if (dev->driver->load) {
                ret = dev->driver->load(dev, flags);
                if (ret)
@@ -785,6 +787,8 @@ void drm_dev_unregister(struct drm_device *dev)
 
        drm_lastclose(dev);
 
+       dev->registered = false;
+
        if (drm_core_check_feature(dev, DRIVER_MODESET))
                drm_modeset_unregister_all(dev);
 

diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 192016e2b5183c7a22fd13fd21372de5862f44d8..9c4ee144b5f6b799baf92a9722cddcaee3eb2b4f 100644 (file)
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -517,6 +517,7 @@ struct drm_device {
        struct drm_minor *control;              /**< Control node */
        struct drm_minor *primary;              /**< Primary node */
        struct drm_minor *render;               /**< Render node */
+       bool registered;
 
        /* currently active master for this device. Protected by master_mutex */
        struct drm_master *master;