4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Daniel Vetter <daniel.vetter@xxxxxxxx> [ Upstream commit e6e7b48b295afa5a5ab440de0a94d9ad8b3ce2d0 ] 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@xxxxxxxxx> Cc: Dave Hansen <dave.hansen@xxxxxxxxx> Acked-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx> Link: http://patchwork.freedesktop.org/patch/msgid/1484237756-2720-1-git-send-email-daniel.vetter@xxxxxxxx Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/gpu/drm/drm_connector.c | 3 +++ drivers/gpu/drm/drm_drv.c | 4 ++++ include/drm/drmP.h | 1 + 3 files changed, 8 insertions(+) --- a/drivers/gpu/drm/drm_connector.c +++ b/drivers/gpu/drm/drm_connector.c @@ -379,6 +379,9 @@ int drm_connector_register(struct drm_co { int ret = 0; + if (!connector->dev->registered) + return 0; + mutex_lock(&connector->mutex); if (connector->registered) goto unlock; --- a/drivers/gpu/drm/drm_drv.c +++ b/drivers/gpu/drm/drm_drv.c @@ -710,6 +710,8 @@ int drm_dev_register(struct drm_device * if (ret) goto err_minors; + dev->registered = true; + if (dev->driver->load) { ret = dev->driver->load(dev, flags); if (ret) @@ -749,6 +751,8 @@ void drm_dev_unregister(struct drm_devic drm_lastclose(dev); + dev->registered = false; + if (drm_core_check_feature(dev, DRIVER_MODESET)) drm_modeset_unregister_all(dev); --- a/include/drm/drmP.h +++ b/include/drm/drmP.h @@ -776,6 +776,7 @@ 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;