On Thu, Jan 12, 2017 at 05:15:56PM +0100, Daniel Vetter wrote:
> 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>
> Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
> ---
> drivers/gpu/drm/drm_connector.c | 3 +++
> drivers/gpu/drm/drm_drv.c | 4 ++++
> include/drm/drmP.h | 1 +
> 3 files changed, 8 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
> index c75ab242f907..5999cb83d05b 100644
> --- a/drivers/gpu/drm/drm_connector.c
> +++ b/drivers/gpu/drm/drm_connector.c
> @@ -378,6 +378,9 @@ 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 7e24103c47f1..cad6df626678 100644
> --- a/drivers/gpu/drm/drm_drv.c
> +++ b/drivers/gpu/drm/drm_drv.c
> @@ -749,6 +749,8 @@ 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)
> @@ -796,6 +798,8 @@ 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 c537c278a4be..ec105c339347 100644
> --- a/include/drm/drmP.h
> +++ b/include/drm/drmP.h
> @@ -518,6 +518,7 @@ 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;
> --
> 2.5.5
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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