drm: Don't race connector registration

[ 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@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
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index a103f1f..0e934a9 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 0f2fa90..362b8cd 100644 (file)
--- 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 *dev, unsigned long flags)
        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_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 e9fb2e8..0c4f9c6 100644 (file)
--- 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;