drm: fail gracefully when proc isn't setup.

If drm can't find proc it should fail more gracefully, than just
oopsing, this tests drm_class is NULL, and sets it to NULL in the
fail paths.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_sysfs.c b/drivers/gpu/drm/drm_sysfs.c
index 45cf1dd3eb9c..45ac8d6c92b7 100644
--- a/drivers/gpu/drm/drm_sysfs.c
+++ b/drivers/gpu/drm/drm_sysfs.c
@@ -134,6 +134,7 @@ void drm_sysfs_destroy(void)
                 return;
         class_remove_file(drm_class, &class_attr_version.attr);
         class_destroy(drm_class);
+        drm_class = NULL;
 }
 
 /**
@@ -554,6 +555,9 @@ void drm_sysfs_device_remove(struct drm_minor *minor)
 
 int drm_class_device_register(struct device *dev)
 {
+        if (!drm_class || IS_ERR(drm_class))
+                return -ENOENT;
+
         dev->class = drm_class;
         return device_register(dev);
 }