--- drivers/gpu/drm/drm_fops.c

+++ drivers/gpu/drm/drm_fops.c

@@ -140,14 +140,16 @@ int drm_open(struct inode *inode, struct

spin_unlock(&dev->count_lock);

}

out:

- mutex_lock(&dev->struct_mutex);

- if (minor->type == DRM_MINOR_LEGACY) {

- BUG_ON((dev->dev_mapping != NULL) &&

- (dev->dev_mapping != inode->i_mapping));

- if (dev->dev_mapping == NULL)

- dev->dev_mapping = inode->i_mapping;

+ if (!retcode) {

+ mutex_lock(&dev->struct_mutex);

+ if (minor->type == DRM_MINOR_LEGACY) {

+ if (dev->dev_mapping == NULL)

+ dev->dev_mapping = inode->i_mapping;

+ else if (dev->dev_mapping != inode->i_mapping)

+ retcode = -ENODEV;

+ }

+ mutex_unlock(&dev->struct_mutex);

}

- mutex_unlock(&dev->struct_mutex);

return retcode;

}