1 files changed, 10 insertions, 1 deletions

diff --git a/drivers/gpu/drm/drm_stub.c b/drivers/gpu/drm/drm_stub.c
index d009661781bc..ef878615c49f 100644
--- a/drivers/gpu/drm/drm_stub.c
+++ b/drivers/gpu/drm/drm_stub.c
@@ -159,6 +159,9 @@ void drm_master_put(struct drm_master **master)
 int drm_setmaster_ioctl(struct drm_device *dev, void *data,
                         struct drm_file *file_priv)
 {
+        if (file_priv->is_master)
+                return 0;
+
         if (file_priv->minor->master && file_priv->minor->master != file_priv->master)
                 return -EINVAL;
 
@@ -169,6 +172,7 @@ int drm_setmaster_ioctl(struct drm_device *dev, void *data,
             file_priv->minor->master != file_priv->master) {
                 mutex_lock(&dev->struct_mutex);
                 file_priv->minor->master = drm_master_get(file_priv->master);
+                file_priv->is_master = 1;
                 mutex_unlock(&dev->struct_mutex);
         }
 
@@ -178,10 +182,15 @@ int drm_setmaster_ioctl(struct drm_device *dev, void *data,
 int drm_dropmaster_ioctl(struct drm_device *dev, void *data,
                          struct drm_file *file_priv)
 {
-        if (!file_priv->master)
+        if (!file_priv->is_master)
                 return -EINVAL;
+
+        if (!file_priv->minor->master)
+                return -EINVAL;
+
         mutex_lock(&dev->struct_mutex);
         drm_master_put(&file_priv->minor->master);
+        file_priv->is_master = 0;
         mutex_unlock(&dev->struct_mutex);
         return 0;
 }