1 files changed, 10 insertions, 7 deletions

diff --git a/drivers/gpu/drm/drm_fops.c b/drivers/gpu/drm/drm_fops.c
index 08d14df3bb42..9d532d7fdf59 100644
--- a/drivers/gpu/drm/drm_fops.c
+++ b/drivers/gpu/drm/drm_fops.c
@@ -36,6 +36,7 @@
 
 #include "drmP.h"
 #include <linux/poll.h>
+#include <linux/slab.h>
 #include <linux/smp_lock.h>
 
 static int drm_open_helper(struct inode *inode, struct file *filp,
@@ -140,14 +141,16 @@ int drm_open(struct inode *inode, struct file *filp)
                 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;
 }