drm: cdev lock_kernel() pushdown

Signed-off-by: Jonathan Corbet <corbet@lwn.net>

1 files changed, 7 insertions, 2 deletions

diff --git a/drivers/char/drm/drm_fops.c b/drivers/char/drm/drm_fops.c
index 68f0da801ed8..7a25726f07f7 100644
--- a/drivers/char/drm/drm_fops.c
+++ b/drivers/char/drm/drm_fops.c
@@ -37,6 +37,7 @@
 #include "drmP.h"
 #include "drm_sarea.h"
 #include <linux/poll.h>
+#include <linux/smp_lock.h>
 
 static int drm_open_helper(struct inode *inode, struct file *filp,
                            struct drm_device * dev);
@@ -174,12 +175,14 @@ int drm_stub_open(struct inode *inode, struct file *filp)
 
         DRM_DEBUG("\n");
 
+        /* BKL pushdown: note that nothing else serializes idr_find() */
+        lock_kernel();
         minor = idr_find(&drm_minors_idr, minor_id);
         if (!minor)
-                return -ENODEV;
+                goto out;
 
         if (!(dev = minor->dev))
-                return -ENODEV;
+                goto out;
 
         old_fops = filp->f_op;
         filp->f_op = fops_get(&dev->driver->fops);
@@ -189,6 +192,8 @@ int drm_stub_open(struct inode *inode, struct file *filp)
         }
         fops_put(old_fops);
 
+out:
+        unlock_kernel();
         return err;
 }