diff --git a/drivers/s390/char/vmur.c b/drivers/s390/char/vmur.c
index 83ae9a8..6154998 100644
--- a/drivers/s390/char/vmur.c
+++ b/drivers/s390/char/vmur.c
@@ -9,6 +9,7 @@
  */
 
 #include <linux/cdev.h>
+#include <linux/smp_lock.h>
 
 #include <asm/uaccess.h>
 #include <asm/cio.h>
@@ -668,7 +669,7 @@
 
 	if (accmode == O_RDWR)
 		return -EACCES;
-
+	lock_kernel();
 	/*
 	 * We treat the minor number as the devno of the ur device
 	 * to find in the driver tree.
@@ -676,8 +677,10 @@
 	devno = MINOR(file->f_dentry->d_inode->i_rdev);
 
 	urd = urdev_get_from_devno(devno);
-	if (!urd)
-		return -ENXIO;
+	if (!urd) {
+		rc = -ENXIO;
+		goto out;
+	}
 
 	spin_lock(&urd->open_lock);
 	while (urd->open_flag) {
@@ -720,6 +723,7 @@
 		goto fail_urfile_free;
 	urf->file_reclen = rc;
 	file->private_data = urf;
+	unlock_kernel();
 	return 0;
 
 fail_urfile_free:
@@ -730,6 +734,8 @@
 	spin_unlock(&urd->open_lock);
 fail_put:
 	urdev_put(urd);
+out:
+	unlock_kernel();
 	return rc;
 }