1 files changed, 6 insertions, 1 deletions

diff --git a/drivers/s390/char/vmwatchdog.c b/drivers/s390/char/vmwatchdog.c
index 19f8389291b6..ee80e936d514 100644
--- a/drivers/s390/char/vmwatchdog.c
+++ b/drivers/s390/char/vmwatchdog.c
@@ -13,6 +13,7 @@
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/watchdog.h>
+#include <linux/smp_lock.h>
 
 #include <asm/ebcdic.h>
 #include <asm/io.h>
@@ -131,11 +132,15 @@ static int __init vmwdt_probe(void)
 static int vmwdt_open(struct inode *i, struct file *f)
 {
         int ret;
-        if (test_and_set_bit(0, &vmwdt_is_open))
+        lock_kernel();
+        if (test_and_set_bit(0, &vmwdt_is_open)) {
+                unlock_kernel();
                 return -EBUSY;
+        }
         ret = vmwdt_keepalive();
         if (ret)
                 clear_bit(0, &vmwdt_is_open);
+        unlock_kernel();
         return ret ? ret : nonseekable_open(i, f);
 }