diff --git a/[refs] b/[refs]
index d33ec5315937..9749f82f1de7 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 6c111d886317513605c459cbe8d1970fab732c90
+refs/heads/master: 3e0420f066c632e135939ccf218ae793e02dccd7
diff --git a/trunk/drivers/s390/char/vmwatchdog.c b/trunk/drivers/s390/char/vmwatchdog.c
index 19f8389291b6..ee80e936d514 100644
--- a/trunk/drivers/s390/char/vmwatchdog.c
+++ b/trunk/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);
 }