1 files changed, 6 insertions, 1 deletions

diff --git a/drivers/rtc/rtc-m41t80.c b/drivers/rtc/rtc-m41t80.c
index a3e0880b38fb..0a19c06019be 100644
--- a/drivers/rtc/rtc-m41t80.c
+++ b/drivers/rtc/rtc-m41t80.c
@@ -17,6 +17,7 @@
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/slab.h>
+#include <linux/smp_lock.h>
 #include <linux/string.h>
 #include <linux/i2c.h>
 #include <linux/rtc.h>
@@ -655,12 +656,16 @@ static int wdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 static int wdt_open(struct inode *inode, struct file *file)
 {
         if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
-                if (test_and_set_bit(0, &wdt_is_open))
+                lock_kernel();
+                if (test_and_set_bit(0, &wdt_is_open)) {
+                        unlock_kernel();
                         return -EBUSY;
+                }
                 /*
                  *      Activate
                  */
                 wdt_is_open = 1;
+                unlock_kernel();
                 return 0;
         }
         return -ENODEV;