1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/char/hpet.c b/drivers/char/hpet.c
index e7fb0bca3667..fb0a85a1eb36 100644
--- a/drivers/char/hpet.c
+++ b/drivers/char/hpet.c
@@ -14,6 +14,7 @@
 #include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/kernel.h>
+#include <linux/smp_lock.h>
 #include <linux/types.h>
 #include <linux/miscdevice.h>
 #include <linux/major.h>
@@ -193,6 +194,7 @@ static int hpet_open(struct inode *inode, struct file *file)
         if (file->f_mode & FMODE_WRITE)
                 return -EINVAL;
 
+        lock_kernel();
         spin_lock_irq(&hpet_lock);
 
         for (devp = NULL, hpetp = hpets; hpetp && !devp; hpetp = hpetp->hp_next)
@@ -207,6 +209,7 @@ static int hpet_open(struct inode *inode, struct file *file)
 
         if (!devp) {
                 spin_unlock_irq(&hpet_lock);
+                unlock_kernel();
                 return -EBUSY;
         }
 
@@ -214,6 +217,7 @@ static int hpet_open(struct inode *inode, struct file *file)
         devp->hd_irqdata = 0;
         devp->hd_flags |= HPET_OPEN;
         spin_unlock_irq(&hpet_lock);
+        unlock_kernel();
 
         return 0;
 }