diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c
index a5d8bcb40000..e1fc193d9396 100644
--- a/drivers/char/tpm/tpm.c
+++ b/drivers/char/tpm/tpm.c
@@ -26,6 +26,7 @@
 #include <linux/poll.h>
 #include <linux/mutex.h>
 #include <linux/spinlock.h>
+#include <linux/smp_lock.h>
 
 #include "tpm.h"
 
@@ -897,6 +898,7 @@ int tpm_open(struct inode *inode, struct file *file)
 	int rc = 0, minor = iminor(inode);
 	struct tpm_chip *chip = NULL, *pos;
 
+	lock_kernel();
 	spin_lock(&driver_lock);
 
 	list_for_each_entry(pos, &tpm_chip_list, list) {
@@ -926,16 +928,19 @@ int tpm_open(struct inode *inode, struct file *file)
 	if (chip->data_buffer == NULL) {
 		chip->num_opens--;
 		put_device(chip->dev);
+		unlock_kernel();
 		return -ENOMEM;
 	}
 
 	atomic_set(&chip->data_pending, 0);
 
 	file->private_data = chip;
+	unlock_kernel();
 	return 0;
 
 err_out:
 	spin_unlock(&driver_lock);
+	unlock_kernel();
 	return rc;
 }
 EXPORT_SYMBOL_GPL(tpm_open);