diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c
index ae766d868454406a6d32bbfc7422975d6a9ce550..ceba6082bd968373c0bb926b26c7eae7a99443a1 100644
--- a/drivers/char/tpm/tpm.c
+++ b/drivers/char/tpm/tpm.c
@@ -954,13 +954,16 @@ EXPORT_SYMBOL_GPL(tpm_store_cancel);
 
 /*
  * Device file system interface to the TPM
+ *
+ * It's assured that the chip will be opened just once,
+ * by the check of is_open variable, which is protected
+ * by driver_lock.
  */
 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) {
@@ -990,19 +993,16 @@ 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);