int tpm_release(struct inode *inode, struct file *file)
 {
        struct tpm_chip *chip = file->private_data;
-       
-       file->private_data = NULL;
 
        spin_lock(&driver_lock);
+       file->private_data = NULL;
        chip->num_opens--;
        del_singleshot_timer_sync(&chip->user_read_timer);
        atomic_set(&chip->data_pending, 0);
-
        pci_dev_put(chip->pci_dev);
+       kfree(chip->data_buffer);
+       spin_unlock(&driver_lock);
        return 0;
 }
 
                return -ENODEV;
        }
 
+       spin_lock(&driver_lock);
+
        pci_set_drvdata(pci_dev, chip);
 
        list_add(&chip->list, &tpm_chip_list);
 
+       spin_unlock(&driver_lock);
+
        sysfs_create_group(&pci_dev->dev.kobj, chip->vendor->attr_group);
 
        return 0;