void free_tty_struct(struct tty_struct *tty)
{
	if (!tty)
		return;
	put_device(tty->dev);
	kfree(tty->write_buf);
	tty->magic = 0xDEADDEAD;
	kfree(tty);
}

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.