[NET]: Introduce protocol-specific destructor for time-wait sockets.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/timewait_sock.h b/include/net/timewait_sock.h
index 2544281..be293d7 100644
--- a/include/net/timewait_sock.h
+++ b/include/net/timewait_sock.h
@@ -19,6 +19,7 @@
 	unsigned int	twsk_obj_size;
 	int		(*twsk_unique)(struct sock *sk,
 				       struct sock *sktw, void *twp);
+	void		(*twsk_destructor)(struct sock *sk);
 };
 
 static inline int twsk_unique(struct sock *sk, struct sock *sktw, void *twp)
@@ -28,4 +29,10 @@
 	return 0;
 }
 
+static inline void twsk_destructor(struct sock *sk)
+{
+	if (sk->sk_prot->twsk_prot->twsk_destructor != NULL)
+		sk->sk_prot->twsk_prot->twsk_destructor(sk);
+}
+
 #endif /* _TIMEWAIT_SOCK_H */