[NET]: Use typesafe inet_twsk() inline function instead of cast.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index f745095..6bbd985 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -355,7 +355,7 @@
 		return;
 	}
 	if (sk->sk_state == TCP_TIME_WAIT) {
-		inet_twsk_put((struct inet_timewait_sock *)sk);
+		inet_twsk_put(inet_twsk(sk));
 		return;
 	}
 
@@ -960,7 +960,7 @@
 			bh_lock_sock(nsk);
 			return nsk;
 		}
-		inet_twsk_put((struct inet_timewait_sock *)nsk);
+		inet_twsk_put(inet_twsk(nsk));
 		return NULL;
 	}
 
@@ -1154,26 +1154,24 @@
 
 do_time_wait:
 	if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
-		inet_twsk_put((struct inet_timewait_sock *) sk);
+		inet_twsk_put(inet_twsk(sk));
 		goto discard_it;
 	}
 
 	if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) {
 		TCP_INC_STATS_BH(TCP_MIB_INERRS);
-		inet_twsk_put((struct inet_timewait_sock *) sk);
+		inet_twsk_put(inet_twsk(sk));
 		goto discard_it;
 	}
-	switch (tcp_timewait_state_process((struct inet_timewait_sock *)sk,
-					   skb, th)) {
+	switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) {
 	case TCP_TW_SYN: {
 		struct sock *sk2 = inet_lookup_listener(&tcp_hashinfo,
 							skb->nh.iph->daddr,
 							th->dest,
 							inet_iif(skb));
 		if (sk2) {
-			inet_twsk_deschedule((struct inet_timewait_sock *)sk,
-					     &tcp_death_row);
-			inet_twsk_put((struct inet_timewait_sock *)sk);
+			inet_twsk_deschedule(inet_twsk(sk), &tcp_death_row);
+			inet_twsk_put(inet_twsk(sk));
 			sk = sk2;
 			goto process;
 		}