tcp: Change return value of tcp_rcv_established()

tcp_rcv_established() returns only one value namely 0. We change the return
value to void (as suggested by David Miller).

After commit 0c24604b (tcp: implement RFC 5961 4.2), we no longer send RSTs in
response to SYNs. We can remove the check and processing on the return value of
tcp_rcv_established().

We also fix jtcp_rcv_established() in tcp_probe.c to match that of
tcp_rcv_established().

Signed-off-by: Vijay Subramanian <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/tcp.h

···
 extern int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
 extern int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
 				 const struct tcphdr *th, unsigned int len);
-extern int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
-			       const struct tcphdr *th, unsigned int len);
+extern void tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
+				const struct tcphdr *th, unsigned int len);
 extern void tcp_rcv_space_adjust(struct sock *sk);
 extern void tcp_cleanup_rbuf(struct sock *sk, int copied);
 extern int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);

net/ipv4/tcp_input.c

···
  *	the rest is checked inline. Fast processing is turned on in
  *	tcp_data_queue when everything is OK.
  */
-int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
-			const struct tcphdr *th, unsigned int len)
+void tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
+			 const struct tcphdr *th, unsigned int len)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 
···
 				tcp_ack(sk, skb, 0);
 				__kfree_skb(skb);
 				tcp_data_snd_check(sk);
-				return 0;
+				return;
 			} else { /* Header too small */
 				TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_INERRS);
 				goto discard;
···
 			if (eaten)
 				kfree_skb_partial(skb, fragstolen);
 			sk->sk_data_ready(sk, 0);
-			return 0;
+			return;
 		}
 	}
 
···
 	 */
 
 	if (!tcp_validate_incoming(sk, skb, th, 1))
-		return 0;
+		return;
 
 step5:
 	if (tcp_ack(sk, skb, FLAG_SLOWPATH | FLAG_UPDATE_TS_RECENT) < 0)
···
 
 	tcp_data_snd_check(sk);
 	tcp_ack_snd_check(sk);
-	return 0;
+	return;
 
 csum_error:
 	TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_CSUMERRORS);
···
 
 discard:
 	__kfree_skb(skb);
-	return 0;
 }
 EXPORT_SYMBOL(tcp_rcv_established);
 

net/ipv4/tcp_ipv4.c

···
 				sk->sk_rx_dst = NULL;
 			}
 		}
-		if (tcp_rcv_established(sk, skb, tcp_hdr(skb), skb->len)) {
-			rsk = sk;
-			goto reset;
-		}
+		tcp_rcv_established(sk, skb, tcp_hdr(skb), skb->len);
 		return 0;
 	}
 

net/ipv4/tcp_probe.c

···
  * Hook inserted to be called before each receive packet.
  * Note: arguments must match tcp_rcv_established()!
  */
-static int jtcp_rcv_established(struct sock *sk, struct sk_buff *skb,
-				const struct tcphdr *th, unsigned int len)
+static void jtcp_rcv_established(struct sock *sk, struct sk_buff *skb,
+				 const struct tcphdr *th, unsigned int len)
 {
 	const struct tcp_sock *tp = tcp_sk(sk);
 	const struct inet_sock *inet = inet_sk(sk);
···
 	}
 
 	jprobe_return();
-	return 0;
 }
 
 static struct jprobe tcp_jprobe = {

net/ipv6/tcp_ipv6.c

···
 			}
 		}
 
-		if (tcp_rcv_established(sk, skb, tcp_hdr(skb), skb->len))
-			goto reset;
+		tcp_rcv_established(sk, skb, tcp_hdr(skb), skb->len);
 		if (opt_skb)
 			goto ipv6_pktoptions;
 		return 0;