tcp: Get rid of inetpeer special cases.

The get_peer method TCP uses is full of special cases that make no
sense accommodating, and it also gets in the way of doing more
reasonable things here.

First of all, if the socket doesn't have a usable cached route, there
is no sense in trying to optimize timewait recycling.

Likewise for the case where we have IP options, such as SRR enabled,
that make the IP header destination address (and thus the destination
address of the route key) differ from that of the connection's
destination address.

Just return a NULL peer in these cases, and thus we're also able to
get rid of the clumsy inetpeer release logic.
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/inet_connection_sock.h

@@ -43,7 +43,7 @@ struct inet_connection_sock_af_ops {
 	struct sock *(*syn_recv_sock)(struct sock *sk, struct sk_buff *skb,
 				      struct request_sock *req,
 				      struct dst_entry *dst);
-	struct inet_peer *(*get_peer)(struct sock *sk, bool *release_it);
+	struct inet_peer *(*get_peer)(struct sock *sk);
 	u16	    net_header_len;
 	u16	    net_frag_header_len;
 	u16	    sockaddr_len;

include/net/tcp.h

@@ -327,7 +327,7 @@ extern void tcp_shutdown (struct sock *sk, int how);
 
 extern int tcp_v4_rcv(struct sk_buff *skb);
 
-extern struct inet_peer *tcp_v4_get_peer(struct sock *sk, bool *release_it);
+extern struct inet_peer *tcp_v4_get_peer(struct sock *sk);
 extern void *tcp_v4_tw_get_peer(struct sock *sk);
 extern int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
 extern int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,

net/ipv4/tcp_ipv4.c

@@ -1820,23 +1820,18 @@ int tcp_v4_rcv(struct sk_buff *skb)
 	goto discard_it;
 }
 
-struct inet_peer *tcp_v4_get_peer(struct sock *sk, bool *release_it)
+struct inet_peer *tcp_v4_get_peer(struct sock *sk)
 {
 	struct rtable *rt = (struct rtable *) __sk_dst_get(sk);
 	struct inet_sock *inet = inet_sk(sk);
-	struct net *net = sock_net(sk);
-	struct inet_peer *peer;
-
-	if (!rt ||
-	    inet->cork.fl.u.ip4.daddr != inet->inet_daddr) {
-		peer = inet_getpeer_v4(net, inet->inet_daddr, 1);
-		*release_it = true;
-	} else {
-		peer = rt_get_peer_create(rt, inet->inet_daddr);
-		*release_it = false;
-	}
 
-	return peer;
+	/* If we don't have a valid cached route, or we're doing IP
+	 * options which make the IPv4 header destination address
+	 * different from our peer's, do not bother with this.
+	 */
+	if (!rt || inet->cork.fl.u.ip4.daddr != inet->inet_daddr)
+		return NULL;
+	return rt_get_peer_create(rt, inet->inet_daddr);
 }
 EXPORT_SYMBOL(tcp_v4_get_peer);
 

net/ipv4/tcp_minisocks.c

@@ -60,9 +60,8 @@ static bool tcp_remember_stamp(struct sock *sk)
 	const struct inet_connection_sock *icsk = inet_csk(sk);
 	struct tcp_sock *tp = tcp_sk(sk);
 	struct inet_peer *peer;
-	bool release_it;
 
-	peer = icsk->icsk_af_ops->get_peer(sk, &release_it);
+	peer = icsk->icsk_af_ops->get_peer(sk);
 	if (peer) {
 		if ((s32)(peer->tcp_ts - tp->rx_opt.ts_recent) <= 0 ||
 		    ((u32)get_seconds() - peer->tcp_ts_stamp > TCP_PAWS_MSL &&
@@ -70,8 +69,6 @@ static bool tcp_remember_stamp(struct sock *sk)
 			peer->tcp_ts_stamp = (u32)tp->rx_opt.ts_recent_stamp;
 			peer->tcp_ts = tp->rx_opt.ts_recent;
 		}
-		if (release_it)
-			inet_putpeer(peer);
 		return true;
 	}
 

net/ipv6/tcp_ipv6.c

@@ -1732,23 +1732,18 @@ static int tcp_v6_rcv(struct sk_buff *skb)
 	goto discard_it;
 }
 
-static struct inet_peer *tcp_v6_get_peer(struct sock *sk, bool *release_it)
+static struct inet_peer *tcp_v6_get_peer(struct sock *sk)
 {
 	struct rt6_info *rt = (struct rt6_info *) __sk_dst_get(sk);
 	struct ipv6_pinfo *np = inet6_sk(sk);
-	struct net *net = sock_net(sk);
-	struct inet_peer *peer;
-
-	if (!rt ||
-	    !ipv6_addr_equal(&np->daddr, &rt->rt6i_dst.addr)) {
-		peer = inet_getpeer_v6(net, &np->daddr, 1);
-		*release_it = true;
-	} else {
-		peer = rt6_get_peer_create(rt);
-		*release_it = false;
-	}
 
-	return peer;
+	/* If we don't have a valid cached route, or we're doing IP
+	 * options which make the IPv6 header destination address
+	 * different from our peer's, do not bother with this.
+	 */
+	if (!rt || !ipv6_addr_equal(&np->daddr, &rt->rt6i_dst.addr))
+		return NULL;
+	return rt6_get_peer_create(rt);
 }
 
 static void *tcp_v6_tw_get_peer(struct sock *sk)