[PATCH] tcp: Cache inetpeer in timewait socket, and only when necessary.

Since it's guarenteed that we will access the inetpeer if we're trying
to do timewait recycling and TCP options were enabled on the
connection, just cache the peer in the timewait socket.

In the future, inetpeer lookups will be context dependent (per routing
realm), and this helps facilitate that as well.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 20 insertions, 7 deletions

diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index fef9dbf3af00..cb015317c9f7 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -77,20 +77,19 @@ static bool tcp_remember_stamp(struct sock *sk)
 
 static bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw)
 {
+	const struct tcp_timewait_sock *tcptw;
 	struct sock *sk = (struct sock *) tw;
 	struct inet_peer *peer;
 
-	peer = twsk_getpeer(sk);
+	tcptw = tcp_twsk(sk);
+	peer = tcptw->tw_peer;
 	if (peer) {
-		const struct tcp_timewait_sock *tcptw = tcp_twsk(sk);
-
 		if ((s32)(peer->tcp_ts - tcptw->tw_ts_recent) <= 0 ||
 		    ((u32)get_seconds() - peer->tcp_ts_stamp > TCP_PAWS_MSL &&
 		     peer->tcp_ts_stamp <= (u32)tcptw->tw_ts_recent_stamp)) {
 			peer->tcp_ts_stamp = (u32)tcptw->tw_ts_recent_stamp;
 			peer->tcp_ts	   = tcptw->tw_ts_recent;
 		}
-		inet_putpeer(peer);
 		return true;
 	}
 	return false;
@@ -314,9 +313,12 @@ void tcp_time_wait(struct sock *sk, int state, int timeo)
 	const struct inet_connection_sock *icsk = inet_csk(sk);
 	const struct tcp_sock *tp = tcp_sk(sk);
 	bool recycle_ok = false;
+	bool recycle_on = false;
 
-	if (tcp_death_row.sysctl_tw_recycle && tp->rx_opt.ts_recent_stamp)
+	if (tcp_death_row.sysctl_tw_recycle && tp->rx_opt.ts_recent_stamp) {
 		recycle_ok = tcp_remember_stamp(sk);
+		recycle_on = true;
+	}
 
 	if (tcp_death_row.tw_count < tcp_death_row.sysctl_max_tw_buckets)
 		tw = inet_twsk_alloc(sk, state);
@@ -324,8 +326,10 @@ void tcp_time_wait(struct sock *sk, int state, int timeo)
 	if (tw != NULL) {
 		struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw);
 		const int rto = (icsk->icsk_rto << 2) - (icsk->icsk_rto >> 1);
+		struct inet_sock *inet = inet_sk(sk);
+		struct inet_peer *peer = NULL;
 
-		tw->tw_transparent	= inet_sk(sk)->transparent;
+		tw->tw_transparent	= inet->transparent;
 		tw->tw_rcv_wscale	= tp->rx_opt.rcv_wscale;
 		tcptw->tw_rcv_nxt	= tp->rcv_nxt;
 		tcptw->tw_snd_nxt	= tp->snd_nxt;
@@ -347,6 +351,12 @@ void tcp_time_wait(struct sock *sk, int state, int timeo)
 		}
 #endif
 
+		if (recycle_on)
+			peer = icsk->icsk_af_ops->get_peer(sk);
+		tcptw->tw_peer = peer;
+		if (peer)
+			atomic_inc(&peer->refcnt);
+
 #ifdef CONFIG_TCP_MD5SIG
 		/*
 		 * The timewait bucket does not have the key DB from the
@@ -398,8 +408,11 @@ void tcp_time_wait(struct sock *sk, int state, int timeo)
 
 void tcp_twsk_destructor(struct sock *sk)
 {
-#ifdef CONFIG_TCP_MD5SIG
 	struct tcp_timewait_sock *twsk = tcp_twsk(sk);
+
+	if (twsk->tw_peer)
+		inet_putpeer(twsk->tw_peer);
+#ifdef CONFIG_TCP_MD5SIG
 	if (twsk->tw_md5_key) {
 		tcp_free_md5sig_pool();
 		kfree_rcu(twsk->tw_md5_key, rcu);