Merge branch 'metrics_restructure'

This patch series works towards the goal of minimizing the amount
of things that can change in an ipv4 route.

In a regime where the routing cache is removed, route changes will
lead to cloning in the FIB tables or similar.

The largest trigger of route metrics writes, TCP, now has it's own
cache of dynamic metric state. The timewait timestamps are stored
there now as well.

As a result of that, pre-cowing metrics is no longer necessary,
and therefore FLOWI_FLAG_PRECOW_METRICS is removed.

Redirect and PMTU handling is moved back into the ipv4 routes. I'm
sorry for all the headaches trying to do this in the inetpeer has
caused, it was the wrong approach for sure.

Since metrics become read-only for ipv4 we no longer need the inetpeer
hung off of the ipv4 routes either. So those disappear too.

Also, timewait sockets no longer need to hold onto an inetpeer either.

After this series, we still have some details to resolve wrt. PMTU and
redirects for a route-cache-less system:

1) With just the plain route cache removal, PMTU will continue to
work mostly fine. This is because of how the local route users
call down into the PMTU update code with the route they already
hold.

However, if we wish to cache pre-computed routes in fib_info
nexthops (which we want for performance), then we need to add
route cloning for PMTU events.

2) Redirects require more work. First, redirects must be changed to
be handled like PMTU. Wherein we call down into the sockets and
other entities, and then they call back into the routing code with
the route they were using.

So we'll be adding an ->update_nexthop() method alongside
->update_pmtu().

And then, like for PMTU, we'll need cloning support once we start
caching routes in the fib_info nexthops.

But that's it, we can completely pull the trigger and remove the
routing cache with minimal disruptions.

As it is, this patch series alone helps a lot of things. For one,
routing cache entry creation should be a lot faster, because we no
longer do inetpeer lookups (even to check if an entry exists).

This patch series also opens the door for non-DST_HOST ipv4 routes,
because nothing fundamentally cares about rt->rt_dst any more. It
can be removed with the base routing cache removal patch. In fact,
that was the primary goal of this patch series.

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

include/linux/rtnetlink.h

···
 extern void rtnl_set_sk_err(struct net *net, u32 group, int error);
 extern int rtnetlink_put_metrics(struct sk_buff *skb, u32 *metrics);
 extern int rtnl_put_cacheinfo(struct sk_buff *skb, struct dst_entry *dst,
-			      u32 id, u32 ts, u32 tsage, long expires,
-			      u32 error);
+			      u32 id, long expires, u32 error);
 
 extern void rtmsg_ifinfo(int type, struct net_device *dev, unsigned change);
 

include/linux/tcp.h

···
 	u32			  tw_rcv_wnd;
 	u32			  tw_ts_recent;
 	long			  tw_ts_recent_stamp;
-	struct inet_peer	  *tw_peer;
 #ifdef CONFIG_TCP_MD5SIG
 	struct tcp_md5sig_key	  *tw_md5_key;
 #endif

include/net/dst.h

···
 	return msecs_to_jiffies(dst_metric(dst, metric));
 }
 
-static inline void set_dst_metric_rtt(struct dst_entry *dst, int metric,
-				      unsigned long rtt)
-{
-	dst_metric_set(dst, metric, jiffies_to_msecs(rtt));
-}
-
 static inline u32
 dst_allfrag(const struct dst_entry *dst)
 {

include/net/flow.h

···
 	__u8	flowic_proto;
 	__u8	flowic_flags;
 #define FLOWI_FLAG_ANYSRC		0x01
-#define FLOWI_FLAG_PRECOW_METRICS	0x02
-#define FLOWI_FLAG_CAN_SLEEP		0x04
-#define FLOWI_FLAG_RT_NOCACHE		0x08
+#define FLOWI_FLAG_CAN_SLEEP		0x02
+#define FLOWI_FLAG_RT_NOCACHE		0x04
 	__u32	flowic_secid;
 };
 

include/net/inet_connection_sock.h

···
 	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);
 	u16	    net_header_len;
 	u16	    net_frag_header_len;
 	u16	    sockaddr_len;

include/net/inet_sock.h

···
 
 	if (inet_sk(sk)->transparent || inet_sk(sk)->hdrincl)
 		flags |= FLOWI_FLAG_ANYSRC;
-	if (sk->sk_protocol == IPPROTO_TCP)
-		flags |= FLOWI_FLAG_PRECOW_METRICS;
 	return flags;
 }
 

include/net/inetpeer.h

···
 	u32			metrics[RTAX_MAX];
 	u32			rate_tokens;	/* rate limiting for ICMP */
 	unsigned long		rate_last;
-	unsigned long		pmtu_expires;
-	u32			pmtu_orig;
-	u32			pmtu_learned;
-	struct inetpeer_addr_base redirect_learned;
 	union {
 		struct list_head	gc_list;
 		struct rcu_head     gc_rcu;
 	};
 	/*
 	 * Once inet_peer is queued for deletion (refcnt == -1), following fields
-	 * are not available: rid, ip_id_count, tcp_ts, tcp_ts_stamp
+	 * are not available: rid, ip_id_count
 	 * We can share memory with rcu_head to help keep inet_peer small.
 	 */
 	union {
 		struct {
 			atomic_t			rid;		/* Frag reception counter */
 			atomic_t			ip_id_count;	/* IP ID for the next packet */
-			__u32				tcp_ts;
-			__u32				tcp_ts_stamp;
 		};
 		struct rcu_head         rcu;
 		struct inet_peer	*gc_next;

include/net/netns/ipv4.h

···
 
 #include <net/inet_frag.h>
 
+struct tcpm_hash_bucket;
 struct ctl_table_header;
 struct ipv4_devconf;
 struct fib_rules_ops;
···
 	struct sock		**icmp_sk;
 	struct sock		*tcp_sock;
 	struct inet_peer_base	*peers;
+	struct tcpm_hash_bucket	*tcp_metrics_hash;
+	unsigned int		tcp_metrics_hash_mask;
 	struct netns_frags	frags;
 #ifdef CONFIG_NETFILTER
 	struct xt_table		*iptable_filter;

include/net/route.h

···
 #define RT_CONN_FLAGS(sk)   (RT_TOS(inet_sk(sk)->tos) | sock_flag(sk, SOCK_LOCALROUTE))
 
 struct fib_nh;
-struct inet_peer;
 struct fib_info;
 struct rtable {
 	struct dst_entry	dst;
···
 	__be32			rt_gateway;
 
 	/* Miscellaneous cached information */
-	u32			rt_peer_genid;
-	unsigned long		_peer; /* long-living peer info */
+	u32			rt_pmtu;
 	struct fib_info		*fi; /* for client ref to shared metrics */
 };
-
-static inline struct inet_peer *rt_peer_ptr(struct rtable *rt)
-{
-	return inetpeer_ptr(rt->_peer);
-}
-
-static inline bool rt_has_peer(struct rtable *rt)
-{
-	return inetpeer_ptr_is_peer(rt->_peer);
-}
-
-static inline void __rt_set_peer(struct rtable *rt, struct inet_peer *peer)
-{
-	__inetpeer_ptr_set_peer(&rt->_peer, peer);
-}
-
-static inline bool rt_set_peer(struct rtable *rt, struct inet_peer *peer)
-{
-	return inetpeer_ptr_set_peer(&rt->_peer, peer);
-}
-
-static inline void rt_init_peer(struct rtable *rt, struct inet_peer_base *base)
-{
-	inetpeer_init_ptr(&rt->_peer, base);
-}
-
-static inline void rt_transfer_peer(struct rtable *rt, struct rtable *ort)
-{
-	rt->_peer = ort->_peer;
-	if (rt_has_peer(ort)) {
-		struct inet_peer *peer = rt_peer_ptr(ort);
-		atomic_inc(&peer->refcnt);
-	}
-}
 
 static inline bool rt_is_input_route(const struct rtable *rt)
 {
···
 
 	if (inet_sk(sk)->transparent)
 		flow_flags |= FLOWI_FLAG_ANYSRC;
-	if (protocol == IPPROTO_TCP)
-		flow_flags |= FLOWI_FLAG_PRECOW_METRICS;
 	if (can_sleep)
 		flow_flags |= FLOWI_FLAG_CAN_SLEEP;
 
···
 		return ip_route_output_flow(sock_net(sk), fl4, sk);
 	}
 	return rt;
-}
-
-extern void rt_bind_peer(struct rtable *rt, __be32 daddr, int create);
-
-static inline struct inet_peer *__rt_get_peer(struct rtable *rt, __be32 daddr, int create)
-{
-	if (rt_has_peer(rt))
-		return rt_peer_ptr(rt);
-
-	rt_bind_peer(rt, daddr, create);
-	return (rt_has_peer(rt) ? rt_peer_ptr(rt) : NULL);
-}
-
-static inline struct inet_peer *rt_get_peer(struct rtable *rt, __be32 daddr)
-{
-	return __rt_get_peer(rt, daddr, 0);
-}
-
-static inline struct inet_peer *rt_get_peer_create(struct rtable *rt, __be32 daddr)
-{
-	return __rt_get_peer(rt, daddr, 1);
 }
 
 static inline int inet_iif(const struct sk_buff *skb)

include/net/tcp.h

···
 extern void tcp_enter_loss(struct sock *sk, int how);
 extern void tcp_clear_retrans(struct tcp_sock *tp);
 extern void tcp_update_metrics(struct sock *sk);
+extern void tcp_init_metrics(struct sock *sk);
+extern void tcp_metrics_init(void);
+extern bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst, bool paws_check);
+extern bool tcp_remember_stamp(struct sock *sk);
+extern bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw);
+extern void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst);
+extern void tcp_disable_fack(struct tcp_sock *tp);
 extern void tcp_close(struct sock *sk, long timeout);
 extern void tcp_init_sock(struct sock *sk);
 extern unsigned int tcp_poll(struct file * file, struct socket *sock,
···
 {
 	return (tp->srtt >> 3) + tp->rttvar;
 }
+
+extern void tcp_set_rto(struct sock *sk);
 
 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
 {

net/core/rtnetlink.c

···
 EXPORT_SYMBOL(rtnetlink_put_metrics);
 
 int rtnl_put_cacheinfo(struct sk_buff *skb, struct dst_entry *dst, u32 id,
-		       u32 ts, u32 tsage, long expires, u32 error)
+		       long expires, u32 error)
 {
 	struct rta_cacheinfo ci = {
 		.rta_lastuse = jiffies_to_clock_t(jiffies - dst->lastuse),
···
 		.rta_clntref = atomic_read(&(dst->__refcnt)),
 		.rta_error = error,
 		.rta_id =  id,
-		.rta_ts = ts,
-		.rta_tsage = tsage,
 	};
 
 	if (expires)

net/decnet/dn_route.c

···
 		goto errout;
 
 	expires = rt->dst.expires ? rt->dst.expires - jiffies : 0;
-	if (rtnl_put_cacheinfo(skb, &rt->dst, 0, 0, 0, expires,
+	if (rtnl_put_cacheinfo(skb, &rt->dst, 0, expires,
 			       rt->dst.error) < 0)
 		goto errout;
 
···
 	char buf1[DN_ASCBUF_LEN], buf2[DN_ASCBUF_LEN];
 
 	seq_printf(seq, "%-8s %-7s %-7s %04d %04d %04d\n",
-			rt->dst.dev ? rt->dst.dev->name : "*",
-			dn_addr2asc(le16_to_cpu(rt->rt_daddr), buf1),
-			dn_addr2asc(le16_to_cpu(rt->rt_saddr), buf2),
-			atomic_read(&rt->dst.__refcnt),
-			rt->dst.__use,
-			(int) dst_metric(&rt->dst, RTAX_RTT));
+		   rt->dst.dev ? rt->dst.dev->name : "*",
+		   dn_addr2asc(le16_to_cpu(rt->rt_daddr), buf1),
+		   dn_addr2asc(le16_to_cpu(rt->rt_saddr), buf2),
+		   atomic_read(&rt->dst.__refcnt),
+		   rt->dst.__use, 0);
 	return 0;
 }
 

net/ipv4/Makefile

···
 	     ip_output.o ip_sockglue.o inet_hashtables.o \
 	     inet_timewait_sock.o inet_connection_sock.o \
 	     tcp.o tcp_input.o tcp_output.o tcp_timer.o tcp_ipv4.o \
-	     tcp_minisocks.o tcp_cong.o \
+	     tcp_minisocks.o tcp_cong.o tcp_metrics.o \
 	     datagram.o raw.o udp.o udplite.o \
 	     arp.o icmp.o devinet.o af_inet.o  igmp.o \
 	     fib_frontend.o fib_semantics.o fib_trie.o \

net/ipv4/fib_semantics.c

···
 				val = nla_get_u32(nla);
 				if (type == RTAX_ADVMSS && val > 65535 - 40)
 					val = 65535 - 40;
+				if (type == RTAX_MTU && val > 65535 - 15)
+					val = 65535 - 15;
 				fi->fib_metrics[type - 1] = val;
 			}
 		}

net/ipv4/icmp.c

···
 
 	/* Limit if icmp type is enabled in ratemask. */
 	if ((1 << type) & net->ipv4.sysctl_icmp_ratemask) {
-		struct inet_peer *peer = rt_get_peer_create(rt, fl4->daddr);
+		struct inet_peer *peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, 1);
 		rc = inet_peer_xrlim_allow(peer,
 					   net->ipv4.sysctl_icmp_ratelimit);
+		inet_putpeer(peer);
 	}
 out:
 	return rc;

net/ipv4/inet_connection_sock.c

···
 	const struct inet_request_sock *ireq = inet_rsk(req);
 	struct ip_options_rcu *opt = inet_rsk(req)->opt;
 	struct net *net = sock_net(sk);
-	int flags = inet_sk_flowi_flags(sk) & ~FLOWI_FLAG_PRECOW_METRICS;
+	int flags = inet_sk_flowi_flags(sk);
 
 	if (nocache)
 		flags |= FLOWI_FLAG_RT_NOCACHE;

net/ipv4/inetpeer.c

···
 				(daddr->family == AF_INET) ?
 					secure_ip_id(daddr->addr.a4) :
 					secure_ipv6_id(daddr->addr.a6));
-		p->tcp_ts_stamp = 0;
 		p->metrics[RTAX_LOCK-1] = INETPEER_METRICS_NEW;
 		p->rate_tokens = 0;
 		p->rate_last = 0;
-		p->pmtu_expires = 0;
-		p->pmtu_orig = 0;
-		memset(&p->redirect_learned, 0, sizeof(p->redirect_learned));
 		INIT_LIST_HEAD(&p->gc_list);
 
 		/* Link the node. */

net/ipv4/route.c

···
 
 static u32 *ipv4_cow_metrics(struct dst_entry *dst, unsigned long old)
 {
-	struct rtable *rt = (struct rtable *) dst;
-	struct inet_peer *peer;
-	u32 *p = NULL;
-
-	peer = rt_get_peer_create(rt, rt->rt_dst);
-	if (peer) {
-		u32 *old_p = __DST_METRICS_PTR(old);
-		unsigned long prev, new;
-
-		p = peer->metrics;
-		if (inet_metrics_new(peer))
-			memcpy(p, old_p, sizeof(u32) * RTAX_MAX);
-
-		new = (unsigned long) p;
-		prev = cmpxchg(&dst->_metrics, old, new);
-
-		if (prev != old) {
-			p = __DST_METRICS_PTR(prev);
-			if (prev & DST_METRICS_READ_ONLY)
-				p = NULL;
-		} else {
-			if (rt->fi) {
-				fib_info_put(rt->fi);
-				rt->fi = NULL;
-			}
-		}
-	}
-	return p;
+	WARN_ON(1);
+	return NULL;
 }
 
 static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst,
···
 		int len;
 
 		seq_printf(seq, "%s\t%08X\t%08X\t%8X\t%d\t%u\t%d\t"
-			      "%08X\t%d\t%u\t%u\t%02X\t%d\t%1d\t%08X%n",
-			r->dst.dev ? r->dst.dev->name : "*",
-			(__force u32)r->rt_dst,
-			(__force u32)r->rt_gateway,
-			r->rt_flags, atomic_read(&r->dst.__refcnt),
-			r->dst.__use, 0, (__force u32)r->rt_src,
-			dst_metric_advmss(&r->dst) + 40,
-			dst_metric(&r->dst, RTAX_WINDOW),
-			(int)((dst_metric(&r->dst, RTAX_RTT) >> 3) +
-			      dst_metric(&r->dst, RTAX_RTTVAR)),
-			r->rt_key_tos,
-			-1, 0, 0, &len);
+			   "%08X\t%d\t%u\t%u\t%02X\t%d\t%1d\t%08X%n",
+			   r->dst.dev ? r->dst.dev->name : "*",
+			   (__force u32)r->rt_dst,
+			   (__force u32)r->rt_gateway,
+			   r->rt_flags, atomic_read(&r->dst.__refcnt),
+			   r->dst.__use, 0, (__force u32)r->rt_src,
+			   dst_metric_advmss(&r->dst) + 40,
+			   dst_metric(&r->dst, RTAX_WINDOW), 0,
+			   r->rt_key_tos,
+			   -1, 0, 0, &len);
 
 		seq_printf(seq, "%*s\n", 127 - len, "");
 	}
···
 static inline int rt_valuable(struct rtable *rth)
 {
 	return (rth->rt_flags & (RTCF_REDIRECTED | RTCF_NOTIFY)) ||
-		(rt_has_peer(rth) && rt_peer_ptr(rth)->pmtu_expires);
+		rth->dst.expires;
 }
 
 static int rt_may_expire(struct rtable *rth, unsigned long tmo1, unsigned long tmo2)
···
 
 	get_random_bytes(&shuffle, sizeof(shuffle));
 	atomic_add(shuffle + 1U, &net->ipv4.rt_genid);
-	inetpeer_invalidate_family(AF_INET);
 }
 
 /*
···
 	return rt;
 }
 
-static atomic_t __rt_peer_genid = ATOMIC_INIT(0);
-
-static u32 rt_peer_genid(void)
-{
-	return atomic_read(&__rt_peer_genid);
-}
-
-void rt_bind_peer(struct rtable *rt, __be32 daddr, int create)
-{
-	struct inet_peer_base *base;
-	struct inet_peer *peer;
-
-	base = inetpeer_base_ptr(rt->_peer);
-	if (!base)
-		return;
-
-	peer = inet_getpeer_v4(base, daddr, create);
-	if (peer) {
-		if (!rt_set_peer(rt, peer))
-			inet_putpeer(peer);
-		else
-			rt->rt_peer_genid = rt_peer_genid();
-	}
-}
-
 /*
  * Peer allocation may fail only in serious out-of-memory conditions.  However
  * we still can generate some output.
···
 
 void __ip_select_ident(struct iphdr *iph, struct dst_entry *dst, int more)
 {
-	struct rtable *rt = (struct rtable *) dst;
+	struct net *net = dev_net(dst->dev);
+	struct inet_peer *peer;
 
-	if (rt && !(rt->dst.flags & DST_NOPEER)) {
-		struct inet_peer *peer = rt_get_peer_create(rt, rt->rt_dst);
-
-		/* If peer is attached to destination, it is never detached,
-		   so that we need not to grab a lock to dereference it.
-		 */
-		if (peer) {
-			iph->id = htons(inet_getid(peer, more));
-			return;
-		}
-	} else if (!rt)
-		pr_debug("rt_bind_peer(0) @%p\n", __builtin_return_address(0));
+	peer = inet_getpeer_v4(net->ipv4.peers, iph->daddr, 1);
+	if (peer) {
+		iph->id = htons(inet_getid(peer, more));
+		inet_putpeer(peer);
+		return;
+	}
 
 	ip_select_fb_ident(iph);
 }
···
 	spin_unlock_bh(rt_hash_lock_addr(hash));
 }
 
-static void check_peer_redir(struct dst_entry *dst, struct inet_peer *peer)
-{
-	struct rtable *rt = (struct rtable *) dst;
-	__be32 orig_gw = rt->rt_gateway;
-	struct neighbour *n;
-
-	dst_confirm(&rt->dst);
-
-	rt->rt_gateway = peer->redirect_learned.a4;
-
-	n = ipv4_neigh_lookup(&rt->dst, NULL, &rt->rt_gateway);
-	if (!n) {
-		rt->rt_gateway = orig_gw;
-		return;
-	}
-	if (!(n->nud_state & NUD_VALID)) {
-		neigh_event_send(n, NULL);
-	} else {
-		rt->rt_flags |= RTCF_REDIRECTED;
-		call_netevent_notifiers(NETEVENT_NEIGH_UPDATE, n);
-	}
-	neigh_release(n);
-}
-
 /* called in rcu_read_lock() section */
 void ip_rt_redirect(__be32 old_gw, __be32 daddr, __be32 new_gw,
 		    __be32 saddr, struct net_device *dev)
···
 	struct in_device *in_dev = __in_dev_get_rcu(dev);
 	__be32 skeys[2] = { saddr, 0 };
 	int    ikeys[2] = { dev->ifindex, 0 };
-	struct inet_peer *peer;
 	struct net *net;
 
 	if (!in_dev)
···
 			rthp = &rt_hash_table[hash].chain;
 
 			while ((rt = rcu_dereference(*rthp)) != NULL) {
+				struct neighbour *n;
+
 				rthp = &rt->dst.rt_next;
 
 				if (rt->rt_key_dst != daddr ||
···
 				    rt->rt_gateway != old_gw)
 					continue;
 
-				peer = rt_get_peer_create(rt, rt->rt_dst);
-				if (peer) {
-					if (peer->redirect_learned.a4 != new_gw) {
-						peer->redirect_learned.a4 = new_gw;
-						atomic_inc(&__rt_peer_genid);
+				n = ipv4_neigh_lookup(&rt->dst, NULL, &new_gw);
+				if (n) {
+					if (!(n->nud_state & NUD_VALID)) {
+						neigh_event_send(n, NULL);
+					} else {
+						rt->rt_gateway = new_gw;
+						rt->rt_flags |= RTCF_REDIRECTED;
+						call_netevent_notifiers(NETEVENT_NEIGH_UPDATE, n);
 					}
-					check_peer_redir(&rt->dst, peer);
+					neigh_release(n);
 				}
 			}
 		}
···
 	;
 }
 
-static bool peer_pmtu_expired(struct inet_peer *peer)
-{
-	unsigned long orig = ACCESS_ONCE(peer->pmtu_expires);
-
-	return orig &&
-	       time_after_eq(jiffies, orig) &&
-	       cmpxchg(&peer->pmtu_expires, orig, 0) == orig;
-}
-
-static bool peer_pmtu_cleaned(struct inet_peer *peer)
-{
-	unsigned long orig = ACCESS_ONCE(peer->pmtu_expires);
-
-	return orig &&
-	       cmpxchg(&peer->pmtu_expires, orig, 0) == orig;
-}
-
 static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst)
 {
 	struct rtable *rt = (struct rtable *)dst;
···
 		if (dst->obsolete > 0) {
 			ip_rt_put(rt);
 			ret = NULL;
-		} else if (rt->rt_flags & RTCF_REDIRECTED) {
+		} else if ((rt->rt_flags & RTCF_REDIRECTED) ||
+			   rt->dst.expires) {
 			unsigned int hash = rt_hash(rt->rt_key_dst, rt->rt_key_src,
 						rt->rt_oif,
 						rt_genid(dev_net(dst->dev)));
 			rt_del(hash, rt);
 			ret = NULL;
-		} else if (rt_has_peer(rt)) {
-			struct inet_peer *peer = rt_peer_ptr(rt);
-			if (peer_pmtu_expired(peer))
-				dst_metric_set(dst, RTAX_MTU, peer->pmtu_orig);
 		}
 	}
 	return ret;
···
 	struct rtable *rt = skb_rtable(skb);
 	struct in_device *in_dev;
 	struct inet_peer *peer;
+	struct net *net;
 	int log_martians;
 
 	rcu_read_lock();
···
 	log_martians = IN_DEV_LOG_MARTIANS(in_dev);
 	rcu_read_unlock();
 
-	peer = rt_get_peer_create(rt, rt->rt_dst);
+	net = dev_net(rt->dst.dev);
+	peer = inet_getpeer_v4(net->ipv4.peers, ip_hdr(skb)->saddr, 1);
 	if (!peer) {
 		icmp_send(skb, ICMP_REDIRECT, ICMP_REDIR_HOST, rt->rt_gateway);
 		return;
···
 	 */
 	if (peer->rate_tokens >= ip_rt_redirect_number) {
 		peer->rate_last = jiffies;
-		return;
+		goto out_put_peer;
 	}
 
 	/* Check for load limit; set rate_last to the latest sent
···
 					     &rt->rt_dst, &rt->rt_gateway);
 #endif
 	}
+out_put_peer:
+	inet_putpeer(peer);
 }
 
 static int ip_error(struct sk_buff *skb)
···
 		break;
 	}
 
-	peer = rt_get_peer_create(rt, rt->rt_dst);
+	peer = inet_getpeer_v4(net->ipv4.peers, ip_hdr(skb)->saddr, 1);
 
 	send = true;
 	if (peer) {
···
 			peer->rate_tokens -= ip_rt_error_cost;
 		else
 			send = false;
+		inet_putpeer(peer);
 	}
 	if (send)
 		icmp_send(skb, ICMP_DEST_UNREACH, code, 0);
···
 	return 0;
 }
 
-static void check_peer_pmtu(struct dst_entry *dst, struct inet_peer *peer)
-{
-	unsigned long expires = ACCESS_ONCE(peer->pmtu_expires);
-
-	if (!expires)
-		return;
-	if (time_before(jiffies, expires)) {
-		u32 orig_dst_mtu = dst_mtu(dst);
-		if (peer->pmtu_learned < orig_dst_mtu) {
-			if (!peer->pmtu_orig)
-				peer->pmtu_orig = dst_metric_raw(dst, RTAX_MTU);
-			dst_metric_set(dst, RTAX_MTU, peer->pmtu_learned);
-		}
-	} else if (cmpxchg(&peer->pmtu_expires, expires, 0) == expires)
-		dst_metric_set(dst, RTAX_MTU, peer->pmtu_orig);
-}
-
 static void ip_rt_update_pmtu(struct dst_entry *dst, u32 mtu)
 {
 	struct rtable *rt = (struct rtable *) dst;
-	struct inet_peer *peer;
 
 	dst_confirm(dst);
 
-	peer = rt_get_peer_create(rt, rt->rt_dst);
-	if (peer) {
-		unsigned long pmtu_expires = ACCESS_ONCE(peer->pmtu_expires);
+	if (mtu < ip_rt_min_pmtu)
+		mtu = ip_rt_min_pmtu;
 
-		if (mtu < ip_rt_min_pmtu)
-			mtu = ip_rt_min_pmtu;
-		if (!pmtu_expires || mtu < peer->pmtu_learned) {
-
-			pmtu_expires = jiffies + ip_rt_mtu_expires;
-			if (!pmtu_expires)
-				pmtu_expires = 1UL;
-
-			peer->pmtu_learned = mtu;
-			peer->pmtu_expires = pmtu_expires;
-
-			atomic_inc(&__rt_peer_genid);
-			rt->rt_peer_genid = rt_peer_genid();
-		}
-		check_peer_pmtu(dst, peer);
-	}
+	rt->rt_pmtu = mtu;
+	dst_set_expires(&rt->dst, ip_rt_mtu_expires);
 }
 
 void ipv4_update_pmtu(struct sk_buff *skb, struct net *net, u32 mtu,
···
 	struct rtable *rt;
 
 	flowi4_init_output(&fl4, oif, mark, RT_TOS(iph->tos), RT_SCOPE_UNIVERSE,
-			   protocol, flow_flags | FLOWI_FLAG_PRECOW_METRICS,
+			   protocol, flow_flags,
 			   iph->daddr, iph->saddr, 0, 0);
 	rt = __ip_route_output_key(net, &fl4);
 	if (!IS_ERR(rt)) {
···
 }
 EXPORT_SYMBOL_GPL(ipv4_sk_update_pmtu);
 
-static void ipv4_validate_peer(struct rtable *rt)
-{
-	if (rt->rt_peer_genid != rt_peer_genid()) {
-		struct inet_peer *peer = rt_get_peer(rt, rt->rt_dst);
-
-		if (peer) {
-			check_peer_pmtu(&rt->dst, peer);
-
-			if (peer->redirect_learned.a4 &&
-			    peer->redirect_learned.a4 != rt->rt_gateway)
-				check_peer_redir(&rt->dst, peer);
-		}
-
-		rt->rt_peer_genid = rt_peer_genid();
-	}
-}
-
 static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie)
 {
 	struct rtable *rt = (struct rtable *) dst;
 
 	if (rt_is_expired(rt))
 		return NULL;
-	ipv4_validate_peer(rt);
 	return dst;
 }
 
···
 		fib_info_put(rt->fi);
 		rt->fi = NULL;
 	}
-	if (rt_has_peer(rt)) {
-		struct inet_peer *peer = rt_peer_ptr(rt);
-		inet_putpeer(peer);
-	}
 }
 
 
···
 	icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_UNREACH, 0);
 
 	rt = skb_rtable(skb);
-	if (rt && rt_has_peer(rt)) {
-		struct inet_peer *peer = rt_peer_ptr(rt);
-		if (peer_pmtu_cleaned(peer))
-			dst_metric_set(&rt->dst, RTAX_MTU, peer->pmtu_orig);
-	}
+	if (rt)
+		dst_set_expires(&rt->dst, 0);
 }
 
 static int ip_rt_bug(struct sk_buff *skb)
···
 static unsigned int ipv4_mtu(const struct dst_entry *dst)
 {
 	const struct rtable *rt = (const struct rtable *) dst;
-	unsigned int mtu = dst_metric_raw(dst, RTAX_MTU);
+	unsigned int mtu = rt->rt_pmtu;
+
+	if (mtu && time_after_eq(jiffies, rt->dst.expires))
+		mtu = 0;
+
+	if (!mtu)
+		mtu = dst_metric_raw(dst, RTAX_MTU);
 
 	if (mtu && rt_is_output_route(rt))
 		return mtu;
···
 static void rt_init_metrics(struct rtable *rt, const struct flowi4 *fl4,
 			    struct fib_info *fi)
 {
-	struct inet_peer_base *base;
-	struct inet_peer *peer;
-	int create = 0;
-
-	/* If a peer entry exists for this destination, we must hook
-	 * it up in order to get at cached metrics.
-	 */
-	if (fl4 && (fl4->flowi4_flags & FLOWI_FLAG_PRECOW_METRICS))
-		create = 1;
-
-	base = inetpeer_base_ptr(rt->_peer);
-	BUG_ON(!base);
-
-	peer = inet_getpeer_v4(base, rt->rt_dst, create);
-	if (peer) {
-		__rt_set_peer(rt, peer);
-		rt->rt_peer_genid = rt_peer_genid();
-		if (inet_metrics_new(peer))
-			memcpy(peer->metrics, fi->fib_metrics,
-			       sizeof(u32) * RTAX_MAX);
-		dst_init_metrics(&rt->dst, peer->metrics, false);
-
-		check_peer_pmtu(&rt->dst, peer);
-
-		if (peer->redirect_learned.a4 &&
-		    peer->redirect_learned.a4 != rt->rt_gateway) {
-			rt->rt_gateway = peer->redirect_learned.a4;
-			rt->rt_flags |= RTCF_REDIRECTED;
-		}
-	} else {
-		if (fi->fib_metrics != (u32 *) dst_default_metrics) {
-			rt->fi = fi;
-			atomic_inc(&fi->fib_clntref);
-		}
-		dst_init_metrics(&rt->dst, fi->fib_metrics, true);
+	if (fi->fib_metrics != (u32 *) dst_default_metrics) {
+		rt->fi = fi;
+		atomic_inc(&fi->fib_clntref);
 	}
+	dst_init_metrics(&rt->dst, fi->fib_metrics, true);
 }
 
 static void rt_set_nexthop(struct rtable *rt, const struct flowi4 *fl4,
 			   const struct fib_result *res,
 			   struct fib_info *fi, u16 type, u32 itag)
 {
-	struct dst_entry *dst = &rt->dst;
-
 	if (fi) {
 		if (FIB_RES_GW(*res) &&
 		    FIB_RES_NH(*res).nh_scope == RT_SCOPE_LINK)
 			rt->rt_gateway = FIB_RES_GW(*res);
 		rt_init_metrics(rt, fl4, fi);
 #ifdef CONFIG_IP_ROUTE_CLASSID
-		dst->tclassid = FIB_RES_NH(*res).nh_tclassid;
+		rt->dst.tclassid = FIB_RES_NH(*res).nh_tclassid;
 #endif
 	}
-
-	if (dst_mtu(dst) > IP_MAX_MTU)
-		dst_metric_set(dst, RTAX_MTU, IP_MAX_MTU);
 
 #ifdef CONFIG_IP_ROUTE_CLASSID
 #ifdef CONFIG_IP_MULTIPLE_TABLES
···
 	rth->rt_iif	= dev->ifindex;
 	rth->rt_oif	= 0;
 	rth->rt_mark    = skb->mark;
+	rth->rt_pmtu	= 0;
 	rth->rt_gateway	= daddr;
-	rth->rt_peer_genid = 0;
-	rt_init_peer(rth, dev_net(dev)->ipv4.peers);
 	rth->fi = NULL;
 	if (our) {
 		rth->dst.input= ip_local_deliver;
···
 	rth->rt_iif 	= in_dev->dev->ifindex;
 	rth->rt_oif 	= 0;
 	rth->rt_mark    = skb->mark;
+	rth->rt_pmtu	= 0;
 	rth->rt_gateway	= daddr;
-	rth->rt_peer_genid = 0;
-	rt_init_peer(rth, &res->table->tb_peers);
 	rth->fi = NULL;
 
 	rth->dst.input = ip_forward;
···
 	rth->rt_iif	= dev->ifindex;
 	rth->rt_oif	= 0;
 	rth->rt_mark    = skb->mark;
+	rth->rt_pmtu	= 0;
 	rth->rt_gateway	= daddr;
-	rth->rt_peer_genid = 0;
-	rt_init_peer(rth, net->ipv4.peers);
 	rth->fi = NULL;
 	if (res.type == RTN_UNREACHABLE) {
 		rth->dst.input= ip_error;
···
 		    rth->rt_mark == skb->mark &&
 		    net_eq(dev_net(rth->dst.dev), net) &&
 		    !rt_is_expired(rth)) {
-			ipv4_validate_peer(rth);
 			if (noref) {
 				dst_use_noref(&rth->dst, jiffies);
 				skb_dst_set_noref(skb, &rth->dst);
···
 	rth->rt_iif	= orig_oif ? : dev_out->ifindex;
 	rth->rt_oif	= orig_oif;
 	rth->rt_mark    = fl4->flowi4_mark;
+	rth->rt_pmtu	= 0;
 	rth->rt_gateway = fl4->daddr;
-	rth->rt_peer_genid = 0;
-	rt_init_peer(rth, (res->table ?
-			   &res->table->tb_peers :
-			   dev_net(dev_out)->ipv4.peers));
 	rth->fi = NULL;
 
 	RT_CACHE_STAT_INC(out_slow_tot);
···
 			    (IPTOS_RT_MASK | RTO_ONLINK)) &&
 		    net_eq(dev_net(rth->dst.dev), net) &&
 		    !rt_is_expired(rth)) {
-			ipv4_validate_peer(rth);
 			dst_use(&rth->dst, jiffies);
 			RT_CACHE_STAT_INC(out_hit);
 			rcu_read_unlock_bh();
···
 		new->__use = 1;
 		new->input = dst_discard;
 		new->output = dst_discard;
-		dst_copy_metrics(new, &ort->dst);
 
 		new->dev = ort->dst.dev;
 		if (new->dev)
···
 		rt->rt_iif = ort->rt_iif;
 		rt->rt_oif = ort->rt_oif;
 		rt->rt_mark = ort->rt_mark;
+		rt->rt_pmtu = ort->rt_pmtu;
 
 		rt->rt_genid = rt_genid(net);
 		rt->rt_flags = ort->rt_flags;
···
 		rt->rt_dst = ort->rt_dst;
 		rt->rt_src = ort->rt_src;
 		rt->rt_gateway = ort->rt_gateway;
-		rt_transfer_peer(rt, ort);
 		rt->fi = ort->fi;
 		if (rt->fi)
 			atomic_inc(&rt->fi->fib_clntref);
···
 	struct rtmsg *r;
 	struct nlmsghdr *nlh;
 	unsigned long expires = 0;
-	u32 id = 0, ts = 0, tsage = 0, error;
+	u32 error;
 
 	nlh = nlmsg_put(skb, pid, seq, event, sizeof(*r), flags);
 	if (nlh == NULL)
···
 		goto nla_put_failure;
 
 	error = rt->dst.error;
-	if (rt_has_peer(rt)) {
-		const struct inet_peer *peer = rt_peer_ptr(rt);
-		inet_peer_refcheck(peer);
-		id = atomic_read(&peer->ip_id_count) & 0xffff;
-		if (peer->tcp_ts_stamp) {
-			ts = peer->tcp_ts;
-			tsage = get_seconds() - peer->tcp_ts_stamp;
-		}
-		expires = ACCESS_ONCE(peer->pmtu_expires);
-		if (expires) {
-			if (time_before(jiffies, expires))
-				expires -= jiffies;
-			else
-				expires = 0;
-		}
+	expires = rt->dst.expires;
+	if (expires) {
+		if (time_before(jiffies, expires))
+			expires -= jiffies;
+		else
+			expires = 0;
 	}
 
 	if (rt_is_input_route(rt)) {
···
 				goto nla_put_failure;
 	}
 
-	if (rtnl_put_cacheinfo(skb, &rt->dst, id, ts, tsage,
-			       expires, error) < 0)
+	if (rtnl_put_cacheinfo(skb, &rt->dst, 0, expires, error) < 0)
 		goto nla_put_failure;
 
 	return nlmsg_end(skb, nlh);

net/ipv4/tcp.c

···
 	pr_info("Hash tables configured (established %u bind %u)\n",
 		tcp_hashinfo.ehash_mask + 1, tcp_hashinfo.bhash_size);
 
+	tcp_metrics_init();
+
 	tcp_register_congestion_control(&tcp_reno);
 
 	memset(&tcp_secret_one.secrets[0], 0, sizeof(tcp_secret_one.secrets));

net/ipv4/tcp_input.c

···
 int sysctl_tcp_max_orphans __read_mostly = NR_FILE;
 int sysctl_tcp_frto __read_mostly = 2;
 int sysctl_tcp_frto_response __read_mostly;
-int sysctl_tcp_nometrics_save __read_mostly;
 
 int sysctl_tcp_thin_dupack __read_mostly;
 
···
 /* Calculate rto without backoff.  This is the second half of Van Jacobson's
  * routine referred to above.
  */
-static inline void tcp_set_rto(struct sock *sk)
+void tcp_set_rto(struct sock *sk)
 {
 	const struct tcp_sock *tp = tcp_sk(sk);
 	/* Old crap is replaced with new one. 8)
···
 	 * guarantees that rto is higher.
 	 */
 	tcp_bound_rto(sk);
-}
-
-/* Save metrics learned by this TCP session.
-   This function is called only, when TCP finishes successfully
-   i.e. when it enters TIME-WAIT or goes from LAST-ACK to CLOSE.
- */
-void tcp_update_metrics(struct sock *sk)
-{
-	struct tcp_sock *tp = tcp_sk(sk);
-	struct dst_entry *dst = __sk_dst_get(sk);
-
-	if (sysctl_tcp_nometrics_save)
-		return;
-
-	if (dst && (dst->flags & DST_HOST)) {
-		const struct inet_connection_sock *icsk = inet_csk(sk);
-		int m;
-		unsigned long rtt;
-
-		dst_confirm(dst);
-
-		if (icsk->icsk_backoff || !tp->srtt) {
-			/* This session failed to estimate rtt. Why?
-			 * Probably, no packets returned in time.
-			 * Reset our results.
-			 */
-			if (!(dst_metric_locked(dst, RTAX_RTT)))
-				dst_metric_set(dst, RTAX_RTT, 0);
-			return;
-		}
-
-		rtt = dst_metric_rtt(dst, RTAX_RTT);
-		m = rtt - tp->srtt;
-
-		/* If newly calculated rtt larger than stored one,
-		 * store new one. Otherwise, use EWMA. Remember,
-		 * rtt overestimation is always better than underestimation.
-		 */
-		if (!(dst_metric_locked(dst, RTAX_RTT))) {
-			if (m <= 0)
-				set_dst_metric_rtt(dst, RTAX_RTT, tp->srtt);
-			else
-				set_dst_metric_rtt(dst, RTAX_RTT, rtt - (m >> 3));
-		}
-
-		if (!(dst_metric_locked(dst, RTAX_RTTVAR))) {
-			unsigned long var;
-			if (m < 0)
-				m = -m;
-
-			/* Scale deviation to rttvar fixed point */
-			m >>= 1;
-			if (m < tp->mdev)
-				m = tp->mdev;
-
-			var = dst_metric_rtt(dst, RTAX_RTTVAR);
-			if (m >= var)
-				var = m;
-			else
-				var -= (var - m) >> 2;
-
-			set_dst_metric_rtt(dst, RTAX_RTTVAR, var);
-		}
-
-		if (tcp_in_initial_slowstart(tp)) {
-			/* Slow start still did not finish. */
-			if (dst_metric(dst, RTAX_SSTHRESH) &&
-			    !dst_metric_locked(dst, RTAX_SSTHRESH) &&
-			    (tp->snd_cwnd >> 1) > dst_metric(dst, RTAX_SSTHRESH))
-				dst_metric_set(dst, RTAX_SSTHRESH, tp->snd_cwnd >> 1);
-			if (!dst_metric_locked(dst, RTAX_CWND) &&
-			    tp->snd_cwnd > dst_metric(dst, RTAX_CWND))
-				dst_metric_set(dst, RTAX_CWND, tp->snd_cwnd);
-		} else if (tp->snd_cwnd > tp->snd_ssthresh &&
-			   icsk->icsk_ca_state == TCP_CA_Open) {
-			/* Cong. avoidance phase, cwnd is reliable. */
-			if (!dst_metric_locked(dst, RTAX_SSTHRESH))
-				dst_metric_set(dst, RTAX_SSTHRESH,
-					       max(tp->snd_cwnd >> 1, tp->snd_ssthresh));
-			if (!dst_metric_locked(dst, RTAX_CWND))
-				dst_metric_set(dst, RTAX_CWND,
-					       (dst_metric(dst, RTAX_CWND) +
-						tp->snd_cwnd) >> 1);
-		} else {
-			/* Else slow start did not finish, cwnd is non-sense,
-			   ssthresh may be also invalid.
-			 */
-			if (!dst_metric_locked(dst, RTAX_CWND))
-				dst_metric_set(dst, RTAX_CWND,
-					       (dst_metric(dst, RTAX_CWND) +
-						tp->snd_ssthresh) >> 1);
-			if (dst_metric(dst, RTAX_SSTHRESH) &&
-			    !dst_metric_locked(dst, RTAX_SSTHRESH) &&
-			    tp->snd_ssthresh > dst_metric(dst, RTAX_SSTHRESH))
-				dst_metric_set(dst, RTAX_SSTHRESH, tp->snd_ssthresh);
-		}
-
-		if (!dst_metric_locked(dst, RTAX_REORDERING)) {
-			if (dst_metric(dst, RTAX_REORDERING) < tp->reordering &&
-			    tp->reordering != sysctl_tcp_reordering)
-				dst_metric_set(dst, RTAX_REORDERING, tp->reordering);
-		}
-	}
 }
 
 __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst)
···
  * Packet counting of FACK is based on in-order assumptions, therefore TCP
  * disables it when reordering is detected
  */
-static void tcp_disable_fack(struct tcp_sock *tp)
+void tcp_disable_fack(struct tcp_sock *tp)
 {
 	/* RFC3517 uses different metric in lost marker => reset on change */
 	if (tcp_is_fack(tp))
···
 static void tcp_dsack_seen(struct tcp_sock *tp)
 {
 	tp->rx_opt.sack_ok |= TCP_DSACK_SEEN;
-}
-
-/* Initialize metrics on socket. */
-
-static void tcp_init_metrics(struct sock *sk)
-{
-	struct tcp_sock *tp = tcp_sk(sk);
-	struct dst_entry *dst = __sk_dst_get(sk);
-
-	if (dst == NULL)
-		goto reset;
-
-	dst_confirm(dst);
-
-	if (dst_metric_locked(dst, RTAX_CWND))
-		tp->snd_cwnd_clamp = dst_metric(dst, RTAX_CWND);
-	if (dst_metric(dst, RTAX_SSTHRESH)) {
-		tp->snd_ssthresh = dst_metric(dst, RTAX_SSTHRESH);
-		if (tp->snd_ssthresh > tp->snd_cwnd_clamp)
-			tp->snd_ssthresh = tp->snd_cwnd_clamp;
-	} else {
-		/* ssthresh may have been reduced unnecessarily during.
-		 * 3WHS. Restore it back to its initial default.
-		 */
-		tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
-	}
-	if (dst_metric(dst, RTAX_REORDERING) &&
-	    tp->reordering != dst_metric(dst, RTAX_REORDERING)) {
-		tcp_disable_fack(tp);
-		tcp_disable_early_retrans(tp);
-		tp->reordering = dst_metric(dst, RTAX_REORDERING);
-	}
-
-	if (dst_metric(dst, RTAX_RTT) == 0 || tp->srtt == 0)
-		goto reset;
-
-	/* Initial rtt is determined from SYN,SYN-ACK.
-	 * The segment is small and rtt may appear much
-	 * less than real one. Use per-dst memory
-	 * to make it more realistic.
-	 *
-	 * A bit of theory. RTT is time passed after "normal" sized packet
-	 * is sent until it is ACKed. In normal circumstances sending small
-	 * packets force peer to delay ACKs and calculation is correct too.
-	 * The algorithm is adaptive and, provided we follow specs, it
-	 * NEVER underestimate RTT. BUT! If peer tries to make some clever
-	 * tricks sort of "quick acks" for time long enough to decrease RTT
-	 * to low value, and then abruptly stops to do it and starts to delay
-	 * ACKs, wait for troubles.
-	 */
-	if (dst_metric_rtt(dst, RTAX_RTT) > tp->srtt) {
-		tp->srtt = dst_metric_rtt(dst, RTAX_RTT);
-		tp->rtt_seq = tp->snd_nxt;
-	}
-	if (dst_metric_rtt(dst, RTAX_RTTVAR) > tp->mdev) {
-		tp->mdev = dst_metric_rtt(dst, RTAX_RTTVAR);
-		tp->mdev_max = tp->rttvar = max(tp->mdev, tcp_rto_min(sk));
-	}
-	tcp_set_rto(sk);
-reset:
-	if (tp->srtt == 0) {
-		/* RFC6298: 5.7 We've failed to get a valid RTT sample from
-		 * 3WHS. This is most likely due to retransmission,
-		 * including spurious one. Reset the RTO back to 3secs
-		 * from the more aggressive 1sec to avoid more spurious
-		 * retransmission.
-		 */
-		tp->mdev = tp->mdev_max = tp->rttvar = TCP_TIMEOUT_FALLBACK;
-		inet_csk(sk)->icsk_rto = TCP_TIMEOUT_FALLBACK;
-	}
-	/* Cut cwnd down to 1 per RFC5681 if SYN or SYN-ACK has been
-	 * retransmitted. In light of RFC6298 more aggressive 1sec
-	 * initRTO, we only reset cwnd when more than 1 SYN/SYN-ACK
-	 * retransmission has occurred.
-	 */
-	if (tp->total_retrans > 1)
-		tp->snd_cwnd = 1;
-	else
-		tp->snd_cwnd = tcp_init_cwnd(tp, dst);
-	tp->snd_cwnd_stamp = tcp_time_stamp;
 }
 
 static void tcp_update_reordering(struct sock *sk, const int metric,

net/ipv4/tcp_ipv4.c

···
 	}
 
 	if (tcp_death_row.sysctl_tw_recycle &&
-	    !tp->rx_opt.ts_recent_stamp && fl4->daddr == daddr) {
-		struct inet_peer *peer = rt_get_peer(rt, fl4->daddr);
-		/*
-		 * VJ's idea. We save last timestamp seen from
-		 * the destination in peer table, when entering state
-		 * TIME-WAIT * and initialize rx_opt.ts_recent from it,
-		 * when trying new connection.
-		 */
-		if (peer) {
-			inet_peer_refcheck(peer);
-			if ((u32)get_seconds() - peer->tcp_ts_stamp <= TCP_PAWS_MSL) {
-				tp->rx_opt.ts_recent_stamp = peer->tcp_ts_stamp;
-				tp->rx_opt.ts_recent = peer->tcp_ts;
-			}
-		}
-	}
+	    !tp->rx_opt.ts_recent_stamp && fl4->daddr == daddr)
+		tcp_fetch_timewait_stamp(sk, &rt->dst);
 
 	inet->inet_dport = usin->sin_port;
 	inet->inet_daddr = daddr;
···
 		isn = cookie_v4_init_sequence(sk, skb, &req->mss);
 		req->cookie_ts = tmp_opt.tstamp_ok;
 	} else if (!isn) {
-		struct inet_peer *peer = NULL;
 		struct flowi4 fl4;
 
 		/* VJ's idea. We save last timestamp seen
···
 		if (tmp_opt.saw_tstamp &&
 		    tcp_death_row.sysctl_tw_recycle &&
 		    (dst = inet_csk_route_req(sk, &fl4, req, want_cookie)) != NULL &&
-		    fl4.daddr == saddr &&
-		    (peer = rt_get_peer((struct rtable *)dst, fl4.daddr)) != NULL) {
-			inet_peer_refcheck(peer);
-			if ((u32)get_seconds() - peer->tcp_ts_stamp < TCP_PAWS_MSL &&
-			    (s32)(peer->tcp_ts - req->ts_recent) >
-							TCP_PAWS_WINDOW) {
+		    fl4.daddr == saddr) {
+			if (!tcp_peer_is_proven(req, dst, true)) {
 				NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PAWSPASSIVEREJECTED);
 				goto drop_and_release;
 			}
···
 		else if (!sysctl_tcp_syncookies &&
 			 (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) <
 			  (sysctl_max_syn_backlog >> 2)) &&
-			 (!peer || !peer->tcp_ts_stamp) &&
-			 (!dst || !dst_metric(dst, RTAX_RTT))) {
+			 !tcp_peer_is_proven(req, dst, false)) {
 			/* Without syncookies last quarter of
 			 * backlog is filled with destinations,
 			 * proven to be alive.
···
 	goto discard_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);
-
-	/* 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);
-
 static struct timewait_sock_ops tcp_timewait_sock_ops = {
 	.twsk_obj_size	= sizeof(struct tcp_timewait_sock),
 	.twsk_unique	= tcp_twsk_unique,
···
 	.rebuild_header	   = inet_sk_rebuild_header,
 	.conn_request	   = tcp_v4_conn_request,
 	.syn_recv_sock	   = tcp_v4_syn_recv_sock,
-	.get_peer	   = tcp_v4_get_peer,
 	.net_header_len	   = sizeof(struct iphdr),
 	.setsockopt	   = ip_setsockopt,
 	.getsockopt	   = ip_getsockopt,

net/ipv4/tcp_metrics.c

···
+#include <linux/rcupdate.h>
+#include <linux/spinlock.h>
+#include <linux/jiffies.h>
+#include <linux/bootmem.h>
+#include <linux/module.h>
+#include <linux/cache.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/tcp.h>
+
+#include <net/inet_connection_sock.h>
+#include <net/net_namespace.h>
+#include <net/request_sock.h>
+#include <net/inetpeer.h>
+#include <net/sock.h>
+#include <net/ipv6.h>
+#include <net/dst.h>
+#include <net/tcp.h>
+
+int sysctl_tcp_nometrics_save __read_mostly;
+
+enum tcp_metric_index {
+	TCP_METRIC_RTT,
+	TCP_METRIC_RTTVAR,
+	TCP_METRIC_SSTHRESH,
+	TCP_METRIC_CWND,
+	TCP_METRIC_REORDERING,
+
+	/* Always last.  */
+	TCP_METRIC_MAX,
+};
+
+struct tcp_metrics_block {
+	struct tcp_metrics_block __rcu	*tcpm_next;
+	struct inetpeer_addr		tcpm_addr;
+	unsigned long			tcpm_stamp;
+	u32				tcpm_ts;
+	u32				tcpm_ts_stamp;
+	u32				tcpm_lock;
+	u32				tcpm_vals[TCP_METRIC_MAX];
+};
+
+static bool tcp_metric_locked(struct tcp_metrics_block *tm,
+			      enum tcp_metric_index idx)
+{
+	return tm->tcpm_lock & (1 << idx);
+}
+
+static u32 tcp_metric_get(struct tcp_metrics_block *tm,
+			  enum tcp_metric_index idx)
+{
+	return tm->tcpm_vals[idx];
+}
+
+static u32 tcp_metric_get_jiffies(struct tcp_metrics_block *tm,
+				  enum tcp_metric_index idx)
+{
+	return msecs_to_jiffies(tm->tcpm_vals[idx]);
+}
+
+static void tcp_metric_set(struct tcp_metrics_block *tm,
+			   enum tcp_metric_index idx,
+			   u32 val)
+{
+	tm->tcpm_vals[idx] = val;
+}
+
+static void tcp_metric_set_msecs(struct tcp_metrics_block *tm,
+				 enum tcp_metric_index idx,
+				 u32 val)
+{
+	tm->tcpm_vals[idx] = jiffies_to_msecs(val);
+}
+
+static bool addr_same(const struct inetpeer_addr *a,
+		      const struct inetpeer_addr *b)
+{
+	const struct in6_addr *a6, *b6;
+
+	if (a->family != b->family)
+		return false;
+	if (a->family == AF_INET)
+		return a->addr.a4 == b->addr.a4;
+
+	a6 = (const struct in6_addr *) &a->addr.a6[0];
+	b6 = (const struct in6_addr *) &b->addr.a6[0];
+
+	return ipv6_addr_equal(a6, b6);
+}
+
+struct tcpm_hash_bucket {
+	struct tcp_metrics_block __rcu	*chain;
+};
+
+static DEFINE_SPINLOCK(tcp_metrics_lock);
+
+static void tcpm_suck_dst(struct tcp_metrics_block *tm, struct dst_entry *dst)
+{
+	u32 val;
+
+	val = 0;
+	if (dst_metric_locked(dst, RTAX_RTT))
+		val |= 1 << TCP_METRIC_RTT;
+	if (dst_metric_locked(dst, RTAX_RTTVAR))
+		val |= 1 << TCP_METRIC_RTTVAR;
+	if (dst_metric_locked(dst, RTAX_SSTHRESH))
+		val |= 1 << TCP_METRIC_SSTHRESH;
+	if (dst_metric_locked(dst, RTAX_CWND))
+		val |= 1 << TCP_METRIC_CWND;
+	if (dst_metric_locked(dst, RTAX_REORDERING))
+		val |= 1 << TCP_METRIC_REORDERING;
+	tm->tcpm_lock = val;
+
+	tm->tcpm_vals[TCP_METRIC_RTT] = dst_metric_raw(dst, RTAX_RTT);
+	tm->tcpm_vals[TCP_METRIC_RTTVAR] = dst_metric_raw(dst, RTAX_RTTVAR);
+	tm->tcpm_vals[TCP_METRIC_SSTHRESH] = dst_metric_raw(dst, RTAX_SSTHRESH);
+	tm->tcpm_vals[TCP_METRIC_CWND] = dst_metric_raw(dst, RTAX_CWND);
+	tm->tcpm_vals[TCP_METRIC_REORDERING] = dst_metric_raw(dst, RTAX_REORDERING);
+	tm->tcpm_ts = 0;
+	tm->tcpm_ts_stamp = 0;
+}
+
+static struct tcp_metrics_block *tcpm_new(struct dst_entry *dst,
+					  struct inetpeer_addr *addr,
+					  unsigned int hash,
+					  bool reclaim)
+{
+	struct tcp_metrics_block *tm;
+	struct net *net;
+
+	spin_lock_bh(&tcp_metrics_lock);
+	net = dev_net(dst->dev);
+	if (unlikely(reclaim)) {
+		struct tcp_metrics_block *oldest;
+
+		oldest = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain);
+		for (tm = rcu_dereference(oldest->tcpm_next); tm;
+		     tm = rcu_dereference(tm->tcpm_next)) {
+			if (time_before(tm->tcpm_stamp, oldest->tcpm_stamp))
+				oldest = tm;
+		}
+		tm = oldest;
+	} else {
+		tm = kmalloc(sizeof(*tm), GFP_ATOMIC);
+		if (!tm)
+			goto out_unlock;
+	}
+	tm->tcpm_addr = *addr;
+	tm->tcpm_stamp = jiffies;
+
+	tcpm_suck_dst(tm, dst);
+
+	if (likely(!reclaim)) {
+		tm->tcpm_next = net->ipv4.tcp_metrics_hash[hash].chain;
+		rcu_assign_pointer(net->ipv4.tcp_metrics_hash[hash].chain, tm);
+	}
+
+out_unlock:
+	spin_unlock_bh(&tcp_metrics_lock);
+	return tm;
+}
+
+#define TCP_METRICS_TIMEOUT		(60 * 60 * HZ)
+
+static void tcpm_check_stamp(struct tcp_metrics_block *tm, struct dst_entry *dst)
+{
+	if (tm && unlikely(time_after(jiffies, tm->tcpm_stamp + TCP_METRICS_TIMEOUT)))
+		tcpm_suck_dst(tm, dst);
+}
+
+#define TCP_METRICS_RECLAIM_DEPTH	5
+#define TCP_METRICS_RECLAIM_PTR		(struct tcp_metrics_block *) 0x1UL
+
+static struct tcp_metrics_block *tcp_get_encode(struct tcp_metrics_block *tm, int depth)
+{
+	if (tm)
+		return tm;
+	if (depth > TCP_METRICS_RECLAIM_DEPTH)
+		return TCP_METRICS_RECLAIM_PTR;
+	return NULL;
+}
+
+static struct tcp_metrics_block *__tcp_get_metrics(const struct inetpeer_addr *addr,
+						   struct net *net, unsigned int hash)
+{
+	struct tcp_metrics_block *tm;
+	int depth = 0;
+
+	for (tm = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain); tm;
+	     tm = rcu_dereference(tm->tcpm_next)) {
+		if (addr_same(&tm->tcpm_addr, addr))
+			break;
+		depth++;
+	}
+	return tcp_get_encode(tm, depth);
+}
+
+static struct tcp_metrics_block *__tcp_get_metrics_req(struct request_sock *req,
+						       struct dst_entry *dst)
+{
+	struct tcp_metrics_block *tm;
+	struct inetpeer_addr addr;
+	unsigned int hash;
+	struct net *net;
+
+	addr.family = req->rsk_ops->family;
+	switch (addr.family) {
+	case AF_INET:
+		addr.addr.a4 = inet_rsk(req)->rmt_addr;
+		hash = (__force unsigned int) addr.addr.a4;
+		break;
+	case AF_INET6:
+		*(struct in6_addr *)addr.addr.a6 = inet6_rsk(req)->rmt_addr;
+		hash = ((__force unsigned int) addr.addr.a6[0] ^
+			(__force unsigned int) addr.addr.a6[1] ^
+			(__force unsigned int) addr.addr.a6[2] ^
+			(__force unsigned int) addr.addr.a6[3]);
+		break;
+	default:
+		return NULL;
+	}
+
+	hash ^= (hash >> 24) ^ (hash >> 16) ^ (hash >> 8);
+
+	net = dev_net(dst->dev);
+	hash &= net->ipv4.tcp_metrics_hash_mask;
+
+	for (tm = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain); tm;
+	     tm = rcu_dereference(tm->tcpm_next)) {
+		if (addr_same(&tm->tcpm_addr, &addr))
+			break;
+	}
+	tcpm_check_stamp(tm, dst);
+	return tm;
+}
+
+static struct tcp_metrics_block *__tcp_get_metrics_tw(struct inet_timewait_sock *tw)
+{
+	struct inet6_timewait_sock *tw6;
+	struct tcp_metrics_block *tm;
+	struct inetpeer_addr addr;
+	unsigned int hash;
+	struct net *net;
+
+	addr.family = tw->tw_family;
+	switch (addr.family) {
+	case AF_INET:
+		addr.addr.a4 = tw->tw_daddr;
+		hash = (__force unsigned int) addr.addr.a4;
+		break;
+	case AF_INET6:
+		tw6 = inet6_twsk((struct sock *)tw);
+		*(struct in6_addr *)addr.addr.a6 = tw6->tw_v6_daddr;
+		hash = ((__force unsigned int) addr.addr.a6[0] ^
+			(__force unsigned int) addr.addr.a6[1] ^
+			(__force unsigned int) addr.addr.a6[2] ^
+			(__force unsigned int) addr.addr.a6[3]);
+		break;
+	default:
+		return NULL;
+	}
+
+	hash ^= (hash >> 24) ^ (hash >> 16) ^ (hash >> 8);
+
+	net = twsk_net(tw);
+	hash &= net->ipv4.tcp_metrics_hash_mask;
+
+	for (tm = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain); tm;
+	     tm = rcu_dereference(tm->tcpm_next)) {
+		if (addr_same(&tm->tcpm_addr, &addr))
+			break;
+	}
+	return tm;
+}
+
+static struct tcp_metrics_block *tcp_get_metrics(struct sock *sk,
+						 struct dst_entry *dst,
+						 bool create)
+{
+	struct tcp_metrics_block *tm;
+	struct inetpeer_addr addr;
+	unsigned int hash;
+	struct net *net;
+	bool reclaim;
+
+	addr.family = sk->sk_family;
+	switch (addr.family) {
+	case AF_INET:
+		addr.addr.a4 = inet_sk(sk)->inet_daddr;
+		hash = (__force unsigned int) addr.addr.a4;
+		break;
+	case AF_INET6:
+		*(struct in6_addr *)addr.addr.a6 = inet6_sk(sk)->daddr;
+		hash = ((__force unsigned int) addr.addr.a6[0] ^
+			(__force unsigned int) addr.addr.a6[1] ^
+			(__force unsigned int) addr.addr.a6[2] ^
+			(__force unsigned int) addr.addr.a6[3]);
+		break;
+	default:
+		return NULL;
+	}
+
+	hash ^= (hash >> 24) ^ (hash >> 16) ^ (hash >> 8);
+
+	net = dev_net(dst->dev);
+	hash &= net->ipv4.tcp_metrics_hash_mask;
+
+	tm = __tcp_get_metrics(&addr, net, hash);
+	reclaim = false;
+	if (tm == TCP_METRICS_RECLAIM_PTR) {
+		reclaim = true;
+		tm = NULL;
+	}
+	if (!tm && create)
+		tm = tcpm_new(dst, &addr, hash, reclaim);
+	else
+		tcpm_check_stamp(tm, dst);
+
+	return tm;
+}
+
+/* Save metrics learned by this TCP session.  This function is called
+ * only, when TCP finishes successfully i.e. when it enters TIME-WAIT
+ * or goes from LAST-ACK to CLOSE.
+ */
+void tcp_update_metrics(struct sock *sk)
+{
+	const struct inet_connection_sock *icsk = inet_csk(sk);
+	struct dst_entry *dst = __sk_dst_get(sk);
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct tcp_metrics_block *tm;
+	unsigned long rtt;
+	u32 val;
+	int m;
+
+	if (sysctl_tcp_nometrics_save || !dst)
+		return;
+
+	if (dst->flags & DST_HOST)
+		dst_confirm(dst);
+
+	rcu_read_lock();
+	if (icsk->icsk_backoff || !tp->srtt) {
+		/* This session failed to estimate rtt. Why?
+		 * Probably, no packets returned in time.  Reset our
+		 * results.
+		 */
+		tm = tcp_get_metrics(sk, dst, false);
+		if (tm && !tcp_metric_locked(tm, TCP_METRIC_RTT))
+			tcp_metric_set(tm, TCP_METRIC_RTT, 0);
+		goto out_unlock;
+	} else
+		tm = tcp_get_metrics(sk, dst, true);
+
+	if (!tm)
+		goto out_unlock;
+
+	rtt = tcp_metric_get_jiffies(tm, TCP_METRIC_RTT);
+	m = rtt - tp->srtt;
+
+	/* If newly calculated rtt larger than stored one, store new
+	 * one. Otherwise, use EWMA. Remember, rtt overestimation is
+	 * always better than underestimation.
+	 */
+	if (!tcp_metric_locked(tm, TCP_METRIC_RTT)) {
+		if (m <= 0)
+			rtt = tp->srtt;
+		else
+			rtt -= (m >> 3);
+		tcp_metric_set_msecs(tm, TCP_METRIC_RTT, rtt);
+	}
+
+	if (!tcp_metric_locked(tm, TCP_METRIC_RTTVAR)) {
+		unsigned long var;
+
+		if (m < 0)
+			m = -m;
+
+		/* Scale deviation to rttvar fixed point */
+		m >>= 1;
+		if (m < tp->mdev)
+			m = tp->mdev;
+
+		var = tcp_metric_get_jiffies(tm, TCP_METRIC_RTTVAR);
+		if (m >= var)
+			var = m;
+		else
+			var -= (var - m) >> 2;
+
+		tcp_metric_set_msecs(tm, TCP_METRIC_RTTVAR, var);
+	}
+
+	if (tcp_in_initial_slowstart(tp)) {
+		/* Slow start still did not finish. */
+		if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
+			val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
+			if (val && (tp->snd_cwnd >> 1) > val)
+				tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
+					       tp->snd_cwnd >> 1);
+		}
+		if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
+			val = tcp_metric_get(tm, TCP_METRIC_CWND);
+			if (tp->snd_cwnd > val)
+				tcp_metric_set(tm, TCP_METRIC_CWND,
+					       tp->snd_cwnd);
+		}
+	} else if (tp->snd_cwnd > tp->snd_ssthresh &&
+		   icsk->icsk_ca_state == TCP_CA_Open) {
+		/* Cong. avoidance phase, cwnd is reliable. */
+		if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH))
+			tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
+				       max(tp->snd_cwnd >> 1, tp->snd_ssthresh));
+		if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
+			val = tcp_metric_get(tm, TCP_METRIC_CWND);
+			tcp_metric_set(tm, RTAX_CWND, (val + tp->snd_cwnd) >> 1);
+		}
+	} else {
+		/* Else slow start did not finish, cwnd is non-sense,
+		 * ssthresh may be also invalid.
+		 */
+		if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
+			val = tcp_metric_get(tm, TCP_METRIC_CWND);
+			tcp_metric_set(tm, TCP_METRIC_CWND,
+				       (val + tp->snd_ssthresh) >> 1);
+		}
+		if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
+			val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
+			if (val && tp->snd_ssthresh > val)
+				tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
+					       tp->snd_ssthresh);
+		}
+		if (!tcp_metric_locked(tm, TCP_METRIC_REORDERING)) {
+			val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
+			if (val < tp->reordering &&
+			    tp->reordering != sysctl_tcp_reordering)
+				tcp_metric_set(tm, TCP_METRIC_REORDERING,
+					       tp->reordering);
+		}
+	}
+	tm->tcpm_stamp = jiffies;
+out_unlock:
+	rcu_read_unlock();
+}
+
+/* Initialize metrics on socket. */
+
+void tcp_init_metrics(struct sock *sk)
+{
+	struct dst_entry *dst = __sk_dst_get(sk);
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct tcp_metrics_block *tm;
+	u32 val;
+
+	if (dst == NULL)
+		goto reset;
+
+	dst_confirm(dst);
+
+	rcu_read_lock();
+	tm = tcp_get_metrics(sk, dst, true);
+	if (!tm) {
+		rcu_read_unlock();
+		goto reset;
+	}
+
+	if (tcp_metric_locked(tm, TCP_METRIC_CWND))
+		tp->snd_cwnd_clamp = tcp_metric_get(tm, TCP_METRIC_CWND);
+
+	val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
+	if (val) {
+		tp->snd_ssthresh = val;
+		if (tp->snd_ssthresh > tp->snd_cwnd_clamp)
+			tp->snd_ssthresh = tp->snd_cwnd_clamp;
+	} else {
+		/* ssthresh may have been reduced unnecessarily during.
+		 * 3WHS. Restore it back to its initial default.
+		 */
+		tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
+	}
+	val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
+	if (val && tp->reordering != val) {
+		tcp_disable_fack(tp);
+		tcp_disable_early_retrans(tp);
+		tp->reordering = val;
+	}
+
+	val = tcp_metric_get(tm, TCP_METRIC_RTT);
+	if (val == 0 || tp->srtt == 0) {
+		rcu_read_unlock();
+		goto reset;
+	}
+	/* Initial rtt is determined from SYN,SYN-ACK.
+	 * The segment is small and rtt may appear much
+	 * less than real one. Use per-dst memory
+	 * to make it more realistic.
+	 *
+	 * A bit of theory. RTT is time passed after "normal" sized packet
+	 * is sent until it is ACKed. In normal circumstances sending small
+	 * packets force peer to delay ACKs and calculation is correct too.
+	 * The algorithm is adaptive and, provided we follow specs, it
+	 * NEVER underestimate RTT. BUT! If peer tries to make some clever
+	 * tricks sort of "quick acks" for time long enough to decrease RTT
+	 * to low value, and then abruptly stops to do it and starts to delay
+	 * ACKs, wait for troubles.
+	 */
+	val = msecs_to_jiffies(val);
+	if (val > tp->srtt) {
+		tp->srtt = val;
+		tp->rtt_seq = tp->snd_nxt;
+	}
+	val = tcp_metric_get_jiffies(tm, TCP_METRIC_RTTVAR);
+	if (val > tp->mdev) {
+		tp->mdev = val;
+		tp->mdev_max = tp->rttvar = max(tp->mdev, tcp_rto_min(sk));
+	}
+	rcu_read_unlock();
+
+	tcp_set_rto(sk);
+reset:
+	if (tp->srtt == 0) {
+		/* RFC6298: 5.7 We've failed to get a valid RTT sample from
+		 * 3WHS. This is most likely due to retransmission,
+		 * including spurious one. Reset the RTO back to 3secs
+		 * from the more aggressive 1sec to avoid more spurious
+		 * retransmission.
+		 */
+		tp->mdev = tp->mdev_max = tp->rttvar = TCP_TIMEOUT_FALLBACK;
+		inet_csk(sk)->icsk_rto = TCP_TIMEOUT_FALLBACK;
+	}
+	/* Cut cwnd down to 1 per RFC5681 if SYN or SYN-ACK has been
+	 * retransmitted. In light of RFC6298 more aggressive 1sec
+	 * initRTO, we only reset cwnd when more than 1 SYN/SYN-ACK
+	 * retransmission has occurred.
+	 */
+	if (tp->total_retrans > 1)
+		tp->snd_cwnd = 1;
+	else
+		tp->snd_cwnd = tcp_init_cwnd(tp, dst);
+	tp->snd_cwnd_stamp = tcp_time_stamp;
+}
+
+bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst, bool paws_check)
+{
+	struct tcp_metrics_block *tm;
+	bool ret;
+
+	if (!dst)
+		return false;
+
+	rcu_read_lock();
+	tm = __tcp_get_metrics_req(req, dst);
+	if (paws_check) {
+		if (tm &&
+		    (u32)get_seconds() - tm->tcpm_ts_stamp < TCP_PAWS_MSL &&
+		    (s32)(tm->tcpm_ts - req->ts_recent) > TCP_PAWS_WINDOW)
+			ret = false;
+		else
+			ret = true;
+	} else {
+		if (tm && tcp_metric_get(tm, TCP_METRIC_RTT) && tm->tcpm_ts_stamp)
+			ret = true;
+		else
+			ret = false;
+	}
+	rcu_read_unlock();
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(tcp_peer_is_proven);
+
+void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst)
+{
+	struct tcp_metrics_block *tm;
+
+	rcu_read_lock();
+	tm = tcp_get_metrics(sk, dst, true);
+	if (tm) {
+		struct tcp_sock *tp = tcp_sk(sk);
+
+		if ((u32)get_seconds() - tm->tcpm_ts_stamp <= TCP_PAWS_MSL) {
+			tp->rx_opt.ts_recent_stamp = tm->tcpm_ts_stamp;
+			tp->rx_opt.ts_recent = tm->tcpm_ts;
+		}
+	}
+	rcu_read_unlock();
+}
+EXPORT_SYMBOL_GPL(tcp_fetch_timewait_stamp);
+
+/* VJ's idea. Save last timestamp seen from this destination and hold
+ * it at least for normal timewait interval to use for duplicate
+ * segment detection in subsequent connections, before they enter
+ * synchronized state.
+ */
+bool tcp_remember_stamp(struct sock *sk)
+{
+	struct dst_entry *dst = __sk_dst_get(sk);
+	bool ret = false;
+
+	if (dst) {
+		struct tcp_metrics_block *tm;
+
+		rcu_read_lock();
+		tm = tcp_get_metrics(sk, dst, true);
+		if (tm) {
+			struct tcp_sock *tp = tcp_sk(sk);
+
+			if ((s32)(tm->tcpm_ts - tp->rx_opt.ts_recent) <= 0 ||
+			    ((u32)get_seconds() - tm->tcpm_ts_stamp > TCP_PAWS_MSL &&
+			     tm->tcpm_ts_stamp <= (u32)tp->rx_opt.ts_recent_stamp)) {
+				tm->tcpm_ts_stamp = (u32)tp->rx_opt.ts_recent_stamp;
+				tm->tcpm_ts = tp->rx_opt.ts_recent;
+			}
+			ret = true;
+		}
+		rcu_read_unlock();
+	}
+	return ret;
+}
+
+bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw)
+{
+	struct tcp_metrics_block *tm;
+	bool ret = false;
+
+	rcu_read_lock();
+	tm = __tcp_get_metrics_tw(tw);
+	if (tw) {
+		const struct tcp_timewait_sock *tcptw;
+		struct sock *sk = (struct sock *) tw;
+
+		tcptw = tcp_twsk(sk);
+		if ((s32)(tm->tcpm_ts - tcptw->tw_ts_recent) <= 0 ||
+		    ((u32)get_seconds() - tm->tcpm_ts_stamp > TCP_PAWS_MSL &&
+		     tm->tcpm_ts_stamp <= (u32)tcptw->tw_ts_recent_stamp)) {
+			tm->tcpm_ts_stamp = (u32)tcptw->tw_ts_recent_stamp;
+			tm->tcpm_ts	   = tcptw->tw_ts_recent;
+		}
+		ret = true;
+	}
+	rcu_read_unlock();
+
+	return ret;
+}
+
+static unsigned long tcpmhash_entries;
+static int __init set_tcpmhash_entries(char *str)
+{
+	ssize_t ret;
+
+	if (!str)
+		return 0;
+
+	ret = kstrtoul(str, 0, &tcpmhash_entries);
+	if (ret)
+		return 0;
+
+	return 1;
+}
+__setup("tcpmhash_entries=", set_tcpmhash_entries);
+
+static int __net_init tcp_net_metrics_init(struct net *net)
+{
+	int slots, size;
+
+	slots = tcpmhash_entries;
+	if (!slots) {
+		if (totalram_pages >= 128 * 1024)
+			slots = 16 * 1024;
+		else
+			slots = 8 * 1024;
+	}
+
+	size = slots * sizeof(struct tcpm_hash_bucket);
+
+	net->ipv4.tcp_metrics_hash = kzalloc(size, GFP_KERNEL);
+	if (!net->ipv4.tcp_metrics_hash)
+		return -ENOMEM;
+
+	net->ipv4.tcp_metrics_hash_mask = (slots - 1);
+
+	return 0;
+}
+
+static void __net_exit tcp_net_metrics_exit(struct net *net)
+{
+	kfree(net->ipv4.tcp_metrics_hash);
+}
+
+static __net_initdata struct pernet_operations tcp_net_metrics_ops = {
+	.init	=	tcp_net_metrics_init,
+	.exit	=	tcp_net_metrics_exit,
+};
+
+void __init tcp_metrics_init(void)
+{
+	register_pernet_subsys(&tcp_net_metrics_ops);
+}

net/ipv4/tcp_minisocks.c

···
 };
 EXPORT_SYMBOL_GPL(tcp_death_row);
 
-/* VJ's idea. Save last timestamp seen from this destination
- * and hold it at least for normal timewait interval to use for duplicate
- * segment detection in subsequent connections, before they enter synchronized
- * state.
- */
-
-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;
-
-	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 &&
-		     peer->tcp_ts_stamp <= (u32)tp->rx_opt.ts_recent_stamp)) {
-			peer->tcp_ts_stamp = (u32)tp->rx_opt.ts_recent_stamp;
-			peer->tcp_ts = tp->rx_opt.ts_recent;
-		}
-		return true;
-	}
-
-	return false;
-}
-
-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;
-
-	tcptw = tcp_twsk(sk);
-	peer = tcptw->tw_peer;
-	if (peer) {
-		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;
-		}
-		return true;
-	}
-	return false;
-}
-
 static bool tcp_in_window(u32 seq, u32 end_seq, u32 s_win, u32 e_win)
 {
 	if (seq == s_win)
···
 	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);
···
 		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->transparent;
 		tw->tw_rcv_wscale	= tp->rx_opt.rcv_wscale;
···
 			tw->tw_ipv6only = np->ipv6only;
 		}
 #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
 		/*
···
 
 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);

net/ipv4/xfrm4_policy.c

···
 	xdst->u.dst.dev = dev;
 	dev_hold(dev);
 
-	rt_transfer_peer(&xdst->u.rt, rt);
-
 	/* Sheit... I remember I did this right. Apparently,
 	 * it was magically lost, so this code needs audit */
 	xdst->u.rt.rt_flags = rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST |
···
 	xdst->u.rt.rt_src = rt->rt_src;
 	xdst->u.rt.rt_dst = rt->rt_dst;
 	xdst->u.rt.rt_gateway = rt->rt_gateway;
+	xdst->u.rt.rt_pmtu = rt->rt_pmtu;
 
 	return 0;
 }
···
 	struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 
 	dst_destroy_metrics_generic(dst);
-
-	if (rt_has_peer(&xdst->u.rt)) {
-		struct inet_peer *peer = rt_peer_ptr(&xdst->u.rt);
-		inet_putpeer(peer);
-	}
 
 	xfrm_dst_destroy(xdst);
 }

net/ipv6/icmp.c

···
 		if (rt->rt6i_dst.plen < 128)
 			tmo >>= ((128 - rt->rt6i_dst.plen)>>5);
 
-		peer = rt6_get_peer_create(rt);
+		peer = inet_getpeer_v6(net->ipv6.peers, &rt->rt6i_dst.addr, 1);
 		res = inet_peer_xrlim_allow(peer, tmo);
+		if (peer)
+			inet_putpeer(peer);
 	}
 	dst_release(dst);
 	return res;

net/ipv6/ip6_output.c

···
 		else
 			target = &hdr->daddr;
 
-		peer = rt6_get_peer_create(rt);
+		peer = inet_getpeer_v6(net->ipv6.peers, &rt->rt6i_dst.addr, 1);
 
 		/* Limit redirects both by destination (here)
 		   and by source (inside ndisc_send_redirect)
 		 */
 		if (inet_peer_xrlim_allow(peer, 1*HZ))
 			ndisc_send_redirect(skb, target);
+		if (peer)
+			inet_putpeer(peer);
 	} else {
 		int addrtype = ipv6_addr_type(&hdr->saddr);
 
···
 	int old, new;
 
 	if (rt && !(rt->dst.flags & DST_NOPEER)) {
-		struct inet_peer *peer = rt6_get_peer_create(rt);
+		struct inet_peer *peer;
+		struct net *net;
 
+		net = dev_net(rt->dst.dev);
+		peer = inet_getpeer_v6(net->ipv6.peers, &rt->rt6i_dst.addr, 1);
 		if (peer) {
 			fhdr->identification = htonl(inet_getid(peer, 0));
+			inet_putpeer(peer);
 			return;
 		}
 	}

net/ipv6/ndisc.c

···
 	int rd_len;
 	int err;
 	u8 ha_buf[MAX_ADDR_LEN], *ha = NULL;
+	bool ret;
 
 	if (ipv6_get_lladdr(dev, &saddr_buf, IFA_F_TENTATIVE)) {
 		ND_PRINTK(2, warn, "Redirect: no link-local address on %s\n",
···
 			  "Redirect: destination is not a neighbour\n");
 		goto release;
 	}
-	peer = rt6_get_peer_create(rt);
-	if (!inet_peer_xrlim_allow(peer, 1*HZ))
+	peer = inet_getpeer_v6(net->ipv6.peers, &rt->rt6i_dst.addr, 1);
+	ret = inet_peer_xrlim_allow(peer, 1*HZ);
+	if (peer)
+		inet_putpeer(peer);
+	if (!ret)
 		goto release;
 
 	if (dev->addr_len) {

net/ipv6/route.c

···
 	memset(&fl6, 0, sizeof(fl6));
 	fl6.flowi6_oif = oif;
 	fl6.flowi6_mark = mark;
-	fl6.flowi6_flags = FLOWI_FLAG_PRECOW_METRICS;
+	fl6.flowi6_flags = 0;
 	fl6.daddr = iph->daddr;
 	fl6.saddr = iph->saddr;
 	fl6.flowlabel = (*(__be32 *) iph) & IPV6_FLOWINFO_MASK;
···
 			 int iif, int type, u32 pid, u32 seq,
 			 int prefix, int nowait, unsigned int flags)
 {
-	const struct inet_peer *peer;
 	struct rtmsg *rtm;
 	struct nlmsghdr *nlh;
 	long expires;
 	u32 table;
 	struct neighbour *n;
-	u32 ts, tsage;
 
 	if (prefix) {	/* user wants prefix routes only */
 		if (!(rt->rt6i_flags & RTF_PREFIX_RT)) {
···
 	else
 		expires = INT_MAX;
 
-	peer = NULL;
-	if (rt6_has_peer(rt))
-		peer = rt6_peer_ptr(rt);
-	ts = tsage = 0;
-	if (peer && peer->tcp_ts_stamp) {
-		ts = peer->tcp_ts;
-		tsage = get_seconds() - peer->tcp_ts_stamp;
-	}
-
-	if (rtnl_put_cacheinfo(skb, &rt->dst, 0, ts, tsage,
-			       expires, rt->dst.error) < 0)
+	if (rtnl_put_cacheinfo(skb, &rt->dst, 0, expires, rt->dst.error) < 0)
 		goto nla_put_failure;
 
 	return nlmsg_end(skb, nlh);

net/ipv6/tcp_ipv6.c

···
 	rt = (struct rt6_info *) dst;
 	if (tcp_death_row.sysctl_tw_recycle &&
 	    !tp->rx_opt.ts_recent_stamp &&
-	    ipv6_addr_equal(&rt->rt6i_dst.addr, &np->daddr)) {
-		struct inet_peer *peer = rt6_get_peer(rt);
-		/*
-		 * VJ's idea. We save last timestamp seen from
-		 * the destination in peer table, when entering state
-		 * TIME-WAIT * and initialize rx_opt.ts_recent from it,
-		 * when trying new connection.
-		 */
-		if (peer) {
-			inet_peer_refcheck(peer);
-			if ((u32)get_seconds() - peer->tcp_ts_stamp <= TCP_PAWS_MSL) {
-				tp->rx_opt.ts_recent_stamp = peer->tcp_ts_stamp;
-				tp->rx_opt.ts_recent = peer->tcp_ts;
-			}
-		}
-	}
+	    ipv6_addr_equal(&rt->rt6i_dst.addr, &np->daddr))
+		tcp_fetch_timewait_stamp(sk, dst);
 
 	icsk->icsk_ext_hdr_len = 0;
 	if (np->opt)
···
 		treq->iif = inet6_iif(skb);
 
 	if (!isn) {
-		struct inet_peer *peer = NULL;
-
 		if (ipv6_opt_accepted(sk, skb) ||
 		    np->rxopt.bits.rxinfo || np->rxopt.bits.rxoinfo ||
 		    np->rxopt.bits.rxhlim || np->rxopt.bits.rxohlim) {
···
 		 */
 		if (tmp_opt.saw_tstamp &&
 		    tcp_death_row.sysctl_tw_recycle &&
-		    (dst = inet6_csk_route_req(sk, &fl6, req)) != NULL &&
-		    (peer = rt6_get_peer((struct rt6_info *)dst)) != NULL &&
-		    ipv6_addr_equal((struct in6_addr *)peer->daddr.addr.a6,
-				    &treq->rmt_addr)) {
-			inet_peer_refcheck(peer);
-			if ((u32)get_seconds() - peer->tcp_ts_stamp < TCP_PAWS_MSL &&
-			    (s32)(peer->tcp_ts - req->ts_recent) >
-							TCP_PAWS_WINDOW) {
+		    (dst = inet6_csk_route_req(sk, &fl6, req)) != NULL) {
+			if (!tcp_peer_is_proven(req, dst, true)) {
 				NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PAWSPASSIVEREJECTED);
 				goto drop_and_release;
 			}
···
 		else if (!sysctl_tcp_syncookies &&
 			 (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) <
 			  (sysctl_max_syn_backlog >> 2)) &&
-			 (!peer || !peer->tcp_ts_stamp) &&
-			 (!dst || !dst_metric(dst, RTAX_RTT))) {
+			 !tcp_peer_is_proven(req, dst, false)) {
 			/* Without syncookies last quarter of
 			 * backlog is filled with destinations,
 			 * proven to be alive.
···
 	goto discard_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);
-
-	/* 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 struct timewait_sock_ops tcp6_timewait_sock_ops = {
 	.twsk_obj_size	= sizeof(struct tcp6_timewait_sock),
 	.twsk_unique	= tcp_twsk_unique,
···
 	.rebuild_header	   = inet6_sk_rebuild_header,
 	.conn_request	   = tcp_v6_conn_request,
 	.syn_recv_sock	   = tcp_v6_syn_recv_sock,
-	.get_peer	   = tcp_v6_get_peer,
 	.net_header_len	   = sizeof(struct ipv6hdr),
 	.net_frag_header_len = sizeof(struct frag_hdr),
 	.setsockopt	   = ipv6_setsockopt,
···
 	.rebuild_header	   = inet_sk_rebuild_header,
 	.conn_request	   = tcp_v6_conn_request,
 	.syn_recv_sock	   = tcp_v6_syn_recv_sock,
-	.get_peer	   = tcp_v4_get_peer,
 	.net_header_len	   = sizeof(struct iphdr),
 	.setsockopt	   = ipv6_setsockopt,
 	.getsockopt	   = ipv6_getsockopt,