Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next

Pull networking changes from David S Miller:

 1) Remove the ipv4 routing cache.  Now lookups go directly into the FIB
    trie and use prebuilt routes cached there.

    No more garbage collection, no more rDOS attacks on the routing
    cache.  Instead we now get predictable and consistent performance,
    no matter what the pattern of traffic we service.

    This has been almost 2 years in the making.  Special thanks to
    Julian Anastasov, Eric Dumazet, Steffen Klassert, and others who
    have helped along the way.

    I'm sure that with a change of this magnitude there will be some
    kind of fallout, but such things ought the be simple to fix at this
    point.  Luckily I'm not European so I'll be around all of August to
    fix things :-)

    The major stages of this work here are each fronted by a forced
    merge commit whose commit message contains a top-level description
    of the motivations and implementation issues.

 2) Pre-demux of established ipv4 TCP sockets, saves a route demux on
    input.

 3) TCP SYN/ACK performance tweaks from Eric Dumazet.

 4) Add namespace support for netfilter L4 conntrack helpers, from Gao
    Feng.

 5) Add config mechanism for Energy Efficient Ethernet to ethtool, from
    Yuval Mintz.

 6) Remove quadratic behavior from /proc/net/unix, from Eric Dumazet.

 7) Support for connection tracker helpers in userspace, from Pablo
    Neira Ayuso.

 8) Allow userspace driven TX load balancing functions in TEAM driver,
    from Jiri Pirko.

 9) Kill off NLMSG_PUT and RTA_PUT macros, more gross stuff with
    embedded gotos.

10) TCP Small Queues, essentially minimize the amount of TCP data queued
    up in the packet scheduler layer.  Whereas the existing BQL (Byte
    Queue Limits) limits the pkt_sched --> netdevice queuing levels,
    this controls the TCP --> pkt_sched queueing levels.

    From Eric Dumazet.

11) Reduce the number of get_page/put_page ops done on SKB fragments,
    from Alexander Duyck.

12) Implement protection against blind resets in TCP (RFC 5961), from
    Eric Dumazet.

13) Support the client side of TCP Fast Open, basically the ability to
    send data in the SYN exchange, from Yuchung Cheng.

    Basically, the sender queues up data with a sendmsg() call using
    MSG_FASTOPEN, then they do the connect() which emits the queued up
    fastopen data.

14) Avoid all the problems we get into in TCP when timers or PMTU events
    hit a locked socket.  The TCP Small Queues changes added a
    tcp_release_cb() that allows us to queue work up to the
    release_sock() caller, and that's what we use here too.  From Eric
    Dumazet.

15) Zero copy on TX support for TUN driver, from Michael S. Tsirkin.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1870 commits)
  genetlink: define lockdep_genl_is_held() when CONFIG_LOCKDEP
  r8169: revert "add byte queue limit support".
  ipv4: Change rt->rt_iif encoding.
  net: Make skb->skb_iif always track skb->dev
  ipv4: Prepare for change of rt->rt_iif encoding.
  ipv4: Remove all RTCF_DIRECTSRC handliing.
  ipv4: Really ignore ICMP address requests/replies.
  decnet: Don't set RTCF_DIRECTSRC.
  net/ipv4/ip_vti.c: Fix __rcu warnings detected by sparse.
  ipv4: Remove redundant assignment
  rds: set correct msg_namelen
  openvswitch: potential NULL deref in sample()
  tcp: dont drop MTU reduction indications
  bnx2x: Add new 57840 device IDs
  tcp: avoid oops in tcp_metrics and reset tcpm_stamp
  niu: Change niu_rbr_fill() to use unlikely() to check niu_rbr_add_page() return value
  niu: Fix to check for dma mapping errors.
  net: Fix references to out-of-scope variables in put_cmsg_compat()
  net: ethernet: davinci_emac: add pm_runtime support
  net: ethernet: davinci_emac: Remove unnecessary #include
  ...

1 files changed, 745 insertions, 0 deletions

diff --git a/net/ipv4/tcp_metrics.c b/net/ipv4/tcp_metrics.c
new file mode 100644
index 000000000000..2288a6399e1e
--- /dev/null
+++ b/net/ipv4/tcp_metrics.c
@@ -0,0 +1,745 @@
+#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 <linux/hash.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_fastopen_metrics {
+	u16	mss;
+	u16	syn_loss:10;		/* Recurring Fast Open SYN losses */
+	unsigned long	last_syn_loss;	/* Last Fast Open SYN loss */
+	struct	tcp_fastopen_cookie	cookie;
+};
+
+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];
+	struct tcp_fastopen_metrics	tcpm_fastopen;
+};
+
+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;
+
+	tm->tcpm_stamp = jiffies;
+
+	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;
+	tm->tcpm_fastopen.mss = 0;
+	tm->tcpm_fastopen.syn_loss = 0;
+	tm->tcpm_fastopen.cookie.len = 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;
+
+	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 = ipv6_addr_hash(&inet6_rsk(req)->rmt_addr);
+		break;
+	default:
+		return NULL;
+	}
+
+	net = dev_net(dst->dev);
+	hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
+
+	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 = ipv6_addr_hash(&tw6->tw_v6_daddr);
+		break;
+	default:
+		return NULL;
+	}
+
+	net = twsk_net(tw);
+	hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
+
+	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 = ipv6_addr_hash(&inet6_sk(sk)->daddr);
+		break;
+	default:
+		return NULL;
+	}
+
+	net = dev_net(dst->dev);
+	hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
+
+	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, TCP_METRIC_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 (tm) {
+		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 DEFINE_SEQLOCK(fastopen_seqlock);
+
+void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
+			    struct tcp_fastopen_cookie *cookie,
+			    int *syn_loss, unsigned long *last_syn_loss)
+{
+	struct tcp_metrics_block *tm;
+
+	rcu_read_lock();
+	tm = tcp_get_metrics(sk, __sk_dst_get(sk), false);
+	if (tm) {
+		struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
+		unsigned int seq;
+
+		do {
+			seq = read_seqbegin(&fastopen_seqlock);
+			if (tfom->mss)
+				*mss = tfom->mss;
+			*cookie = tfom->cookie;
+			*syn_loss = tfom->syn_loss;
+			*last_syn_loss = *syn_loss ? tfom->last_syn_loss : 0;
+		} while (read_seqretry(&fastopen_seqlock, seq));
+	}
+	rcu_read_unlock();
+}
+
+void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
+			    struct tcp_fastopen_cookie *cookie, bool syn_lost)
+{
+	struct tcp_metrics_block *tm;
+
+	rcu_read_lock();
+	tm = tcp_get_metrics(sk, __sk_dst_get(sk), true);
+	if (tm) {
+		struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
+
+		write_seqlock_bh(&fastopen_seqlock);
+		tfom->mss = mss;
+		if (cookie->len > 0)
+			tfom->cookie = *cookie;
+		if (syn_lost) {
+			++tfom->syn_loss;
+			tfom->last_syn_loss = jiffies;
+		} else
+			tfom->syn_loss = 0;
+		write_sequnlock_bh(&fastopen_seqlock);
+	}
+	rcu_read_unlock();
+}
+
+static unsigned int tcpmhash_entries;
+static int __init set_tcpmhash_entries(char *str)
+{
+	ssize_t ret;
+
+	if (!str)
+		return 0;
+
+	ret = kstrtouint(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)
+{
+	size_t size;
+	unsigned int slots;
+
+	slots = tcpmhash_entries;
+	if (!slots) {
+		if (totalram_pages >= 128 * 1024)
+			slots = 16 * 1024;
+		else
+			slots = 8 * 1024;
+	}
+
+	net->ipv4.tcp_metrics_hash_log = order_base_2(slots);
+	size = sizeof(struct tcpm_hash_bucket) << net->ipv4.tcp_metrics_hash_log;
+
+	net->ipv4.tcp_metrics_hash = kzalloc(size, GFP_KERNEL);
+	if (!net->ipv4.tcp_metrics_hash)
+		return -ENOMEM;
+
+	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);
+}