1 files changed, 298 insertions, 161 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 1da0ade98236..0185eea59342 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -73,6 +73,7 @@
 #include <net/inet_common.h>
 #include <linux/ipsec.h>
 #include <asm/unaligned.h>
+#include <linux/errqueue.h>
 
 int sysctl_tcp_timestamps __read_mostly = 1;
 int sysctl_tcp_window_scaling __read_mostly = 1;
@@ -666,11 +667,11 @@ static void tcp_event_data_recv(struct sock *sk, struct sk_buff *skb)
  * To save cycles in the RFC 1323 implementation it was better to break
  * it up into three procedures. -- erics
  */
-static void tcp_rtt_estimator(struct sock *sk, const __u32 mrtt)
+static void tcp_rtt_estimator(struct sock *sk, long mrtt_us)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
-	long m = mrtt; /* RTT */
-	u32 srtt = tp->srtt;
+	long m = mrtt_us; /* RTT */
+	u32 srtt = tp->srtt_us;
 
 	/*	The following amusing code comes from Jacobson's
 	 *	article in SIGCOMM '88.  Note that rtt and mdev
@@ -693,7 +694,7 @@ static void tcp_rtt_estimator(struct sock *sk, const __u32 mrtt)
 		srtt += m;		/* rtt = 7/8 rtt + 1/8 new */
 		if (m < 0) {
 			m = -m;		/* m is now abs(error) */
-			m -= (tp->mdev >> 2);   /* similar update on mdev */
+			m -= (tp->mdev_us >> 2);   /* similar update on mdev */
 			/* This is similar to one of Eifel findings.
 			 * Eifel blocks mdev updates when rtt decreases.
 			 * This solution is a bit different: we use finer gain
@@ -705,28 +706,29 @@ static void tcp_rtt_estimator(struct sock *sk, const __u32 mrtt)
 			if (m > 0)
 				m >>= 3;
 		} else {
-			m -= (tp->mdev >> 2);   /* similar update on mdev */
+			m -= (tp->mdev_us >> 2);   /* similar update on mdev */
 		}
-		tp->mdev += m;	    	/* mdev = 3/4 mdev + 1/4 new */
-		if (tp->mdev > tp->mdev_max) {
-			tp->mdev_max = tp->mdev;
-			if (tp->mdev_max > tp->rttvar)
-				tp->rttvar = tp->mdev_max;
+		tp->mdev_us += m;		/* mdev = 3/4 mdev + 1/4 new */
+		if (tp->mdev_us > tp->mdev_max_us) {
+			tp->mdev_max_us = tp->mdev_us;
+			if (tp->mdev_max_us > tp->rttvar_us)
+				tp->rttvar_us = tp->mdev_max_us;
 		}
 		if (after(tp->snd_una, tp->rtt_seq)) {
-			if (tp->mdev_max < tp->rttvar)
-				tp->rttvar -= (tp->rttvar - tp->mdev_max) >> 2;
+			if (tp->mdev_max_us < tp->rttvar_us)
+				tp->rttvar_us -= (tp->rttvar_us - tp->mdev_max_us) >> 2;
 			tp->rtt_seq = tp->snd_nxt;
-			tp->mdev_max = tcp_rto_min(sk);
+			tp->mdev_max_us = tcp_rto_min_us(sk);
 		}
 	} else {
 		/* no previous measure. */
 		srtt = m << 3;		/* take the measured time to be rtt */
-		tp->mdev = m << 1;	/* make sure rto = 3*rtt */
-		tp->mdev_max = tp->rttvar = max(tp->mdev, tcp_rto_min(sk));
+		tp->mdev_us = m << 1;	/* make sure rto = 3*rtt */
+		tp->rttvar_us = max(tp->mdev_us, tcp_rto_min_us(sk));
+		tp->mdev_max_us = tp->rttvar_us;
 		tp->rtt_seq = tp->snd_nxt;
 	}
-	tp->srtt = max(1U, srtt);
+	tp->srtt_us = max(1U, srtt);
 }
 
 /* Set the sk_pacing_rate to allow proper sizing of TSO packets.
@@ -741,20 +743,12 @@ static void tcp_update_pacing_rate(struct sock *sk)
 	u64 rate;
 
 	/* set sk_pacing_rate to 200 % of current rate (mss * cwnd / srtt) */
-	rate = (u64)tp->mss_cache * 2 * (HZ << 3);
+	rate = (u64)tp->mss_cache * 2 * (USEC_PER_SEC << 3);
 
 	rate *= max(tp->snd_cwnd, tp->packets_out);
 
-	/* Correction for small srtt and scheduling constraints.
-	 * For small rtt, consider noise is too high, and use
-	 * the minimal value (srtt = 1 -> 125 us for HZ=1000)
-	 *
-	 * We probably need usec resolution in the future.
-	 * Note: This also takes care of possible srtt=0 case,
-	 * when tcp_rtt_estimator() was not yet called.
-	 */
-	if (tp->srtt > 8 + 2)
-		do_div(rate, tp->srtt);
+	if (likely(tp->srtt_us))
+		do_div(rate, tp->srtt_us);
 
 	/* ACCESS_ONCE() is needed because sch_fq fetches sk_pacing_rate
 	 * without any lock. We want to make sure compiler wont store
@@ -1112,7 +1106,7 @@ static bool tcp_check_dsack(struct sock *sk, const struct sk_buff *ack_skb,
 	}
 
 	/* D-SACK for already forgotten data... Do dumb counting. */
-	if (dup_sack && tp->undo_marker && tp->undo_retrans &&
+	if (dup_sack && tp->undo_marker && tp->undo_retrans > 0 &&
 	    !after(end_seq_0, prior_snd_una) &&
 	    after(end_seq_0, tp->undo_marker))
 		tp->undo_retrans--;
@@ -1121,10 +1115,10 @@ static bool tcp_check_dsack(struct sock *sk, const struct sk_buff *ack_skb,
 }
 
 struct tcp_sacktag_state {
-	int reord;
-	int fack_count;
-	int flag;
-	s32 rtt; /* RTT measured by SACKing never-retransmitted data */
+	int	reord;
+	int	fack_count;
+	long	rtt_us; /* RTT measured by SACKing never-retransmitted data */
+	int	flag;
 };
 
 /* Check if skb is fully within the SACK block. In presence of GSO skbs,
@@ -1168,12 +1162,12 @@ static int tcp_match_skb_to_sack(struct sock *sk, struct sk_buff *skb,
 			unsigned int new_len = (pkt_len / mss) * mss;
 			if (!in_sack && new_len < pkt_len) {
 				new_len += mss;
-				if (new_len > skb->len)
+				if (new_len >= skb->len)
 					return 0;
 			}
 			pkt_len = new_len;
 		}
-		err = tcp_fragment(sk, skb, pkt_len, mss);
+		err = tcp_fragment(sk, skb, pkt_len, mss, GFP_ATOMIC);
 		if (err < 0)
 			return err;
 	}
@@ -1185,14 +1179,15 @@ static int tcp_match_skb_to_sack(struct sock *sk, struct sk_buff *skb,
 static u8 tcp_sacktag_one(struct sock *sk,
 			  struct tcp_sacktag_state *state, u8 sacked,
 			  u32 start_seq, u32 end_seq,
-			  int dup_sack, int pcount, u32 xmit_time)
+			  int dup_sack, int pcount,
+			  const struct skb_mstamp *xmit_time)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	int fack_count = state->fack_count;
 
 	/* Account D-SACK for retransmitted packet. */
 	if (dup_sack && (sacked & TCPCB_RETRANS)) {
-		if (tp->undo_marker && tp->undo_retrans &&
+		if (tp->undo_marker && tp->undo_retrans > 0 &&
 		    after(end_seq, tp->undo_marker))
 			tp->undo_retrans--;
 		if (sacked & TCPCB_SACKED_ACKED)
@@ -1226,8 +1221,13 @@ static u8 tcp_sacktag_one(struct sock *sk,
 				if (!after(end_seq, tp->high_seq))
 					state->flag |= FLAG_ORIG_SACK_ACKED;
 				/* Pick the earliest sequence sacked for RTT */
-				if (state->rtt < 0)
-					state->rtt = tcp_time_stamp - xmit_time;
+				if (state->rtt_us < 0) {
+					struct skb_mstamp now;
+
+					skb_mstamp_get(&now);
+					state->rtt_us = skb_mstamp_us_delta(&now,
+								xmit_time);
+				}
 			}
 
 			if (sacked & TCPCB_LOST) {
@@ -1286,7 +1286,7 @@ static bool tcp_shifted_skb(struct sock *sk, struct sk_buff *skb,
 	 */
 	tcp_sacktag_one(sk, state, TCP_SKB_CB(skb)->sacked,
 			start_seq, end_seq, dup_sack, pcount,
-			TCP_SKB_CB(skb)->when);
+			&skb->skb_mstamp);
 
 	if (skb == tp->lost_skb_hint)
 		tp->lost_cnt_hint += pcount;
@@ -1564,7 +1564,7 @@ static struct sk_buff *tcp_sacktag_walk(struct sk_buff *skb, struct sock *sk,
 						TCP_SKB_CB(skb)->end_seq,
 						dup_sack,
 						tcp_skb_pcount(skb),
-						TCP_SKB_CB(skb)->when);
+						&skb->skb_mstamp);
 
 			if (!before(TCP_SKB_CB(skb)->seq,
 				    tcp_highest_sack_seq(tp)))
@@ -1621,7 +1621,7 @@ static int tcp_sack_cache_ok(const struct tcp_sock *tp, const struct tcp_sack_bl
 
 static int
 tcp_sacktag_write_queue(struct sock *sk, const struct sk_buff *ack_skb,
-			u32 prior_snd_una, s32 *sack_rtt)
+			u32 prior_snd_una, long *sack_rtt_us)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	const unsigned char *ptr = (skb_transport_header(ack_skb) +
@@ -1639,7 +1639,7 @@ tcp_sacktag_write_queue(struct sock *sk, const struct sk_buff *ack_skb,
 
 	state.flag = 0;
 	state.reord = tp->packets_out;
-	state.rtt = -1;
+	state.rtt_us = -1L;
 
 	if (!tp->sacked_out) {
 		if (WARN_ON(tp->fackets_out))
@@ -1823,7 +1823,7 @@ out:
 	WARN_ON((int)tp->retrans_out < 0);
 	WARN_ON((int)tcp_packets_in_flight(tp) < 0);
 #endif
-	*sack_rtt = state.rtt;
+	*sack_rtt_us = state.rtt_us;
 	return state.flag;
 }
 
@@ -1893,7 +1893,7 @@ static void tcp_clear_retrans_partial(struct tcp_sock *tp)
 	tp->lost_out = 0;
 
 	tp->undo_marker = 0;
-	tp->undo_retrans = 0;
+	tp->undo_retrans = -1;
 }
 
 void tcp_clear_retrans(struct tcp_sock *tp)
@@ -1904,16 +1904,17 @@ void tcp_clear_retrans(struct tcp_sock *tp)
 	tp->sacked_out = 0;
 }
 
-/* Enter Loss state. If "how" is not zero, forget all SACK information
+/* Enter Loss state. If we detect SACK reneging, forget all SACK information
  * and reset tags completely, otherwise preserve SACKs. If receiver
  * dropped its ofo queue, we will know this due to reneging detection.
  */
-void tcp_enter_loss(struct sock *sk, int how)
+void tcp_enter_loss(struct sock *sk)
 {
 	const struct inet_connection_sock *icsk = inet_csk(sk);
 	struct tcp_sock *tp = tcp_sk(sk);
 	struct sk_buff *skb;
 	bool new_recovery = false;
+	bool is_reneg;			/* is receiver reneging on SACKs? */
 
 	/* Reduce ssthresh if it has not yet been made inside this window. */
 	if (icsk->icsk_ca_state <= TCP_CA_Disorder ||
@@ -1934,7 +1935,11 @@ void tcp_enter_loss(struct sock *sk, int how)
 		tcp_reset_reno_sack(tp);
 
 	tp->undo_marker = tp->snd_una;
-	if (how) {
+
+	skb = tcp_write_queue_head(sk);
+	is_reneg = skb && (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED);
+	if (is_reneg) {
+		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPSACKRENEGING);
 		tp->sacked_out = 0;
 		tp->fackets_out = 0;
 	}
@@ -1948,7 +1953,7 @@ void tcp_enter_loss(struct sock *sk, int how)
 			tp->undo_marker = 0;
 
 		TCP_SKB_CB(skb)->sacked &= (~TCPCB_TAGBITS)|TCPCB_SACKED_ACKED;
-		if (!(TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_ACKED) || how) {
+		if (!(TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_ACKED) || is_reneg) {
 			TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_ACKED;
 			TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
 			tp->lost_out += tcp_skb_pcount(skb);
@@ -1981,19 +1986,21 @@ void tcp_enter_loss(struct sock *sk, int how)
  * remembered SACKs do not reflect real state of receiver i.e.
  * receiver _host_ is heavily congested (or buggy).
  *
- * Do processing similar to RTO timeout.
+ * To avoid big spurious retransmission bursts due to transient SACK
+ * scoreboard oddities that look like reneging, we give the receiver a
+ * little time (max(RTT/2, 10ms)) to send us some more ACKs that will
+ * restore sanity to the SACK scoreboard. If the apparent reneging
+ * persists until this RTO then we'll clear the SACK scoreboard.
  */
 static bool tcp_check_sack_reneging(struct sock *sk, int flag)
 {
 	if (flag & FLAG_SACK_RENEGING) {
-		struct inet_connection_sock *icsk = inet_csk(sk);
-		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPSACKRENEGING);
+		struct tcp_sock *tp = tcp_sk(sk);
+		unsigned long delay = max(usecs_to_jiffies(tp->srtt_us >> 4),
+					  msecs_to_jiffies(10));
 
-		tcp_enter_loss(sk, 1);
-		icsk->icsk_retransmits++;
-		tcp_retransmit_skb(sk, tcp_write_queue_head(sk));
 		inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
-					  icsk->icsk_rto, TCP_RTO_MAX);
+					  delay, TCP_RTO_MAX);
 		return true;
 	}
 	return false;
@@ -2034,10 +2041,12 @@ static bool tcp_pause_early_retransmit(struct sock *sk, int flag)
 	 * available, or RTO is scheduled to fire first.
 	 */
 	if (sysctl_tcp_early_retrans < 2 || sysctl_tcp_early_retrans > 3 ||
-	    (flag & FLAG_ECE) || !tp->srtt)
+	    (flag & FLAG_ECE) || !tp->srtt_us)
 		return false;
 
-	delay = max_t(unsigned long, (tp->srtt >> 5), msecs_to_jiffies(2));
+	delay = max(usecs_to_jiffies(tp->srtt_us >> 5),
+		    msecs_to_jiffies(2));
+
 	if (!time_after(inet_csk(sk)->icsk_timeout, (jiffies + delay)))
 		return false;
 
@@ -2239,7 +2248,8 @@ static void tcp_mark_head_lost(struct sock *sk, int packets, int mark_head)
 				break;
 
 			mss = skb_shinfo(skb)->gso_size;
-			err = tcp_fragment(sk, skb, (packets - oldcnt) * mss, mss);
+			err = tcp_fragment(sk, skb, (packets - oldcnt) * mss,
+					   mss, GFP_ATOMIC);
 			if (err < 0)
 				break;
 			cnt = packets;
@@ -2472,7 +2482,7 @@ static bool tcp_try_undo_loss(struct sock *sk, bool frto_undo)
  *	losses and/or application stalls), do not perform any further cwnd
  *	reductions, but instead slow start up to ssthresh.
  */
-static void tcp_init_cwnd_reduction(struct sock *sk, const bool set_ssthresh)
+static void tcp_init_cwnd_reduction(struct sock *sk)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 
@@ -2482,8 +2492,7 @@ static void tcp_init_cwnd_reduction(struct sock *sk, const bool set_ssthresh)
 	tp->prior_cwnd = tp->snd_cwnd;
 	tp->prr_delivered = 0;
 	tp->prr_out = 0;
-	if (set_ssthresh)
-		tp->snd_ssthresh = inet_csk(sk)->icsk_ca_ops->ssthresh(sk);
+	tp->snd_ssthresh = inet_csk(sk)->icsk_ca_ops->ssthresh(sk);
 	TCP_ECN_queue_cwr(tp);
 }
 
@@ -2525,14 +2534,14 @@ static inline void tcp_end_cwnd_reduction(struct sock *sk)
 }
 
 /* Enter CWR state. Disable cwnd undo since congestion is proven with ECN */
-void tcp_enter_cwr(struct sock *sk, const int set_ssthresh)
+void tcp_enter_cwr(struct sock *sk)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 
 	tp->prior_ssthresh = 0;
 	if (inet_csk(sk)->icsk_ca_state < TCP_CA_CWR) {
 		tp->undo_marker = 0;
-		tcp_init_cwnd_reduction(sk, set_ssthresh);
+		tcp_init_cwnd_reduction(sk);
 		tcp_set_ca_state(sk, TCP_CA_CWR);
 	}
 }
@@ -2561,7 +2570,7 @@ static void tcp_try_to_open(struct sock *sk, int flag, const int prior_unsacked)
 		tp->retrans_stamp = 0;
 
 	if (flag & FLAG_ECE)
-		tcp_enter_cwr(sk, 1);
+		tcp_enter_cwr(sk);
 
 	if (inet_csk(sk)->icsk_ca_state != TCP_CA_CWR) {
 		tcp_try_keep_open(sk);
@@ -2662,12 +2671,12 @@ static void tcp_enter_recovery(struct sock *sk, bool ece_ack)
 
 	tp->prior_ssthresh = 0;
 	tp->undo_marker = tp->snd_una;
-	tp->undo_retrans = tp->retrans_out;
+	tp->undo_retrans = tp->retrans_out ? : -1;
 
 	if (inet_csk(sk)->icsk_ca_state < TCP_CA_CWR) {
 		if (!ece_ack)
 			tp->prior_ssthresh = tcp_current_ssthresh(sk);
-		tcp_init_cwnd_reduction(sk, true);
+		tcp_init_cwnd_reduction(sk);
 	}
 	tcp_set_ca_state(sk, TCP_CA_Recovery);
 }
@@ -2677,18 +2686,16 @@ static void tcp_enter_recovery(struct sock *sk, bool ece_ack)
  */
 static void tcp_process_loss(struct sock *sk, int flag, bool is_dupack)
 {
-	struct inet_connection_sock *icsk = inet_csk(sk);
 	struct tcp_sock *tp = tcp_sk(sk);
 	bool recovered = !before(tp->snd_una, tp->high_seq);
 
 	if (tp->frto) { /* F-RTO RFC5682 sec 3.1 (sack enhanced version). */
-		if (flag & FLAG_ORIG_SACK_ACKED) {
-			/* Step 3.b. A timeout is spurious if not all data are
-			 * lost, i.e., never-retransmitted data are (s)acked.
-			 */
-			tcp_try_undo_loss(sk, true);
+		/* Step 3.b. A timeout is spurious if not all data are
+		 * lost, i.e., never-retransmitted data are (s)acked.
+		 */
+		if (tcp_try_undo_loss(sk, flag & FLAG_ORIG_SACK_ACKED))
 			return;
-		}
+
 		if (after(tp->snd_nxt, tp->high_seq) &&
 		    (flag & FLAG_DATA_SACKED || is_dupack)) {
 			tp->frto = 0; /* Loss was real: 2nd part of step 3.a */
@@ -2704,12 +2711,9 @@ static void tcp_process_loss(struct sock *sk, int flag, bool is_dupack)
 
 	if (recovered) {
 		/* F-RTO RFC5682 sec 3.1 step 2.a and 1st part of step 3.a */
-		icsk->icsk_retransmits = 0;
 		tcp_try_undo_recovery(sk);
 		return;
 	}
-	if (flag & FLAG_DATA_ACKED)
-		icsk->icsk_retransmits = 0;
 	if (tcp_is_reno(tp)) {
 		/* A Reno DUPACK means new data in F-RTO step 2.b above are
 		 * delivered. Lower inflight to clock out (re)tranmissions.
@@ -2884,7 +2888,7 @@ static void tcp_fastretrans_alert(struct sock *sk, const int acked,
 }
 
 static inline bool tcp_ack_update_rtt(struct sock *sk, const int flag,
-				      s32 seq_rtt, s32 sack_rtt)
+				      long seq_rtt_us, long sack_rtt_us)
 {
 	const struct tcp_sock *tp = tcp_sk(sk);
 
@@ -2894,10 +2898,10 @@ static inline bool tcp_ack_update_rtt(struct sock *sk, const int flag,
 	 * is acked (RFC6298).
 	 */
 	if (flag & FLAG_RETRANS_DATA_ACKED)
-		seq_rtt = -1;
+		seq_rtt_us = -1L;
 
-	if (seq_rtt < 0)
-		seq_rtt = sack_rtt;
+	if (seq_rtt_us < 0)
+		seq_rtt_us = sack_rtt_us;
 
 	/* RTTM Rule: A TSecr value received in a segment is used to
 	 * update the averaged RTT measurement only if the segment
@@ -2905,14 +2909,14 @@ static inline bool tcp_ack_update_rtt(struct sock *sk, const int flag,
 	 * left edge of the send window.
 	 * See draft-ietf-tcplw-high-performance-00, section 3.3.
 	 */
-	if (seq_rtt < 0 && tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr &&
+	if (seq_rtt_us < 0 && tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr &&
 	    flag & FLAG_ACKED)
-		seq_rtt = tcp_time_stamp - tp->rx_opt.rcv_tsecr;
+		seq_rtt_us = jiffies_to_usecs(tcp_time_stamp - tp->rx_opt.rcv_tsecr);
 
-	if (seq_rtt < 0)
+	if (seq_rtt_us < 0)
 		return false;
 
-	tcp_rtt_estimator(sk, seq_rtt);
+	tcp_rtt_estimator(sk, seq_rtt_us);
 	tcp_set_rto(sk);
 
 	/* RFC6298: only reset backoff on valid RTT measurement. */
@@ -2924,22 +2928,23 @@ static inline bool tcp_ack_update_rtt(struct sock *sk, const int flag,
 static void tcp_synack_rtt_meas(struct sock *sk, const u32 synack_stamp)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
-	s32 seq_rtt = -1;
+	long seq_rtt_us = -1L;
 
 	if (synack_stamp && !tp->total_retrans)
-		seq_rtt = tcp_time_stamp - synack_stamp;
+		seq_rtt_us = jiffies_to_usecs(tcp_time_stamp - synack_stamp);
 
 	/* If the ACK acks both the SYNACK and the (Fast Open'd) data packets
 	 * sent in SYN_RECV, SYNACK RTT is the smooth RTT computed in tcp_ack()
 	 */
-	if (!tp->srtt)
-		tcp_ack_update_rtt(sk, FLAG_SYN_ACKED, seq_rtt, -1);
+	if (!tp->srtt_us)
+		tcp_ack_update_rtt(sk, FLAG_SYN_ACKED, seq_rtt_us, -1L);
 }
 
-static void tcp_cong_avoid(struct sock *sk, u32 ack, u32 acked, u32 in_flight)
+static void tcp_cong_avoid(struct sock *sk, u32 ack, u32 acked)
 {
 	const struct inet_connection_sock *icsk = inet_csk(sk);
-	icsk->icsk_ca_ops->cong_avoid(sk, ack, acked, in_flight);
+
+	icsk->icsk_ca_ops->cong_avoid(sk, ack, acked);
 	tcp_sk(sk)->snd_cwnd_stamp = tcp_time_stamp;
 }
 
@@ -3022,26 +3027,32 @@ static u32 tcp_tso_acked(struct sock *sk, struct sk_buff *skb)
  * arrived at the other end.
  */
 static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
-			       u32 prior_snd_una, s32 sack_rtt)
+			       u32 prior_snd_una, long sack_rtt_us)
 {
-	struct tcp_sock *tp = tcp_sk(sk);
 	const struct inet_connection_sock *icsk = inet_csk(sk);
-	struct sk_buff *skb;
-	u32 now = tcp_time_stamp;
+	struct skb_mstamp first_ackt, last_ackt, now;
+	struct tcp_sock *tp = tcp_sk(sk);
+	u32 prior_sacked = tp->sacked_out;
+	u32 reord = tp->packets_out;
 	bool fully_acked = true;
-	int flag = 0;
+	long ca_seq_rtt_us = -1L;
+	long seq_rtt_us = -1L;
+	struct sk_buff *skb;
 	u32 pkts_acked = 0;
-	u32 reord = tp->packets_out;
-	u32 prior_sacked = tp->sacked_out;
-	s32 seq_rtt = -1;
-	s32 ca_seq_rtt = -1;
-	ktime_t last_ackt = net_invalid_timestamp();
 	bool rtt_update;
+	int flag = 0;
+
+	first_ackt.v64 = 0;
 
 	while ((skb = tcp_write_queue_head(sk)) && skb != tcp_send_head(sk)) {
+		struct skb_shared_info *shinfo = skb_shinfo(skb);
 		struct tcp_skb_cb *scb = TCP_SKB_CB(skb);
-		u32 acked_pcount;
 		u8 sacked = scb->sacked;
+		u32 acked_pcount;
+
+		if (unlikely(shinfo->tx_flags & SKBTX_ACK_TSTAMP) &&
+		    between(shinfo->tskey, prior_snd_una, tp->snd_una - 1))
+			__skb_tstamp_tx(skb, NULL, sk, SCM_TSTAMP_ACK);
 
 		/* Determine how many packets and what bytes were acked, tso and else */
 		if (after(scb->end_seq, tp->snd_una)) {
@@ -3063,11 +3074,11 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
 				tp->retrans_out -= acked_pcount;
 			flag |= FLAG_RETRANS_DATA_ACKED;
 		} else {
-			ca_seq_rtt = now - scb->when;
-			last_ackt = skb->tstamp;
-			if (seq_rtt < 0) {
-				seq_rtt = ca_seq_rtt;
-			}
+			last_ackt = skb->skb_mstamp;
+			WARN_ON_ONCE(last_ackt.v64 == 0);
+			if (!first_ackt.v64)
+				first_ackt = last_ackt;
+
 			if (!(sacked & TCPCB_SACKED_ACKED))
 				reord = min(pkts_acked, reord);
 			if (!after(scb->end_seq, tp->high_seq))
@@ -3113,7 +3124,13 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
 	if (skb && (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED))
 		flag |= FLAG_SACK_RENEGING;
 
-	rtt_update = tcp_ack_update_rtt(sk, flag, seq_rtt, sack_rtt);
+	skb_mstamp_get(&now);
+	if (first_ackt.v64) {
+		seq_rtt_us = skb_mstamp_us_delta(&now, &first_ackt);
+		ca_seq_rtt_us = skb_mstamp_us_delta(&now, &last_ackt);
+	}
+
+	rtt_update = tcp_ack_update_rtt(sk, flag, seq_rtt_us, sack_rtt_us);
 
 	if (flag & FLAG_ACKED) {
 		const struct tcp_congestion_ops *ca_ops
@@ -3141,25 +3158,11 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
 
 		tp->fackets_out -= min(pkts_acked, tp->fackets_out);
 
-		if (ca_ops->pkts_acked) {
-			s32 rtt_us = -1;
-
-			/* Is the ACK triggering packet unambiguous? */
-			if (!(flag & FLAG_RETRANS_DATA_ACKED)) {
-				/* High resolution needed and available? */
-				if (ca_ops->flags & TCP_CONG_RTT_STAMP &&
-				    !ktime_equal(last_ackt,
-						 net_invalid_timestamp()))
-					rtt_us = ktime_us_delta(ktime_get_real(),
-								last_ackt);
-				else if (ca_seq_rtt >= 0)
-					rtt_us = jiffies_to_usecs(ca_seq_rtt);
-			}
+		if (ca_ops->pkts_acked)
+			ca_ops->pkts_acked(sk, pkts_acked, ca_seq_rtt_us);
 
-			ca_ops->pkts_acked(sk, pkts_acked, rtt_us);
-		}
-	} else if (skb && rtt_update && sack_rtt >= 0 &&
-		   sack_rtt > (s32)(now - TCP_SKB_CB(skb)->when)) {
+	} else if (skb && rtt_update && sack_rtt_us >= 0 &&
+		   sack_rtt_us > skb_mstamp_us_delta(&now, &skb->skb_mstamp)) {
 		/* Do not re-arm RTO if the sack RTT is measured from data sent
 		 * after when the head was last (re)transmitted. Otherwise the
 		 * timeout may continue to extend in loss recovery.
@@ -3350,7 +3353,7 @@ static void tcp_process_tlp_ack(struct sock *sk, u32 ack, int flag)
 		tp->tlp_high_seq = 0;
 		/* Don't reduce cwnd if DSACK arrives for TLP retrans. */
 		if (!(flag & FLAG_DSACKING_ACK)) {
-			tcp_init_cwnd_reduction(sk, true);
+			tcp_init_cwnd_reduction(sk);
 			tcp_set_ca_state(sk, TCP_CA_CWR);
 			tcp_end_cwnd_reduction(sk);
 			tcp_try_keep_open(sk);
@@ -3369,12 +3372,11 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 	u32 ack_seq = TCP_SKB_CB(skb)->seq;
 	u32 ack = TCP_SKB_CB(skb)->ack_seq;
 	bool is_dupack = false;
-	u32 prior_in_flight, prior_cwnd = tp->snd_cwnd, prior_rtt = tp->srtt;
 	u32 prior_fackets;
 	int prior_packets = tp->packets_out;
 	const int prior_unsacked = tp->packets_out - tp->sacked_out;
 	int acked = 0; /* Number of packets newly acked */
-	s32 sack_rtt = -1;
+	long sack_rtt_us = -1L;
 
 	/* If the ack is older than previous acks
 	 * then we can probably ignore it.
@@ -3398,11 +3400,12 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 	    icsk->icsk_pending == ICSK_TIME_LOSS_PROBE)
 		tcp_rearm_rto(sk);
 
-	if (after(ack, prior_snd_una))
+	if (after(ack, prior_snd_una)) {
 		flag |= FLAG_SND_UNA_ADVANCED;
+		icsk->icsk_retransmits = 0;
+	}
 
 	prior_fackets = tp->fackets_out;
-	prior_in_flight = tcp_packets_in_flight(tp);
 
 	/* ts_recent update must be made after we are sure that the packet
 	 * is in window.
@@ -3432,7 +3435,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 
 		if (TCP_SKB_CB(skb)->sacked)
 			flag |= tcp_sacktag_write_queue(sk, skb, prior_snd_una,
-							&sack_rtt);
+							&sack_rtt_us);
 
 		if (TCP_ECN_rcv_ecn_echo(tp, tcp_hdr(skb)))
 			flag |= FLAG_ECE;
@@ -3451,12 +3454,13 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 
 	/* See if we can take anything off of the retransmit queue. */
 	acked = tp->packets_out;
-	flag |= tcp_clean_rtx_queue(sk, prior_fackets, prior_snd_una, sack_rtt);
+	flag |= tcp_clean_rtx_queue(sk, prior_fackets, prior_snd_una,
+				    sack_rtt_us);
 	acked -= tp->packets_out;
 
 	/* Advance cwnd if state allows */
 	if (tcp_may_raise_cwnd(sk, flag))
-		tcp_cong_avoid(sk, ack, acked, prior_in_flight);
+		tcp_cong_avoid(sk, ack, acked);
 
 	if (tcp_ack_is_dubious(sk, flag)) {
 		is_dupack = !(flag & (FLAG_SND_UNA_ADVANCED | FLAG_NOT_DUP));
@@ -3474,8 +3478,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 
 	if (icsk->icsk_pending == ICSK_TIME_RETRANS)
 		tcp_schedule_loss_probe(sk);
-	if (tp->srtt != prior_rtt || tp->snd_cwnd != prior_cwnd)
-		tcp_update_pacing_rate(sk);
+	tcp_update_pacing_rate(sk);
 	return 1;
 
 no_queue:
@@ -3504,7 +3507,7 @@ old_ack:
 	 */
 	if (TCP_SKB_CB(skb)->sacked) {
 		flag |= tcp_sacktag_write_queue(sk, skb, prior_snd_una,
-						&sack_rtt);
+						&sack_rtt_us);
 		tcp_fastretrans_alert(sk, acked, prior_unsacked,
 				      is_dupack, flag);
 	}
@@ -4418,7 +4421,7 @@ queue_and_out:
 		if (eaten > 0)
 			kfree_skb_partial(skb, fragstolen);
 		if (!sock_flag(sk, SOCK_DEAD))
-			sk->sk_data_ready(sk, 0);
+			sk->sk_data_ready(sk);
 		return;
 	}
 
@@ -4708,28 +4711,6 @@ static int tcp_prune_queue(struct sock *sk)
 	return -1;
 }
 
-/* RFC2861, slow part. Adjust cwnd, after it was not full during one rto.
- * As additional protections, we do not touch cwnd in retransmission phases,
- * and if application hit its sndbuf limit recently.
- */
-void tcp_cwnd_application_limited(struct sock *sk)
-{
-	struct tcp_sock *tp = tcp_sk(sk);
-
-	if (inet_csk(sk)->icsk_ca_state == TCP_CA_Open &&
-	    sk->sk_socket && !test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) {
-		/* Limited by application or receiver window. */
-		u32 init_win = tcp_init_cwnd(tp, __sk_dst_get(sk));
-		u32 win_used = max(tp->snd_cwnd_used, init_win);
-		if (win_used < tp->snd_cwnd) {
-			tp->snd_ssthresh = tcp_current_ssthresh(sk);
-			tp->snd_cwnd = (tp->snd_cwnd + win_used) >> 1;
-		}
-		tp->snd_cwnd_used = 0;
-	}
-	tp->snd_cwnd_stamp = tcp_time_stamp;
-}
-
 static bool tcp_should_expand_sndbuf(const struct sock *sk)
 {
 	const struct tcp_sock *tp = tcp_sk(sk);
@@ -4919,7 +4900,7 @@ static void tcp_urg(struct sock *sk, struct sk_buff *skb, const struct tcphdr *t
 				BUG();
 			tp->urg_data = TCP_URG_VALID | tmp;
 			if (!sock_flag(sk, SOCK_DEAD))
-				sk->sk_data_ready(sk, 0);
+				sk->sk_data_ready(sk);
 		}
 	}
 }
@@ -5214,7 +5195,7 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
 no_ack:
 			if (eaten)
 				kfree_skb_partial(skb, fragstolen);
-			sk->sk_data_ready(sk, 0);
+			sk->sk_data_ready(sk);
 			return;
 		}
 	}
@@ -5334,9 +5315,12 @@ static bool tcp_rcv_fastopen_synack(struct sock *sk, struct sk_buff *synack,
 				break;
 		}
 		tcp_rearm_rto(sk);
+		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPFASTOPENACTIVEFAIL);
 		return true;
 	}
 	tp->syn_data_acked = tp->syn_data;
+	if (tp->syn_data_acked)
+		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPFASTOPENACTIVE);
 	return false;
 }
 
@@ -5836,3 +5820,156 @@ discard:
 	return 0;
 }
 EXPORT_SYMBOL(tcp_rcv_state_process);
+
+static inline void pr_drop_req(struct request_sock *req, __u16 port, int family)
+{
+	struct inet_request_sock *ireq = inet_rsk(req);
+
+	if (family == AF_INET)
+		LIMIT_NETDEBUG(KERN_DEBUG pr_fmt("drop open request from %pI4/%u\n"),
+			       &ireq->ir_rmt_addr, port);
+#if IS_ENABLED(CONFIG_IPV6)
+	else if (family == AF_INET6)
+		LIMIT_NETDEBUG(KERN_DEBUG pr_fmt("drop open request from %pI6/%u\n"),
+			       &ireq->ir_v6_rmt_addr, port);
+#endif
+}
+
+int tcp_conn_request(struct request_sock_ops *rsk_ops,
+		     const struct tcp_request_sock_ops *af_ops,
+		     struct sock *sk, struct sk_buff *skb)
+{
+	struct tcp_options_received tmp_opt;
+	struct request_sock *req;
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct dst_entry *dst = NULL;
+	__u32 isn = TCP_SKB_CB(skb)->when;
+	bool want_cookie = false, fastopen;
+	struct flowi fl;
+	struct tcp_fastopen_cookie foc = { .len = -1 };
+	int err;
+
+
+	/* TW buckets are converted to open requests without
+	 * limitations, they conserve resources and peer is
+	 * evidently real one.
+	 */
+	if ((sysctl_tcp_syncookies == 2 ||
+	     inet_csk_reqsk_queue_is_full(sk)) && !isn) {
+		want_cookie = tcp_syn_flood_action(sk, skb, rsk_ops->slab_name);
+		if (!want_cookie)
+			goto drop;
+	}
+
+
+	/* Accept backlog is full. If we have already queued enough
+	 * of warm entries in syn queue, drop request. It is better than
+	 * clogging syn queue with openreqs with exponentially increasing
+	 * timeout.
+	 */
+	if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1) {
+		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
+		goto drop;
+	}
+
+	req = inet_reqsk_alloc(rsk_ops);
+	if (!req)
+		goto drop;
+
+	tcp_rsk(req)->af_specific = af_ops;
+
+	tcp_clear_options(&tmp_opt);
+	tmp_opt.mss_clamp = af_ops->mss_clamp;
+	tmp_opt.user_mss  = tp->rx_opt.user_mss;
+	tcp_parse_options(skb, &tmp_opt, 0, want_cookie ? NULL : &foc);
+
+	if (want_cookie && !tmp_opt.saw_tstamp)
+		tcp_clear_options(&tmp_opt);
+
+	tmp_opt.tstamp_ok = tmp_opt.saw_tstamp;
+	tcp_openreq_init(req, &tmp_opt, skb, sk);
+
+	af_ops->init_req(req, sk, skb);
+
+	if (security_inet_conn_request(sk, skb, req))
+		goto drop_and_free;
+
+	if (!want_cookie || tmp_opt.tstamp_ok)
+		TCP_ECN_create_request(req, skb, sock_net(sk));
+
+	if (want_cookie) {
+		isn = cookie_init_sequence(af_ops, sk, skb, &req->mss);
+		req->cookie_ts = tmp_opt.tstamp_ok;
+	} else if (!isn) {
+		/* VJ's idea. We save last timestamp seen
+		 * from the destination in peer table, when entering
+		 * state TIME-WAIT, and check against it before
+		 * accepting new connection request.
+		 *
+		 * If "isn" is not zero, this request hit alive
+		 * timewait bucket, so that all the necessary checks
+		 * are made in the function processing timewait state.
+		 */
+		if (tcp_death_row.sysctl_tw_recycle) {
+			bool strict;
+
+			dst = af_ops->route_req(sk, &fl, req, &strict);
+
+			if (dst && strict &&
+			    !tcp_peer_is_proven(req, dst, true,
+						tmp_opt.saw_tstamp)) {
+				NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PAWSPASSIVEREJECTED);
+				goto drop_and_release;
+			}
+		}
+		/* Kill the following clause, if you dislike this way. */
+		else if (!sysctl_tcp_syncookies &&
+			 (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) <
+			  (sysctl_max_syn_backlog >> 2)) &&
+			 !tcp_peer_is_proven(req, dst, false,
+					     tmp_opt.saw_tstamp)) {
+			/* Without syncookies last quarter of
+			 * backlog is filled with destinations,
+			 * proven to be alive.
+			 * It means that we continue to communicate
+			 * to destinations, already remembered
+			 * to the moment of synflood.
+			 */
+			pr_drop_req(req, ntohs(tcp_hdr(skb)->source),
+				    rsk_ops->family);
+			goto drop_and_release;
+		}
+
+		isn = af_ops->init_seq(skb);
+	}
+	if (!dst) {
+		dst = af_ops->route_req(sk, &fl, req, NULL);
+		if (!dst)
+			goto drop_and_free;
+	}
+
+	tcp_rsk(req)->snt_isn = isn;
+	tcp_openreq_init_rwin(req, sk, dst);
+	fastopen = !want_cookie &&
+		   tcp_try_fastopen(sk, skb, req, &foc, dst);
+	err = af_ops->send_synack(sk, dst, &fl, req,
+				  skb_get_queue_mapping(skb), &foc);
+	if (!fastopen) {
+		if (err || want_cookie)
+			goto drop_and_free;
+
+		tcp_rsk(req)->listener = NULL;
+		af_ops->queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
+	}
+
+	return 0;
+
+drop_and_release:
+	dst_release(dst);
+drop_and_free:
+	reqsk_free(req);
+drop:
+	NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
+	return 0;
+}
+EXPORT_SYMBOL(tcp_conn_request);