1 files changed, 118 insertions, 95 deletions

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 00e5a300ddb9..9c34b97d365d 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -45,6 +45,21 @@
 
 #include <trace/events/tcp.h>
 
+/* Refresh clocks of a TCP socket,
+ * ensuring monotically increasing values.
+ */
+void tcp_mstamp_refresh(struct tcp_sock *tp)
+{
+	u64 val = tcp_clock_ns();
+
+	if (val > tp->tcp_clock_cache)
+		tp->tcp_clock_cache = val;
+
+	val = div_u64(val, NSEC_PER_USEC);
+	if (val > tp->tcp_mstamp)
+		tp->tcp_mstamp = val;
+}
+
 static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
 			   int push_one, gfp_t gfp);
 
@@ -160,7 +175,8 @@ static void tcp_event_data_sent(struct tcp_sock *tp,
 }
 
 /* Account for an ACK we sent. */
-static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts)
+static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts,
+				      u32 rcv_nxt)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 
@@ -171,25 +187,13 @@ static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts)
 		if (hrtimer_try_to_cancel(&tp->compressed_ack_timer) == 1)
 			__sock_put(sk);
 	}
+
+	if (unlikely(rcv_nxt != tp->rcv_nxt))
+		return;  /* Special ACK sent by DCTCP to reflect ECN */
 	tcp_dec_quickack_mode(sk, pkts);
 	inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
 }
 
-
-u32 tcp_default_init_rwnd(u32 mss)
-{
-	/* Initial receive window should be twice of TCP_INIT_CWND to
-	 * enable proper sending of new unsent data during fast recovery
-	 * (RFC 3517, Section 4, NextSeg() rule (2)). Further place a
-	 * limit when mss is larger than 1460.
-	 */
-	u32 init_rwnd = TCP_INIT_CWND * 2;
-
-	if (mss > 1460)
-		init_rwnd = max((1460 * init_rwnd) / mss, 2U);
-	return init_rwnd;
-}
-
 /* Determine a window scaling and initial window to offer.
  * Based on the assumption that the given amount of space
  * will be offered. Store the results in the tp structure.
@@ -224,7 +228,10 @@ void tcp_select_initial_window(const struct sock *sk, int __space, __u32 mss,
 	if (sock_net(sk)->ipv4.sysctl_tcp_workaround_signed_windows)
 		(*rcv_wnd) = min(space, MAX_TCP_WINDOW);
 	else
-		(*rcv_wnd) = space;
+		(*rcv_wnd) = min_t(u32, space, U16_MAX);
+
+	if (init_rcv_wnd)
+		*rcv_wnd = min(*rcv_wnd, init_rcv_wnd * mss);
 
 	(*rcv_wscale) = 0;
 	if (wscale_ok) {
@@ -237,11 +244,6 @@ void tcp_select_initial_window(const struct sock *sk, int __space, __u32 mss,
 			(*rcv_wscale)++;
 		}
 	}
-
-	if (!init_rcv_wnd) /* Use default unless specified otherwise */
-		init_rcv_wnd = tcp_default_init_rwnd(mss);
-	*rcv_wnd = min(*rcv_wnd, init_rcv_wnd * mss);
-
 	/* Set the clamp no higher than max representable value */
 	(*window_clamp) = min_t(__u32, U16_MAX << (*rcv_wscale), *window_clamp);
 }
@@ -973,42 +975,28 @@ enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer)
 	return HRTIMER_NORESTART;
 }
 
-/* BBR congestion control needs pacing.
- * Same remark for SO_MAX_PACING_RATE.
- * sch_fq packet scheduler is efficiently handling pacing,
- * but is not always installed/used.
- * Return true if TCP stack should pace packets itself.
- */
-static bool tcp_needs_internal_pacing(const struct sock *sk)
-{
-	return smp_load_acquire(&sk->sk_pacing_status) == SK_PACING_NEEDED;
-}
-
-static void tcp_internal_pacing(struct sock *sk, const struct sk_buff *skb)
+static void tcp_update_skb_after_send(struct sock *sk, struct sk_buff *skb,
+				      u64 prior_wstamp)
 {
-	u64 len_ns;
-	u32 rate;
+	struct tcp_sock *tp = tcp_sk(sk);
 
-	if (!tcp_needs_internal_pacing(sk))
-		return;
-	rate = sk->sk_pacing_rate;
-	if (!rate || rate == ~0U)
-		return;
+	skb->skb_mstamp_ns = tp->tcp_wstamp_ns;
+	if (sk->sk_pacing_status != SK_PACING_NONE) {
+		unsigned long rate = sk->sk_pacing_rate;
 
-	/* Should account for header sizes as sch_fq does,
-	 * but lets make things simple.
-	 */
-	len_ns = (u64)skb->len * NSEC_PER_SEC;
-	do_div(len_ns, rate);
-	hrtimer_start(&tcp_sk(sk)->pacing_timer,
-		      ktime_add_ns(ktime_get(), len_ns),
-		      HRTIMER_MODE_ABS_PINNED_SOFT);
-	sock_hold(sk);
-}
+		/* Original sch_fq does not pace first 10 MSS
+		 * Note that tp->data_segs_out overflows after 2^32 packets,
+		 * this is a minor annoyance.
+		 */
+		if (rate != ~0UL && rate && tp->data_segs_out >= 10) {
+			u64 len_ns = div64_ul((u64)skb->len * NSEC_PER_SEC, rate);
+			u64 credit = tp->tcp_wstamp_ns - prior_wstamp;
 
-static void tcp_update_skb_after_send(struct tcp_sock *tp, struct sk_buff *skb)
-{
-	skb->skb_mstamp = tp->tcp_mstamp;
+			/* take into account OS jitter */
+			len_ns -= min_t(u64, len_ns / 2, credit);
+			tp->tcp_wstamp_ns += len_ns;
+		}
+	}
 	list_move_tail(&skb->tcp_tsorted_anchor, &tp->tsorted_sent_queue);
 }
 
@@ -1023,8 +1011,8 @@ static void tcp_update_skb_after_send(struct tcp_sock *tp, struct sk_buff *skb)
  * We are working here with either a clone of the original
  * SKB, or a fresh unique copy made by the retransmit engine.
  */
-static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
-			    gfp_t gfp_mask)
+static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb,
+			      int clone_it, gfp_t gfp_mask, u32 rcv_nxt)
 {
 	const struct inet_connection_sock *icsk = inet_csk(sk);
 	struct inet_sock *inet;
@@ -1035,6 +1023,7 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
 	struct sk_buff *oskb = NULL;
 	struct tcp_md5sig_key *md5;
 	struct tcphdr *th;
+	u64 prior_wstamp;
 	int err;
 
 	BUG_ON(!skb || !tcp_skb_pcount(skb));
@@ -1055,7 +1044,11 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
 		if (unlikely(!skb))
 			return -ENOBUFS;
 	}
-	skb->skb_mstamp = tp->tcp_mstamp;
+
+	prior_wstamp = tp->tcp_wstamp_ns;
+	tp->tcp_wstamp_ns = max(tp->tcp_wstamp_ns, tp->tcp_clock_cache);
+
+	skb->skb_mstamp_ns = tp->tcp_wstamp_ns;
 
 	inet = inet_sk(sk);
 	tcb = TCP_SKB_CB(skb);
@@ -1100,7 +1093,7 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
 	th->source		= inet->inet_sport;
 	th->dest		= inet->inet_dport;
 	th->seq			= htonl(tcb->seq);
-	th->ack_seq		= htonl(tp->rcv_nxt);
+	th->ack_seq		= htonl(rcv_nxt);
 	*(((__be16 *)th) + 6)	= htons(((tcp_header_size >> 2) << 12) |
 					tcb->tcp_flags);
 
@@ -1141,12 +1134,12 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
 	icsk->icsk_af_ops->send_check(sk, skb);
 
 	if (likely(tcb->tcp_flags & TCPHDR_ACK))
-		tcp_event_ack_sent(sk, tcp_skb_pcount(skb));
+		tcp_event_ack_sent(sk, tcp_skb_pcount(skb), rcv_nxt);
 
 	if (skb->len != tcp_header_size) {
 		tcp_event_data_sent(tp, sk);
 		tp->data_segs_out += tcp_skb_pcount(skb);
-		tcp_internal_pacing(sk, skb);
+		tp->bytes_sent += skb->len - tcp_header_size;
 	}
 
 	if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq)
@@ -1158,8 +1151,7 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
 	skb_shinfo(skb)->gso_segs = tcp_skb_pcount(skb);
 	skb_shinfo(skb)->gso_size = tcp_skb_mss(skb);
 
-	/* Our usage of tstamp should remain private */
-	skb->tstamp = 0;
+	/* Leave earliest departure time in skb->tstamp (skb->skb_mstamp_ns) */
 
 	/* Cleanup our debris for IP stacks */
 	memset(skb->cb, 0, max(sizeof(struct inet_skb_parm),
@@ -1172,12 +1164,19 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
 		err = net_xmit_eval(err);
 	}
 	if (!err && oskb) {
-		tcp_update_skb_after_send(tp, oskb);
+		tcp_update_skb_after_send(sk, oskb, prior_wstamp);
 		tcp_rate_skb_sent(sk, oskb);
 	}
 	return err;
 }
 
+static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
+			    gfp_t gfp_mask)
+{
+	return __tcp_transmit_skb(sk, skb, clone_it, gfp_mask,
+				  tcp_sk(sk)->rcv_nxt);
+}
+
 /* This routine just queues the buffer for sending.
  *
  * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames,
@@ -1700,8 +1699,9 @@ static u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now,
 {
 	u32 bytes, segs;
 
-	bytes = min(sk->sk_pacing_rate >> sk->sk_pacing_shift,
-		    sk->sk_gso_max_size - 1 - MAX_TCP_HEADER);
+	bytes = min_t(unsigned long,
+		      sk->sk_pacing_rate >> sk->sk_pacing_shift,
+		      sk->sk_gso_max_size - 1 - MAX_TCP_HEADER);
 
 	/* Goal is to send at least one packet per ms,
 	 * not one big TSO packet every 100 ms.
@@ -1968,7 +1968,7 @@ static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb,
 	head = tcp_rtx_queue_head(sk);
 	if (!head)
 		goto send_now;
-	age = tcp_stamp_us_delta(tp->tcp_mstamp, head->skb_mstamp);
+	age = tcp_stamp_us_delta(tp->tcp_mstamp, tcp_skb_timestamp_us(head));
 	/* If next ACK is likely to come too late (half srtt), do not defer */
 	if (age < (tp->srtt_us >> 4))
 		goto send_now;
@@ -2174,10 +2174,23 @@ static int tcp_mtu_probe(struct sock *sk)
 	return -1;
 }
 
-static bool tcp_pacing_check(const struct sock *sk)
+static bool tcp_pacing_check(struct sock *sk)
 {
-	return tcp_needs_internal_pacing(sk) &&
-	       hrtimer_is_queued(&tcp_sk(sk)->pacing_timer);
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	if (!tcp_needs_internal_pacing(sk))
+		return false;
+
+	if (tp->tcp_wstamp_ns <= tp->tcp_clock_cache)
+		return false;
+
+	if (!hrtimer_is_queued(&tp->pacing_timer)) {
+		hrtimer_start(&tp->pacing_timer,
+			      ns_to_ktime(tp->tcp_wstamp_ns),
+			      HRTIMER_MODE_ABS_PINNED_SOFT);
+		sock_hold(sk);
+	}
+	return true;
 }
 
 /* TCP Small Queues :
@@ -2194,10 +2207,12 @@ static bool tcp_pacing_check(const struct sock *sk)
 static bool tcp_small_queue_check(struct sock *sk, const struct sk_buff *skb,
 				  unsigned int factor)
 {
-	unsigned int limit;
+	unsigned long limit;
 
-	limit = max(2 * skb->truesize, sk->sk_pacing_rate >> sk->sk_pacing_shift);
-	limit = min_t(u32, limit,
+	limit = max_t(unsigned long,
+		      2 * skb->truesize,
+		      sk->sk_pacing_rate >> sk->sk_pacing_shift);
+	limit = min_t(unsigned long, limit,
 		      sock_net(sk)->ipv4.sysctl_tcp_limit_output_bytes);
 	limit <<= factor;
 
@@ -2306,18 +2321,19 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
 	while ((skb = tcp_send_head(sk))) {
 		unsigned int limit;
 
+		if (unlikely(tp->repair) && tp->repair_queue == TCP_SEND_QUEUE) {
+			/* "skb_mstamp_ns" is used as a start point for the retransmit timer */
+			skb->skb_mstamp_ns = tp->tcp_wstamp_ns = tp->tcp_clock_cache;
+			list_move_tail(&skb->tcp_tsorted_anchor, &tp->tsorted_sent_queue);
+			goto repair; /* Skip network transmission */
+		}
+
 		if (tcp_pacing_check(sk))
 			break;
 
 		tso_segs = tcp_init_tso_segs(skb, mss_now);
 		BUG_ON(!tso_segs);
 
-		if (unlikely(tp->repair) && tp->repair_queue == TCP_SEND_QUEUE) {
-			/* "skb_mstamp" is used as a start point for the retransmit timer */
-			tcp_update_skb_after_send(tp, skb);
-			goto repair; /* Skip network transmission */
-		}
-
 		cwnd_quota = tcp_cwnd_test(tp, skb);
 		if (!cwnd_quota) {
 			if (push_one == 2)
@@ -2439,8 +2455,8 @@ bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto)
 	if (rto_delta_us > 0)
 		timeout = min_t(u32, timeout, usecs_to_jiffies(rto_delta_us));
 
-	inet_csk_reset_xmit_timer(sk, ICSK_TIME_LOSS_PROBE, timeout,
-				  TCP_RTO_MAX);
+	tcp_reset_xmit_timer(sk, ICSK_TIME_LOSS_PROBE, timeout,
+			     TCP_RTO_MAX, NULL);
 	return true;
 }
 
@@ -2700,9 +2716,8 @@ static bool tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	struct sk_buff *next_skb = skb_rb_next(skb);
-	int skb_size, next_skb_size;
+	int next_skb_size;
 
-	skb_size = skb->len;
 	next_skb_size = next_skb->len;
 
 	BUG_ON(tcp_skb_pcount(skb) != 1 || tcp_skb_pcount(next_skb) != 1);
@@ -2873,6 +2888,7 @@ int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs)
 	if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)
 		__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS);
 	tp->total_retrans += segs;
+	tp->bytes_retrans += skb->len;
 
 	/* make sure skb->data is aligned on arches that require it
 	 * and check if ack-trimming & collapsing extended the headroom
@@ -2889,7 +2905,7 @@ int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs)
 		} tcp_skb_tsorted_restore(skb);
 
 		if (!err) {
-			tcp_update_skb_after_send(tp, skb);
+			tcp_update_skb_after_send(sk, skb, tp->tcp_wstamp_ns);
 			tcp_rate_skb_sent(sk, skb);
 		}
 	} else {
@@ -3004,9 +3020,10 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
 
 		if (skb == rtx_head &&
 		    icsk->icsk_pending != ICSK_TIME_REO_TIMEOUT)
-			inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
-						  inet_csk(sk)->icsk_rto,
-						  TCP_RTO_MAX);
+			tcp_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
+					     inet_csk(sk)->icsk_rto,
+					     TCP_RTO_MAX,
+					     skb);
 	}
 }
 
@@ -3207,10 +3224,10 @@ struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
 	memset(&opts, 0, sizeof(opts));
 #ifdef CONFIG_SYN_COOKIES
 	if (unlikely(req->cookie_ts))
-		skb->skb_mstamp = cookie_init_timestamp(req);
+		skb->skb_mstamp_ns = cookie_init_timestamp(req);
 	else
 #endif
-		skb->skb_mstamp = tcp_clock_us();
+		skb->skb_mstamp_ns = tcp_clock_ns();
 
 #ifdef CONFIG_TCP_MD5SIG
 	rcu_read_lock();
@@ -3426,7 +3443,7 @@ static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn)
 
 	err = tcp_transmit_skb(sk, syn_data, 1, sk->sk_allocation);
 
-	syn->skb_mstamp = syn_data->skb_mstamp;
+	syn->skb_mstamp_ns = syn_data->skb_mstamp_ns;
 
 	/* Now full SYN+DATA was cloned and sent (or not),
 	 * remove the SYN from the original skb (syn_data)
@@ -3571,7 +3588,7 @@ void tcp_send_delayed_ack(struct sock *sk)
 }
 
 /* This routine sends an ack and also updates the window. */
-void tcp_send_ack(struct sock *sk)
+void __tcp_send_ack(struct sock *sk, u32 rcv_nxt)
 {
 	struct sk_buff *buff;
 
@@ -3604,9 +3621,14 @@ void tcp_send_ack(struct sock *sk)
 	skb_set_tcp_pure_ack(buff);
 
 	/* Send it off, this clears delayed acks for us. */
-	tcp_transmit_skb(sk, buff, 0, (__force gfp_t)0);
+	__tcp_transmit_skb(sk, buff, 0, (__force gfp_t)0, rcv_nxt);
+}
+EXPORT_SYMBOL_GPL(__tcp_send_ack);
+
+void tcp_send_ack(struct sock *sk)
+{
+	__tcp_send_ack(sk, tcp_sk(sk)->rcv_nxt);
 }
-EXPORT_SYMBOL_GPL(tcp_send_ack);
 
 /* This routine sends a packet with an out of date sequence
  * number. It assumes the other end will try to ack it.
@@ -3731,9 +3753,10 @@ void tcp_send_probe0(struct sock *sk)
 			icsk->icsk_probes_out = 1;
 		probe_max = TCP_RESOURCE_PROBE_INTERVAL;
 	}
-	inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
-				  tcp_probe0_when(sk, probe_max),
-				  TCP_RTO_MAX);
+	tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
+			     tcp_probe0_when(sk, probe_max),
+			     TCP_RTO_MAX,
+			     NULL);
 }
 
 int tcp_rtx_synack(const struct sock *sk, struct request_sock *req)