1 files changed, 42 insertions, 103 deletions

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 1d5331a1b1dc..22548b5f05cb 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -76,16 +76,15 @@ static void tcp_event_new_data_sent(struct sock *sk, const struct sk_buff *skb)
 	tp->snd_nxt = TCP_SKB_CB(skb)->end_seq;
 
 	tp->packets_out += tcp_skb_pcount(skb);
-	if (!prior_packets || icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS ||
-	    icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) {
+	if (!prior_packets || icsk->icsk_pending == ICSK_TIME_LOSS_PROBE)
 		tcp_rearm_rto(sk);
-	}
 
 	NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT,
 		      tcp_skb_pcount(skb));
 }
 
-/* SND.NXT, if window was not shrunk.
+/* SND.NXT, if window was not shrunk or the amount of shrunk was less than one
+ * window scaling factor due to loss of precision.
  * If window has been shrunk, what should we make? It is not clear at all.
  * Using SND.UNA we will fail to open window, SND.NXT is out of window. :-(
  * Anything in between SND.UNA...SND.UNA+SND.WND also can be already
@@ -95,7 +94,9 @@ static inline __u32 tcp_acceptable_seq(const struct sock *sk)
 {
 	const struct tcp_sock *tp = tcp_sk(sk);
 
-	if (!before(tcp_wnd_end(tp), tp->snd_nxt))
+	if (!before(tcp_wnd_end(tp), tp->snd_nxt) ||
+	    (tp->rx_opt.wscale_ok &&
+	     ((tp->snd_nxt - tcp_wnd_end(tp)) < (1 << tp->rx_opt.rcv_wscale))))
 		return tp->snd_nxt;
 	else
 		return tcp_wnd_end(tp);
@@ -966,6 +967,13 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
 	 */
 	skb->ooo_okay = sk_wmem_alloc_get(sk) < SKB_TRUESIZE(1);
 
+	/* If we had to use memory reserve to allocate this skb,
+	 * this might cause drops if packet is looped back :
+	 * Other socket might not have SOCK_MEMALLOC.
+	 * Packets not looped back do not care about pfmemalloc.
+	 */
+	skb->pfmemalloc = 0;
+
 	skb_push(skb, tcp_header_size);
 	skb_reset_transport_header(skb);
 
@@ -975,6 +983,8 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
 	skb_set_hash_from_sk(skb, sk);
 	atomic_add(skb->truesize, &sk->sk_wmem_alloc);
 
+	skb_set_dst_pending_confirm(skb, sk->sk_dst_pending_confirm);
+
 	/* Build TCP header and checksum it. */
 	th = (struct tcphdr *)skb->data;
 	th->source		= inet->inet_sport;
@@ -2289,8 +2299,6 @@ bool tcp_schedule_loss_probe(struct sock *sk)
 	u32 timeout, tlp_time_stamp, rto_time_stamp;
 	u32 rtt = usecs_to_jiffies(tp->srtt_us >> 3);
 
-	if (WARN_ON(icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS))
-		return false;
 	/* No consecutive loss probes. */
 	if (WARN_ON(icsk->icsk_pending == ICSK_TIME_LOSS_PROBE)) {
 		tcp_rearm_rto(sk);
@@ -2309,8 +2317,9 @@ bool tcp_schedule_loss_probe(struct sock *sk)
 	/* Schedule a loss probe in 2*RTT for SACK capable connections
 	 * in Open state, that are either limited by cwnd or application.
 	 */
-	if (sysctl_tcp_early_retrans < 3 || !tp->packets_out ||
-	    !tcp_is_sack(tp) || inet_csk(sk)->icsk_ca_state != TCP_CA_Open)
+	if ((sysctl_tcp_early_retrans != 3 && sysctl_tcp_early_retrans != 4) ||
+	    !tp->packets_out || !tcp_is_sack(tp) ||
+	    icsk->icsk_ca_state != TCP_CA_Open)
 		return false;
 
 	if ((tp->snd_cwnd > tcp_packets_in_flight(tp)) &&
@@ -2518,9 +2527,11 @@ u32 __tcp_select_window(struct sock *sk)
 	int full_space = min_t(int, tp->window_clamp, allowed_space);
 	int window;
 
-	if (mss > full_space)
+	if (unlikely(mss > full_space)) {
 		mss = full_space;
-
+		if (mss <= 0)
+			return 0;
+	}
 	if (free_space < (full_space >> 1)) {
 		icsk->icsk_ack.quick = 0;
 
@@ -2774,6 +2785,13 @@ int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs)
 	if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN_ECN) == TCPHDR_SYN_ECN)
 		tcp_ecn_clear_syn(sk, skb);
 
+	/* Update global and local TCP statistics. */
+	segs = tcp_skb_pcount(skb);
+	TCP_ADD_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS, segs);
+	if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)
+		__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS);
+	tp->total_retrans += segs;
+
 	/* make sure skb->data is aligned on arches that require it
 	 * and check if ack-trimming & collapsing extended the headroom
 	 * beyond what csum_start can cover.
@@ -2791,14 +2809,9 @@ int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs)
 	}
 
 	if (likely(!err)) {
-		segs = tcp_skb_pcount(skb);
-
 		TCP_SKB_CB(skb)->sacked |= TCPCB_EVER_RETRANS;
-		/* Update global TCP statistics. */
-		TCP_ADD_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS, segs);
-		if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)
-			__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS);
-		tp->total_retrans += segs;
+	} else if (err != -EBUSY) {
+		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPRETRANSFAIL);
 	}
 	return err;
 }
@@ -2821,8 +2834,6 @@ int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs)
 		if (!tp->retrans_stamp)
 			tp->retrans_stamp = tcp_skb_timestamp(skb);
 
-	} else if (err != -EBUSY) {
-		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPRETRANSFAIL);
 	}
 
 	if (tp->undo_retrans < 0)
@@ -2831,36 +2842,6 @@ int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs)
 	return err;
 }
 
-/* Check if we forward retransmits are possible in the current
- * window/congestion state.
- */
-static bool tcp_can_forward_retransmit(struct sock *sk)
-{
-	const struct inet_connection_sock *icsk = inet_csk(sk);
-	const struct tcp_sock *tp = tcp_sk(sk);
-
-	/* Forward retransmissions are possible only during Recovery. */
-	if (icsk->icsk_ca_state != TCP_CA_Recovery)
-		return false;
-
-	/* No forward retransmissions in Reno are possible. */
-	if (tcp_is_reno(tp))
-		return false;
-
-	/* Yeah, we have to make difficult choice between forward transmission
-	 * and retransmission... Both ways have their merits...
-	 *
-	 * For now we do not retransmit anything, while we have some new
-	 * segments to send. In the other cases, follow rule 3 for
-	 * NextSeg() specified in RFC3517.
-	 */
-
-	if (tcp_may_send_now(sk))
-		return false;
-
-	return true;
-}
-
 /* This gets called after a retransmit timeout, and the initially
  * retransmitted data is acknowledged.  It tries to continue
  * resending the rest of the retransmit queue, until either
@@ -2875,24 +2856,16 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
 	struct tcp_sock *tp = tcp_sk(sk);
 	struct sk_buff *skb;
 	struct sk_buff *hole = NULL;
-	u32 max_segs, last_lost;
+	u32 max_segs;
 	int mib_idx;
-	int fwd_rexmitting = 0;
 
 	if (!tp->packets_out)
 		return;
 
-	if (!tp->lost_out)
-		tp->retransmit_high = tp->snd_una;
-
 	if (tp->retransmit_skb_hint) {
 		skb = tp->retransmit_skb_hint;
-		last_lost = TCP_SKB_CB(skb)->end_seq;
-		if (after(last_lost, tp->retransmit_high))
-			last_lost = tp->retransmit_high;
 	} else {
 		skb = tcp_write_queue_head(sk);
-		last_lost = tp->snd_una;
 	}
 
 	max_segs = tcp_tso_segs(sk, tcp_current_mss(sk));
@@ -2915,31 +2888,14 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
 		 */
 		segs = min_t(int, segs, max_segs);
 
-		if (fwd_rexmitting) {
-begin_fwd:
-			if (!before(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp)))
-				break;
-			mib_idx = LINUX_MIB_TCPFORWARDRETRANS;
-
-		} else if (!before(TCP_SKB_CB(skb)->seq, tp->retransmit_high)) {
-			tp->retransmit_high = last_lost;
-			if (!tcp_can_forward_retransmit(sk))
-				break;
-			/* Backtrack if necessary to non-L'ed skb */
-			if (hole) {
-				skb = hole;
-				hole = NULL;
-			}
-			fwd_rexmitting = 1;
-			goto begin_fwd;
-
+		if (tp->retrans_out >= tp->lost_out) {
+			break;
 		} else if (!(sacked & TCPCB_LOST)) {
 			if (!hole && !(sacked & (TCPCB_SACKED_RETRANS|TCPCB_SACKED_ACKED)))
 				hole = skb;
 			continue;
 
 		} else {
-			last_lost = TCP_SKB_CB(skb)->end_seq;
 			if (icsk->icsk_ca_state != TCP_CA_Loss)
 				mib_idx = LINUX_MIB_TCPFASTRETRANS;
 			else
@@ -2960,7 +2916,8 @@ begin_fwd:
 		if (tcp_in_cwnd_reduction(sk))
 			tp->prr_out += tcp_skb_pcount(skb);
 
-		if (skb == tcp_write_queue_head(sk))
+		if (skb == tcp_write_queue_head(sk) &&
+		    icsk->icsk_pending != ICSK_TIME_REO_TIMEOUT)
 			inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
 						  inet_csk(sk)->icsk_rto,
 						  TCP_RTO_MAX);
@@ -3117,7 +3074,6 @@ struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
 	struct sk_buff *skb;
 	int tcp_header_size;
 	struct tcphdr *th;
-	u16 user_mss;
 	int mss;
 
 	skb = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC);
@@ -3147,10 +3103,7 @@ struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
 	}
 	skb_dst_set(skb, dst);
 
-	mss = dst_metric_advmss(dst);
-	user_mss = READ_ONCE(tp->rx_opt.user_mss);
-	if (user_mss && user_mss < mss)
-		mss = user_mss;
+	mss = tcp_mss_clamp(tp, dst_metric_advmss(dst));
 
 	memset(&opts, 0, sizeof(opts));
 #ifdef CONFIG_SYN_COOKIES
@@ -3256,9 +3209,7 @@ static void tcp_connect_init(struct sock *sk)
 
 	if (!tp->window_clamp)
 		tp->window_clamp = dst_metric(dst, RTAX_WINDOW);
-	tp->advmss = dst_metric_advmss(dst);
-	if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < tp->advmss)
-		tp->advmss = tp->rx_opt.user_mss;
+	tp->advmss = tcp_mss_clamp(tp, dst_metric_advmss(dst));
 
 	tcp_initialize_rcv_mss(sk);
 
@@ -3324,31 +3275,19 @@ static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	struct tcp_fastopen_request *fo = tp->fastopen_req;
-	int syn_loss = 0, space, err = 0;
-	unsigned long last_syn_loss = 0;
+	int space, err = 0;
 	struct sk_buff *syn_data;
 
 	tp->rx_opt.mss_clamp = tp->advmss;  /* If MSS is not cached */
-	tcp_fastopen_cache_get(sk, &tp->rx_opt.mss_clamp, &fo->cookie,
-			       &syn_loss, &last_syn_loss);
-	/* Recurring FO SYN losses: revert to regular handshake temporarily */
-	if (syn_loss > 1 &&
-	    time_before(jiffies, last_syn_loss + (60*HZ << syn_loss))) {
-		fo->cookie.len = -1;
-		goto fallback;
-	}
-
-	if (sysctl_tcp_fastopen & TFO_CLIENT_NO_COOKIE)
-		fo->cookie.len = -1;
-	else if (fo->cookie.len <= 0)
+	if (!tcp_fastopen_cookie_check(sk, &tp->rx_opt.mss_clamp, &fo->cookie))
 		goto fallback;
 
 	/* MSS for SYN-data is based on cached MSS and bounded by PMTU and
 	 * user-MSS. Reserve maximum option space for middleboxes that add
 	 * private TCP options. The cost is reduced data space in SYN :(
 	 */
-	if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < tp->rx_opt.mss_clamp)
-		tp->rx_opt.mss_clamp = tp->rx_opt.user_mss;
+	tp->rx_opt.mss_clamp = tcp_mss_clamp(tp, tp->rx_opt.mss_clamp);
+
 	space = __tcp_mtu_to_mss(sk, inet_csk(sk)->icsk_pmtu_cookie) -
 		MAX_TCP_OPTION_SPACE;