1 files changed, 62 insertions, 54 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index c28976a7e59..5ecd7aa2597 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1178,10 +1178,18 @@ static void tcp_mark_lost_retrans(struct sock *sk)
 		if (!(TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS))
 			continue;
 
-		if (after(received_upto, ack_seq) &&
-		    (tcp_is_fack(tp) ||
-		     !before(received_upto,
-			     ack_seq + tp->reordering * tp->mss_cache))) {
+		/* TODO: We would like to get rid of tcp_is_fack(tp) only
+		 * constraint here (see above) but figuring out that at
+		 * least tp->reordering SACK blocks reside between ack_seq
+		 * and received_upto is not easy task to do cheaply with
+		 * the available datastructures.
+		 *
+		 * Whether FACK should check here for tp->reordering segs
+		 * in-between one could argue for either way (it would be
+		 * rather simple to implement as we could count fack_count
+		 * during the walk and do tp->fackets_out - fack_count).
+		 */
+		if (after(received_upto, ack_seq)) {
 			TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS;
 			tp->retrans_out -= tcp_skb_pcount(skb);
 
@@ -2453,6 +2461,44 @@ static int tcp_time_to_recover(struct sock *sk)
 	return 0;
 }
 
+/* New heuristics: it is possible only after we switched to restart timer
+ * each time when something is ACKed. Hence, we can detect timed out packets
+ * during fast retransmit without falling to slow start.
+ *
+ * Usefulness of this as is very questionable, since we should know which of
+ * the segments is the next to timeout which is relatively expensive to find
+ * in general case unless we add some data structure just for that. The
+ * current approach certainly won't find the right one too often and when it
+ * finally does find _something_ it usually marks large part of the window
+ * right away (because a retransmission with a larger timestamp blocks the
+ * loop from advancing). -ij
+ */
+static void tcp_timeout_skbs(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct sk_buff *skb;
+
+	if (!tcp_is_fack(tp) || !tcp_head_timedout(sk))
+		return;
+
+	skb = tp->scoreboard_skb_hint;
+	if (tp->scoreboard_skb_hint == NULL)
+		skb = tcp_write_queue_head(sk);
+
+	tcp_for_write_queue_from(skb, sk) {
+		if (skb == tcp_send_head(sk))
+			break;
+		if (!tcp_skb_timedout(sk, skb))
+			break;
+
+		tcp_skb_mark_lost(tp, skb);
+	}
+
+	tp->scoreboard_skb_hint = skb;
+
+	tcp_verify_left_out(tp);
+}
+
 /* Mark head of queue up as lost. With RFC3517 SACK, the packets is
  * is against sacked "cnt", otherwise it's against facked "cnt"
  */
@@ -2525,30 +2571,7 @@ static void tcp_update_scoreboard(struct sock *sk, int fast_rexmit)
 		tcp_mark_head_lost(sk, sacked_upto);
 	}
 
-	/* New heuristics: it is possible only after we switched
-	 * to restart timer each time when something is ACKed.
-	 * Hence, we can detect timed out packets during fast
-	 * retransmit without falling to slow start.
-	 */
-	if (tcp_is_fack(tp) && tcp_head_timedout(sk)) {
-		struct sk_buff *skb;
-
-		skb = tp->scoreboard_skb_hint ? tp->scoreboard_skb_hint
-			: tcp_write_queue_head(sk);
-
-		tcp_for_write_queue_from(skb, sk) {
-			if (skb == tcp_send_head(sk))
-				break;
-			if (!tcp_skb_timedout(sk, skb))
-				break;
-
-			tcp_skb_mark_lost(tp, skb);
-		}
-
-		tp->scoreboard_skb_hint = skb;
-
-		tcp_verify_left_out(tp);
-	}
+	tcp_timeout_skbs(sk);
 }
 
 /* CWND moderation, preventing bursts due to too big ACKs
@@ -3273,18 +3296,15 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
 		if (tcp_is_reno(tp)) {
 			tcp_remove_reno_sacks(sk, pkts_acked);
 		} else {
+			int delta;
+
 			/* Non-retransmitted hole got filled? That's reordering */
 			if (reord < prior_fackets)
 				tcp_update_reordering(sk, tp->fackets_out - reord, 0);
 
-			/* No need to care for underflows here because
-			 * the lost_skb_hint gets NULLed if we're past it
-			 * (or something non-trivial happened)
-			 */
-			if (tcp_is_fack(tp))
-				tp->lost_cnt_hint -= pkts_acked;
-			else
-				tp->lost_cnt_hint -= prior_sacked - tp->sacked_out;
+			delta = tcp_is_fack(tp) ? pkts_acked :
+						  prior_sacked - tp->sacked_out;
+			tp->lost_cnt_hint -= min(tp->lost_cnt_hint, delta);
 		}
 
 		tp->fackets_out -= min(pkts_acked, tp->fackets_out);
@@ -3396,7 +3416,7 @@ static int tcp_ack_update_window(struct sock *sk, struct sk_buff *skb, u32 ack,
 
 	if (tcp_may_update_window(tp, ack, ack_seq, nwin)) {
 		flag |= FLAG_WIN_UPDATE;
-		tcp_update_wl(tp, ack, ack_seq);
+		tcp_update_wl(tp, ack_seq);
 
 		if (tp->snd_wnd != nwin) {
 			tp->snd_wnd = nwin;
@@ -3601,7 +3621,7 @@ static int tcp_ack(struct sock *sk, struct sk_buff *skb, int flag)
 		 * No more checks are required.
 		 * Note, we use the fact that SND.UNA>=SND.WL2.
 		 */
-		tcp_update_wl(tp, ack, ack_seq);
+		tcp_update_wl(tp, ack_seq);
 		tp->snd_una = ack;
 		flag |= FLAG_WIN_UPDATE;
 
@@ -4079,7 +4099,6 @@ static void tcp_dsack_set(struct sock *sk, u32 seq, u32 end_seq)
 		tp->rx_opt.dsack = 1;
 		tp->duplicate_sack[0].start_seq = seq;
 		tp->duplicate_sack[0].end_seq = end_seq;
-		tp->rx_opt.eff_sacks = tp->rx_opt.num_sacks + 1;
 	}
 }
 
@@ -4134,8 +4153,6 @@ static void tcp_sack_maybe_coalesce(struct tcp_sock *tp)
 			 * Decrease num_sacks.
 			 */
 			tp->rx_opt.num_sacks--;
-			tp->rx_opt.eff_sacks = tp->rx_opt.num_sacks +
-					       tp->rx_opt.dsack;
 			for (i = this_sack; i < tp->rx_opt.num_sacks; i++)
 				sp[i] = sp[i + 1];
 			continue;
@@ -4198,7 +4215,6 @@ new_sack:
 	sp->start_seq = seq;
 	sp->end_seq = end_seq;
 	tp->rx_opt.num_sacks++;
-	tp->rx_opt.eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack;
 }
 
 /* RCV.NXT advances, some SACKs should be eaten. */
@@ -4212,7 +4228,6 @@ static void tcp_sack_remove(struct tcp_sock *tp)
 	/* Empty ofo queue, hence, all the SACKs are eaten. Clear. */
 	if (skb_queue_empty(&tp->out_of_order_queue)) {
 		tp->rx_opt.num_sacks = 0;
-		tp->rx_opt.eff_sacks = tp->rx_opt.dsack;
 		return;
 	}
 
@@ -4233,11 +4248,8 @@ static void tcp_sack_remove(struct tcp_sock *tp)
 		this_sack++;
 		sp++;
 	}
-	if (num_sacks != tp->rx_opt.num_sacks) {
+	if (num_sacks != tp->rx_opt.num_sacks)
 		tp->rx_opt.num_sacks = num_sacks;
-		tp->rx_opt.eff_sacks = tp->rx_opt.num_sacks +
-				       tp->rx_opt.dsack;
-	}
 }
 
 /* This one checks to see if we can put data from the
@@ -4313,10 +4325,8 @@ static void tcp_data_queue(struct sock *sk, struct sk_buff *skb)
 
 	TCP_ECN_accept_cwr(tp, skb);
 
-	if (tp->rx_opt.dsack) {
+	if (tp->rx_opt.dsack)
 		tp->rx_opt.dsack = 0;
-		tp->rx_opt.eff_sacks = tp->rx_opt.num_sacks;
-	}
 
 	/*  Queue data for delivery to the user.
 	 *  Packets in sequence go to the receive queue.
@@ -4436,7 +4446,6 @@ drop:
 		if (tcp_is_sack(tp)) {
 			tp->rx_opt.num_sacks = 1;
 			tp->rx_opt.dsack     = 0;
-			tp->rx_opt.eff_sacks = 1;
 			tp->selective_acks[0].start_seq = TCP_SKB_CB(skb)->seq;
 			tp->selective_acks[0].end_seq =
 						TCP_SKB_CB(skb)->end_seq;
@@ -5409,7 +5418,7 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
 		 * never scaled.
 		 */
 		tp->snd_wnd = ntohs(th->window);
-		tcp_init_wl(tp, TCP_SKB_CB(skb)->ack_seq, TCP_SKB_CB(skb)->seq);
+		tcp_init_wl(tp, TCP_SKB_CB(skb)->seq);
 
 		if (!tp->rx_opt.wscale_ok) {
 			tp->rx_opt.snd_wscale = tp->rx_opt.rcv_wscale = 0;
@@ -5670,8 +5679,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
 				tp->snd_una = TCP_SKB_CB(skb)->ack_seq;
 				tp->snd_wnd = ntohs(th->window) <<
 					      tp->rx_opt.snd_wscale;
-				tcp_init_wl(tp, TCP_SKB_CB(skb)->ack_seq,
-					    TCP_SKB_CB(skb)->seq);
+				tcp_init_wl(tp, TCP_SKB_CB(skb)->seq);
 
 				/* tcp_ack considers this ACK as duplicate
 				 * and does not calculate rtt.