[TCP]: Tighten tcp_sock's belt, drop left_out

It is easily calculable when needed and user are not that many
after all.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/tcp.h

@@ -304,7 +304,6 @@ struct tcp_sock {
 	u32	rtt_seq;	/* sequence number to update rttvar	*/
 
 	u32	packets_out;	/* Packets which are "in flight"	*/
-	u32	left_out;	/* Packets which leaved network	*/
 	u32	retrans_out;	/* Retransmitted packets out		*/
 /*
  *      Options received (usually on last packet, some only on SYN packets).

include/net/tcp.h

@@ -735,7 +735,8 @@ static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
  */
 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
 {
-	return (tp->packets_out - tp->left_out + tp->retrans_out);
+	return tp->packets_out - (tp->sacked_out + tp->lost_out) +
+		tp->retrans_out;
 }
 
 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
@@ -757,7 +758,6 @@ static inline void tcp_sync_left_out(struct tcp_sock *tp)
 {
 	BUG_ON(tp->rx_opt.sack_ok &&
 	       (tp->sacked_out + tp->lost_out > tp->packets_out));
-	tp->left_out = tp->sacked_out + tp->lost_out;
 }
 
 extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh);

net/ipv4/tcp_input.c

@@ -1346,8 +1346,6 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
 		}
 	}
 
-	tp->left_out = tp->sacked_out + tp->lost_out;
-
 	if ((reord < tp->fackets_out) && icsk->icsk_ca_state != TCP_CA_Loss &&
 	    (!tp->frto_highmark || after(tp->snd_una, tp->frto_highmark)))
 		tcp_update_reordering(sk, ((tp->fackets_out + 1) - reord), 0);
@@ -1408,7 +1406,6 @@ static void tcp_remove_reno_sacks(struct sock *sk, int acked)
 static inline void tcp_reset_reno_sack(struct tcp_sock *tp)
 {
 	tp->sacked_out = 0;
-	tp->left_out = tp->lost_out;
 }
 
 int tcp_use_frto(struct sock *sk)
@@ -1573,7 +1570,6 @@ static void tcp_enter_frto_loss(struct sock *sk, int allowed_segments, int flag)
 
 void tcp_clear_retrans(struct tcp_sock *tp)
 {
-	tp->left_out = 0;
 	tp->retrans_out = 0;
 
 	tp->fackets_out = 0;
@@ -1973,7 +1969,7 @@ static void DBGUNDO(struct sock *sk, const char *msg)
 	printk(KERN_DEBUG "Undo %s %u.%u.%u.%u/%u c%u l%u ss%u/%u p%u\n",
 	       msg,
 	       NIPQUAD(inet->daddr), ntohs(inet->dport),
-	       tp->snd_cwnd, tp->left_out,
+	       tp->snd_cwnd, tp->sacked_out + tp->lost_out,
 	       tp->snd_ssthresh, tp->prior_ssthresh,
 	       tp->packets_out);
 }
@@ -2102,7 +2098,6 @@ static int tcp_try_undo_loss(struct sock *sk)
 
 		DBGUNDO(sk, "partial loss");
 		tp->lost_out = 0;
-		tp->left_out = tp->sacked_out;
 		tcp_undo_cwr(sk, 1);
 		NET_INC_STATS_BH(LINUX_MIB_TCPLOSSUNDO);
 		inet_csk(sk)->icsk_retransmits = 0;
@@ -2126,8 +2121,6 @@ static void tcp_try_to_open(struct sock *sk, int flag)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 
-	tcp_sync_left_out(tp);
-
 	if (tp->retrans_out == 0)
 		tp->retrans_stamp = 0;
 
@@ -2137,7 +2130,7 @@ static void tcp_try_to_open(struct sock *sk, int flag)
 	if (inet_csk(sk)->icsk_ca_state != TCP_CA_CWR) {
 		int state = TCP_CA_Open;
 
-		if (tp->left_out || tp->retrans_out || tp->undo_marker)
+		if (tp->sacked_out || tp->retrans_out || tp->undo_marker)
 			state = TCP_CA_Disorder;
 
 		if (inet_csk(sk)->icsk_ca_state != state) {

net/ipv4/tcp_minisocks.c

@@ -405,7 +405,6 @@ struct sock *tcp_create_openreq_child(struct sock *sk, struct request_sock *req,
 		newicsk->icsk_rto = TCP_TIMEOUT_INIT;
 
 		newtp->packets_out = 0;
-		newtp->left_out = 0;
 		newtp->retrans_out = 0;
 		newtp->sacked_out = 0;
 		newtp->fackets_out = 0;

net/ipv4/tcp_output.c

@@ -732,10 +732,8 @@ int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, unsigned int mss
 		if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS)
 			tp->retrans_out -= diff;
 
-		if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) {
+		if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST)
 			tp->lost_out -= diff;
-			tp->left_out -= diff;
-		}
 
 		if (diff > 0) {
 			/* Adjust Reno SACK estimate. */
@@ -1727,15 +1725,11 @@ static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *skb, int m
 		TCP_SKB_CB(skb)->sacked |= TCP_SKB_CB(next_skb)->sacked&(TCPCB_EVER_RETRANS|TCPCB_AT_TAIL);
 		if (TCP_SKB_CB(next_skb)->sacked&TCPCB_SACKED_RETRANS)
 			tp->retrans_out -= tcp_skb_pcount(next_skb);
-		if (TCP_SKB_CB(next_skb)->sacked&TCPCB_LOST) {
+		if (TCP_SKB_CB(next_skb)->sacked&TCPCB_LOST)
 			tp->lost_out -= tcp_skb_pcount(next_skb);
-			tp->left_out -= tcp_skb_pcount(next_skb);
-		}
 		/* Reno case is special. Sigh... */
-		if (!tp->rx_opt.sack_ok && tp->sacked_out) {
+		if (!tp->rx_opt.sack_ok && tp->sacked_out)
 			tcp_dec_pcount_approx(&tp->sacked_out, next_skb);
-			tp->left_out -= tcp_skb_pcount(next_skb);
-		}
 
 		/* Not quite right: it can be > snd.fack, but
 		 * it is better to underestimate fackets.