[TCP]: Add tcp_left_out(tp) "back" to get cleaner looking lines

tp->left_out got removed but nothing came to replace it back
then (users just did addition by themselves), so add function
for users now.
Signed-off-by: NIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/net/tcp.h

@@ -719,6 +719,11 @@ static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
 		icsk->icsk_ca_ops->cwnd_event(sk, event);
 }
 
+static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
+{
+	return tp->sacked_out + tp->lost_out;
+}
+
 /* This determines how many packets are "in the network" to the best
  * of our knowledge.  In many cases it is conservative, but where
  * detailed information is available from the receiver (via SACK
@@ -735,8 +740,7 @@ 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->sacked_out + tp->lost_out) +
-		tp->retrans_out;
+	return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
 }
 
 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
@@ -756,8 +760,7 @@ static inline __u32 tcp_current_ssthresh(const struct sock *sk)
 
 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));
+	BUG_ON(tp->rx_opt.sack_ok && (tcp_left_out(tp) > tp->packets_out));
 }
 
 extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh);

net/ipv4/tcp_input.c

@@ -1969,7 +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->sacked_out + tp->lost_out,
+	       tp->snd_cwnd, tcp_left_out(tp),
 	       tp->snd_ssthresh, tp->prior_ssthresh,
 	       tp->packets_out);
 }