tcp: fix stretch ACK bugs in Veno

Change Veno to properly handle stretch ACKs in additive
increase mode by passing in the count of ACKed packets
to tcp_cong_avoid_ai().

Signed-off-by: Pengcheng Yang <[e-mail]>
Acked-by: Neal Cardwell <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/ipv4/tcp_veno.c

···
 
 		if (tcp_in_slow_start(tp)) {
 			/* Slow start. */
-			tcp_slow_start(tp, acked);
-			goto done;
+			acked = tcp_slow_start(tp, acked);
+			if (!acked)
+				goto done;
 		}
 
 		/* Congestion avoidance. */
···
 			/* In the "non-congestive state", increase cwnd
 			 * every rtt.
 			 */
-			tcp_cong_avoid_ai(tp, tp->snd_cwnd, 1);
+			tcp_cong_avoid_ai(tp, tp->snd_cwnd, acked);
 		} else {
 			/* In the "congestive state", increase cwnd
 			 * every other rtt.
···
 					veno->inc = 1;
 				tp->snd_cwnd_cnt = 0;
 			} else
-				tp->snd_cwnd_cnt++;
+				tp->snd_cwnd_cnt += acked;
 		}
 done:
 		if (tp->snd_cwnd < 2)