tcp: fix the timid additive increase on stretch ACKs

[deliverable/linux.git] / net / ipv4 / tcp_cong.c

diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
index 6826017c12d1e38bd0cd7301f369fb33ebd3dbd0..faaee5338beac17c64389b2dc2998ad43fcd5436 100644 (file)
--- a/net/ipv4/tcp_cong.c
+++ b/net/ipv4/tcp_cong.c
@@ -304,16 +304,19 @@ u32 tcp_slow_start(struct tcp_sock *tp, u32 acked)
 }
 EXPORT_SYMBOL_GPL(tcp_slow_start);
 
-/* In theory this is tp->snd_cwnd += 1 / tp->snd_cwnd (or alternative w) */
+/* In theory this is tp->snd_cwnd += 1 / tp->snd_cwnd (or alternative w),
+ * for every packet that was ACKed.
+ */
 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked)
 {
+       tp->snd_cwnd_cnt += acked;
        if (tp->snd_cwnd_cnt >= w) {
-               if (tp->snd_cwnd < tp->snd_cwnd_clamp)
-                       tp->snd_cwnd++;
-               tp->snd_cwnd_cnt = 0;
-       } else {
-               tp->snd_cwnd_cnt += acked;
+               u32 delta = tp->snd_cwnd_cnt / w;
+
+               tp->snd_cwnd_cnt -= delta * w;
+               tp->snd_cwnd += delta;
        }
+       tp->snd_cwnd = min(tp->snd_cwnd, tp->snd_cwnd_clamp);
 }
 EXPORT_SYMBOL_GPL(tcp_cong_avoid_ai);