tcp: fix stretch ACK bugs in Yeah

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

In addition, we re-implemented the scalable path using
tcp_cong_avoid_ai() and removed the pkts_acked variable.

Signed-off-by: Pengcheng Yang <yangpc@wangsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/tcp_yeah.c b/net/ipv4/tcp_yeah.c
index e00570d..3bb4487 100644 (file)
--- a/net/ipv4/tcp_yeah.c
+++ b/net/ipv4/tcp_yeah.c
@@ -36,8 +36,6 @@ struct yeah {
 
        u32 reno_count;
        u32 fast_count;
-
-       u32 pkts_acked;
 };
 
 static void tcp_yeah_init(struct sock *sk)
@@ -57,18 +55,6 @@ static void tcp_yeah_init(struct sock *sk)
        tp->snd_cwnd_clamp = min_t(u32, tp->snd_cwnd_clamp, 0xffffffff/128);
 }
 
-static void tcp_yeah_pkts_acked(struct sock *sk,
-                               const struct ack_sample *sample)
-{
-       const struct inet_connection_sock *icsk = inet_csk(sk);
-       struct yeah *yeah = inet_csk_ca(sk);
-
-       if (icsk->icsk_ca_state == TCP_CA_Open)
-               yeah->pkts_acked = sample->pkts_acked;
-
-       tcp_vegas_pkts_acked(sk, sample);
-}
-
 static void tcp_yeah_cong_avoid(struct sock *sk, u32 ack, u32 acked)
 {
        struct tcp_sock *tp = tcp_sk(sk);
@@ -77,24 +63,19 @@ static void tcp_yeah_cong_avoid(struct sock *sk, u32 ack, u32 acked)
        if (!tcp_is_cwnd_limited(sk))
                return;
 
-       if (tcp_in_slow_start(tp))
-               tcp_slow_start(tp, acked);
+       if (tcp_in_slow_start(tp)) {
+               acked = tcp_slow_start(tp, acked);
+               if (!acked)
+                       goto do_vegas;
+       }
 
-       else if (!yeah->doing_reno_now) {
+       if (!yeah->doing_reno_now) {
                /* Scalable */
-
-               tp->snd_cwnd_cnt += yeah->pkts_acked;
-               if (tp->snd_cwnd_cnt > min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT)) {
-                       if (tp->snd_cwnd < tp->snd_cwnd_clamp)
-                               tp->snd_cwnd++;
-                       tp->snd_cwnd_cnt = 0;
-               }
-
-               yeah->pkts_acked = 1;
-
+               tcp_cong_avoid_ai(tp, min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT),
+                                 acked);
        } else {
                /* Reno */
-               tcp_cong_avoid_ai(tp, tp->snd_cwnd, 1);
+               tcp_cong_avoid_ai(tp, tp->snd_cwnd, acked);
        }
 
        /* The key players are v_vegas.beg_snd_una and v_beg_snd_nxt.
@@ -118,7 +99,7 @@ static void tcp_yeah_cong_avoid(struct sock *sk, u32 ack, u32 acked)
         * of bytes we send in an RTT is often less than our cwnd will allow.
         * So we keep track of our cwnd separately, in v_beg_snd_cwnd.
         */
-
+do_vegas:
        if (after(ack, yeah->vegas.beg_snd_nxt)) {
                /* We do the Vegas calculations only if we got enough RTT
                 * samples that we can be reasonably sure that we got
@@ -232,7 +213,7 @@ static struct tcp_congestion_ops tcp_yeah __read_mostly = {
        .set_state      = tcp_vegas_state,
        .cwnd_event     = tcp_vegas_cwnd_event,
        .get_info       = tcp_vegas_get_info,
-       .pkts_acked     = tcp_yeah_pkts_acked,
+       .pkts_acked     = tcp_vegas_pkts_acked,
 
        .owner          = THIS_MODULE,
        .name           = "yeah",