1 files changed, 20 insertions, 12 deletions

diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
index 27ead0dd16bc..8670e68e2ce6 100644
--- a/net/ipv4/tcp_cong.c
+++ b/net/ipv4/tcp_cong.c
@@ -291,26 +291,32 @@ int tcp_set_congestion_control(struct sock *sk, const char *name)
  * ABC caps N to 2. Slow start exits when cwnd grows over ssthresh and
  * returns the leftover acks to adjust cwnd in congestion avoidance mode.
  */
-void tcp_slow_start(struct tcp_sock *tp, u32 acked)
+u32 tcp_slow_start(struct tcp_sock *tp, u32 acked)
 {
         u32 cwnd = tp->snd_cwnd + acked;
 
         if (cwnd > tp->snd_ssthresh)
                 cwnd = tp->snd_ssthresh + 1;
+        acked -= cwnd - tp->snd_cwnd;
         tp->snd_cwnd = min(cwnd, tp->snd_cwnd_clamp);
+
+        return acked;
 }
 EXPORT_SYMBOL_GPL(tcp_slow_start);
 
-/* In theory this is tp->snd_cwnd += 1 / tp->snd_cwnd (or alternative w) */
-void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 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++;
+                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);
 
@@ -329,11 +335,13 @@ void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked)
                 return;
 
         /* In "safe" area, increase. */
-        if (tp->snd_cwnd <= tp->snd_ssthresh)
-                tcp_slow_start(tp, acked);
+        if (tp->snd_cwnd <= tp->snd_ssthresh) {
+                acked = tcp_slow_start(tp, acked);
+                if (!acked)
+                        return;
+        }
         /* In dangerous area, increase slowly. */
-        else
-                tcp_cong_avoid_ai(tp, tp->snd_cwnd);
+        tcp_cong_avoid_ai(tp, tp->snd_cwnd, acked);
 }
 EXPORT_SYMBOL_GPL(tcp_reno_cong_avoid);